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Judging by the millions of reviews left by guests on the Airbnb platform, this "trusted community marketplace" is fulfilling its mission of matching travelers seeking accommodation with hosts who have room to spare remarkably well. Based on our analysis of ratings we collected for over 600,000 properties listed on Airbnb worldwide, we find that nearly 95% of Airbnb properties boast an average user-generated rating of either 4.5 or 5 stars (the maximum); virtually none have less than a 3.5 star rating. We contrast this with the ratings of approximately half a million hotels worldwide that we collected on TripAdvisor, where there is a much lower average rating of 3.8 stars, and more variance across reviews. Considering properties by accommodation type and by location, we find considerable variability in ratings, and observe that vacation rental properties on TripAdvisor have ratings most similar to ratings of Airbnb properties. Last, we consider several thousand properties that are listed on both platforms. For these cross-listed properties, we find that even though the average ratings on Airbnb and TripAdvisor are similar, proportionally more properties receive the highest ratings (4.5 stars and above) on Airbnb than on TripAdvisor. Moreover, there is only weak correlation in the ratings of individual cross-listed properties across the two platforms. Our work is a first step towards understanding and interpreting nuances of user-generated ratings in the context of the sharing economy.

The problem of optimizing social welfare objectives on multi-sided ride-hailing platforms such as Uber, Lyft, etc., is challenging, due to misalignment of objectives between drivers, passengers, and the platform itself. An ideal solution aims to minimize the response time for each hyperlocal passenger ride request, while simultaneously maintaining high demand satisfaction and supply utilization across the entire city. Economists tend to rely on dynamic pricing mechanisms that stifle price-sensitive excess demand and resolve supply-demand imbalances that emerge in specific neighborhoods. In contrast, computer scientists primarily view it as a demand prediction problem with the goal of preemptively repositioning supply to such neighborhoods using black-box coordinated multi-agent deep reinforcement learning-based approaches. Here, we introduce explainability in the existing supply-repositioning approaches by establishing the need for coordination between the drivers at specific locations and times. Explicit need-based coordination allows our framework to use a simpler non-deep reinforcement learning-based approach, thereby enabling it to explain its recommendations ex-post. Moreover, it provides envy-free recommendations i.e., drivers at the same location and time do not envy one another’s expected future earnings. Our experimental evaluation demonstrates the effectiveness, robustness, and generalizability of our framework. Finally, in contrast to previous works, we make available a reinforcement learning environment for end-to-end reproducibility of our work and to encourage future comparative studies.

Conservation biological control is a fundamental tactic in integrated pest management (IPM). Greater biological control services can be achieved by enhancing agroecosystems to be more favorable to the presence, survival, and growth of natural enemy populations. One approach that has been tested in numerous agricultural systems is the deployment of synthetic chemicals that mimic those produced by the plant when under attack by pests. These signals may attract arthropod natural enemies to crop habitats and thus potentially improve biological control activity locally. A 2-yr field study was conducted in the cotton agroecosystem to evaluate the potential of synthetic methyl salicylate (MeSA) to attract native arthropod natural enemies and to enhance biological control services on two key pests. Slow-release packets of MeSA were deployed in replicated cotton plots season long. The abundance of multiple taxa of natural enemies and two major pests were monitored weekly by several sampling methods. The deployment of MeSA failed to increase natural enemy abundance and pest densities did not decline. Predator to prey ratios, used as a proxy to estimate biological control function, also largely failed to increase with MeSA deployment. One exception was a season-long increase in the ratio of Orius tristicolor (White) (Hemiptera: Anthocoridae) to Bemisia argentifolii Bellows and Perring (= Bemisia tabaci MEAM1) (Hemiptera: Aleyrodidae) adults within the context of biological control informed action thresholds. Overall results suggest that MeSA would not likely enhance conservation biological control by the natural enemy community typical of U.S. western cotton production systems.

Euwallacea fornicatus (Eichhoff), the polyphagous shot hole borer (PSHB), is an ambrosia beetle infesting avocado Persea americana Mill. limbs in North America and Israel. We conducted field experiments with sticky traps in avocado orchards to develop push–pull semiochemical methods of managing PSHB. Traps baited with 10-fold increasing doses (0.01 to 100× or 1.26 µg to 12.6 mg/d) of attractant quercivorol were previously shown to increasingly capture female PSHB (males flightless). We converted trap catch of this relationship to a standardized effective attraction radius (EAR) that predicts capture power of baited-traps regardless of insect flight density. Earlier, piperitone and verbenone were shown to strongly inhibit attraction of PSHB to quercivorol-traps. We tested increasing numbers of 1× piperitone dispensers at 0.75-m distance surrounding a quercivorol-trap and found PSHB catch to decline exponentially. Increasing decadic doses (0.01 to 10×) of either verbenone or piperitone released at 1× quercivorol-traps caused a sigmoidal first-order kinetic-decay in catch. Verbenone (1×) placed at increasing distances (0, 0.25, 0.5, 1, and 2 m) from a 1× quercivorol-trap became increasingly ineffective in reducing catch of PSHB. We found no evidence that ethanol released from 7.5 to 480 mg/d affected attraction of PSHB, but Scobicia chevrieri (Villa and Villa) (Coleoptera: Bostrichidae) was increasingly attracted. Due to their relatively short-range (

We revisit the long-standing problem of providing network QoS to applications, and propose the concept of judicious QoS -- combining the cheaper, best effort IP service with the cloud, which offers a highly reliable infrastructure and the ability to add in-network services, albeit at higher cost. Our proposed J-QoS framework offers a range of reliability services with different cost vs. delay trade-offs, including: i) a forwarding service that forwards packets over the cloud overlay, ii) a caching service, which stores packets inside the cloud and allows them to be pulled in case of packet loss or disruption on the Internet, and iii) a novel coding service that provides the least expensive packet recovery option by combining packets of multiple application streams and sending a small number of coded packets across the more expensive cloud paths. We demonstrate the feasibility of these services using measurements from RIPE Atlas and a live deployment on PlanetLab. We also consider case studies on how J-QoS works with services up and down the network stack, including Skype video conferencing, TCP-based web transfers, and cellular access networks., Compared to the previous version, we have made a number of changes, including new experiments on RIPE ATLAS testbed to evaluate the feasibility of our services, discussion on end-to-end working of the system, and several other changes in writing to clarify ambiguities in design or positioning of the work. arXiv admin note: substantial text overlap with arXiv:1812.10835

After a bottleneck in a closed population of pronghorn (Antilocapra americana), some inbred matings occurred, and we detected significant inbreeding depression. But inbred matings occurred less frequently than would be expected by chance. Pronghorn females chose mates after a sampling period and had complete control of the mating decision. Therefore, to discover the behavioral mechanism by which females avoided mating with close kin, we studied female movements and courtship sequences. When females moved from one harem to another in the sampling process, they did not shift to harem males of lower coancestry as they approached estrus. Rather, females progressed more slowly through the later courtship stages when the harem male was related vs. unrelated. Also, the rates of male courtship acts were higher within unrelated vs. related pairs. Some females appeared to use multiple mating as an inbreeding avoidance strategy. Our results suggested that inbreeding avoidance by female pronghorn occurred primarily by reactions to the late stages of male courtship, rather than by spatial avoidance of related males.

The Trivers–Willard hypothesis (TWH) predicts that in a polygynous mating system, when fitness of male offspring is more variable than fitness of female offspring, mothers should invest more heavily in the sex with the highest marginal fitness returns. Females in good condition or high social rank should benefit by investing in sons, and females in poor condition or low social rank should benefit by investing in daughters. Many empirical studies have tested different aspects of the TWH, but no study has tested the assumptions and predictions in a single polygynous species using measures of maternal condition and maternal social rank, while accounting for random effects that can also influence offspring growth and survival. Here, we followed individuals in an isolated population of pronghorn on the National Bison Range, Montana, over multiple generations and tested the assumptions and predictions of the TWH. Pronghorn females who were in good condition or were socially dominant weaned larger fawns that were in better condition, but this advantage did not increase male fawn survival or reproductive success. We detected a slight bias in birth sex ratios according to maternal social rank, but overall we did not detect any adaptive benefit to mothers adopting a sex-biased investment strategy.

Passive mechanisms of mate guarding are used by males to promote sperm precedence with little cost, but these tactics can be disadvantageous for their mates and other males. Mated females of the plant bug Lygus hesperus are rendered temporarily unattractive by seminal fluids containing myristyl acetate and geranylgeranyl acetate. These antiaphrodisiac pheromones are gradually released from the female’s gonopore, declining until they no longer suppress male courtship. Because starting quantities of these compounds can vary widely, the repellant signal becomes less reliable over time. Evidence was found of a complimentary mechanism that more accurately conveys female mating status. Once inside the female, geranylgeranyl acetate is progressively converted to geranylgeraniol then externalized. Geranylgeraniol counteracts the antiaphrodisiac effect despite having no inherent attractant properties of its own. This is the first evidence for such an anti-antiaphrodisiac pheromone, adding a new element to the communication mechanisms regulating reproductive behaviors. DOI: http://dx.doi.org/10.7554/eLife.24063.001, eLife digest In many animal species, males guard females to prevent rivals from mating so that they can be sure that they fathered the female’s offspring. Some guarding methods work even when the male is not present. For example, the semen of some male insects contains chemicals known as antiaphrodisiacs that repel other males from females who have recently mated. Over the course of several days or weeks, the females expel or degrade the antiaphrodisiacs, making themselves attractive to other mates again. How long it takes to eliminate the antiaphrodisiacs depends on how much of the chemicals were deposited in the first place. Therefore, males could gain an advantage in fertilizing more eggs by depositing excess antiaphrodisiac to make the females unattractive to other mates for a long time. The Western tarnished plant bug (Lygus hesperus) is an agricultural pest that targets cotton, strawberries and other crops. One antiaphrodisac had already been identified in the semen of male Lygus bugs. To investigate whether the males produced any others, Brent et al. tested the molecules emitted by recently mated females. This search identified another potential antiaphrodisiac. However, females are able to convert this second chemical into a third one that neither attracts nor repels males. This “anti-antiaphrodisiac” acts against the males’ two antiaphrodisiacs, and allows the females to more accurately signal when they are ready to mate again, giving them more control over their reproduction. Anti-antiaphrodisiacs were not previously known to exist, but now that scientists know where to look, more are likely to be found in other species. A better understanding of how different chemicals interact to influence the mating behavior of insects could also lead to new methods of targeting pests of crops, which are safer for the environment than existing chemical pesticides. DOI: http://dx.doi.org/10.7554/eLife.24063.002

Phenotypic plasticity in reproductive traits is of theoretical and applied interest as one avenue by which organisms might maintain an optimal annual reproductive routine in the face of cyclic and/or directional change in environmental conditions. We used long‐term, individual‐based data from parapatric populations of bighorn sheep (Ovis canadensis canadensis) and pronghorn (Antilocapra americana) to evaluate plasticity in breeding date, gestation duration, birth date, birth mass, and fetal growth rate in response to inter‐annual (cyclic) variation in indices of maternal energy income and expense. Traits in both species responded plastically to variation in maternal energy balance. However, despite nearly identical climate and similar vegetative habitat, plasticity was expressed in fundamentally different ways in the study species. Variation in bighorn birth date was primarily due to plasticity in breeding date, whereas variation in pronghorn birth date was primarily due to variation in gestation duration. Across traits, bighorn plastic responses were more consistent with explanations that invoked periodic energy surplus as the basis for plasticity, whereas pronghorn plastic responses were more consistent with explanations that invoked periodic energy deficiency. Later birth date was associated with increased fetal growth rate in bighorn but decreased fetal growth rate in pronghorn. Finally, we detected strong directional selection for early birth among bighorn mothers but found no evidence of selection on pronghorn birth date. Collectively, our results indicate markedly different maternal tactics for timing birth. Bighorn mothers appeared to use stored energy to subsidize the cost of birth prior to the local environmental optimum in an energy‐mediated competition with other females to minimize birth order rank. Pronghorn mothers, committed to high levels of energy allocation to offspring and subject therefore to frequent energy deficiency, timed birth conservatively to more closely match peak reproductive expenditure with peak energy income at the local environmental optimum.

Dose-response curves of the effects of semioche- micals on neurophysiology and behavior are reported in many articles in insect chemical ecology. Most curves are shown in figures representing points connected by straight lines, in which the x-axis has order of magnitude increases in dosage vs. responses on the y-axis. The lack of regression curves indicates that the nature of the dose-response relationship is not well understood. Thus, a computer model was developed tosimulateafluxofvariousnumbersofpheromonemolecules (10 3 to 5×10 6 ) passing by 10 4 receptors distributed among 10 6 positions along an insect antenna. Each receptor was depolarized by at least one strike by a molecule, and subse- quent strikeshad noadditionaleffect.Thesimulationsshowed that with an increase in pheromone release rate, the antennal response would increase in a convex fashion and not in a logarithmic relation as suggested previously. Non-linear re- gression showed that a family of kinetic formation functions fit the simulated data nearly perfectly (R 2 >0.999). This is reasonable because olfactory receptors have proteins that bind to the pheromone molecule and are expected to exhibit en- zyme kinetics. Over 90 dose-response relationships reported in the literature of electroantennographic and behavioral bio- assays in the laboratory and field were analyzed by the loga- rithmic and kinetic formation functions. This analysis showed that in 95 % of the cases, the kinetic functions explained the relationships better than the logarithmic (mean of about 20 % better). The kinetic curves become sigmoid when graphed on a log scale on the x-axis. Dose-catch relationships in the field are similar todose-EAR(effectiveattractionradius,inwhicha spherical radius indicates the trapping effect of a lure) and the circular EARc in two dimensions used in mass trapping models. The use of kinetic formation functions for dose- response curves of attractants, and kinetic decay curves for inhibitors, will allow more accurate predictions of insect catch in monitoring and control programs.

Acute otitis media with tympanostomy tubes (AOMT) in children commonly presents with otorrhea and negatively affects their daily activities.To evaluate the efficacy and safety of topical ciprofloxacin, 0.3%, plus fluocinolone acetonide, 0.025%, otic solution relative to ciprofloxacin, 0.3%, otic solution alone and fluocinolone acetonide, 0.025%, otic solution alone in the treatment of AOMT in children.Two twin multicenter, randomized, double-blind clinical trials with identical designs were conducted from June 24, 2011, through June 23, 2014, at ear, nose, and throat pediatric practices, general practices, hospitals, and clinical research centers. The study population comprised 662 children (331 in each trial) with AOMT in at least 1 ear who presented with moderate or severe purulent otorrhea for 3 weeks or less. Data analyses were performed on an intention-to-treat basis.Patients were randomly assigned to receive ciprofloxacin plus fluocinolone, ciprofloxacin alone, or fluocinolone alone twice daily for 7 days and were evaluated on days 1 (baseline), 3 to 5 (undergoing therapy), 8 to 10 (end of therapy), and 18 to 22 (test of cure).The primary efficacy measure was time to cessation of otorrhea. The principal secondary end point was sustained microbiological cure, defined as eradication or presumed eradication at end-of-therapy and test-of-cure visits.A total of 662 children participating in the 2 studies were randomized to receive ciprofloxacin plus fluocinolone (n = 223), ciprofloxacin alone (n = 221), or fluocinolone alone (n = 218). The median age was 2.5 years (range, 0.6-12.7 years). The median time to cessation of otorrhea was 4.23 days (95% CI, 3.65-4.95 days) in patients receiving ciprofloxacin plus fluocinolone compared with 6.95 days (95% CI, 5.66-8.20 days) in those receiving ciprofloxacin and not estimable findings in those receiving fluocinolone alone (P .001). The clinical cure rate at the test-of-cure visit was 80.6% in the ciprofloxacin plus fluocinolone group, 67.4% in the ciprofloxacin group (difference, 13.2%; 95% CI, 5.0%-21.4%; P = .002), and 47.6% in the fluocinolone group (difference, 33.0%; 95% CI, 24.0%-42.0%; P .001). The sustained microbiological cure rate was 79.7% in the ciprofloxacin plus fluocinolone group vs 67.7% in the ciprofloxacin group (difference, 12.0%; 95% CI, 0.8%-23.0%; P = .04) and 37.6% in the fluocinolone group (difference, 42.1%; 95% CI, 29.3%-54.8%; P .001). Only 7 (3.1%) of the patients receiving ciprofloxacin plus fluocinolone, 8 (3.6%) of the patients receiving ciprofloxacin, and 10 (4.7%) of the patients receiving fluocinolone presented with adverse events related to study medication.The combination of ciprofloxacin plus fluocinolone is more effective than treatment with ciprofloxacin or fluocinolone alone for AOMT, and it is safe and well tolerated in children.clinicaltrials.gov Identifiers: NCT01395966 and NCT01404611.

Plants release volatiles in response to caterpillar feeding that attract natural enemies of the herbivores, a tri-trophic interaction which has been considered an indirect plant defence against herbivores. The caterpillar-induced plant volatiles have been reported to repel or attract conspecific adult herbivores. To date however, no volatile signals that either repel or attract conspecific adults under field conditions have been chemically identified. Apple seedlings uniquely released seven compounds including acetic acid, acetic anhydride, benzyl alcohol, benzyl nitrile, indole, 2-phenylethanol, and (E)-nerolidol only when infested by larvae of the light brown apple moth, Epiphyas postvittana. In field tests in New Zealand, a blend of two of these, benzyl nitrile and acetic acid, attracted a large number of conspecific male and female adult moths. In North America, male and female adults of the tortricid, oblique-banded leafroller, Choristoneura rosaceana, were most attracted to a blend of 2-phenylethanol and acetic acid. Both sexes of the eye-spotted bud moth, Spilonota ocellana, were highly attracted to a blend of benzyl nitrile and acetic acid. This study provides the first identification of caterpillar-induced plant volatiles that attract conspecific adult herbivores under natural conditions, challenging the expectation of herbivore avoidance of these induced volatiles.

Insect-pollinated carnivorous plants are expected to have higher fitness if they resolve pollinator-prey conflicts by sparing insects pollinating their flowers while trapping prey insects. We examined whether separation between flowers and traps of the carnivorous sundew species or pollinator preferences for colours of flowers enable these plants to spare pollinators. In addition, we collected odours from flowers and traps of each carnivorous species in order to identify volatile chemicals that are attractive or repellent to pollinators and prey insects. In Drosera spatulata and D. arcturi, no volatiles were detected from either their flowers or traps that could serve as kairomone attractants for insects. However, behavioural experiments indicated white colour and spatial separation between flowers and traps aid in reducing pollinator entrapment while capturing prey. In contrast, D. auriculata have flowers that are adjacent to their traps. In this species we identified chemical signals emanating from flowers that comprised an eight-component blend, while the plant’s traps emitted a unique four-component blend. The floral odour attracted both pollinator and prey insects, while trap odour only attracted prey. This is the first scientific report to demonstrate that carnivorous plants utilize visual, spatial and chemical signals to spare flower visitors while trapping prey insects.

Simulation models of insects encountering sex pheromone with or without mass trapping in which the searching sex is either male (moths and many insect species) or female (some true bugs, beetles, and flies) were developed. The searching sex moved as a correlated random walk, while the opposite sex remained stationary (calling) and released an attractive sex pheromone. The searching sex was caught when encountering a pheromone-baited trap, and females mated when encountering a male. Anencounterwith pheromone was defined by the searcher’s interceptionofa circletermedtheeffective attraction radius (EARc). Parameters of movement (speed and duration), initial numbers of calling sex and searching sex, number of traps, area, and EARc of traps and calling sex were varied individually to evaluate effects on the percentage of females mating. In the natural condition without traps, female mating success in both models was identical. Increasing the EARc of the calling sex caused diminishing increases in female mating success, suggesting that evolution of larger pheromone release and EARc is limited by increasing costs (production/sensitivity) relative to diminishing increases and benefits of mating encounters. With mass trapping, increasing the EARc of traps or density of traps caused similar declines in female mating in both models, but the female-searching modelpredictedslightlylower matingsuccess thanthe male-searching model. Increasingthe EARcof calling insects or the initial density of insects caused similar increases in female mating in both models, but again the female-searching model had slightly lower mating success than the malesearching model. The models have implications for mating lek formation and for understanding the variables affecting the success of mass trapping programs for insect pests with either male or female sex pheromones.

The existence of a direct link between intensity of sexual selection and mating-system type is widely accepted. However, the quantification of sexual selection has proven problematic. Several measures of sexual selection have been proposed, including the operational sex ratio (OSR), the breeding sex ratio (BSR), and the opportunity for sexual selection (I(mates)). For a wild population of pronghorn (Antilocapra americana), we calculated OSR and BSR. We estimated I(mates) from census data on the spatial and temporal distribution of receptive females in rut and from a multigenerational genetic pedigree. OSR and BSR indicated weak sexual selection on males, but census and pedigree I(mates) suggested stronger sexual selection on males than on females. OSR and BSR correlated with census but not pedigree estimates of I(mates), and census I(mates) did not correlate with pedigree estimates. This suggests that the behavioral mating system, as deduced from the spatial and temporal distribution of females, does not predict the genetic mating system of pronghorn. The differences we observed between estimators were primarily due to female mate sampling and choice and to the sex ratio. For most species, behavioral data are not perfectly accurate and therefore will be an insufficient alternative to using multigenerational pedigrees to quantify sexual selection.

Spring and summer-autumn nutrition are the prime determinants of reproductive investment in most largeherbivore populations, though winter severity is known to affect reproductive rates in some situations. To evaluate the effects of a long-term decline in winter habitat quality, a diet shift away from sagebrush (Artemisia spp.) during winter, and differential habitat selection during spring-autumn on pronghorn (Antilocapra americana) reproduction, we assessed female and fawn condition, maternal investment, and early fawn survival in migrant and nonmigrant portions of the Yellowstone pronghorn population in Montana and Wyoming during 1999–2001. Mean female mass at capture in late winter (46.81 kg, SE = 0.66), pregnancy rate (0.94, SE = 0.03), date of birthing (median = 1 June), litter size (1.90, SE = 0.07), ratio of litter mass to maternal mass (0.134, SE = 0.005), fawn mass at birth (3.08 kg, SE = 0.07), and fawn survival to August (0.15, SE = 0.04) were within the ranges reported for populatio...

In an n-way broadcast application, each one of n overlay nodes wants to push its own distinct large data file to all other n-1 destinations as well as download their respective data files. BitTorrent-like swarming protocols are ideal choices for handling such massive data volume transfers. The original BitTorrent targets one-to-many broadcasts of a single file to a very large number of receivers, and thus, by necessity, employs a suboptimized overlay topology. n-way broadcast applications, on the other hand, owing to their inherent complexity, are realizable only in small to medium scale networks. In this paper, we show that we can leverage this scale constraint to construct optimized overlay topologies that take into consideration the end-to-end characteristics of the network and as a consequence deliver far superior performance compared to random and myopic (greedy) approaches. We present the Max-Min and Max-Sum peer-selection policies used by individual nodes to select their neighbors. The first one strives to maximize the available bandwidth to the slowest destination, while the second maximizes the aggregate output rate. We design a swarming protocol suitable for n-way broadcast and operate it on top of overlay graphs formed by nodes that employ Max-Min or Max-Sum policies. Using measurements from a PlanetLab prototype implementation and trace-driven simulations, we demonstrate that the performance of swarming protocols on top of our constructed topologies is far superior to the performance of random and myopic overlays.

Mitigation of predation risk promotes high-elevation dispersion prior to birthing in many ungulate populations. Coyotes (Canis latrans) account for nearly 80% of pronghorn (Antilocapra americana) fawn mortality in Yellowstone National Park, but reintroduced gray wolves (Canis lupus) and factors associated with mountainous terrain can strongly influence space use by predators during summer and are likely to underlie significant spatial variation in survival rates of pronghorn fawns. We used generalized logit models paneled by maternal identity to assess the relative and interactive influences of summer wolf density, winter snow depth, and terrain slope on survival of pronghorn fawns in Yellowstone during 1999–2001 and 2004–2006. In this partially migratory population only migrant pronghorn accessed areas where wolves were numerous and winter snow depths were high. Survival of migrant fawns was higher in areas that experienced deep winter snow and had steeper slope. The influence of wolves on fawn survival was positive only in areas of low winter snowfall where coyotes were abundant, supporting predictions of a coyote-mediated effect of wolves and winter snowfall on pronghorn reproductive success. Our results suggest that deep winter snow, coupled with constraints on mobility imposed by reproduction in populations of social carnivores, can lead to the formation of highelevation refugia for migrant ungulates. This research offers novel insights into the indirect effects of wolf restoration and climatic factors on the Yellowstone predator–prey complex and a conceptual framework for examining the ecological effects in other mountain communities of restoration of, and seasonal space use by, large carnivores. DOI: 10.1644/09-MAMM-A-057.1.

Yellowstone National Park supports a small population (

A new type of dispenser for slow-release of sex pheromones and other semiochemicals was developed based on sol-gel polymers that can be useful for moni- toring, mass trapping, and mating disruption in integrated pest management (IPM). Sol-gel matrices exhibit glass characteristics and allow control of the degree of cross- linking during the polymerization process in order to pro- vide an optimal release rate for a particular pheromone. The advantages of sol-gel (silica) matrixes include keeping the added molecules chemically stable and enabling the sol-gel material to be applied in any desired thickness and pheromone quantity, and thereby readily modify release rates. In addition, sol-gels are primarily silica and water that are common in the environment and therefore safe for field dispensing. We developed a method for the entrap- ment of pheromones in sol-gel matrices that allowed release at an almost constant rate over many days in the field. For example, 2.5 mg (E)-5-decenyl acetate phero- mone of peach twig borer, Anarsia lineatella, entrapped in various sol-gel formulations released 14-45 lg/day for up to 28 days. The codling moth (Cydia pomonella) phero- mone in sol-gels was used in field tests to capture more codling moth males than unbaited control traps. We describe how the method may be modified to entrap other types of pheromones by making sol-gels with different pore sizes.

Accurate measurement of network bandwidth is important for network management applications as well as flexible Internet applications and protocols which actively manage and dynamically adapt to changing utilization of network resources. Extensive work has focused on two approaches to measuring bandwidth: measuring it hop-by-hop, and measuring it end-to-end along a path. Unfortunately, best-practice techniques for the former are inefficient and techniques for the latter are only able to observe bottlenecks visible at end-to-end scope. In this paper, we develop end-to-end probing methods which can measure bottleneck capacity bandwidth along arbitrary, targeted subpaths of a path in the network, including subpaths shared by a set of flows. We evaluate our technique through ns simulations, then provide a comparative Internet performance evaluation against hop-by-hop and end-to-end techniques. We also describe a number of applications which we foresee as standing to benefit from solutions to this problem, ranging from network troubleshooting and capacity provisioning to optimizing the layout of application-level overlay networks, to optimized replica placement.

The long-term viability of small, isolated populations has been questioned in light of stochasticity and bottlenecks. Following a drought in northwestern Montana in 2003, the pronghorn (Antilocapra americana )o f the National Bison Range experienced a demographic bottleneck. We used information theoretic approaches to examine the influence of sex, age, genetic variation, summer lactation, mate-search effort by females, and mating effort by males on subsequent winter survival and spring fecundity. Survival of males was influenced by age, whereas survival of females was influenced by prior energy expenditure and genetic variation, implicating inbreeding depression as the mechanism. Fecundity of females also was influenced by prior energy expenditure and genetic variation, with heterosis as the apparent mechanism. Our results agree with those of other studies that have emphasized the need to maintain genetic variation and limit inbreeding in small, isolated populations, and to account for stochasticity in population viability assessments and long-term management planning.

The release rate of a semiochemical lure that attracts flying insects has a specific effective attraction radius (EAR) that corresponds to the lure's orientation response strength. EAR is defined as the radius of a passive sphere that intercepts the same number of insects as a semiochemical-baited trap. It is estimated by calculating the ratio of trap catches in the field in baited and unbaited traps and the interception area of the unbaited trap. EAR serves as a standardized method for comparing the attractive strengths of lures that is independent of population density. In two-dimensional encounter rate models that are used to describe insect mass trapping and mating disruption, a circular EAR (EAR(c)) describes a key parameter that affects catch or influence by pheromone in the models. However, the spherical EAR, as measured in the field, should be transformed to an EAR(c) for appropriate predictions in such models. The EAR(c) is calculated as (pi/2EAR(2))/F (L), where F (L) is the effective thickness of the flight layer where the insect searches. F (L) was estimated from catches of insects (42 species in the orders Coleoptera, Lepidoptera, Diptera, Hemiptera, and Thysanoptera) on traps at various heights as reported in the literature. The EAR(c) was proposed further as a simple but equivalent alternative to simulations of highly complex active-space plumes with variable response surfaces that have proven exceedingly difficult to quantify in nature. This hypothesis was explored in simulations where flying insects, represented as coordinate points, moved about in a correlated random walk in an area that contained a pheromone plume, represented as a sector of active space composed of a capture probability surface of variable complexity. In this plume model, catch was monitored at a constant density of flying insects and then compared to simulations in which a circular EAR(c) was enlarged until an equivalent rate was caught. This demonstrated that there is a circular EAR(c), where all insects that enter are caught, which corresponds in catch effect to any plume. Thus, the EAR(c), based on the field-observed EAR, can be used in encounter rate models to develop effective control programs based on mass trapping and/or mating disruption.

Both sexes of adult western tarnished plant bug, Lygus hesperus Knight (Heteroptera: Miridae), released three volatile chemicals in relatively large amounts when attacked by ants (Pogonomyrmex rugosus and Solenopsis xyloni) or when grabbed by forceps, as determined by solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS). The relative amounts of the volatile compounds, hexyl butyrate, (E)-4-oxo-2-hexenal, and (E)-2-hexenyl butyrate, absorbed by SPME as a percentage of the largest were 100%, 44%, and 4%, respectively, from females, and 83%, 37%, and 3% from males. Both ant species were repelled by the defensive discharges (confirmed by SPME) when the ants attacked L. hesperus adults. Sexually mature L. hesperus were individually extracted in pentane to quantify the mean amounts of hexyl butyrate (14.9 microg/female; 10.3 microg/male), (E)-4-oxo-2-hexenal (2.7 microg/female; 3.1 microg/male), and (E)-2-hexenyl butyrate (1.2 microg/female; 0.6 microg/male). (E)-4-Oxo-2-hexenal was unstable in solvent when in contact with a macerated adult, but relatively stable when the solution was decanted within minutes. The production of the three major volatile components began soon after the emergence of the adult and amounts increased for about 5-10 d with little or no increase thereafter. Minor additional constituents were cross-correlated in many cases with the three major ones. A cost of defensive secretion is suggested for females but not for males, because heavier females produced more volatile compounds than lighter females. The initial discharge percentage, defined as the proportion of volatile compounds initially present that is discharged to defend against predation was estimated at about 50% in males and 70% in females. Newly eclosed adults did not produce volatile chemicals until 2 d after molting.

Although a variety of species exhibit birth-site fidelity, examples from ungulate species are rare. We recorded birth-site locations of pronghorns (Antilocapra americana) at the National Bison Range in northwestern Montana during 2000–2004 and found that 82% of females changed locations from the previous year. Females that exhibited birth-site fidelity had successfully weaned more fawns and were less likely to have experienced a fawn mortality event in the previous year than females that changed birth sites. Females that weaned a single fawn or weaned 0 fawns were equally likely to change birth sites. There was a year effect on distribution of birth sites as well as on birth-site fidelity. Dry range conditions in 2003 after multiple years of low precipitation may have caused more females to move their birth sites to areas of greater forage availability. The low observed frequency of birth-site fidelity may be a result of high fawn mortality rates at the National Bison Range. Success in the previo...

Summary 1 The Pherolist internet site listing moth sex pheromone components reported in the literature was downloaded and processed by a basic program into a database with 2931 combinations of 377 unique chemical names of sex pheromone attractants used by 1572 moth species in 619 genera and 49 families. Names of pheromone compounds were analysed for aliphatic chain length, unsaturation position, geometric configuration, functional group (aldehyde, alcohol, acetate, epoxide, methyl-branched and hydrocarbon) and number of instances such combinations are used by species and families. 2 The analyses revealed pheromone blends of species ranged from one to eight components (45% species with one component, 36% two, 12% three, 5% four, 1% five, ≤ 0·5% for ≥ six). The numbers of different components of various chain lengths and functional groups, the numbers of instances such compounds are used by species and the numbers of species using such compounds are presented. 3 The average number of pheromone components per species increased as the number of species in a family increased based on linear regression of components in the 10 largest families, with species numbers ranging from 19 to 461. Pooling the four largest families gave a mean of 1·96 components per species that was significantly greater than the mean of the next 14 smaller families (1·63). Because related species in a large family would need more communication channels, this suggests that these species on average evolved to produce and detect more components in their pheromone blends to achieve a unique communication channel than was needed by species in smaller families. 4 Speciation in moths would entail evolutionary changes in both pheromone biosynthetic and sensory systems that avoided competition for communication channels of existing species. Regression analysis indicated that the more species in a family the more unique pheromone components, but the increase diminishes progressively. This suggests that, as the number of components increases with species number in a family, new species are more likely to evolve a unique blend comprising a communication channel from among existing components of the family.

A significant impediment to deployment of multicast services is the daunting technical complexity of developing, testing and validating congestion control protocols fit for wide-area deployment. Protocols such as pragmatic general multicast congestion control (pgmcc) and TCP-friendly multicast congestion control (TFMCC) have recently made considerable progress on the single rate case, i.e., where one dynamic reception rate is maintained for all receivers in the session. However, these protocols have limited applicability, since scaling to session sizes beyond tens of participants with heterogeneous available bandwidth necessitates the use of multiple rate protocols. Unfortunately, while existing multiple rate protocols exhibit better scalability, they are both less mature than single rate protocols and suffer from high complexity. We propose a new approach to multiple rate congestion control that leverages proven single rate congestion control methods by orchestrating an ensemble of independently controlled single rate sessions. We describe a new multiple rate congestion control algorithm for layered multicast sessions that employs a single rate multicast congestion control as the primary underlying control mechanism for each layer. Our new scheme combines the benefits of single rate congestion control with the scalability and flexibility of multiple rates to provide a sound multiple rate multicast congestion control policy.

Today's networking community is becoming increasingly skeptical of the significance of research results founded wholly upon experimental results conducted in simulation. Now, with the availability of wide-area distributed testbeds such as PlanetLab, it is feasible to move beyond evaluation by simulation, and to perform wide-area experiments across the Internet as an alternate. However, while use of a distributed testbed affords much greater realism than a network simulation, there is a significant downside, as tight control over one's experiments is relinquished.We argue that providing services for distributed testbeds that capture aspects of the specifiable, repeatable behavior implicit in simulation and emulation will be an integral component of next-generation textbeds. As a case study, we consider the following problem: given a desired end-system topology consisting of a set of pairwise constraints (such as upper and lower bounds on bandwidth and delay), locate a representative subtopology within a wide-area testbed that satisfies those constraints. Previous work on Netbed addresses wide-area embedding problems of this form using an optimization framework, whereas we employ constraint satisfaction. We discuss the relative merits of these approaches, outline the theoretical foundations of a distributed service that provides a synergy between adaptive network measurements and the embedding process, and report on preliminary experimental results conducted on PlanetLab.

Although multiple paternity has been observed in various groups of mammals with litter sizes >1, it has not been documented in wild ungulate populations. With the use of DNA microsatellites, we investigated multiple paternity in pronghorn (Antilocapra americana) at the National Bison Range. Females in this population twin every year, and we were able to assign paternity to 25 sets of twins sired in 1999 and 2000, eleven (44%) of which were fathered by different males. Complex female mate choice is the most likely explanation for the observed pattern; however, sperm competition might contribute if a female has mated multiple times. This study represents the 1st reported example of multiple paternity in a natural ungulate population and indicates that some aspects of mammalian mating systems still are not fully understood.

We describe fair layered increase/decrease with dynamic layering (FLID-DL): a new multirate congestion control algorithm for layered multicast sessions. FLID-DL generalizes the receiver-driven layered congestion control protocol (RLC) introduced by Vicisano et al. (Proc. IEEE INFOCOM, San Francisco, CA, , p.996-1003, Mar. 1998)ameliorating the problems associated with large Internet group management protocol (IGMP) leave latencies and abrupt rate increases. Like RLC, FLID-DL, is a scalable, receiver-driven congestion control mechanism in which receivers add layers at sender-initiated synchronization points and leave layers when they experience congestion. FLID-DL congestion control coexists with transmission control protocol (TCP) flows as well as other FLID-DL sessions and supports general rates on the different multicast layers. We demonstrate via simulations that our congestion control scheme exhibits better fairness properties and provides better throughput than previous methods. A key contribution that enables FLID-DL and may be useful elsewhere is dynamic layering (DL), which mitigates the negative impact of long IGMP leave latencies and eliminates the need for probe intervals present in RLC. We use DL to respond to congestion much faster than IGMP leave operations, which have proven to be a bottleneck in practice for prior work.

The neuropeptide galanin has not been localized previously in the primate uvea, and the neuropeptide somatostatin has not been localized in the uvea of any mammal. Here, the distribution of galanin-like and somatostatin-like immunoreactive axons in the iris, ciliary body and choroid of macaques and baboons using double and triple immunofluorescence labeling techniques and confocal microscopy was reported. In the ciliary body, galanin-like immunoreactive axons innervated blood vessels and the ciliary processes, particularly at their bases. In the iris, the majority of these axons was associated with the loose connective tissue in the stroma. Somatostatin-like immunoreactive axons were found in many of the same areas of the uvea supplied by cholinergic nerves. In the ciliary body, there were labelled axons within the ciliary processes and ciliary muscle. They were also found alongside blood vessels in the ciliary stroma. In the iris, somatostatin-like immunoreactive axons were abundant in the sphincter muscle and less so in the dilator muscle. A unilateral sympathectomy had no effect on the distribution of somatostatin-like or galanin-like immunoreactive axons, and these axons did not contain the sympathetic marker tyrosine hydroxylase. They did not contain the parasympathetic marker choline acetyltransferase, either. The galanin-like immunoreactive axons contained other neuropeptides found in sensory nerves, including calcitonin gene-related peptide, substance P and cholecystokinin. Somatostatin-like immunoreactive axons did not contain any of these sensory neuropeptides or galanin-like immunoreactivity, and they were neither labelled with an antibody to 200kDa neurofilament protein, nor did they bind isolectin-IB(4). Nevertheless, they are likely to be of sensory origin because somatostatin-like immunoreactive perikarya have previously been localized in the trigeminal ganglion of primates. Taken together, these findings indicate galanin and somatostatin are present in two different subsets of sensory axons in primate uvea.

We propose a new web server architecture optimized for delivery of large, popular files. Delivery of such files currently pose a scalability problem for conventional content providers, which must devote server-side resources in direct proportion to the high multiprogramming level induced by a set of these connections. While use of scalable multicast may remedy this problem some day, multicast is rarely supported in today's wide-area infrastructure. Our approach alleviates many of the most serious scalability problems by developing new server-side mechanisms capable of managing a large set of TCP connections transporting the same content. The strategy we employ relies on the use of fast forward error correcting (FEC) codes to generate encodings of popular content, of which only a small sliding window is cached in memory at any time instant. The concurrent TCP connections then access the content only from this shared window, which is globally useful to all clients. Our method hinges on eliminating unscalable TCP retransmission buffers, as we can ''retransmit'' fresh encoding packets in lieu of the originals with no performance degradation and with no modifications to client TCP stacks. Ultimately, our Cyclone server capitalizes on concurrency to maximize sharing of state across different request threads while minimizing context switching, disk I/O, thrashing under high load and the cache memory footprint. In this paper, we describe the design and prototype implementation of our approach as a Linux kernel subsystem.

Animal movement and dispersal can be described as a correlated random walk dependent on three parameters: number of steps, step size, and distribution of random turning angles. Equations of Kareiva and Shigesada use the parameters to predict the mean square displacement distance (MSDD), but this is less meaningful than the mean dispersal distance (MDD) about which the population would be distributed. I found that the MDD can be estimated by multiplying the square root of the MSDD by a three-dimensional surface correction factor obtained from simulations. The correction factors ranged from 0.89 to 1 depending on the number of steps and the variation in random turns, expressed as the standard deviation of the turning angles (SDA) about 0° (straight ahead). Corrected equations were used to predict MDDs for bark beetles, butterflies, ants, and beetles (based on parameters from the literature) and the nematode Steinernema carpocapsae (Weiser). Another equation from the literature finds the MDD directly, and this agreed with the MDD obtained by simulation at some combinations of SDA and numbers of steps. However, the equation has an error that increases as a power function when the standard deviation of turning angles becomes smaller (e.g.

On July 15 and 16, 1996, profiles of temperature, water vapor, carbon dioxide concentration, and its carbon isotopic composition were made within and above the convective boundary layer (CBL), near the village of Zotino in central Siberia (60 degreesN, 89 degreesE). On both days the CBL grew to a height of around 1000 m at midday after which little further growth was observed. This was despite high rates of sensible heat flux into the CBL from the predominantly coniferous vegetation below and was attributable to a high subsidence velocity. For all flights, marked discontinuities across the top of the CBL were observed for water vapor and CO2 concentrations with differences between the CBL and the free troposphere above being as high as 10 mmol mol(-1) and 13 mu mol mol(-1), respectively. Associated with the lower CO2 concentrations within the CBL was an enrichment of the delta C-13 in CO2 of up to 0.7 parts per thousand. Although for any one flight, fluctuations in CO2 and delta C-13 within the CBL were small (less than 3 mu mol mol(-1) and 0.1 parts per thousand); they were well correlated and suggested a photosynthetic discrimination, Delta, by the vegetation below of similar to 17 parts per thousand. Estimates of regional Delta based on CBL budgeting techniques suggested values ranging from 14.8 to 20.4 parts per thousand. CBL budgeting techniques were also used to estimate regional ecosystem carbon fluxes (-3 to -9 mu mol m(-2) s(-1)) and evaporation rates (1-3 mmol m(-2) s(-1)). Agreement with ground-based tower measurements was reasonable, but a bootstrap error analysis suggested that errors associated with the integral CBL technique were sometimes unacceptably large, especially for estimates of regional photosynthetic C-13 discrimination and regional evaporation rates. Conditions under which CBL techniques should result in reasonably accurate estimations of regional fluxes and isotopic fractionations are evaluated. [References: 51]

Recent empirical studies [6] have shown that Internet topologies exhibit power laws of the form y = x α for the following relationships: (P1) outdegree of node (domain or router) versus rank; (P2) number of nodes versus outdegree; (P3) number of node pairs within a neighborhood versus neighborhood size (in hops); and (P4) eigenvalues of the adjacency matrix versus rank. However, causes for the appearance of such power laws have not been convincingly given. In this paper, we examine four factors in the formation of Internet topologies. These factors are (F1) preferential connectivity of a new node to existing nodes; (F2) incremental growth of the network; (F3) distribution of nodes in space; and (F4) locality of edge connections. In synthetically generated network topologies, we study the relevance of each factor in causing the aforementioned power laws as well as other properties, namely diameter, average path length and clustering coefficient. Different kinds of network topologies are generated: (T1) topologies generated using our parametrized generator, we call BRITE; (T2) random topologies generated using the well-known Waxman model [12]; (T3) Transit-Stub topologies generated using GT-ITM tool [3]; and (T4) regular grid topologies. We observe that some generated topologies may not obey power laws P1 and P2. Thus, the existence of these power laws can be used to validate the accuracy of a given tool in generating representative Internet topologies. Power laws P3 and P4 were observed in nearly all considered topologies, but different topologies showed different values of the power exponent α. Thus, while the presence of power laws P3 and P4 do not give strong evidence for the representativeness of a generated topology, the value of α in P3 and P4 can be used as a litmus test for the representativeness of a generated topology. We also find that factors F1 and F2 are the key contributors in our study which provide the resemblance of our generated topologies to that of the Internet.

Larger bark beetles such as Ips typographus (Coleoptera: Scolytidae) fly at abou t2ms 1 for up to several hours. Computer simulations in two dimensions showed that bark beetles are capable of dispersing from a brood tree over wide areas while drifting with the wind. For example, if beetles take an angle of maximum turn (AMT) at random up to 10° either left or right each second, about 90% of the beetles become distributed over a 31.9 km 2 area after 1 h of flight. Larger maximum turning angles by beetles decrease the area of dispersal in proportion to the reciprocal of the square of the AMT. An increase in the dispersal time causes a linear increase in dispersal area and downwind drift distance, while increases in wind speed have no affect on the ultimate dispersal area but do increase the drift distance. Dispersal of bark beetles in a 1010 km forest of 5 million trees of 0.15 m trunk radius, corresponding to the natural density and trunk size of a 70-year-old Norway spruce forest (Picea abies), was simulated by spacing trees at appropriate density in a 50 m radial area centred on a beetle. A new area with trees was constructed similarly whenever the beetle left the former area. These simulations showed trees reduced the size of the dispersal area by 11% and downwind drift by 18% afte r1ho fflight due to the effect of turning some beetles back toward the release point, similar to the effects of increasing the AMT. The average dispersal distance and downwind distance decreased as linear functions of trunk density. Given step size, number of steps, and AMT, the correlated random walk equation of Kareiva and Shigesada [1983, Oecologia 56, 234‐238] predicts mean squared dispersal distance. This can be transformed to the more meaningful average dispersal distance by taking the square root and multiplying by a proportion obtained from a three dimensional surface equation fitted from simulation results. © 2000 Elsevier Science B.V. All rights reserved.

The proliferation of applications that must reliably distribute bulk data to a large number of autonomous clients motivates the design of new multicast and broadcast protocols. We describe an ideal, fully scalable protocol for these applications that we call a digital fountain. A digital fountain allows any number of heterogeneous clients to acquire bulk data with optimal efficiency at times of their choosing. Moreover, no feedback channels are needed to ensure reliable delivery, even in the face of high loss rates.We develop a protocol that closely approximates a digital fountain using a new class of erasure codes that for large block sizes are orders of magnitude faster than standard erasure codes. We provide performance measurements that demonstrate the feasibility of our approach and discuss the design, implementation and performance of an experimental system.

Whether the mate sampling and choice performed by females in nature influences offspring performance is a controversial issue in theory and an open empirical question. Pronghorn ( Antilocapra americana ) females engage in an obvious and energetically expensive mate sampling process to identify vigorous males. Although individual females sample independently, their choices converge on a small proportion of males that sire most young. Offspring of attractive males were more likely to survive to weaning and to age classes as late as 5 years, resulting in a selection differential, calculated by expected differences in lifetime number of offspring weaned, of 0.32 against random mating. Enhanced survival to weaning appeared to be accomplished by faster growth rates. Females compensated for matings with a less attractive mate by elevating rates of milk delivery to their young. Because pronghorn males do not have costly ornaments, we conclude that female choice for good genes can exist in the absence of ornaments. Furthermore, female choice may be important and unrecognized as a force that can lower population genetic load.

Because of scientific, management, and ethical considerations, it is important to know if capture and handling of neonatal ungulates increases their mortality risk. At the National Bison Range in northwestern Montana, where coyotes annually kill many young, I captured and marked young pronghorns (Antilocapra americana) in most years from 1981 to 1996 and recorded the number that were born and the number that survived to weaning each year. Mortality of young was ≥56% in all years, and the number of coyotes removed from the range of pronghorns in May and June was significantly correlated with the percentage of young that survived. Capture effort varied from none to intense among years, and not all young were captured in any year. I found no evidence that mortality risk was increased due to handling. With proper precautions, one may handle young pronghorns without exposing them to additional risk.