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About 20 per 100,000 children have convulsive status epilepticus every year, a life-threatening condition. Benzodiazepines are the first-line treatment for prolonged and recurrent seizures. Our study was designed to gain understanding of caregiver perception of acute seizure treatments.Our project uses a cross-sectional survey study design using the electronic medical record and a survey at a large academic tertiary children's medical center. Subjects were patients with epilepsy prescribed intranasal (IN) midazolam and/or per rectum (PR) diazepam. The survey was administered to caregivers of children with epilepsy regarding information on the comfort, efficacy, ease of use, and time of administration for patients receiving both abortive seizure medications. Exact binomial tests were employed to determine whether or not differences in caregiver preference exist.One hundred and sixty responses were obtained. Incomplete and duplicate surveys were excluded, leaving 153 responses. Of those responses, 59 respondents reported administering both medications. Among parents who expressed a preference for one medication over the other, more parents felt overall greater comfort with IN midazolam compared with rectal diazepam (p = 0.0004 and p = 0.001), IN midazolam was perceived as easier to use (68%, p = 0.0038 and 74%, p = 0.0004) and more effective (87%, p 0.0001) than rectal diazepam. Intranasal midazolam was found to be superior to rectal diazepam in several other categories as well.These parents of children with epilepsy report increased ease of use, comfort, and efficacy with IN midazolam as compared with rectal diazepam suggesting that a readily available form of IN midazolam would be well received in the pediatric population.

Objective Caring for a child with illness or a child with disability impacts family in various ways. The ability to assess the impact of this care on families is one way to proactively provide the necessary support and resources for impacted families. Accordingly, the goal of the current study was to assess the impact of pediatric epilepsy on individual families in a comprehensive epilepsy clinic using a slightly modified version of the Impact on Families Scale (IFS). Methods Families of patients with epilepsy completed the IFS up to three times. The IFS score and the six categories (i.e., total impact, financial impact, general impact, family/social impact, coping, and sibling impact) were assessed using Student's two sample t-test to determine the differences between binary groups and Pearson's correlation to assess the associations with continuous variables. Linear regression modeling was used to develop a model to predict IFS score. Results Three hundred and forty-one patients completed the scale at one time point, 314 at two time points, and 61 at three time points. The overall impact of epilepsy on families was 109 (95% confidence interval (CI): 106–112) at time point 1, 111 (95% CI: 108–114) at time point 2, and 112 (95% CI: 105–119) at time point 3. There was no statistical difference in IFS score among the three time points. There were no associations with age or gender. Multivariable modeling using stepwise regression indicated that treatment resistance and seizure-free status were associated with IFS score. No interaction effects were identified. Conclusions Findings from the current study suggest that the impact of epilepsy is highest for families that have children with active seizures at the time of their clinical visit and for those with children having treatment-resistant epilepsy. Although intuitive, this is the first study, to our knowledge, that has empirically verified these findings.

Significant increases in the population of the echinoid bioeroder Diadema mexicanum that may soon follow severe El Nino events, such as in 1982–1983, can have a significant negative impact on the carbonate budget of coral reefs. We developed a spatially explicit model that uses agent-based modeling techniques to simulate the interactions between damselfish and sea urchins on an eastern Pacific coral reef following an El Nino-Southern Oscillation (ENSO) event where high echinoid abundances and low coral cover were prevalent. Our modeling study suggests that the agonistic behavior of damselfish towards echinoids invading their defended algal lawn territories has a magnifying effect on the degree of bioerosion attributed to echinoids. This is due to the increased likelihood that sea urchins ejected from damselfish territories will form concentrated aggregations and remain grazing and eroding coral for longer periods of time. This is a novel insight that contrasts with the previous understanding of the positive effect that damselfish have on reef carbonate budgets by protecting carbonate substrates that lie within their defended algal lawn territories. The increased degradation of coral stands attributed to the indirect damselfish effect, if it results in sea urchins eroding subsurface coral framework structures, causing instability and collapse (especially during periods of high-water motion), may contribute to the fracturing of large portions of coral framework blocks, affecting the recovery trajectory of reefs following a severe El Nino disturbance event.

This paper is on the asymptotic behavior of the spectral density of finite autoregressive (AR) and moving average (MA) approximations for a wide sense stationary time series. We consider two aspects: convergence of spectral density of moving average and autoregressive approximations when the covariances are known and when they are estimated. Under certain mild conditions on the spectral density and the covariance sequence, it is shown that the spectral densities of both approximations converge in L"2 as the order of approximation increases. It is also shown that the spectral density of AR approximations converges at the origin under the same conditions. Under additional regularity assumptions, we show that similar results hold for approximations from empirical covariance estimates.

Since the early 1980s, episodes of coral reef bleaching and mortality, due primarily to climate-induced ocean warming, have occurred almost annually in one or more of the world's tropical or subtropical seas. Bleaching is episodic, with the most severe events typically accompanying coupled ocean–atmosphere phenomena, such as the El Nino-Southern Oscillation (ENSO), which result in sustained regional elevations of ocean temperature. Using this extended dataset (25+ years), we review the short- and long-term ecological impacts of coral bleaching on reef ecosystems, and quantitatively synthesize recovery data worldwide. Bleaching episodes have resulted in catastrophic loss of coral cover in some locations, and have changed coral community structure in many others, with a potentially critical influence on the maintenance of biodiversity in the marine tropics. Bleaching has also set the stage for other declines in reef health, such as increases in coral diseases, the breakdown of reef framework by bioeroders, and the loss of critical habitat for associated reef fishes and other biota. Secondary ecological effects, such as the concentration of predators on remnant surviving coral populations, have also accelerated the pace of decline in some areas. Although bleaching severity and recovery have been variable across all spatial scales, some reefs have experienced relatively rapid recovery from severe bleaching impacts. There has been a significant overall recovery of coral cover in the Indian Ocean, where many reefs were devastated by a single large bleaching event in 1998. In contrast, coral cover on western Atlantic reefs has generally continued to decline in response to multiple smaller bleaching events and a diverse set of chronic secondary stressors. No clear trends are apparent in the eastern Pacific, the central-southern-western Pacific or the Arabian Gulf, where some reefs are recovering and others are not. The majority of survivors and new recruits on regenerating and recovering coral reefs have originated from broadcast spawning taxa with a potential for asexual growth, relatively long distance dispersal, successful settlement, rapid growth and a capacity for framework construction. Whether or not affected reefs can continue to function as before will depend on: (1) how much coral cover is lost, and which species are locally extirpated; (2) the ability of remnant and recovering coral communities to adapt or acclimatize to higher temperatures and other climatic factors such as reductions in aragonite saturation state; (3) the changing balance between reef accumulation and bioerosion; and (4) our ability to maintain ecosystem resilience by restoring healthy levels of herbivory, macroalgal cover, and coral recruitment. Bleaching disturbances are likely to become a chronic stress in many reef areas in the coming decades, and coral communities, if they cannot recover quickly enough, are likely to be reduced to their most hardy or adaptable constituents. Some degraded reefs may already be approaching this ecological asymptote, although to date there have not been any global extinctions of individual coral species as a result of bleaching events. Since human populations inhabiting tropical coastal areas derive great value from coral reefs, the degradation of these ecosystems as a result of coral bleaching and its associated impacts is of considerable societal, as well as biological concern. Coral reef conservation strategies now recognize climate change as a principal threat, and are engaged in efforts to allocate conservation activity according to geographic-, taxonomic-, and habitat-specific priorities to maximize coral reef survival. Efforts to forecast and monitor bleaching, involving both remote sensed observations and coupled ocean–atmosphere climate models, are also underway. In addition to these efforts, attempts to minimize and mitigate bleaching impacts on reefs are immediately required. If significant reductions in greenhouse gas emissions can be achieved within the next two to three decades, maximizing coral survivorship during this time may be critical to ensuring healthy reefs can recover in the long term.

Motivated by a problem arising in the regenerative analysis of discrete-event system simulation, we ask whether a certain class of random variate generation schemes exists or not. Under very reasonable conditions, we prove that such variate generation schemes do not exist. The implications of this result for regenerative steady-state simulation of discrete-event systems are discussed.

We show that sufficient conditions in terms of moments for cumulative processes (additive functionals of regenerative processes) to satisfy the central limit theorem and the weak law of large numbers established in Glynn and Whitt (Stochastic Process. Appl. 47 (1993) 299–314) are also necessary, as previously conjectured.

We provide a generalization of Hoeffding's inequality to partial sums that are derived from a uniformly ergodic Markov chain. Our exponential inequality on the deviation of these sums from their expectation is particularly useful in situations where we require uniform control on the constants appearing in the bound.

In this paper, we show how to exactly sample from the distribution of the maximum of a random walk with negative drift. We also explore related variance reduction methods.

We investigate the question of when sampling a stochastic process X={X(t) : t⩾0} at the times of an independent point process ψ leads to the same empirical distribution as the time-average limiting distribution of X. Two main cases are considered. The first is when X is asymptotically stationary and ergodic, and ψ satisfies a mixing condition. In this case, the pathwise limiting distributions in function space are shown to be the same. The second main case is when X is only assumed to have a constant finite time average and ψ is assumed a positive recurrent renewal processes with a spread-out cycle length distribution. In this latter case, the averages are shown to be the same when some further conditions are placed on X and ψ.

We consider the maximum waiting time among the first n customers in the GI/G/1 queue. We use strong approximations to prove, under regularity conditions, convergence of the normalized maximum wait to the Gumbel extreme-value distribution when the traffic intensity ρ approaches 1 from below and n approaches infinity at a suitable rate. The normalization depends on the interarrival-time and service-time distributions only through their first two moments, corresponding to the iterated limit in which first ρ approaches 1 and then n approaches infinity. We need n to approach infinity sufficiently fast so that n ( 1 − ρ )2 → ∞. We also need n to approach infinity sufficiently slowly: If the service time has a pth moment for ρ > 2, then it suffices for ( 1 − ρ ) n 1 / p to remain bounded; if the service time has a finite moment generating function, then it suffices to have ( 1 − ρ ) log n → 0. This limit can hold even when the normalized maximum waiting time fails to converge to the Gumbel distribution as n → ∞ for each fixed ρ. Similar limits hold for the queue length process.

As part of a two-phased study, sediment and biota were collected from Pennekamp Coral Reef State Park and Key Largo National Marine Sanctuary and analysed for organochlorine pesticide residues. Phase 1 consisted of an inter-laboratory comparison using replicates of unspiked field samples. The five participating contract-laboratories differed in methodology, detection limits and their ability to detect pesticides. The highest concentration of pesticide reported in Phase 1 samples was 4.4 ng g−1 wet wt aldrin, found in a fillet of Haemulon plumieri. Based on the inter-laboratory comparison, one laboratory was selected to analyse additional samples collected in Phase 2. Pesticides were detected in 43 of the 52 Phase 2 samples. The highest concentration reported in Phase 2 samples was 2.3 ng g−1 α-BHC in Panulirus argus tail muscle. These results suggest that while most samples contained one or more residues, pesticide concentrations were low and trends in residue profiles were minor.

Several authors have called attention to pollution and the insidious deterioration of nearshore waters and associated marine habitats of the Florida Keys. Some of the recognized and potential sources of pollution that have been reported are sewage effluents (Bright et al., 1981; LaPointe & O'Connell, 1988), marinas (Heatwole, 1987), surface water run-off from urban areas in the Keys (Heatwole, 1987) and the southeast Florida mainland (Jaap, 1984), wastes from fish processing facilities (Heatwole, 1987), and shipping wastes and oil spills (Jaap, 1975, 1984; Romero et al., 1981; Zheng & Van Vleet, 1988). Although any of these sources could be a causal factor of pollution in a regional context, only nutrient enrichment from sewage run-off has thus far been implicated as a significant and relatively widespread problem (LaPointe & O'Connell, 1988), albeit only in the shallow nearshore waters of the Keys. As part of a larger study to determine the principal source(s) and ecological consequences of pollution, samples of marine vertebrates (snappers and groupers), invertebrates (decapod crustaceans, scleractinian corals and molluscs), and sediments were collected at various times and locations and analysed for the n-alkane aliphatic hydrocarbons C-12 to C-30, and the isoprenoids pristane and phytane. Whereas the straightchain hydrocarbons are commonly present in both biological materials and petroleum, specific carbon suites and indices of n-alkanes have been used in pollution studies to help distinguish between biogenic and petrogenic sources (Lamparczyk et al., 1988; Pelletier et al., 1991). For example, odd number carbon chains tend to dominate in biological materials, whereas petrogenic (fossil carbon) materials have a high preponderance of even numbered carbons. The Caribbean corals, however, have been shown not to exhibit a strong odd or even carbon preference (Meyers, 1977). Sediment and tissue samples were collected during 10 trips to the Florida Keys from 1990 to 1992. Sampling locations, and regions corresponding to post hoc data pooling for sediment, are shown in Fig. 1. Briefly, the Florida Keys were divided into five regions: bay, nearshore Atlantic, Hawk Channel, reef track and ABC channels. Approximately the top 4 cm of sediments were collected from each site by a diver using pre-cleaned glass jars (I-Chem TM Research, Hayward, California) as scoops. To prevent contamination, jars were opened

Before the 1982–1983 El Nino disturbance event low diversity coral communities and small, actively accreting coral reefs were present on Galapagos shallow shelves in areas protected from strong upwelling. Prolonged El Nino 1982–1983 sea warming resulted in 95–99% coral mortality, virtually eliminating corals throughout the archipelago. The population size of an ubiquitous, large sea urchin species (Eucidaris thouarsii) was unaffected by the warming event. Urchins later showed increased abundance on dead coral colonies and frameworks, and caused bioerosion that exceeded the net calcification capacity of disturbed reefs. Known human impacts on corals result mainly from anchor damage, the collection of corals for sale as curios, and mechanical damage resulting from the activities of fishermen. An evaluation of natural and anthropogenic damage to Galapagos coral communities indicates that natural disturbances, especially strong ENSO episodes, are of greatest concern. However, rapidly increasing human pressures could exacerbate the recovery capacity of naturally perturbed coral communities.

We show that there is no batch-means estimation procedure for consistently estimating the asymptotic variance when the number of batches is held fixed as the run length increases. This result suggests that the number of batches should increase as the run length increases for sequential stopping rules based on batch means.

Consider the method of independent replications with initial transient deletion for generating confidence intervals for 'steady-state' quantities. To produce intervals with good convergence characteristics, the relative growth rates of the number of replications, the length of each replication, and the deletion period must be controlled. Critical rates for these parameters are determined. The applicability of these results to simultaneously running multiple replications on a highly parallel computer is discussed.

For a given countable partition of the range of a regenerative sequence {Xn: n ⩾ 0}, let Rn be the number of distinct sets in the partition visited by X up to time n. We study convergence issues associated with the range sequence {Rn: n ⩾ 0}. As an application, we generalize a theorem of Chosid and Isaac to Harris recurrent Markov chains.

Herbicide residues including 2,4-D and 2,4,5-T have been detected in the tissues of corals subject to massive mortality in the Gulf of Chiriqui, Panama. Tolerance tests conducted using Pocillopora damicornis demonstrated a toxic effect of a commercial herbicide (incorporating 2,4-D) on this coral.

Let X be a possible recurrent regenerative process on state space S with steady-state distribution @p. Given a function @?: S -> R, we consider the problem of estimating the steady-state central moments @m"k(@?) = @?"s(@?(x)-r)^k@p(dx) where r is the steady-state mean of @?(X(.)). We obtain laws, central limit theorems, and confidence for our estimators, and present numerical results.

We study precise conditions under which the cyclic regenerative confidence intervals of Sargent and Shanthikumar are asymptotically valid. We also obtain an optimal way of implementing the cyclic regenerative variance reduction technique, and obtain a sufficient condition under which the procedure yields a lower variance than that of the standard regenerative method.

Upper bounds on the left and right tails of the Poisson distribution are given. These bounds can be easily computed in a numerically stable way, even when the Poisson parameter is large. Such bounds can be applied to variate generation schemes and to numerical algorithms for computing terminal rewards of uniformizable continuous-time Markov chains.

A standard strategy in simulation, for comparing two stochastic systems, is to use a common sequence of random numbers to drive both systems. Since regenerative output analysis of the steady-state of a system requires that the process be regenerative, it is of interest to derive conditions under which the method of common random numbers yields a regenerative process. It is shown here that if the stochastic systems are positive recurrent Markov chains with countable state space, then the coupled system is necessarily regenerative; in fact, we allow couplings more general than those induced by common random numbers. An example is given which shows that the regenerative property can fail to hold in general state space, even if the individual systems are regenerative.

We simulate long-run averages of time integrals of a recurrent semi-Markov process efficiently. Converting to discrete-time by simulating only an imbedded chain and computing the conditional expectations of everything else needed given the sequence of studies visited reduces asymptotic variance, eliminates generating holding-time variates, and (when advantageous) gets rid of the future event schedule. In this setting, uniformizing continuous-time Markov chains is not worthwhile. We generalize beyond semi-Markov processes and cut ties to regenerative simulation methodology. Implementation of discrete-time conversion is discussed. It often requires no more work or even less work than the naive method. We give sufficient conditions for work savings. Continuous-time Markov chains, for example, satisfy them.

Scleractinian corals and octocorals from two reefs within Biscayne National Park off southeast Florida were compared with respect to 1. relative abundances, 2. gross field condition, 3. concentrations of pesticides and heavy metals, and 4. histopathological condition. The northernmost reef, Bache Shoal, is near a large urban area (Miami) and potentially receives pollutants from this source. The southernmost reef, Alina's Reef, is less likely to be influenced by runoff from Miami, but may receive runoff from an important agricultural centre (Homestead). No consistent differences between the two coral reef communities were found; however, high frequencies of blemishes and abnormalities (bite marks, unusual growth forms, bleached tissues), tissue necrosis, and invading pathogens were evident at both sites. Additionally, high levels (to ppm) of organochlorine pesticides (lindane, heptachlor/heptachlor epoxide, α/γchlordane, and DDT residues) and heavy metals (As, Cu, Pb) were detected in several of the reef coelenterates from both sites.

The principal problem associated with steady-state simulation is the estimation of the variance term in an associated central limit theorem. This paper develops several strongly consistent estimates for this term using the strong approximations available for Brownian motion. A comparison of rates of convergence is given for a variety of estimators.

Several traits were examined in four potential coral prey species (colony form, organic matter content, caloric density, tissue accessibility, mucus release, cnidocyst composition, toxicity, and colony defense by crustacean coral guards) to help understand the feeding preference of the Hawaiian asteroid corallivore Culcita novaeguineae Muller & Troschel. In laboratory experiments, C. novaeguineae exhibits a preference for Pocillopora damicornis (L.) and Pocillopora meandrina Dana over Porites compressa Dana, Montipora verrucosa (Lamarck) and Fungia scutaria (Lamarck). The feeding rate of Culcita novaeguineae on Pocillopora damicornis was ≈ 28 cm 2 or 250 cm 3 per day. In limited field observations, a preference was shown by Culcita novaeguineae for small colonies of Pocillopora meandrina which were totally killed (all tissues removed from branches) after attack by the sea star. Although the organic matter content (mg dry wt/cm 3 ) of Pocillopora was the lowest of the four corals, the percent loss of organic matter after feeding (“utilization” by Culcita ) was the highest. This high intake of organic matter corresponds with the superficial location of the tissue layers and the ease of removal of tissues (by “water piking”) in Pocillopora compared with the other corals. Small colonies of Pocillopora are eaten more frequently than large colonies; the former harbor relatively low numbers of crustacean guards (crabs and shrimp) and their guards are small compared with large colonies. Coral mortality caused by Culcita ( 1.0 m 2 /yr) is only about one-fifth of that by Acanthaster (5.3 m 2 /yr), but the selective feeding of Culcita on Pocillopora , and its avoidance of nonpocilloporid corals, could affect significantly the relative abundance of corals in Hawaiian reef assemblages.

Growth of epiphytic algae on the sphaeromatid isopod, Dynamenella perforata (Moore), occurred within a week in individuals exposed to direct sunlight. Algal growth interfered with crawling and swimming movements, feeding, ventilation of respiratory surfaces, and possibly moulting. Isopods living together performed reciprocal cleansing activities and epiphytic growth was not so pronounced in those provided with surfaces allowing frequent contact. Animals provided with rock shelter all remained essentially free of injurious algal growth.

1. 1. The absorption efficiency for E. thouarsii fed P. damicornis is 44.7% for carbohydrate, 85.3% for protein and 69.3% for lipid. 2. 2. E. thouarsii fed P. damicornis absorbs 0.402 mg carbohydrate, 2.814 mg protein and 1.108 mg lipid for each g of P. damicornis ingested. 3. 3. E. thouarsii fed P. damicornis absorbs 0.201 mg carbohydrate, 1.407 mg protein and 0.554 mg lipid per individual per day. 4. 4. E. thouarsii fed P. damicornis absorbs 0.824 × 10 −3 kcal carbohydrate, 7.950 × 10 −3 kcal protein and 5. 5.235 × 10 −3 kcal lipid per individual per day. 6. 5. Despite the high efficiency of digestive absorprion of organic constituents of the coral ingested, E. thouarsii must consume large quantities to meet its nutritional requirements.