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Coastal communities, land covers and intertidal habitats are vulnerable receptors of erosion, flooding or both in combination. This vulnerability is likely to increase with sea level rise and greater storminess over future decadal-scale time periods. The accurate, rapid and wide-scale determination of shoreline position, and its migration, is therefore imperative for future coastal risk adaptation and management. Developments in the spectral and temporal resolution and availability of multispectral satellite imagery opens new opportunities to rapidly and repeatedly monitor change in shoreline position to inform coastal risk management decisions. This presentation discusses the development and application of an automated tool, VEdge_Detector, to extract the coastal vegetation line from high spatial resolution (Planet's 3 – 5 m) remote sensing imagery, training a very deep convolutional neural network (Holistically-Nested Edge Detection) to predict sequential vegetation line locations on annual/decadal timescales. The VEdge_Detector outputs were compared with vegetation lines derived from ground-referenced positional measurements and manually digitised aerial photographs, revealing a mean distance error of 84% producer accuracy at six out of the seven sites. Extracting vegetation lines from Planet imagery of the rapidly retreating cliffed coastline at Covehithe, Suffolk, UK identified a mean landward retreat rate >3 m a-1 (2010 - 2020). Plausible vegetation lines were successfully retrieved from images of other global locations, which were not used to train the neural network; although significant areas of exposed rocky coastline proved to be less well recovered by VEdge_Detector. The method therefore promises the possibility of generalising to estimate retreat of sandy coastlines in otherwise data-poor areas, which lack ground-referenced measurements. Vegetation line outputs derived from VEdge_Detector are produced rapidly and efficiently compared to more traditional non-automated methods. These outputs also have the potential to inform upon a range of future coastal risk management decisions, including hazard and risk mapping considering future shoreline change.

We analyze the rest-frame near-UV and optical nebular spectra of three $z > 7$ galaxies from the Early Release Observations taken with the Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope (JWST). These three high-z galaxies show the detection of several strong-emission nebular lines, including the temperature-sensitive [O III] $\lambda$4363 line, allowing us to directly determine the nebular conditions and abundances for O/H, C/O, and Ne/O. We derive O/H abundances and ionization parameters that are generally consistent with other recent analyses. We analyze the mass-metallicity relationship (i.e., slope) and its redshift evolution by comparing between the three z > 7 galaxies and local star-forming galaxies. We also detect the C III] $\lambda\lambda$1907,1909 emission in a z > 8 galaxy from which we determine the most distant C/O abundance to date. This valuable detection of log(C/O) = $-0.83\pm0.38$ provides the first test of C/O redshift evolution out to high-redshift. For neon, we use the high-ionization [Ne III] $\lambda$3869 line to measure the first Ne/O abundances at z>7, finding no evolution in this $\alpha$-element ratio. We explore the tentative detection of [Fe II] and [Fe III] lines in a z>8 galaxy, which would indicate a rapid build up of metals. Importantly, we demonstrate that properly flux-calibrated and higher S/N spectra are crucial to robustly determine the abundance pattern in z>7 galaxies with NIRSpec/JWST., Comment: Accepted for publication on ApJL

Strong nebular emission lines are an important diagnostic tool for tracing the evolution of star-forming galaxies across cosmic time. However, different observational setups can affect these lines, and the derivation of the physical nebular properties. We analyze 12 local star-forming galaxies from the COS Legacy Spectroscopy SurveY (CLASSY) to assess the impact of using different aperture combinations on the determination of the physical conditions and gas-phase metallicity. We compare optical spectra observed with the SDSS aperture, which has a 3" of diameter similar to COS, to IFU and longslit spectra, including new LBT/MODS observations of five CLASSY galaxies. We calculate the reddening, electron densities and temperatures, metallicities, star formation rates, and equivalent widths (EWs). We find that measurements of the electron densities and temperatures, and metallicity remained roughly constant with aperture size, indicating that the gas conditions are relatively uniform for this sample. However, using the IFU observations of 3 galaxies, we find that the E(B-V) values derived from the Balmer ratios decrease ( by up to 53%) with increasing aperture size. The values change most significantly in the center of the galaxies, and level out near the COS aperture diameter of 2.5". We examine the relative contributions from the gas and stars using the H$\alpha$ and [OIII] $\lambda$5007 EWs as a function of aperture light fraction, but find little to no variations within a given galaxy. These results imply that the optical spectra provide nebular properties appropriate for the FUV CLASSY spectra, even when narrow 1.0" long-slit observations are used., Comment: Accepted for publication in ApJ

The dispersion in chemical abundances provides a very strong constraint on the processes that drive the chemical enrichment of galaxies. Due to its proximity, the spiral galaxy M33 has been the focus of numerous chemical abundance surveys to study the chemical enrichment and dispersion in abundances over large spatial scales. The CHemical Abundances Of Spirals (CHAOS) project has observed $\sim$100 H II regions in M33 with the Large Binocular Telescope (LBT), producing the largest homogeneous sample of electron temperatures (T$_e$) and direct abundances in this galaxy. Our LBT observations produce a robust oxygen abundance gradient of $-$0.037 $\pm$ 0.007 dex/kpc and indicate a relatively small (0.043 $\pm$ 0.015 dex) intrinsic dispersion in oxygen abundance relative to this gradient. The dispersions in N/H and N/O are similarly small and the abundances of Ne, S, Cl, and Ar relative to O are consistent with the solar ratio as expected for $\alpha$-process or $\alpha$-process-dependent elements. Taken together, the ISM in M33 is chemically well-mixed and homogeneously enriched from inside-out with no evidence of significant abundance variations at a given radius in the galaxy. Our results are compared to those of the numerous studies in the literature, and we discuss possible contaminating sources that can inflate abundance dispersion measurements. Importantly, if abundances are derived from a single T$_e$ measurement and T$_e$-T$_e$ relationships are relied on for inferring the temperature in the unmeasured ionization zone, this can lead to systematic biases which increase the measured dispersion up to 0.11 dex., Comment: 52 pages, 13 figures, accepted for publication in The Astrophysical Journal

We re-examine the extremely metal-poor (XMP) dwarf galaxy AGC 198691 using a high quality spectrum obtained by the LBT's MODS instrument. Previous spectral observations obtained from KOSMOS on the Mayall 4-m and the Blue Channel spectrograph on the MMT 6.5-m telescope did not allow for the determination of sulfur, argon, or helium abundances. We report an updated and full chemical abundance analysis for AGC 198691, including confirmation of the extremely low "direct" oxygen abundance with a value of 12 + log(O/H) = 7.06 $\pm$ 0.03. AGC 198691's low metallicity potentially makes it a high value target for helping determine the primordial helium abundance ($Y_p$). Though complicated by a Na I night sky line partially overlaying the He I $\lambda$5876 emission line, the LBT/MODS spectrum proved adequate for determining AGC 198691's helium abundance. We employ the recently expanded and improved model of Aver et al. (2021), incorporating higher Balmer and Paschen lines, augmented by the observation of the infrared helium emission line He I $\lambda$10830 obtained by Hsyu et al. (2020). Applying our full model produced a reliable helium abundance determination, consistent with the expectation for its metallicity. Although this is the lowest metallicity object with a detailed helium abundance, unfortunately, due to its faintness (EW(H$\beta$) $, Comment: 10 pages, 2 figures

Accurately determining gas-phase metal-abundances within galaxies is critical as metals strongly affect the physics of the interstellar medium (ISM). To date, the vast majority of widely-used gas-phase abundance-indicators rely on emission from bright optical-lines, whose emissivities are highly sensitive to the electron temperature. Alternatively, direct-abundance methods exist that measure the temperature of the emitting gas directly, though these methods usually require challenging observations of highly-excited auroral lines. Low-lying far-infrared (FIR) fine-structure lines are largely insensitive to electron temperature and thus provide an attractive alternative to optically-derived abundances. Here, we introduce the far-infrared abundances (FIRA) project, which employs these FIR transitions, together with both radio free-free emission and hydrogen recombination-lines, to derive direct, absolute gas-phase oxygen-abundances. Our first target is M101, a nearby spiral-galaxy with a relatively steep abundance gradient. Our results are consistent with the O$^{++}$ electron-temperatures and absolute oxygen-abundances derived using optical direct-abundance methods by the CHemical Abundance Of Spirals (CHAOS) program, with a small difference ($\sim$ 1.5$\sigma$) in the radial abundance-gradients derived by the FIR/free-free-normalized vs. CHAOS/direct-abundance techniques. This initial result demonstrates the validity of the FIRA methodology $-$ with the promise of determining absolute metal-abundances within dusty star-forming galaxies, both locally and at high redshift., Comment: 28 pages, 11 figures, 5 tables, accepted for publication in the Astrophysical Journal

The CHAOS project is building a large database of LBT H II region spectra in nearby spiral galaxies to use direct abundances to better determine the dispersion in metallicity as a function of galactic radius. Here, we present CHAOS LBT observations of C II $\lambda$4267 emission detected in 10 H II regions in M 101, and, using a new photoionization model based ionization correction factor, we convert these measurements into total carbon abundances. A comparison with M101 C II recombination line observations from the literature shows excellent agreement, and we measure a relatively steep gradient in log(C/H) of -0.37 +/- 0.06 dex/R_e. The C/N observations are consistent with a constant value of log(C/N) = 0.84 with a dispersion of only 0.09 dex, which, given the different nucleosynthetic sources of C and N, is challenging to understand. We also note that when plotting N/O versus O/H, all of the H II regions with detections of CII $\lambda$4267 present N/O abundances at the minimum of the scatter in N/O at a given value of O/H. If the high surface brightness necessary for the detection of the faint recombination lines is interpreted as an indicator of H II region youth, then this may point to a lack of nitrogen pollution in the youngest H II regions. In the future, we anticipate that the CHAOS project will significantly increase the total number of C II $\lambda$4267 measurements in extragalactic H II regions., Comment: 9 pages, 5 figures, accepted for publication in The Astrophysical Journal

The chemical abundances of spiral galaxies, as probed by HII regions across their disks, are key to understanding the evolution of galaxies over a wide range of environments. We present LBT/MODS spectra of 52 HII regions in NGC3184 as part of the CHemical Abundances Of Spirals (CHAOS) project. We explore the direct-method gas-phase abundance trends for the first four CHAOS galaxies, using temperature measurements from one or more auroral line detections in 190 individual HII regions. We find the dispersion in Te-Te relationships is dependent on ionization, as characterized by F_5007/F_3727, and so recommend ionization-based temperature priorities for abundance calculations. We confirm our previous results that [NII] and [SIII] provide the most robust measures of electron temperature in low-ionization zones, while [OIII] provides reliable electron temperatures in high-ionization nebula. We measure relative and absolute abundances for O, N, S, Ar, and Ne. The four CHAOS galaxies marginally conform with a universal O/H gradient, as found by empirical IFU studies when plotted relative to effective radius. However, after adjusting for vertical offsets, we find a tight universal N/O gradient of alpha_N/O = -0.33 dex/Re with sigma_tot. = 0.08 for Rg/Re < 2.0, where N is dominated by secondary production. Despite this tight universal N/O gradient, the scatter in the N/O-O/H relationship is significant. Interestingly, the scatter is similar when N/O is plotted relative to O/H or S/H. The observable ionic states of S probe lower ionization and excitation energies than O, which might be more appropriate for characterizing abundances in metal-rich HII regions., Accepted for publication in ApJ

co-auteur étranger; International audience; The Trematoda are a group of phylogenetically diverse metazoan parasites that exhibit complex life cycles that often pass through invertebrate and vertebrate hosts. Some trematodes influence their host's behaviour to benefit transmission. Their parasitic influence may impact host population size by inhibiting an individual's reproductive capacity. We assessed the impact of infection by Podocotyle atomon on the reproductive behaviour and fecundity of its amphipod intermediate host, Gammarus zaddachi, using laboratory and field studies. Parasite prevalence was high in the field, with males more likely to be infected (prevalence in males 64%, in females 39%). Males also suffered a higher parasite burden than females. Infected females were less active, but we found no evidence for a reduction in female reproductive success. Infected females also had comparable pairing success to uninfected females. In males, infection reduced survival and fecundity, with mortality being highest, and sperm numbers lowest, in heavily infected individuals. Trematode parasites are sometimes associated with altered host fecundity, but studies often lack the relevant experimental data to explore the evolution of the trait. We discuss this among information specific to the effect of P. atomon infection in G. zaddachi.

We report the direct abundances for the galaxy NGC 2403 as observed by the CHemical Abundances Of Spirals (CHAOS) project. Using the Multi-Object Double Spectrograph on the Large Binocular Telescope, we observe two fields with H II regions that cover an R$_g$/R$_e$ range of 0.18 to 2.31. 32 H II regions contain at least one auroral line detection, and we detect a total of 122 temperature-sensitive auroral lines. Here, for the first time, we use the intrinsic scatter in the T$_e$-T$_e$ diagrams, added in quadrature to the uncertainty on the measured temperature, to determine the uncertainty on an electron temperature inferred for one ionization zone from a measurement in a different ionization zone. We then use all available temperature data within an H II region to obtain a weighted average temperature within each ionization zone. We re-derive the oxygen abundances of all CHAOS galaxies using this new temperature prioritization method, and we find that the gradients are consistent with the results of Berg et al. (2020). For NGC 2403, we measure a direct oxygen abundance gradient of -0.09($\pm$0.03) dex/Re, with an intrinsic dispersion of 0.037($\pm$0.017) dex, and an N/O abundance gradient of -0.17($\pm$0.03) dex/Re with an intrinsic dispersion of 0.060($\pm$0.018) dex. For direct comparison, we use the line intensities from the study of NGC 2403 by Berg et al. (2013), and find their recomputed values for the O/H and N/O gradients are consistent with ours., Comment: 34 pages, 14 figures, accepted for publication in The Astrophysical Journal

A recent (1988–1991) decline of Vallisneria americana Michx. (wildcelery) in Lake Onalaska, Wisconsin, prompted coordinated laboratory and field studies to evaluate die capacity of different sediments in die lake to support Vallisneria growth. Two sites were selected that formerly supported Vallisneria beds but differed in hydrologic patterns and sediment characteristics. SedimentfromSitel (die protectedsite) was predominandyfine-textured, with a silt-clay particle fraction of 77 percent; sediment from Site 2 (die unprotected/open water site) contained 79 percent coarse-grained sand. In die laboratory study, production and morphology of Vallisneria were examined on nonamended sediments from each site and on die same sediments amended by additions of N and P. In die field study, Vallisneria tubers were planted at die two sites and harvested after 12 weeks of growth to compare morphology and tissue nutrient concentrations. In order to account for local temperature and light conditions, surface wate...

Declines in submersed aquatic macrophytes, notably Vallisneria americana Michx., recently have been observed in portions of the Upper Mississippi River (UMR). Coincidentally, Myriophyllum spicatum L. appears to have become more common, frequently occurring in locations formerly occupied by Vallisneria or other submersed aquatic species. Mechanisms causing these changes in the abundance and composition of aquatic vegetation are unknown. However, a 3-year drought may have affected nutrient transport and phytoplankton production, thereby influencing growth and reproduction of Vallisneria and other macrophyte species. Other factors may potentially affect populations of submersed macrophytes within the UMRS. Foremost among these are suspended sediment concentrations, flooding, herbicides, and grazing.

A backprojected reconstruction method is presented that has been developed by imaging buildings in an area 91.4×91.4 m using the echoes from a revolver fired into an exponential horn. The signals were received with a nondirectional microphone. Frequencies above 1 kHz were used to emphasize diffuse scattering rather than specular reflection. Consideration was given to the variation in echo amplitudes and arrival times arising from air turbulence. Acceptable images were produced when an iterative cleanup algorithm and an amplitude‐limited point‐spread deconvolution were used.

Social dysfunction is perhaps the most defining and handicapping feature of autism. Improved social functioning has long been considered one of the most important intervention outcomes. A variety of social interventions have been designed, empirically examined, and published in the autism literature. Children with autism have been found to be responsive to a wide variety of interventions aimed at increasing their social engagement with others, both adults and peers. Successful strategies employing peer-mediated approaches and peer tutoring have involved typically developing peers. Furthermore, several studies have demonstrated that social engagement directly affects other important behaviors like language, even when these behaviors are not specifically targeted by the teaching program. Thus, while an area of severe involvement, social behavior is also responsive to intervention.

When attempting to interpret CT scans after radiofrequency thermal ablation (RFA) of liver tumors, it is sometimes difficult to distinguish ablated from viable tumor tissue. Identification of the two types of tissue is specially problematic for lesions that are hypodense before ablation. The aim of this study was to determine whether quantitative Hounsfield unit (HU) density measurements can be used to document the lack of tumor perfusion and thereby identify ablated tissue.Liver spiral CT scans of 13 patients with 51 lesions undergoing laparoscopic RFA for metastatic liver tumors within a 2-year time period were reviewed. HU density of the lesions as well as normal liver were measured pre- and postoperatively in each CT phase (noncontrast, arterial, portovenous). Statistical analyses were performed using Student's paired t-test and ANOVA.Normal liver parenchyma, which was used as a control, showed a similar increase with contrast injection in both pre- and postprocedure CT scans (56.4 +/- 2.4 vs 57.1 +/- 2.4 HU, respectively; p = 0.3). In contrast, ablated liver lesions showed a preablation increase of 45.7 +/- 3.4 HU but only a minimal postablation increase of 6.6 +/- 0.7 HU (p0.0001). This was true for highly vascular tumors (neuroendocrine) as well as hypovascular ones (adenocarcinoma).This is the first study to define quantitative radiological criteria using HU density for the evaluation of ablated tissues. A lack of increase in HU density with contrast injection indicates necrotic tissue, whereas perfused tissue shows an increase in HU density. This technique can be used in the evaluation of patients undergoing RFA.

Study Design: A report of two cases of orthostatic hypotension in acute tetraplegia that were resistant to classic treatment interventions. Objective: To discuss the use of midodrine hydrochloride for the treatment of orthostatic hypotension in early tetraplegia. Setting: Department of Rehabilitation Medicine, The University of Texas Health Science Center at San Antonio, Texas, USA. Methods: Presentation of two cases. Results: Midodrine hydrochloride successfully treated two cases of orthostatic hypotension that had been refractory to classic treatment interventions. Conclusion: Midodrine hydrochloride should be included in the armamentarium of the physician treating orthostatic hypotension in spinal cord injury. Spinal Cord (2000) 38, 109–111.

Urinary tract infection (UTI) continues to be the most frequent secondary medical complication experienced by persons with spinal cord injury (SCI). We developed a carepath designed to minimize recurrent UTIs in patients identified as at risk. Data were collected in a prospective fashion for 1,000 consecutive days at an outpatient SCI clinic. The number of UTIs decreased to below threshold in 65 percent of the patients when the nurse clinician counseled them regarding proper technique and hygiene related to clean intermittent catheterization. Of the patients who responded to this intervention, 73 percent required multiple counseling sessions. We conclude that educational intervention by a clinic nurse is a simple, cost-effective means of decreasing the risk of UTIs in individuals with SCI who are identified as at risk.

The Child Neurology Society and American Academy of Neurology recently proposed to formulate Practice Parameters for the Diagnosis and Evaluation of Autism for their memberships. This endeavor was expanded to include representatives from nine professional organizations and four parent organizations, with liaisons from the National Institutes of Health. This document was written by this multidisciplinary Consensus Panel after systematic analysis of over 2,500 relevant scientific articles in the literature. The Panel concluded that appropriate diagnosis of autism requires a dual-level approach: (a) routine developmental surveillance, and (b) diagnosis and evaluation of autism. Specific detailed recommendations for each level have been established in this document, which are intended to improve the rate of early suspicion and diagnosis of, and therefore early intervention for, autism.

A number of proprietary disinfectant products (18) used in the food industry were tested for their bactericidal efficacy against Pseudomonas aeruginosa and Escherichia coli O157:H7 at 20 and 10 degrees C according to the BS EN 1276 (1997) quantitative suspension test for the evaluation of bactericidal activity of chemical disinfectants and antiseptics used in food, industrial, domestic and institutional areas. At 20 degrees C, 13 products passed at their in-use concentration (under clean and dirty conditions) against Ps. aeruginosa and 15 passed against E. coli O157:H7. The number of products passing the test at 10 degrees C was 11 and 14 for Ps. aeruginosa and E. coli O157:H7, respectively. The products exhibiting reduced efficacy at the lower temperature were amphoterics and quaternary ammonium compounds although some of these types of products were effective at both temperatures. Products that passed against Ps. aeruginosa generally also passed against E. coli O157:H7. Taking all the results together, only 11 of the total of 18 products achieved a pass result under all the parameters tested. This work demonstrates the need for final verification of disinfectant efficacy by undertaking field trials in the food-processing environment in which the product is intended for use.

Due to ongoing improvements in medical care, the life expectancy of persons with spinal cord injury (SCI) continues to improve and approach that of the able-bodied population. As the SCI population ages, cancer would be expected to increase as a cause of death. When a patient presents with occult fecal blood and anemia, colonscopy to the cecum is often pursued. It has been our experience that 80 percent of patients are found to have inadequate bowel preps resulting in suboptimal colonoscopy when the prep is attempted at home. Because of this, we developed a nurse-administered carepath necessitating a 48-hour admission for bowel prep and colonoscopy. The bowel prep consists of magnesium citrate, polyethylene glycol-electrolyte solution, and sodium phosphate/biphosphate enemas. Throughout hospitalization, the patient receives a clear liquid diet. Eighteen patients have been placed on the carepath. At the time of colonoscopy, all 18 were noted to have received an acceptable bowel prep allowing vizualization to the cecum. A description of the carepath and its benefits is presented.

The authors conducted formative research on the use of partner notification with HIV-infected drug users (i.e. those who use/abuse injectable drugs, crack or cocaine) in order to guide the development of an effective intervention for this population in New York City. Structured focus group and personal interviews were conducted with 25 in- and out-of-treatment drug users, 23 counsellors from a sexually transmitted disease (STD) clinic and a methadone maintenance treatment programme (MMTP), and nine experts in the field of HIV partner notification and/or substance abuse prevention and treatment. Results revealed factors associated with HIV-positive disclosure, the strengths and barriers of existing partner notification programmes and issues that should be considered in designing an effective intervention with HIV-infected drug users. Further research and planning activities are recommended before piloting and evaluating such a programme.

Although previous studies have described the hypothalamo–pituitary–adrenal (HPA) response to the stress of acute myocardial infarction, it is not possible to study the hormone changes immediately after infarction in humans. Accordingly, we have examined the HPA response to microembolization of coronary arteries in 13 sheep compared with 5 sham control sheep. Plasma vasopressin (AVP; PP=0·005) and cortisol (P=0·005) were all increased 2 h (first sample time) after embolization. Plasma ACTH and cortisol levels returned to baseline levels by 6 h but plasma AVP levels did not return to baseline levels until more than 12 h after embolization. Plasma corticotrophin-releasing hormone (CRH) showed no significant change in response to embolization. In a subset of six animals which were sampled more frequently, the peak responses for plasma AVP, ACTH and cortisol occurred at 40 min after embolization. The maximum responses in any individual sheep observed at this time point were 744 pmol/l for AVP, 144 pmol/l for ACTH and 492 nmol/l for cortisol. CRH levels tended to increase across the first hour but these changes were not statistically significant. In conclusion, the stress hormone responses to microembolization of the coronary arteries have been defined in an ovine model of myocardial infarction. This model is suitable for studying the effects of novel treatments to reduce the stress of myocardial infarction. Journal of Endocrinology (1997) 152, 489–493

A study was designed to test 2 alternative hypotheses--a symbolic hypothesis and an executive function hypotheses--for the imitation and pantomime deficits found in previous studies of autism. The subjects were 17 adolescent high-functioning subjects with autism spectrum disorders and 15 clinical comparison subjects who were matched on chronological age and verbal IQ. Meaning and sequence were manipulated in facial and manual imitation tasks. Sequence was manipulated in the pantomime and control tasks. Recognition memory and motor control tasks were matched to the experimental tasks. The results provided no support for the symbolic deficit hypothesis; meaning aided rather than hindered the performance of the group with autism. Partial support for the executive deficit hypothesis was found. There were no group differences on motor control tasks, and few on the memory control tasks, arguing against deficits in motor initiation, basic motor coordination, or visual recognition memory.

This study examined memory functions in individuals with autism. Based on previous evidence of executive function (EF) deficits, we hypothesized that subjects with autism would demonstrate a pattern of intact and impaired memory functions similar to that found in other groups with EF deficits, such as patients with frontal lobe pathology. We compared the performance of high-functioning children and adolescents with autism (n = 19) and clinical comparison subjects (n = 19) matched on sex, CA, and VIQ on measures of memory and EF. The group with autism performed significantly worse than comparison subjects on measures of temporal order memory, source memory, supraspan free recall, working memory, and EF, but not on short- and long-term recognition, cued recall, or new learning ability, consistent with the predictions of the EF theory. The cognitive measures were significantly more intercorrelated in the autism group than the comparison group, consistent with a limit in central cognition.

Permeability values in a borehole are predicted by an artificial neural network from the porosity values at the same depths. The network used in this study employs an architecture called backpropagation that is good at making predictions. The traditional approach for permeability prediction is regression analysis. In regression analysis, the relationship between porosity and permeability is assumed to be known. In reality, the functional form of this relationship, i.e., the model equation, is unknown. In contrast, the neural-network approach assumes no functional relationship. Six wells from Big Escambia Creek (Jurassic Smackover carbonate) field in southern Alabama were used to test predicting permeability from porosity using a neural network. Porosity and spatial data alone were used to predict permeability because these data are readily available from any hydrocarbon field. Three scenarios were performed; in each one, a subset of the six wells was used for a training set, one well for calibration, and one or two wells were used for prediction. For each scenario, simple linear regression was also used to predict permeability from porosity. The neural net predicted permeability much better than did regression in one scenario; in the other two scenarios the two methods performed equally well. The neural net predicted permeability accurately using minimal da a, but other kinds of information (e.g., log- or core-derived lithologic information) are easily incorporated if available. In addition, compartmentalization of carbonate reservoirs may be recognizable by this approach.

Risk factors, pathogenesis, clinical manifestations, diagnosis, and surgical and pharmacological treatment of ischemic stroke are reviewed. Risk factors play an important part in the pathogenesis of ischemic stroke. Knowledge of the complex metabolic and cellular changes that occur during ischemic stroke is rapidly growing. Choosing the correct treatment is dependent upon obtaining a thorough and accurate clinical assessment of the patient. Diagnostic tests help in determining the size, location, etiology, and characteristics of the lesion. Currently no single agent or mode of therapy appears to be most efficacious. Many drugs are still in the human clinical testing stage; promising agents include thrombolytics, low-molecular-weight heparin, and heparinoids. Hemodilution, pentoxifylline, epoprostenol, nimodipine, naloxone, and GM1 therapy have had mixed results in clinical trials, partly because some of these agents were not tested in enough patients to provide an accurate assessment of their efficacy. Atenolol and propranolol are ineffective. Ticlopidine and aspirin decrease the incidence of subsequent stroke but have not been tested in acute ischemic stroke. Heparin may be effective in preventing further cardioembolic stroke or in treating stroke in progress. Nondrug therapies include carotid endarterectomy and surgical decompression for cerebellar stroke. No single agent can be recommended for treatment of ischemic stroke at this time. Promising regimens include ancrod, low-molecular-weight heparin and heparinoids, or thrombolytics.

The mechanism of DNA damage induced by Cr(III) complexes is currently unknown even though it is considered to be the ultimate biologically active oxidation state of chromium. In this study, we have employed the Salmonella reversion assay to identify mutagenic Cr(III) complexes. Cyclic voltammetry was used to differentiate the redox kinetics between mutagenic and selected nonmutagenic Cr(III) species. Plasmid relaxation of supercoiled DNA was employed to show in vitro interactions with plasmid DNA and correlate the interactions with the electrochemical behavior and biological activity. The results of this study demonstrate that the mutagenic Cr(III) complexes identified in the Salmonella reversion assay display characteristics of reversibility and positive shifts of the Cr(III)/Cr(II) redox couple consistent with the ability of these Cr(III) complexes to serve as cyclical electron donors in a Fenton-like reaction. These same mutagenic complexes display an ability to relax supercoiled DNA in vitro, presumably by the induction of single-strand breaks. Nonmutagenic complexes were selected to test different ligands to determine how the ligand directs the activity of Cr(III) complexes. All nonmutagenic complexes tested thus far have shown classical irreversibility, more negative reduction potentials, and an inability to relax supercoiled plasmid DNA. These results suggest that the mechanism by which chromium complexes potentiate mutagenesis involves an oxygen radical as an active intermediate. These data also demonstrate the effect of associated ligands with regard to the ability of a metal to generate an active redox center.

We determined the role of specific thrombin "exosites" in the mechanism of inhibition by the plasma serine proteinase inhibitors heparin cofactor II (HC) and antithrombin (AT) in the absence and presence of a glycosaminoglycan by comparing the inhibition of alpha-thrombin to epsilon- and gamma T-thrombin (produced by partial proteolysis of alpha-thrombin by elastase and trypsin, respectively). All of the thrombin derivatives were inhibited in a similar manner by AT, either in the absence or presence of heparin, which confirmed the integrity of both heparin binding abilities and serpin reactivities of epsilon- and gamma T-thrombin compared to alpha-thrombin. Antithrombin activities of HC in the absence of a glycosaminoglycan with alpha-, epsilon, and gamma T-thrombin were similar with rate constants of 3.5, 2.4, and 1.2 x 10(4) M-1 min-1, respectively. Interestingly, in the presence of glycosaminoglycans the maximal inhibition rate constants by HC with heparin and dermatan sulfate, respectively, were as follows: 30.0 x 10(7) and 60.5 x 10(7) for alpha-thrombin, 14.6 x 10(7) and 24.3 x 10(7) for epsilon-thrombin, and 0.017 x 10(7) and 0.034 x 10(7) M-1 min-1 for gamma T-thrombin. A hirudin carboxyl-terminal peptide, which binds to anion-binding exosite-I of alpha-thrombin, dramatically reduced alpha-thrombin inhibition by HC in the presence of heparin but not in its absence. We analyzed our results in relation to the recently determined x-ray structure of D-Phe-Pro-Arg-chloromethyl ketone-alpha-thrombin (Bode, W., Mayr, I., Baumann, U., Huber, R., Stone, S. R., and Hofsteenge, J. (1989) EMBO J. 8, 3467-3475). Our results suggest that the beta-loop region of anion-binding exosite-I in alpha-thrombin, which is not present in gamma T-thrombin, is essential for the rapid inhibition reaction by HC in the presence of a glycosaminoglycan. Therefore, alpha-thrombin and its derivatives would be recognized and inhibited differently by HC and AT in the presence of a glycosaminoglycan.

We assess the impact of maternal sense of mastery and maternal working conditions on maternal perceptions of children's behavior problems as a means to study the transmission of social control across generations. We use a sample of 521 employed mothers and their four-to six-year-old children from the National Longitudinal Survey's Youth Cohort in 1986. Regarding working conditions, we consider mother's hourly wage, work hours, and job content including involvement with things (vs. people), the requisite level of physical activity, and occupational complexity. We also consider maternal and child background and current family characteristics, including marital status, family size, and home environment. Maternal mastery was related to fewer reported behavior problems among children. Lower involvement with people and higher involvement with things, as well as low physical activity, were related significantly to higher levels of perceived problems. In addition, recent changes in maternal marital status, including maternal marriage or remarriage, increased reports of problems; stronger home environments had the opposite effect. We interpret these findings as suggesting how maternal experiences of control in the workplace and personal resources of control can influence the internalization of control in children.

Because we are social animals, people have norms and value schemes which strongly influence behaviour. Social scientists are firstly people and bring value schemes to their work, A simple model is proposed of three entities — the observed, the observer and the paradigm used by the observer — which involves three value schemes and the relationships among them. Some examples are given from economics and psychology to illustrate how value schemes affect the practice of the social sciences and its results, often deleteriously. It is then argued that it is not possible to practise social science in a value-free way, that is, amorally. This leads to the conclusion that in educating and re-educating social scientists some formal exposure to value schemes and their implications for psychological practice is essential.

The propagation of short thermal pulses has been studied in very pure samples of NaF, ${\mathrm{Li}}^{7}$F, and NaI in various crystallographic directions. In each of these crystals the flow of heat at high temperatures is by diffusion, and at the lowest temperatures, by the direct flight of phonons from heater to detector. In the ballistic region, the elastic anisotropy gives rise to a channeling of mode energy into certain preferred directions. Over a limited intermediate temperature range, the effect of normal-process scattering on the propagated heat pulse has been observed in NaF and ${\mathrm{Li}}^{7}$F: In the best NaF crystals the pulse velocity approaches the expected second-sound velocity. The observations can be explained satisfactorily in terms of the hydrodynamics of a weakly interacting phonon gas. Computer solutions generated to fit the observed thermal pulse shapes suggest that in NaF, the mean free path for normal-process scattering can be represented by ${l}_{N}=1.42\ifmmode\times\else\texttimes\fi{}{10}^{3}{T}^{\ensuremath{-}3.71}$ cm in the temperature range 10-20 \ifmmode^\circ\else\textdegree\fi{}K.

The thermal transport properties of solid mixtures of the neon isotopes 20Ne and 22Ne have been studied by means of heat-pulse and steady-state thermal conductivity measurements. The results have been interpreted numerically using the Callaway formalism to establish the relaxation rates for phonon scattering. The rate for three-phonon normal processes which is of particular interest can be represented by tau N-1=(4.5+or-0.5)*105x2T4s-1, where x=h(cross) omega /kT and W is the phonon frequency. The phonon scattering by isotopic impurity atoms was found to be 40% stronger than that predicted on the basis of the mass difference alone, but accords well with calculations that include the effects of strain field scattering. The intrinsic process relaxation rates have been used to assess the possibility of second-sound propagation in perfect neon crystals.

Despite numerous optimistic forecasts of the effects of EEC entry the authors of this article expect that, in the longer term, British farming will experience a continuing cost-price squeeze. Increasing the size of farm business either by acquisition of additional land or by combining farming with the provision of contract services, or by cooperative grouping, is suggested as a means of increasing income.

The thermal conductivity of solid mixtures of the helium isotopes has been determined from 1°K to near the melting temperatures. In the hexagonal close-packed phase, pure 4 He and three 4 He-rich mixtures were measured at three different pressures of formation (60, 90 and 140 atm) and pure 3 He and six 3 He-rich mixtures at a single pressure of formation (145 atm). The results are analysed on the basis of Callaway’s relaxation-time theory, and a consistent explanation is obtained if the relaxation rate for three-phonon normal processes is assumed to be proportional to w 2 T 2 . Scattering of phonons by the isotopic impurities is greater than corresponds to the mass difference alone and the additional scattering is attributed to the effect of lattice strain around the impurity. Although the magnitude of this effect is considerably less than has been calculated, its variation with pressure is as predicted. These conclusions are supported by consideration of the behaviour of the conductivity in the limit of low isotopic concentration, when the calculated conductivity is independent of the form of the relaxation rate for normal processes.