cssi/SciSciGPT-SciSciNet huggingface dataset:
Effect of threonine-to-methionine substitution at position 265 on structure and function of TEM-1 beta-lactamase.

TEM beta-lactamase variants with the amino acid substitutions R164S, E104K, G238S, and E240K (ABL numbering) display increased activity toward extended-spectrum cephalosporins. The T265M substitution is frequently found to be associated with the above substitutions in extended-spectrum beta-lactamases. However, the residue is located away from the active site in the three-dimensional structure and has been assumed to have no effect on catalysis. To examine the effect of the substitution on the structure and function of TEM beta-lactamase we constructed the following mutants: G238S, T265M, T265M:G238S, and T265M:G238S:E240K. Each enzyme was purified to homogeneity and the kinetic parameters kcat, Km and kcat/Km were determined for cefotaxime, ceftazidime, cephaloridine, and ampicillin. The results indicate that the T265M mutation has little effect on hydrolysis. In addition, we used immunoblotting to show that the substitution has little or no effect on the in vivo steady-state levels of beta-lactamase. Images
Role of opioid tone in the pathophysiology of hyperinsulinemia and insulin resistance in polycystic ovarian disease

Hyperinsulinemia secondary to a poorly characterized disorder of insulin action is a feature of polycystic ovarian disease (PCOD). On the other hand, being generally admitted that opioids may play a role in glycoregulation and that opioid tone is altered in PCOD, an involvement of the opioids in determining the hyperinsulinemia of PCOD patients could be suggested. The aim of this study was to evaluate the effect of a chronic opioid blockade on insulin metabolism and peripheral insulin sensitivity in PCOD hyperinsulinemic patients. Twenty-three women with PCOD were studied. An oral glucose tolerance test (OGTT) and a clamp study were performed at baseline (during the follicular phase) and after 6 weeks of naltrexone administration (50 mg/d orally). Based on the insulinemic response to the OGTT, 16 women were classified as hyperinsulinemic and seven as normoinsulinemic. Naltrexone treatment significantly reduced fasting (P < .05) and area under the curve (AUC) (P < .02) plasma insulin levels only in the hyperinsulinemic group. Moreover, hyperinsulinemic patients showed similar C-peptide incremental areas after naltrexone treatment, whereas in the same patients the fractional hepatic insulin extraction calculated from the incremental areas of insulin and C-peptide was found to be increased after chronic opioid blockade by naltrexone. For peripheral insulin sensitivity, the hyperinsulinemic group showed significantly lower (P < .01) total-body glucose utilization (M) compared with the normoinsulinemic group. No change in the M value was found after treatment in both groups. These data suggest that the insulin sensitivity and hyperinsulinemia after an OGTT are two distinct deranged features of the insulin disorder of PCOD patients.
Restoration of E-cadherin/β-catenin expression in pancreatic cancer cells inhibits growth by induction of apoptosis * **

Background. β-Catenin is a component of the E-cadherin/catenin adhesion complex that maintains epithelial cell integrity. We have previously observed decreased β-catenin expression in both human pancreatic cancer cell lines and primary tumors. To determine the significance of this finding with respect to pancreatic carcinogenesis, this study evaluated the effects of restoring expression of β-catenin with and without E-cadherin in pancreatic cancer cells. Methods. MiaPaca-2 cells were stably transfected with full-length cDNAs for β-catenin, E-cadherin, or a mutated E-cadherin lacking the β-catenin-binding domain. Doubly transfected cell clones containing β-catenin and either E-cadherin or deleted E-cadherin were also selected. Assays for cell adhesion, cell cycle profile, motility, and apoptosis were performed. Results. Cell clones expressing β-catenin alone or β-catenin and deleted E-cadherin did not differ significantly from the parental cell lines in any of the assays performed. In contrast, MiaPaca-2 cell clones expressing both β-catenin and E-cadherin showed tight adhesion, decreased cell growth, and a significantly increased apoptotic index as compared to the parental line or singly transfected clones. Conclusions. MiaPaca-2 cells undergo apoptosis at a significantly increased rate after restoration of the E-cadherin/β-catenin adhesion complex. This increase in apoptosis is dependent on the ability of E-cadherin to bind β-catenin. Loss of β-catenin expression may therefore provide pancreatic cancer cells with a growth advantage that contributes to tumor progression. (Surgery 2002;132:141-8.)
Smelling on the fly: sensory cues and strategies for olfactory navigation in Drosophila

Navigating toward (or away from) a remote odor source is a challenging problem that requires integrating olfactory information with visual and mechanosensory cues. Drosophila melanogaster is a useful organism for studying the neural mechanisms of these navigation behaviors. There are a wealth of genetic tools in this organism, as well as a history of inventive behavioral experiments. There is also a large and growing literature in Drosophila on the neural coding of olfactory, visual, and mechanosensory stimuli. Here we review recent progress in understanding how these stimulus modalities are encoded in the Drosophila nervous system. We also discuss what strategies a fly might use to navigate in a natural olfactory landscape while making use of all these sources of sensory information. We emphasize that Drosophila are likely to switch between multiple strategies for olfactory navigation, depending on the availability of various sensory cues. Finally, we highlight future research directions that will be important in understanding the neural circuits that underlie these behaviors.
Complexes of polypyrazolylborate ligands. V. Characterization of acety(tri-1-pyrazolylborato)(dicarbonyl)iron, (HBpz3)(COCH3)(CO)2Fe, in solution and in the crystal

Abstract The reaction of diiron enneacarbonyl with potassium tris-1-pyrazolylborate in the presence of excess methyl iodide affords an 8% yield of the new compound acetyl(tri-1-pyrazolylborato)(dicarbonyl)iron, 1 in addition to a larger quantity of the previously characterized by compound bis-(tri-1-pyrazolylborato)iron, 2. Compound 1 has been unequivocally characterized by elemental analyses, molecular weight measurement pmr spectrum, and X-ray crystallographic structure determination. The infrared spectrum of 1 in solution shows that conformers are present; these presumably differ in the rotational orientation of the acetyl group relative to the rest of the molecule. The principal crystallographic data are: space group P21/c; cell dimensions a = 9.233(1), b = 12.331(4), c = 15.507(2) A, β = 109.64(1)°, V = 1662.7(6) A3; observed and calculated densities ϱo = 1.40 gcm −3 ϱc = 1.36 gcm−3 for Z = 4. Least-squares refinement using 1804 counter data gave final conventional R factors of 0.035 and 0.040. The structure consists of well-separated monomeric units of (HBpz3) (COCH3)(CO)2Fe. Although not required crystallographically, the molecules possess near mirror symmetry. The coordination of the Fe atom is slightly perturbed from an octahedral arrangement, owing primarily to the non-orthogonal N-Fe-N angles of 86.8° (av). The pyrazolylborate nitrogen atoms occupy three mutually cis positions and the two CO groups are cis each other. the oxygen atom of the acetyl group lies over the bisector of the angle subtended at Fe by the carbonyl groups. The FeN bond distances are 1.992(4), 1.99(3), and 2.082(4) A (trans to acetyl); the Fe-C distances are 1.758(6), 1.771(5), and 1.968(5) A (acetyl).
Toxicity of pokeberries (fruit of Phytolacca americana large) for turkey poults

Fresh pokeberries were picked from the cluster and liquified in a blender for 3 to 5 minutes. The liquified berries were mixed into a standard turkey starter at the rate of 0, 2-1/2, 5 and 10%. Addition was at the expense of the total diet. Two separate experiments were conducted with day old Broad White turkeys. Weight gain, mortality and gross lesions were observed to 3 weeks of age. Growth rate was reduced with each increase in level of pokeberries. In Experiment 1, 3-week gains were 376, 354, 314 and 205 g. for 0, 2-1/2, 5 and 10% pokeberries. Weight gains in Experiment 2 were 339, 317, 254 and 172. Mortality was 33 and 43% in the two experiments when 10% pokeberries were fed. Lower levels produced erratic mortality results. Poults fed 5 and 10% pokeberries exhibited ataxia and occasional inability to walk. The hock joints frequently became enlarged and crooked. Ascites was observed in some birds at all dietary levels of added pokeberries. The gall bladder of dead birds was frequently much enlarged and filled with brownish fluid rather than normal bile.
Dendrimeric ion exchange materials

Abstract New high-capacity ion exchange materials have been prepared utilizing the structural feature of dendrimeric ‘balloons’ or ‘strings’ attached to a polymer backbone. The dendrimeric regions have covalently incorporated ionic sites at the core and branch points (anion exchanging materials) or at the termini of the chains (cation exchanging materials).
Transit-Oriented Development and Household Transportation Costs: Household-Level Analysis

Transit-oriented development (TOD) is a comprehensive approach to sustainable community and regional planning that integrates critical environmental, economic, and social issues. This study focuses on a fundamental question for end users, that is, travelers: Can TOD, as a planning concept, serve people's needs and expectations as well as translate into tangible savings in expenditures on transportation? The role of TOD as a distinct planning strategy in affecting household transportation costs is specified within a sample selection regression model that controls for residential self-selection bias. With a sample of 6,526 households in the San Francisco, California, Bay Area in 2000, the regression results indicate that TOD has a dominant influence on household transportation costs. However, it makes only a moderately positive contribution to reductions in household expenditures on transportation. The regression results also indicate that the self-selection effect accounts for about 21% of the total influe...
Structural and Functional Changes in the αA-Crystallin R116C Mutant in Hereditary Cataracts

alpha-Crystallin, the major protein component of vertebrate lenses, forms a large complex comprised of two homologous subunits, alphaA- and alphaB-crystallin. It has the ability to suppress stress-induced protein aggregation in vitro, bind saturably to lens plasma membranes, and aid in light refraction through short-range ordering. Recently, a missense mutation in alphaA-crystallin that changes arginine 116 to a cysteine residue (R116C) was genetically linked to one form of autosomal dominant congenital cataracts. This point mutation is reported to cause structural alterations at many levels as well as a 4-fold reduction in chaperone-like activity. To extend these findings, we examined the quaternary stability of the alphaA R116C mutant protein and its effect on chaperone-like activity, subunit exchange, and membrane association. Homocomplexes of mutant subunits become highly polydisperse following incubation at 37 degrees C, reflecting the likely in vivo distribution of the complexes. Chaperone-like activity of the alphaA R116C mutant is approximately 4-fold lower than wild type, whether measured before or after conversion to a polydisperse population with incubation. alphaA R116C complexes also have a 4-fold reduced ability to exchange subunits with wild-type complexes. Finally, membrane binding capacity measurements of mutant subunits showed a 10-fold increase over wild type. Our results, in conjunction with previous reports, suggest that the changes in complex polydispersity, the reduction of subunit exchange, and increased membrane binding capacity are all potential factors in the pathogenesis of alphaA R116C associated congenital cataracts.
Voltage-gated potassium channels in human immunodeficiency virus type-1 (HIV-1)-associated neurocognitive disorders.

Human immunodeficiency virus type-1 (HIV-1)-associated dementia (HAD), a severe form of HIV-associated neurocognitive disorders (HAND), describes the cognitive impairments and behavioral disturbances which afflict many HIV-infected individuals. Although the precise mechanism leading to HAD is incompletely understood, it is commonly accepted its progression involves a critical mass of infected and activated mononuclear phagocytes (brain perivascular macrophages and microglia) releasing immune and viral products in the brain. These cellular and viral products induce neuronal dysfunction and injury via various signaling pathways. Emerging evidence indicates voltage-gated potassium (Kv) channels, key regulators of cell excitability and animal behavior (learning and memory), are involved in the pathogenesis of HAD/HAND. Here we survey the literature and find that HAD-related alterations in cellular and viral products can increase neuronal Kv channel activity, leading to neuronal dysfunction and cognitive deficits. Thus, neuronal Kv channels may be a new target in the effort to develop therapies for HAD and perhaps other inflammatory neurodegenerative disorders.
A non-linear finite element analysis of some early collapse processes in femoral head osteonecrosis

Some aspects of the early collapse biomechanics of the segmentally necrotic adult human femoral head were studied, using a small-deformation plane strain, elasto-plastic finite element model. The computational procedure used was based upon the initial stress technique, and permitted study of stress and strain fields and of the progression of failure regions as a function of incrementally applied joint loads. The results consistently demonstrated both subchondral and deep cancellous failure patterns similar to those seen clinically. There was a clear distinction, however, between these two failure regimes, dependent primarily upon the relative strength deficits input for the subchondral versus the deep cancellous regions. Usually, the failure zone was appreciable only at significantly supra-physiological loads, reflecting the likely importance of fatigue events in the clinical collapse process. Although subchondral failure was always limited to the entire base region of the infarction wedge, the zones of deep failure varied considerably with changes in lesion geometry, usually being concentrated within the infarct near the underlying necrotic/viable interface.
FASTA barcodes: a simple method for the identification of yeast ORF deletions

A consortium of yeast geneticists have created -6000 individual ORF deletions, representing > 96% of the currently verified or predicted ORFs in S. cerevisiae. Importantly, molecular barcodes (each a unique 20 bp sequence termed either Uptag or Downtag) were used as identifiers for every ORF deletion. Microarray analyses of pooled yeast deletions has been used to identify thousands of genes involved in general fitness, haploinsufficiency, drug resistance and DNA damage repair. However, application of this powerful technology requires considerable expense, expertise and specialized equipment. While standard PCR techniques and specifically designed PCR primers can be used to confirm that a given ORF is in fact deleted, this procedure cannot be used to identify unknown deletions. In theory, every ORF deletion could be determined by barcode sequencing. However, neither a consolidated barcode database nor a reliable search engine is currently available for this purpose. To address this need, we have adapted a FASTA sequence program that utilizes the unique barcode database to allow users to identify individual ORF deletions, based upon simple sequencing reactions of PCR amplifications of either Uptag or Downtag barcodes. In silico and practical testing of this application reveals that it is an inexpensive, reliable and reproducible method for rapidly identifying unknown deletions. This approach allows laboratories to conduct small- or large-scale genetic screens with pooled yeast deletion strains and identify or verify any ORF deletion without the need for microarray technology.
Evidence that pH induced activation of the rat hepatic glucocorticoid-receptor complex is irreversible

Abstract The possible reversibility of pH induced activation of the glucocorticoid-receptor complex was studied. Generally, this was accomplished by activating rat liver cytosol at pH 8.5 (15°C, 30 min), and then returning it to pH 6.5 for a second incubation (15°C, 30 min). Activation was quantitated by measuring the binding of [3H]triamcinolone acetonide ([3H]TA)-receptor complexes to DNA-cellulose. When cytosol was incubated at pH 6.5, only 4.1% of the [3H]TA-receptor complexes bound to DNA-cellulose. However, 39.2% of the complexes bound when the cytosol was pH activated. When pH activation was followed by a second incubation at pH 6.5, 47.0% of the steroid-receptor complexes bound. Thus, according to the DNA-cellulose binding assay, pH induced activation was irreversible. In order to visualize both activated and unactivated [3H]TA-receptor complexes during this process, diethylaminoethyl (DEAE)-cellulose chromatography was performed. When cytosol was incubated at pH 6.5, only 19.6% of the [3H]TA-receptor complexes were eluted in the activated form from DEAE-cellulose. However, 67.5% of the complexes were eluted in the activated form when cytosol was pH activated. When pH activation was followed by a second incubation at pH 6.5, 74.9% of the steroid-receptor complexes were eluted in the activated form. Thus, DEAE-cellulose chromatography also showed that pH induced activation was irreversible. This is the first known report that the combination of DNA-cellulose binding and DEAE-cellulose chromatography have been used to study pH induced activation of the glucocorticoid-receptor complex. By these criteria, we conclude that in vitro pH induced activation is irreversible.
CBF changes associated with focal ischemic preconditioning in the spontaneously hypertensive rat

Experimental stroke models exhibit robust protection after prior preconditioning (PC) insults. This study comprehensively examined cerebral blood flow (CBF) responses to permanent middle cerebral artery (MCA) occlusion in spontaneously hypertensive rats preconditioned by noninjurious transient focal ischemia, using [(14)C]iodoantipyrine autoradiography at varied occlusion intervals. Preconditioning was produced by 10-min occlusion of the MCA and ipsilateral common carotid artery under halothane anesthesia. These vessels were permanently coagulated 24 h later in naive, PC, and sham-operated rats. Infarct volumes were determined from hematoxylin-eosin-stained frozen sections after 1 or 3 days. Edema-corrected infarct volume was reduced from 127+/-21 in naive rats to 101+/-31 and 52+/-28 mm(3) in sham and PC groups, respectively, at 1 day, with similar results at 3 days. All animals exhibited a consistent CBF threshold for infarction (approximately 30 mL/100 g/min). Tissue volumes below this threshold were identical in naive and PC groups after 15-min occlusion. However, by 3 h the volume of ischemic cortex decreased in the PC group but remained unchanged in naive rats, predicting final infarct volumes. Cerebral blood flow recovery was confirmed in brains of individual rats evaluated by repeated laser Doppler perfusion imaging during the same 3-h interval. Modest sham protection correlated with better-maintained global perfusion, detectable also in the contralateral cortex, apparently reflecting the PC effects of prior anesthesia. These results establish that timely reperfusion of penumbra, achieved by synergistic mechanisms, is a primary determinant of PC-induced protection in experimental stroke.
3.4.2 Supporting Object-Oriented Analysis of Human Performance Systems

There is a move towards conceptualizing, packaging and building human performance support systems, such as e-learning, around reusable objects. As with the software engineering domain this approach may only be successful if analysis and design also moves to an object model. There is a need for new methodological thinking and automated tools to support the change. An automated object-oriented performance analysis system is described, which enables modeling and collaboration during human performance systems analysis. The system is based on web services and uses a repository model to support the sharing and reuse of analysis knowledge both within and between organizations.
On the Use of Normal Coordinates for the Solution of Lumped Parameter Transient Heat-Transfer Problems

T USE of normal coordinates in solving lumped parameter forced vibration problems has been a valuable asset to the vibration analyst. The same method may be applied to the lumped parameter transient heat-transfer problem. Standard digital computer programs are available which will solve the matrix eigenvalue problem. Using a method such as the serial Jacobi method,' 2 the eigenvalues and eigenvectors of a 45 X 45 matrix can be obtained in about 6 minutes on an IBM 704 computer. This report shows how the matrix eigenvalue problem for heat transfer is set up and how the eigenvalues and eigenvectors are used to construct the transient solution.
Molecular complexes of several aromatic hydrocarbon-ketone systems

Abstract The association constants ( K AD ) between several aromatic hydrocarbons and several ketones were determined by a NMR spectrometric method in carbon tetrachloride as a solvent. Thermodynamic parameters for the formation of complexes for benzene-acetone and benzene-actophenone are also reported. The effect of competing complexation with the solvent is discussed. A new equation, which was derived without assuming that the concentration of one solute is far greater than that of the other, was used for the computation of the K AD -values.
Flavin-Catalyzed Insertion of Oxygen into Rhenium–Methyl Bonds

Flavins and related molecules catalyze organic Baeyer–Villiger reactions. Combined experimental and DFT studies indicate that these molecules also catalyze the insertion of oxygen into metal–carbon bonds through a Baeyer–Villiger-like transition state.
A mixture theory approach for the constitutive modeling of coupled hygro-thermo-elastic phenomena in fiber-reinforced polymeric composite materials

Abstract Several theoretical and experimental investigations have highlighted the vulnerability of polymeric fiber-reinforced composite materials to severe hygro-thermal environments. Traditionally, single constituent theories have been employed to model the constitutive response of idealized polymeric composite materials in hygro-thermal environments. Typically, these theories do not incorporate moisture as a distinct constituent in an explicit sense, and the moisture and temperature effects are treated as being uncoupled from the mechanical response of the composite material. The deficiencies of traditional techniques in modeling the hygro-thermo-elastic response of polymeric composites are addressed in this paper by treating the moisture-composite aggregate within the context of Mixture Theory. This approach not only permits the explicit incorporation of moisture and its effects, but it also allows the possibility of deriving constitutive equations to model the coupled hygro-thermo-elastic response of idealized fiber-reinforced composite materials undergoing small deformations. An illustrative example is presented in order to highlight the significant role of the fibers in modifying the hygro-thermo-elastic characteristics of the overall composite material. The authors believe that this is the first paper which rigorously treats the hygro-thermo-elastic behavior of polymeric composites in the context of Mixture Theory, and it is anticipated that this approach will have significant relevance in solving practical problems in defense, aerospace and manufacturing environments, where significant variations in moisture and temperature conditions are routinely encountered.
A fourth-order divergence-free method for MHD flows

This paper extends our previous third-order method [S. Li, High order central scheme on overlapping cells for magneto-hydrodynamic flows with and without constrained transport method, J. Comput. Phys. 227 (2008) 7368-7393] to the fourth-order. Central finite-volume schemes on overlapping grid are used for both the volume-averaged variables and the face-averaged magnetic field. The magnetic field at the cell boundaries falls within the dual grid and is naturally continuous so that our method eliminates the instability triggered by the discontinuity in the normal component of the magnetic field. Our fourth-order scheme has much smaller numerical dissipation than the third-order scheme. The divergence-free condition of the magnetic field is preserved by our fourth-order divergence-free reconstruction and the constrained transport method. Numerical examples show that the divergence-free condition is essential to the accuracy of the method when a limiter is used in the reconstruction. The high-order, low-dissipation, and divergence-free properties of this method make it an ideal tool for direct magneto-hydrodynamic turbulence simulations.
Metagenomic analysis of a permafrost microbial community reveals a rapid response to thaw

We employed deep metagenomic sequencing to determine the impact of thaw on microbial phylogenetic and functional genes and related this data to measurements of methane emissions. Metagenomics, the direct sequencing of DNA from the environment, allows for the examination of whole biochemical pathways and associated processes, as opposed to individual pieces of the metabolic puzzle. Our metagenome analyses revealed that during transition from a frozen to a thawed state there were rapid shifts in many microbial, phylogenetic and functional gene abundances and pathways. After one week of incubation at 5°C, permafrost metagenomes converged to be more similar to each other than while they were frozen. We found that multiple genes involved in cycling of C and nitrogen shifted rapidly during thaw. We also constructed the first draft genome from a complex soil metagenome, which corresponded to a novel methanogen. Methane previously accumulated in permafrost was released during thaw and subsequently consumed by methanotrophic bacteria. Together these data point towards the importance of rapid cycling of methane and nitrogen in thawing permafrost.
Operative risk factors and durability of repair of coarctation of the aorta in the neonate

The risk factors for the operative mortality and long-term durability of repair after surgical correction of coarctation of the aorta in neonates remain controversial. Between January 1970 and January 1993, 139 patients under 1 month of age underwent repair of coarctation of the aorta. Complex intracardiac defects were present in 59 patients. Another 44 patients had an associated ventricular septal defect. Subclavian artery flap repair was performed in 92 patients; end-to-end anastomosis (38 patients) and patch angioplasty (9 patients) were performed less commonly. The hospital mortality was significantly higher in patients with complex intracardiac defects (9 of 59 patients; 15.2%) than in those with a ventricular septal defect (1 of 44 patients; 2.3%) or with isolated coarctation (none of 36 patients; p = 0.007). Elevated pulmonary artery diastolic pressure (p = 0.041) and complex intracardiac anomalies (p = 0.048) were found to be independent predictors of hospital mortality. The presence of a complex cardiac defect (p < 0.001) was an independent predictor of poor long-term survival. Recurrent stenosis requiring reoperation had occurred or balloon dilation had been necessary in 27.9% of the children at 5 years postoperatively. In patients followed up for at least 5 years, the recurrence-free survival was better in those who had undergone subclavian artery flap repair than in those who had undergone end-to-end repair (p = 0.017). When coarctation of the aorta must be repaired in the neonate, operative mortality and long-term survival are affected by the complexity of associated intracardiac anomalies.(ABSTRACT TRUNCATED AT 250 WORDS)
Elimination of dendritic spines with long-term memory is specific to active circuits

Structural changes in brain circuits active during learning are thought to be important for long-term memory storage. If these changes support long-term information storage, they might be expected to be present at distant time points after learning, as well as to be specific to the circuit activated with learning, and sensitive to the contingencies of the behavioral paradigm. Here, we show such changes in the hippocampus as a result of contextual fear conditioning. There were significantly fewer spines specifically on active neurons of fear-conditioned mice. This spine loss did not occur in homecage mice or in mice exposed to the training context alone. Mice exposed to unpaired shocks showed a generalized reduction in spines. These learning-related changes in spine density could reflect a direct mechanism of encoding or alternately could reflect a compensatory adaptation to previously described enhancement in transmission due to glutamate receptor insertion.
Analysis of Case-Control Age-at-Onset Data Using a Modified Case-Cohort Method

Case-control designs are widely used in rare disease studies. In a typical case-control study, data are collected from a sample of all available subjects who have experienced a disease (cases) and a sub-sample of subjects who have not experienced the disease (controls) in a study cohort. Cases are oversampled in case-control studies. Logistic regression is a common tool to estimate the relative risks of the disease with respect to a set of covariates. Very often in such a study, information of ages-at-onset of the disease for all cases and ages at survey of controls are known. Standard logistic regression analysis using age as a covariate is based on a dichotomous outcome and does not efficiently use such age-at-onset (time-to-event) information. We propose to analyze age-at-onset data using a modified case-cohort method by treating the control group as an approximation of a subcohort assuming rare events. We investigate the asymptotic bias of this approximation and show that the asymptotic bias of the proposed estimator is small when the disease rate is low. We evaluate the finite sample performance of the proposed method through a simulation study and illustrate the method using a breast cancer case-control data set.
Nanoporous layered silicate AMH-3/cellulose acetate nanocomposite membranes for gas separations

Abstract Nanoporous layered silicate/polymer composite membranes are of interest because they can exploit the high aspect ratio of exfoliated selective flakes/layers to enhance molecular sieving and create a highly tortuous transport path for the slower molecules. In this work, we combine membrane synthesis, detailed microstructural characterization, and mixed gas permeation measurements to demonstrate that nanoporous flake/polymer membranes allows significant improvement in gas permeability while maintaining selectivity. We begin with the primary-amine-intercalated porous layered silicate SAMH-3 and show that it can be exfoliated using a high shear rate generated by a high-speed mixer. The exfoliated SAMH-3 flakes were used to form SAMH-3/cellulose acetate (CA) membranes. Their microstructure was analyzed by small angle X-ray scattering (SAXS), revealing a high degree of exfoliation of AMH-3 layers in the CA membrane with a small number of layers (4–8) in the exfoliated flakes. TEM analysis visualized the thickness of the flakes as 15–30 nm, and is consistent with the SAXS analysis. The CO2/CH4 gas separation performance of the CA membrane was significantly increased by incorporating only 2–6 wt% of SAMH-3 flakes. There was a large increase in CO2 permeability with maintenance of selectivity. This cannot be explained by conventional models of transport in flake-containing membranes, and indicates complex transport paths in the membrane. It is also in contrast to the much higher loadings of isotropic particles required for similar enhancements. The present approach may allow avoidance of particle aggregation and poor interfacial adhesion associated with larger quantities of inorganic fillers.
Effect of varying monoterpene concentrations on the response of Ips pini (Coleoptera: Scolytidae) to its aggregation pheromone: implications for pest management and ecology of bark beetles.

Host plant terpenes can influence attraction of conifer bark beetles to their aggregation pheromones: both synergistic and inhibitory compounds have been reported. However, we know little about how varying concentrations of individual monoterpenes affect responses. 2 We tested a gradient of ratios of a-pinene, the predominant monoterpene in host pines in the Great Lakes region of North America, to Ips pini's phero- mone, racemic ipsdienol plus lanierone. 3 Ips pini demonstrated a parabolic response, in which low concentrations of a-pinene had no effect on attraction to its pheromone, intermediate concentra- tions were synergistic and high concentrations were inhibitory. These results suggest optimal release rates for population monitoring and suppression programmes. 4 Inhibition of bark beetle attraction to pheromones may be an important component of conifer defences. At terpene to pheromone ratios emulating emissions from trees actively responding to a first attack, arrival of flying beetles was low. This may constitute an additional defensive role of terpenes, which are also toxic to bark beetles at high concentrations. 5 Reduced attraction to a low ratio of a-pinene to pheromone, as occurs when colonization densities become high and the tree's resin is largely depleted, might reflect a mechanism for preventing excessive crowding. 6 Thanasimus dubius, the predominant predator of I. pini, was also attracted to ipsdienol plus lanierone, but its response differed from that of its prey. Attrac- tion increased across all concentrations of a-pinene. This indicates that separate lures are needed to sample both predators and bark beetles effectively. It also provides an opportunity for maximizing pest removal while reducing adverse effects on beneficial species. This disparity further illustrates the complexity confronting natural enemies that track chemical signals to locate herbivores.
A MEASUREMENT OF THE ERRORS IN INTRA‐PERIOD COMPOUNDING AND BOND VALUATION

The errors in intra-period compounding and bond pricing are widespread in textbooks, and they also periodically occur in published research. This article deals with the measurement of error and the magnitude of error when, given the market price of other than annual bonds, the yield to maturity is calculated using the incorrect formula. The authors demonstrate that the errors are (1) the result of confusion, not oversight, (2) large in magnitude when the effective yearly interest rate is high, and (3) not symmetrical; that is, the characteristics of the errors when determining yields, given bond prices, differ from the characteristics of the errors when determining bond prices, given interest rates.
Sampling Problems and Nonparametric Solutions in Clinical Neuropsychological Research

Abstract Research data in clinical neuropsychology frequently do not conform to the requirements for parametric statistical analysis. In some of these cases, data analysis by parametric techniques does not identify existing differences. The usefulness of nonparametric statistical tools in evaluating irregular data sets is demonstrated in three case examples. Methodological considerations arising from these examples are discussed.
Adding regular expressions to Pascal

One generally praiseworthy characteristic of Pascal is that it allows the programmer to define new data types. However, not all operations that can be performed on indigenous types can also be performed on programmer-defined types. I/O is an example. This paper proposes an extension to Pascal that allows generalized input of enumerated types. Syntax is defined which lets the programmer use regular expressions to exercise considerable control over the translation of strings of input characters into the internal representation used for enumerated types.
Facilitation of opiate-and enkephalin-induced motor activity in the mouse by phenytoin sodium and carbamazepine

In the first experiment, adult male Swiss-Webster mice were systemically injected with a standard dose of morphine. Compared to the influence of vehicle, the motor activity of morphine-injected mice was increased. Neither phenytoin sodium nor carbamazepine alone facilitated motor activity, but pretreatment with both drugs further facilitated the increased motor activity produced by morphine. In a second experiment, mice were injected centrally with a long-acting analog of leu-enkephalin. It also increased motor activity in comparison with vehicle. Again, both phenytoin sodium and carbamazepine further facilitated this response. Both experiments suggest a facilitatory interaction between some aspects of these anticonvulsants and opiate-induced motor activity.
Regge Trajectories for Light Nuclear Systems

A large number of nuclear levels in the light nuclei ${\mathrm{O}}^{16}$, ${\mathrm{Ne}}^{20}$, ${\mathrm{O}}^{17}$, ${\mathrm{F}}^{17}$, ${\mathrm{C}}^{13}$, and ${\mathrm{N}}^{13}$ are classified in terms of the Regge trajectories in the channels (${\mathrm{C}}^{12},\ensuremath{\alpha}$), (${\mathrm{O}}^{16},\ensuremath{\alpha}$), (${\mathrm{O}}^{16},n$), (${\mathrm{O}}^{16},p$), (${\mathrm{C}}^{12},n$), and (${\mathrm{C}}^{12},p$), respectively. The mirror nuclei (${\mathrm{O}}^{17}$, ${\mathrm{F}}^{17}$) and (${\mathrm{C}}^{13}$, ${\mathrm{N}}^{13}$) have isobaric analog trajectories. The Regge trajectories obtained by coupling a nucleon with the first excited state of an ${\mathrm{O}}^{16}$ or ${\mathrm{C}}^{12}$ nucleus are also constructed from the levels of ${\mathrm{O}}^{17}$ (or ${\mathrm{F}}^{17}$) and ${\mathrm{C}}^{13}$ (or ${\mathrm{N}}^{13}$), respectively. (${\mathrm{O}}^{16}$, nucleon) and (${\mathrm{C}}^{12}$, nucleon) are spin-zero-spin-\textonehalf{} systems and contain trajectories corresponding to both $J=l\ensuremath{-}\frac{1}{2}$ and $J=l+\frac{1}{2}$ couplings.
Theory of alignment and orientation in beam-foil experiments

The preferential population of magnetic quantum levels of atomic states produced in beam-foil collisions is explained using a density-matrix formulation. The density matrix for the beam in the interior of the foil is evolved in time to obtain the density matrix after emergence from the foil. The dependence upon tilt angle of the foil relative to the beam is calculated. The Stokes parameters of the light emitted by decay of the atomic state are given in terms of the density matrix. Formulas which are valid for arbitrary angular momentum of the atomic state are derived. Comparison with experiment shows good agreement with data. (AIP)
Ultraviolet-visible diode-array spectrophotometer as a detector for gas chromatography

Abstract An ultraviolet-visible diode-array spectrophotometer is used as a detector for gas chromatography. This detector can provide a full u.v.-visible spectrum of each compound as it elutes from the column, thus enhancing discrimination between incompletely separated components. A discrimination of ca. 1:5000 could be achieved for a mixture of toluene and benzene. The detection limit is comparable to that of the thermal conductivity detector, i.e., about 0.5 μg for the various components. The detector is particularly useful when gases other than helium are used because the sensitivity does not depend on the gas used.
Hemangio-endothelioma arising in a mediastinal teratoma.

A case of hemangio-endothelioma with many metastases arising from a mediastinal teratoma is presented. The rarity of this tumor, its unusual anatomic location and the relevent clinical features, on the basis of which the diagnosis might have been suspected, are discussed.
Genetic and experiential antecedents of alcoholism: a prospective study.

SUMMARY The present work builds on an extensively studied obstetrical cohort that includes a group of individuals, now in their midteens, who had a parent treated for alcoholism. To generate a comparable sample today would not only require a very large effort (many years and considerable expense), but might not be possible in most countries because of lack of records or restricted access to them, as well as difficulty in, locating people after long periods. Such a study is still possible in Denmark, which has a long tradition of cooperation between public officials and scientific investigators and invaluable centralized population and psychiatric registers. Since such an opportunity may not present itself again, and since it is difficult to anticipate which avenues of investigation will be more profitable, the study is designed as a collaborative effort by investigators from a number of disciplines: psychiatric, psychological, neurologic, sociologic, biochemical, and electrophysiologic. From the enormous amount of data collected, genetic and experiential antecedents of alcoholism and associated psychopathology can be identified.
Band structure and optical transitions in LaFeO3: Theory and experiment

The optical absorption properties of LaFeO(3) (LFO) have been calculated using density functional theory and experimentally measured from several high quality epitaxial films using variable angle spectroscopic ellipsometry. We have analyzed the calculated absorption spectrum using different Tauc models and find the model based on a direct-forbidden transition gives the best agreement with the ab initio band gap energies and band dispersions. We have applied this model to the experimental data and determine the band gap of epitaxial LFO to be ∼2.34 eV, with a slight dependence on strain state. This approach has also been used to analyze the higher indirect transition at ∼3.4 eV. Temperature dependent ellipsometry measurements further confirm our theoretical analysis of the nature of the transitions. This works helps to provide a general approach for accurate determination of band gaps and transition energies in complex oxide materials.
The association of race and sex with the underuse of stroke prevention measures.

Background Underuse of effective stroke prevention measures has been demonstrated in the general population. Blacks and Hispanics are at increased risk of recurrent stroke relative to white non-Hispanics. More profound underuse of prevention measures may contribute to this disparity. In this study we attempted to compare the degree of underuse of diagnostic and treatment strategies in patients of these racial/ethnic groups with recent ischemic stroke. Methods At 4 participating urban hospitals, patient charts were reviewed with regard to the completeness of the diagnostic evaluation, discharge treatment regimen, and stroke risk factor and antithrombotic medication use at 6 months postdischarge. Results Of 501 patients hospitalized with acute ischemic stroke, almost all received electrocardiograms and brain imaging, 75% had carotid artery evaluations, and 70% had serum lipid determinations. Blacks and women were less likely to have complete evaluations. At discharge, 88% of patients received antithrombotic medications and 89% of patients were prescribed antihypertensive medications appropriately, but only 65% were prescribed lipid-lowering medications appropriately, with blacks least likely to receive appropriate prescriptions. At 6 months poststroke, of the 200 patients with data available for evaluation, 72% exhibited underuse of at least one stroke prevention measure. Blacks (81.6%) were more likely to experience underuse than Hispanics (62.5%) or whites (66.7%). Women were more likely to receive incomplete inhospital evaluations and discharge regimens. Conclusions There is clinically important underuse of effective diagnostic and prevention measures in each of the groups studied, especially among blacks.
The Lure of the Mean Axes

A variety of aerospace structures, such as missiles, spacecraft, aircraft, and helicopters, can be modeled as unrestrained flexible bodies. The state equations of motion of such systems tend to be quite involved. Because some of these formulations were carried out decades ago when computers were inadequate, the emphasis was on analytical solutions. This, in turn, prompted some investigators to simplify the formulations beyond all reasons, a practice continuing to this date. In particular, the concept of mean axes has often been used without regard to the negative implications. The allure of the mean axes lies in the fact that in some cases they can help decouple the system inertially. Whereas in the case of some space structures this may mean complete decoupling, in the case of missiles, aircraft, and helicopters the systems remain coupled through the aerodynamic forces. In fact, in the latter case the use of mean axes only complicates matters. With the development of powerful computers and software capable of producing numerical solutions to very complex problems, such as MATLAB and MATHEMATICA , there is no compelling reason to insist on closed-form solutions, particularly when undue simplifications can lead to erroneous results.
Buoyancy-induced deformations in a compressible elastic solid

Given a rectangular slab of a purely elastic material (neo-Hookean) with different temperatures imposed on the lateral surfaces, it is shown, within the context of a linearized theory, that the resulting deformation field is, under suitable boundary conditions, virtually identical to its fluid-mechanical counterpart given by a rectangular trench filled with a Newtonian liquid. A second, more general analogy between problems involving buoyancy induced deformations and the classical theory of thin plates is also presented.
Analysis of Hot-Carrier Luminescence for Infrared Single-Photon Upconversion and Readout

We propose and analyze a new method for single-photon wavelength up-conversion using optical coupling between a primary infrared (IR) single-photon avalanche diode (SPAD) and a complementary metal oxide semiconductor (CMOS) silicon SPAD, which are fused through a silicon dioxide passivation layer. A primary IR photon induces an avalanche in the IR SPAD. The photons produced by hot-carrier recombination are subsequently sensed by the silicon SPAD, thus, allowing for on-die data processing. Because the devices are fused through their passivation layers, lattice mismatch issues between the semiconductor materials are avoided. We develop a model for calculating the conversion efficiency of the device, and use realistic device parameters to estimate up to 97% upconversion efficiency and 33% system efficiency, limited by the IR detector alone. The new scheme offers a low-cost means to manufacture dense IR-SPAD arrays, while significantly reducing their afterpulsing. We show that this high-speed compact method for upconverting IR photons is feasible and efficient.
Regulatory errors, optimal fines and the level of compliance

Abstract This paper shows that with a hierarchical structure of enforcement, regulatory errors cause the optimal penalty to be non-maximal even if offenders are risk neutral (and fines are pure transfers), and the private benefit from violation is strictly less than the social cost for all individuals. In contrast, with error-free monitoring, no finite fine is optimal within the same hierarchical structure. Also, full compliance is an equilibrium outcome in the presence of errors whereas, in the absence of errors, the regulator can achieve only partial compliance.
Detection of ectopic parathyroid adenoma by early Tc-99m sestamibi imaging

Localization of Tc-99m sestamibi (MIBI) by parathyroid adenomas (PA) is well known. Typically the radionuclide washes out slowly from the PAs located in the neck. Rapid washout from some PAs has been reported. Various hypotheses have been postulated for slow and rapid clearance of MIBI from PAs, located in the neck. However, the washout of MIBI from ectopic parathyroid adenoma (EPA) in not well reported. We present a case of EPA with rapid washout of MIBI. Hence, early MIBI imaging plays an important role in the evaluation of EPA.