cssi/SciSciGPT-SciSciNet huggingface dataset:
A graphite resistance heater for a hypersonic wind tunnel using nitrogen: Part II. Analysis of heater performance

Abstract A formula is derived for the rise in total temperature of nitrogen flowing through an electric resistance element made of graphite. The derivation of the formula involves, firstly, the consideration of an idealized heating system based on a simple graphite tube, and, secondly, the assumption that the solution of the internal heat transfer problem possesses certain properties. The formula provides a useful basis for the analysis of experimental results from practical heating systems which resemble the idealized system. Such a practical system is exemplified by the graphite heater in the pilot hypersonic nitrogen tunnel at Princeton University (as described in Part I), and the results obtained with this heater are shown to be well represented by the formula.
Induction of Pemphigus in Neonatal Mice by Passive Transfer of IgG from Patients with the Disease

We examined the role of circulating autoantibodies in the pathogenesis of pemphigus vulgaris by passively transferring IgG fractions from five patients with pemphigus vulgaris into neonatal Balb/c mice, in doses of 1.5 to 16 mg per gram of body weight per day. Cutaneous blisters and erosions with the histologic, ultrastructural, and immunofluorescence features of pemphigus occurred in 39 to 55 mice given intraperitoneal injections of IgG from patients with pemphigus and in none of 58 control mice given normal human IgG. IgG fractions with high titers of pemphigus antibodies were most effective in inducing disease, and this effect was dose dependent. Titers of circulating IgG in mouse serum closely correlated with the extent of disease induced (P less than 0.002). This study strongly supports the proposed role of pemphigus autoantibodies in the pathogenesis of pemphigus vulgaris in human beings and demonstrates that pemphigus can be passively transferred to laboratory animals.
Tolerance to vehicle rotation of subjects using turning and nodding motion of the head while performing simple tasks

Rotation of space stations to provide artificial gravity may be used to combat the effects of long exposure to weightlessness. It has been established that motion of the head out of the plane of vehicle rotation results in nystagmus, visual illusions, sweating, and nausea. Crosscoupled accelerations are induced by these motions and are the cause of these disturbances. In order to obtain quantitative data on the magnitude of these induced cross-coupled accelerations that can be tolerated by man, an investigation was initiated at NASA Langley. The Langley subjects, lying on their backs, feet outward, were inclosed in a small cabin on a simple rota ting-vehicle simulator. The subjects were required to move their heads in a specified manner in response to light signals. The head position and rate of motion, as well as reaction time, were recorded. Results have been obtained for cases where the subject is required to make turning and nodding motions of his head. The results indicate that the subjects cannot tolerate the stimulation experienced when nodding as well as they can tolerate the stimulus of the turning-head motion. The toleration to these various stimulations is discussed. Experiments to determine what value of cross-coupled acceleration can be tolerated for the nodding case are also mentioned and referenced.
Heterogeneity of the apolipoprotein H * 3 allele and its role in affecting the binding of apolipoprotein H (β2-glycoprotein I) to anionic phospholipids

Apolipoprotein H (apoH, protein; APOH, gene) has been implicated as a necessary cofactor for the binding of certain autoimmune antiphospholipid antibodies to anionic phospholipids. APOH exhibits genetically determined structural polymorphism with the occurrence of four alleles. Recently three IgG1k monoclonal antibodies (mAb) to human apoH, designated 3G9, 1B4, and 3D11, have been produced. The mAb 3D11 does not recognize apoH bound to anionic phospholipids in contrast to mAb 3G9 and 1B4, which recognize free and phospholipid-bound apoH. In this investigation we have determined the reactivity of the three mAb with four APOH allele products and the binding ability of these allele products with anionic phospholipids. The mAb 3G9 and 1B4, like the polyclonal anti-apoH, were equally reactive with all four allelic products, but the 3D11 recognized only the APOH*3 allele product. In the 159 APOH*3 carriers tested from five ethnic groups, the reactivity of mAb 3D11 was observed with all the Chinese but none of the African blacks. For the U.S. whites and Polynesians 89% and 75%, respectively, of the APOH*3 allele products were recognized by 3D11, while 87% of the U.S. blacks with this allele had no 3D11 reactivity. These data show that the APOH*3 allele, originally identified as a single entity by the polyclonal anti-apoH, is heterogeneous with at least one distinct variation based on mAb 3D11 reactivity. Our data also demonstrate that the apoH from certain homozygous APOH*3 individuals is unable to bind to anionic phospholipids. Such ethnic-specific apoH variations could play a significant role in the binding properties of autoimmune antiphospholipid antibodies to anionic phospholipids.
Reasoning about variation in the intensity of change in covarying quantities involved in rate of change

Abstract This paper extends work in the area of quantitative reasoning related to rate of change by investigating numerical and nonnumerical reasoning about covarying quantities involved in rate of change via tasks involving multiple representations of covarying quantities. The findings suggest that by systematically varying one quantity, an individual could simultaneously attend to variation in the intensity of change in a quantity indicating a relationship between covarying quantities. The results document how a secondary student, prior to formal instruction in calculus, reasoned numerically and nonnumerically about covarying quantities involved in rate of change in a way that was mathematically powerful and yet not ratio-based. I discuss how coordinating covariational and transformational reasoning supports attending to variation in the intensity of change in quantities involved in rate of change.
Density functional calculation of p K(a) values and redox potentials in the bovine Rieske iron-sulfur protein.

The redox potential of the Rieske iron-sulfur protein depends on pH. It has been proposed that the histidines coordinating one of the irons are responsible for this pH dependence, but an experimental proof for this proposal is still lacking. In this work, we present a density functional/continuum electrostatics calculation of the pK a values of the histidines in the Rieske iron-sulfur center. The calculated apparent pK a values are 6.9 and 8.8 in the oxidized state, which are in good agreement with the corresponding experimental values of 7.5 and 9.2 and the measured pH dependence of the redox potential. Neither of these two pK a values can, however, be assigned to only one of the histidines. We find that both histidines titrate over a wide pH range in the oxidized state. Reduction of the iron-sulfur center shifts the pK a values to 11.3 and 12.8, thus above 10.0 as found experimentally. The results provide a complete picture of the coupling of proton and electron binding, showing strongly cooperative binding of protons at electrode potentials near the redox midpoint potential of the cluster. The potential biological function of the low pK a value of the histidines and the shift upon reduction are briefly discussed. Electronic supplementary material to this paper (comprising tables with the partial charges of the Rieske iron-sulfur cluster, optimized geometries of the 12 different states, and pK 1/2 values for the non-coordinating residues of the Rieske protein in the oxidized and reduced state) can be obtained by using the Springer Link server located at http://dx.doi.org/10.1007/s00775-002-0342-6.
Structural analogue for determination of post–tensioning forces in a cable stayed bridge

Structural model investigations require fewer simplifying assumptions and can thus be a more realistic aid to design than computations. A suitable model investigation is described and results are compared with computation.
Toxicity of water-soluble gasoline fractions to fourth-instar larvae of the mosquito Aedes aegypti L.

Abstract The toxicity of water-soluble components of gasoline to laboratory-reared fourth-instar larvae of the mosquito, Aedes aegypti (L.) was investigated. A median lethal dose (LD50) and a non-lethal dose (NLD) were established for these larvae following a 24 h exposure to water-soluble fractions of benzene, toluene, and xylenes. Based on the actual amount of each component in solution, static toxicity/bioassays showed that acute toxicity of these monoaromatics increased in the sequence benzene, toluene, xylenes. However, toxicity increased in the sequence xylenes, benzene, toluene when results were examined with respect to the amount of aromatic added to water to produce the LD50. The importance of determining the concentrations of compounds dissolved in water when conducting any investigation of biological effects of water pollutants is stressed.
Infant categorization of containment, support and tight‐fit spatial relationships

Two experiments examined infant categorization of containment, support or tight-fit spatial relationships. English-learning infants of 10 months (Experiment 1) and 18 months (Experiment 2) were habituated to four pairs of objects in one of these relationships. They were then tested with one event from habituation, one with novel objects in the familiar relationship, one with familiar objects in a novel relationship and one with novel objects in a novel relationship. Infants at both ages generalized their habituation of the containment relationship to novel objects in this relationship. In the support and tight-fit conditions, the younger infants responded only to the novel objects in the test while the older infants responded to the novel relationship, but only with familiar objects. The results indicate that infants learn to categorize containment prior to support or tight-fit relationships and suggest that infants can recognize a relationship between familiar objects prior to novel objects.
Systematic risk over various frequency bands: An empirical analysis of returns on size-ranked portfolios

Abstract This paper finds negative risk premia for market betas obtained from some of the high frequency components of portfolio returns and value weighted market returns. The size effect is likely to be more pronounced for the high frequency components.
Utility of preoperative ultrasound for predicting pN2 or higher stage axillary lymph node involvement in patients with newly diagnosed breast cancer.

OBJECTIVE. The objective of our study was to report the positive predictive value (PPV) of ultrasound of the axilla to predict pN2 or higher disease in breast cancer patients. MATERIALS AND METHODS. A retrospective study of 559 patients with newly diagnosed invasive breast cancer from 2005 through 2009 was performed. All patients underwent ipsilateral axillary ultrasound for staging purposes. Ultrasound findings were considered suspicious for metastasis if cortical thickening or nonhilar blood flow to the cortex was present. Suspicious lymph nodes were classified on the basis of their features as high, intermediate, or low suspicion. The standard of truth was confirmed pathologically. RESULTS. Either pN2 or pN3 disease was found in 50 of 181 (28%) patients with positive findings on an ultrasound study and 10 of 378 (3%) patients with a negative ultrasound study (p < 0.01). When two or more lymph nodes of high suspicion or a total of three or more lymph nodes of any combination of high suspicion and interm...
The influence of flip angle on the magic angle effect.

Objective. To assess the impact of flip angle with gradient sequences on the ”magic angle effect”. We characterized the magic angle effect in various gradient echo sequences and compared the signal- to-noise ratios present on these sequences with the signal-to-noise ratios of spin echo sequences.
The practicability of new endpoint measures in pulmonary hypertension trials.

Dear Editor, I read with interest the thoughtful article by Hassoun et al.1 titled “Updating clinical endpoint definitions.” One of the primary tasks in my role as a pulmonary hypertension (PH) research nurse coordinator is to identify PH patients in our clinic who are eligible and willing to participate in research studies. This is not always an easy task. As Hassoun et al. point out in their article, PH studies historically have run 12 weeks, requiring several hundred patients, based on a primary endpoint of 6-minute walk distance (6-MWD) test, an endpoint which has fallen out of vogue in the PH community. More recent studies have used morbidity/mortality as primary endpoint. These types of studies require very large numbers of patients (some 1,000 or more) and take many years, some five or more years, to complete. At the recent American Thoracic Society meeting in Philadelphia, vocal PH experts declared this endpoint the be-all-end-all solution to future PH studies. The worrisome scenario that comes to my mind is that in the near future, when a truly novel and potentially curative agent comes to phase II/III testing, there will be no eligible, willing, and available PH patients left to enroll because most will be committed to years-long morbidity/mortality trials. Given the rarity of PH, requiring morbidity/mortality outcomes for all clinical trials may have the unintended consequence of suppressing innovation of novel therapies in the field, thereby reducing any progress in this disease. Progress will come to a slow crawl. While I do not claim to have the answer for what should be the best endpoint of study, I suggest that there could be a compromise between a historic 12-week outcome measure like the 6-MWD test and a multiyear outcome measure like morbidity/mortality. Practicability ought to be taken into account. I can only hope that regulatory agencies, along with the PH physician community and pharmaceutical companies, consider recruitment implications and keep the best interest of the PH patient in mind when determining the future of drug trial design in this patient population.
Outcome following intracranial hemorrhage associated with novel oral anticoagulants

The emergence of dabigatran, rivaroxaban and apixaban has changed the approach to anticoagulation for patients worldwide. Continued approval of novel oral anticoagulants (NOAC) for non-valvular atrial fibrillation and venous thromboembolism will result in increasing use of these medications over warfarin. Morbidity and mortality of anticoagulant related intracranial hemorrhage (ICH) is relatively high and there is concern that outcomes may be worse with NOAC as there is a lack of specific antidotes for these agents with a greater risk for hematoma expansion. Unfortunately, the evidence supporting effective reversal strategies is lacking. Therefore, to gain further insight into the outcome after the management of NOAC related ICH, we present our experience with two patients with NOAC-induced ICH.
Numerical simulations and backscattering enhancement of electromagnetic waves from two-dimensional dielectric random rough surfaces with the sparse-matrix canonical grid method

Numerical simulations exhibiting backscattering enhancement of electromagnetic waves from two-dimensional dielectric random rough surfaces (three-dimensional scattering problem) are presented. The Stratton–Chu surface integral equation formulation is used with the method of moments to solve for the tangential and normal components of surface fields. The solution of the matrix equation is calculated efficiently by using the sparse-matrix canonical grid (SMCG) method. The accuracy of the solution is assessed by comparing the bistatic scattering coefficients obtained from the SMCG and the matrix inversion method. Also, a sufficient sampling rate is established with respect to the dielectric constant below the rough-surface boundary. Numerical simulations are illustrated for moderate rms heights of 0.2 and 0.5 electromagnetic wavelengths with rms slopes of 0.5 and 0.7. The magnitude of the relative permittivity ranges from 3 to 7. With use of the SMCG method, scattered fields from a surface area of 256 square wavelengths (98,304 surface unknowns) are found. For a rms height of 0.5 wavelength and a correlation length of 1.0 wavelength, backscattering enhancement is observed in both co-polarization and cross polarization. However, in the case in which the rms height is 0.2 wavelength and the correlation length is 0.6 wavelength, backscattering enhancement is observed in cross polarization only.
Diagnostic tunica vaginoscopy in a rodent model of testicular torsion

Abstract Objectives To evaluate the effectiveness of percutaneous endoscopy of the tunica vaginalis for identifying testicular torsion in a rodent model. Methods One testis was randomly selected in 10 Wistar rats weighing 500 to 600 g. Following 2 hours of 720 ° torsion, bilateral percutaneous endoscopy of the tunica vaginalis was performed by a blinded investigator utilizing a 70 ° cystoscope lens through a single midline 3 to 4 mm scrotal cutdown incision. Results Using this technique, the blinded investigator was able to identify the torsed testis rapidly in every case, which was distinguished by its cyanotic color and by the size and color of the testicular surface vessels. Conclusions Tunica vaginoscopy is a simple, accurate, rapidly performed, minimally invasive, diagnostic technique in this experimental model of testicular torsion.
Spectroscopy of heavy elements in stars.

A brief history is given of astronomical observations of the spectra of heavy elements in stars, with emphasis on those elements produced by slow capture of neutrons in the stellar interior. As an example, an abundance analysis of the electrons zirconium through ruthenium, including the unstable element technetium, is described. Schemes for explaining the presence of technetium (probably 99Tc with a half-life of 2 × 105 years) and the presence of niobium (formed by decay of 93Zr with a half-life of 1.5 × 106 years) are discussed. The importance of radioactive decay of technetium from an excited nuclear state is stressed.
Effects of Jack Pine Plantation Management on Barrens Flora and Potential Kirtland's Warbler Nest Habitat

Jack pine barrens, once common in northern lower Michigan, mostly have been converted to managed jack pine plantations. Management of the disturbances associated with logging provides the opportunity to maintain the unique plant assemblages of jack pine barrens and nest habitat of the federally endangered Kirtland's warbler. Studies indicate that Carex pensylvanica can develop into dense mats and strongly compete with other barrens species such as Vaccinium angustifolium, which seem to be important species for Kirtland's warbler nest locations. According to forest managers, the most important factors facilitating high cover of V. angustifolium and reducing cover of C. pensylvanica are the amount of shade produced by tree crowns before harvest (pre-harvest shade), the length of time between harvest and planting (planting delay), and fire. We found that high or low levels of pre-harvest shade had no effect on cover of either V. angustifolium or C. pensylvanica. Planting delays of at least three years following prescribed burns generally increased cover of V. angustifolium in forest plots, which are important for warbler nesting. Analysis of community composition in openings indicated that burning enhanced the growth of barrens species. We found only weak evidence for a negative correlation between the cover of V. angustifolium and C. pensylvanica on our study sites. The openings created in the jack pine plantation are important refugia for barrens flora that would likely be lost under forests managed strictly for jack pine. Maintenance of jack pine barrens flora and Kirtland's warbler nest habitat is possible within the context of a heavily managed forest plantation system.
Sciatic nerve lesions during cardiac surgery

Sciatic nerve lesions occur only rarely in cardiac surgery patients. To evaluate potential causes for sciatic neuropathy, we reviewed the cardiac surgery performed at one institution during the last 15 years and found only six instances of sciatic neuropathy. We examined medical records for these six patients for potential etiologic factors and determined that four of the six patients had undergone prolonged periods of intra-aortic balloon pump therapy with a catheter placed through the femoral artery ipsilateral to the sciatic nerve lesion, and the other two patients had an ipsilateral femoral artery occlusion. In addition, four of the six patients had severe symptomatic peripheral vascular disease, and one of the other patients had severe and prolonged perioperative hypoxia. Although all these patients had pure sciatic neuropathy clinically, two of the four patients studied with electromyography had evidence of damage to the femoral nerve or quadriceps muscles ipsilaterally. In addition to the neurogenic changes, there were electromyographic findings suggestive of muscle ischemia. These results indicate that patients undergoing cardiac surgery may be at risk for development of a sciatic neuropathy if they have compromised blood flow through the femoral artery together with another cause for tissue hypoxia. Furthermore, asymptomatic ischemia of the femoral nerve or quadriceps muscles may occur in this clinical setting.
Minimizing total area of low-voltage SRAM arrays through joint optimization of cell size, redundancy, and ECC

The increasing power consumption of processors has made power reduction a first-order priority in their design. Voltage scaling is one of the most successful power-reduction techniques introduced to date, but it is limited to some minimum voltage, VDDMIN, below which all components cannot operate reliably. In particular, ever-increasing process variability due to shrinking feature size further degrades the low-voltage reliability of, e.g., SRAM cells. Larger SRAM cells are less sensitive to process variability and their use would allow a reduction in VDDMIN. However, large-scale memory structures, e.g., last-level caches (LLCs) that often determine the VDDMIN of processors, cannot afford to use such large SRAM cells due to the resulting increase in die area. In this paper we propose a joint optimization of LLC cell size, number of redundant cells, and ECC (error-correction coding) strength to minimize total SRAM area while meeting target yields and VDDMIN. The use of redundant cells and ECC enable the use of smaller cell sizes while maintaining target yields and VDDMIN. Smaller cell sizes more than make up for the extra cells required by redundancy and ECC. We first assess each approach individually, i.e., only redundancy or ECC for various cell sizes. We then consider a combined approach and observe significant improvements. For example, in 32nm technology our combined approach yields a 27% reduction in total SRAM area (including redundant cells) when targeting a VDDMIN of 600mV.
Regulation of Phospholipase C-β Activity by Phosphatidic Acid: Isoform Dependence, Role of Protein Kinase C, and G Protein Subunits†

Phosphatidic acid (PA) stimulates phospholipase C-beta(1) (PLC-beta(1)) activity and promotes G protein stimulation of PLC-beta(1) activity. The isoform dependence for PA regulation of PLC-beta activity as well as the role of PA in modulating regulation of PLC-beta activity by protein kinase C (PKC) and G protein subunits was determined. As compared to PLC-beta(1), the phospholipase C-beta(3) (PLC-beta(3)) isoform was less sensitive to PA, requiring greater than 15 mol % PA for stimulation. PLC-beta(3) bound weakly to PA. PKC had little effect on PA stimulation of PLC-beta(3) activity. PKC, however, inhibited PA stimulation of PLC-beta(1) activity through a mechanism dependent on the mol % PA. Stimulation by 7.5 mol % PA was completely inhibited by PKC. Increasing the PA and Ca(2+) concentration attenuated PKC inhibition. The binding of PLC-beta(1) to PA containing phospholipid vesicles was also reduced by PKC, in a manner dependent on the mol % PA. PA increased the stimulation of PLC-beta(1) activity by G alpha q but had little effect on the stimulation by beta gamma subunits. These results demonstrate that PA stimulation of PLC-beta activity is tightly regulated, suggesting the existence of a distinct PA binding region in PLC-beta(1). PA may be an important component of a receptor mediated signaling mechanism that determines PLC-beta(1) activation.
Co-occurrence patterns among Australian centropagid copepods

Data sets from existing limnological surveys carried out on Australian zooplankton communities are examined, and co-occurrences of species in the centropagid copepod genera Boeckella and Calamoecia are tabulated. One experiment to determine the extent of mating errors among four species of Boeckella is performed. The data are examined with respect to the hypotheses that mating errors of similar sized copepods preclude co-occurrence and that competition for resources by similar size species preclude occurrence. It is concluded that neither hypothesis is valid, instead, that co-occurrence patterns among these Australian centropagids are a function of dispersal and colonization ability, and that zooplankton species composition in Australian lakes and ponds is probably in a state of disequilibrium.
Pharmacological dissociation of modulatory effects of serotonin in Aplysia sensory neurons

In the mollusk Aplysia the neurotransmitter serotonin (5HT) has a fundamental modulatory role in several forms of learning and memory that involve an increase in the efficacy of synaptic transmission between tail sensory neurons (SNs) and motor neurons. The classical 5HT antagonist cyproheptadine (CYP) permits dissociation of three forms of serotonergic modulation in these SNs: (i) CYP reversibly blocks spike-broadening induced either by exogenous application of 5HT or by sensitizing stimulation of a tail nerve. (ii) CYP does not block 5HT-induced or tail input-induced increases in SN somatic excitability. (iii) Concomitant with its block of spike-broadening, CYP reversibly blocks 5HT-induced facilitation of synaptic transmission from SNs. These results suggest that endogenously released 5HT may act at different receptor subtypes that are coupled to different forms of neuromodulation in tail SNs of Aplysia.
The detection of nitrated tyrosine in neuropeptides: a MALDI matrix-dependent response.

Neuropeptides are a diverse class of signaling molecules that typically have one or more posttranslational modifications. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is an effective tool for identification and characterization of neuropeptides from samples as small as individual neurons. However, the detection of one particular posttranslational modification—nitrotyrosine—has been problematic because of the lability of the nitro group of nitrotyrosine under MALDI-MS conditions. The detection of nitrated tyrosine in peptide standards was dependent on the MALDI matrix used for the analysis. Specifically, sinapinic acid was the optimum matrix tested to observe this modification while it was not consistently detected with matrices such as 2,5-dihydroxybenzoic acid. Using the optimized procedures, several identified nitric-oxide-synthase positive neurons from Lymnaea stagnalis were tested to determine if the neuropeptides present were nitrated. In all cases, the nitrated form of the neuropeptide was not observed. The dependence on the sample-preparation procedures of observing this particular chemical modification demonstrates the need for careful selection of sample-preparation methods with MALDI or the use of other ionization methods.
How to Teach to the Child When the Stakes Are High: Examples of Implementing Developmentally Appropriate and Culturally Relevant Practices in Prekindergarten

The landscape of publicly funded early education in the U.S. has changed significantly. For instance, policy makers have increased access to such programs as prekindergarten, and at the same time, required these programs to align their goals and practices with those found in K–12 education systems. Other changes include increased cultural and linguistic diversity among children attending these programs. Such transformations have created new challenges for early educators as they strive to meet their children's developmental, individual, and cultural needs. This in turn has affected the field of early childhood teacher education. Teacher educators are trying to address these issues by providing their students with meaningful coursework and field experiences, but putting such components in place can be difficult. This article addresses this issue by developing a case study of how three exemplar pre-K teachers met these challenges in teaching a diverse population of children in a high-stakes context. Through...
Film cooling with helium injection into an incompressible air flow

Abstract An experimental study of film cooling effects produced by injection of a helium secondary flow into a low speed air mainstream is presented. The helium was injected through a porous section into a turbulent boundary layer flowing over a flat plate. For comparison, measurements were also made using air as the secondary fluid. The adiabatic wall temperature, presented in a dimensionless group known as the film cooling effectiveness, was measured for both helium and air secondary flows. The experimental data are compared with predictions. It is found that helium injection produces higher film cooling effectiveness than anticipated. The measured helium concentration along the wall is in relatively good agreement with predictions. Temperature and helium concentration profiles are also presented. The concentration and temperature profiles are very similar and in good agreement with profiles measured with air injection.
Carotenoids as possible interphotoreceptor retinoid-binding protein (IRBP) ligands: A surface plasmon resonance (SPR) based study

Abstract Uptake, transport and stabilization of xanthophylls in the human retina are important components of a complex multistep process that culminates in a non-uniform distribution of these important nutrients in the retina. The process is far from understood; here, we consider the potential role of interphotoreceptor retinoid-binding protein (IRBP) in this process. IRBP is thought to facilitate the exchange of 11- cis -retinal, 11- cis -retinol and all -trans -retinol between the retinal pigment epithelium (RPE), photoreceptors and Muller cells in the visual cycle. Structural and biochemical studies suggest that IRBP has a variety of nonequivalent ligand binding sites that function in this process. IRBP is multifunctional, being able to bind a variety of physiologically significant molecules including fatty acids in the subretinal space. This wide range of binding activities is of particular interest because it is unknown whether the lutein and zeaxanthin found in the macula originate from the choroidal or retinal circulations. If from the choroidal circulation, then IRBP is a likely mediator for their transport across the interphotoreceptor matrix. In this report, we explore the binding interactions of retinoids, fatty acids, and carotenoids with IRBP using surface plasmon resonance (SPR)-based biosensors. IRBP showed similar affinity toward retinoids and carotenoids (1–2 μM), while fatty acids had approximately 10 times less affinity. These results suggest that further studies should be carried out to evaluate whether IRBP has a physiologically relevant role in binding lutein and zeaxanthin in the interphotoreceptor matrix.
Semiconductor Lifetime as a Function of Recombination State Density

The analysis of the Shockley-Read model is extended to describe the transient behaviour. The results are compared with those already given by Fan and by Rittner, and it is concluded that the latter cease to be valid at high recombination state densities. The relation between steady state and transient measurements of photoconductivity is examined, and. some numerical examples are presented.
QRS Duration Widening: Reduced Synchronization of Endocardial Activation or Transseptal Conduction Time?

Antegrade activation of the His-Purkinje system (HPS) results in synchronized activation of the right ventricular (RV) and left ventricular (LV) endocardia forming normal, narrow QRS duration (QRSD). An alteration in septal activation and transseptal conduction time have been reported to be the causes for QRSD widening seen with bundle branch block. However, reduced synchronization of activation of RV and LV endocardia as another potential mechanism for QRSD widening has not been systematically studied. Fifteen consecutive patients underwent radiofrequency ablation (RFA) for treatment of supraventricular tachycardia. After RFA, mean QRSD in normal sinus rhythm was 86 +/- 8 ms with mean HV interval of 40 +/- 5 ms. Right atrial (RA), coronary sinus (CS), simultaneous (S) RA-CS, RV apex (RVA), LV apex (LVA), and SRVA-LVA pacing were performed. Mean QRSD with RA, CS, SRA-CS pacing was similar to normal sinus rhythm (87 +/- 7, 87 +/- 8 and 88 +/- 8 ms respectively). Mean QRSD was significantly longer with SRVA-LVA and either RVA or LVA pacing alone compared to normal sinus rhythm (106 +/- 8, 146 +/- 12 and 157 +/- 13 ms, respectively). However, QRSD was significantly shorter with SRVA-LVA pacing compared to either RVA or LVA pacing alone (P < 0.0001). We conclude that shorter QRSD with SRVA-LVA pacing compared to either RVA or LVA pacing alone is due to elimination of transseptal conduction delay; longer QRSD with SRVA-LVA pacing compared to sinus or atrial paced rhythm is due to reduced synchronization of endocardial activation secondary to ectopic entry of impulses into the HPS network and inability to take advantage of the branching structure of the HPS. Therefore, in addition to transseptal conduction delay, reduced synchronization of endocardial activation is another potential mechanism for QRSD widening.
Specific release of proteoglycans from human natural killer cells during target lysis

Natural killer (NK) activity is mediated by a small population of peripheral blood cells that exhibit the homogeneous morphology of large granular lymphocytes (LGL). In recent studies, human NK cell clones have been shown to contain a 200,000-Mr (relative molecular mass) protease-resistant chondroitin sulphate A proteoglycan, which has been localized to the secretory granule by X-ray dispersive analysis and by its resistance to cleavage by extracellular addition of chondroitinase AC or ABC (ref. 7). In the present study, we have used six different human NK cell clones to demonstrate that release of 35S-proteoglycan correlates closely with cytolytic activity against various NK cell targets. When NK activity is blocked by monoclonal antibodies at either the effector cell level (LFA-1) or at the target cell level (TNKTAR), there is a concomitant decrease in exocytosis of proteoglycan. Monoclonal antibodies directed against recognition structures, for example anti-NKTa and anti-T3 (ref. 10), function as soluble stimuli, capable of initiating the release of 35S-proteoglycan. Taken together, these results provide strong evidence for the stimulus-specific release of chondroitin sulphate A proteoglycans from NK cells when the cytolytic process is activated.
Resident cataract surgical training in United States residency programs

A comprehensive survey was sent to the residency directors of 129 ophthalmology training programs in the United States. Forty percent of residents gained experience as primary surgeon during their first year; 43% performed only part of the surgery. Seventy-three percent began learning cataract extraction using the extracapsular cataract extraction (ECCE) technique, 24% began with phacoemulsification, and 2% began with either method. If beginning with ECCE, 18% must have completed more than 10 before moving to phacoemulsification, 37% more than 5, and 45% more than 1. Seventy-five percent learned various phacoemulsification techniques; 25% learned only 1 technique. If beginning with 1 technique, 44% began with the scleral tunnel combined with divide and conquer. Sixty-four percent learned phacoemulsification on the Alcon Legacy, 21% on the Alcon Legacy and Storz Millennium, and 6% on the Storz Millennium. Sixty-eight percent of residents rotated out of their main facility to perform cataract surgery. The mean and median number of cataract procedures a resident completed by the end of training was 113 and 100, respectively.
Experimental compressions for sodium, potassium, and rubidium metals to 20 kbar from 4.2 to 300 K

Experimental piston-displacement equations of state are given for sodium, potassium, and rubidium to 20 kbar for temperatures from 4 K to just below the melting line in each case. Except for sodium at high pressures, where the low-temperature bcc-hcp martensitic transition appears to cause problems, these data can be represented by a room-temperature pressure-volume reference function and a thermal pressure which is a function of temperature only. In addition, these three solids appear to obey a reduced equation of state at both 4 K and room temperature, for which $\frac{V}{{V}_{0}}$ is a common function of $\frac{P}{{B}_{0}}$. A modification of the second-order Murnaghan equation which is well behaved at large compressions is used to extrapolate these results to 40 kbar for comparison with higher-pressure, room-temperature results. These data are compared with other high-pressure equation-of-state experiments and are extrapolated to $P=0$ to obtain thermal expansions and isothermal bulk moduli, which in turn are compared with results from other measurements. These comparisons and those with theoretical calculations show, on the whole, satisfactory agreement. The elementary form for the temperature-dependent equation of state is in agreement with a previous suggestion that the Gr\"uneisen parameter is temperature independent and is a linear function of the volume for temperatures greater than the Debye temperature. The 295-K Gr\"uneisen parameters for these solids, as deduced from the high-pressure results, are 1.24 for sodium and potassium and 1.26 for rubidium.
Diurnal patterns in PM2.5 mass and composition at a background, complex terrain site

Abstract Current fine particle NAAQS specify 24 h integrated mass measurements as the compliance metric. However, the value of continuous short-time resolution sampling (1 h or less) is recognized and being included in US EPA-monitoring strategies. An extensive body of fine mass concentration data has been acquired using continuous PM2.5 monitoring by TEOM at Look Rock, TN, augmented by trace gas measurements and, during enhanced monitoring periods, continuous sampling for aerosol sulfate (2 methods) and elemental (black) carbon. Continuous data are compared to the 24 h-averaged values of mass and composition from integrated samplers at the site, and for fine mass and sulfate are found to be excellent ( r 2 = 0.97 – 0.99 ). We then report the diurnal variations in concentrations from extensive continuous monitoring during 3 summer periods (2000–2002) and for more limited periods throughout calendar year 2001. Levels of the several continuously measured gases and particulate constituents vary in magnitude diurnally according to expected patterns based on their emissions, their formation and loss processes, their lifetimes toward wet and dry deposition, the dynamics of up-slope—down-slope circulation, and solar-driven boundary layer growth and decay. Thus, concentrations of short-lifetime gases have minima at sunrise and maxima in the evening. Long-lived primary species (CO and black carbon) increase in mid-morning as the boundary layer height reaches the site and decay thereafter. Long-lived secondary species (sulfate and fine mass) show little diurnal variability. Factors controlling the observed diurnal variability thus significantly influence the extent and timing of human exposure to pollutant species, as well as affecting visibility impairment in complex terrain environments near the Great Smoky Mountains National Park.
Phase transitions of ethylene on graphite.

The results of an extensive thermodynamic study of the phase transitions of monolayer and multilayer ethylene on graphite are presented. In the submonolayer and near-monolayer completion regions, the melting transition is found to be continuous. Heat-capacity anomalies indicative of orientational and structural transitions of monolayer solid phases are found. Our result indicates the existence of a third monolayer solid phase in addition to the low- and high-density phases defined according to the orientation of the carbon-carbon axis of the molecule with respect to the substrate surface. In the multilayer region, our result is consistent with the interpretation that the wetting transition is pinned at ${T}_{t}$, the bulk triple-point temperature, and it is approached via a sequence of layering transitions. Liquidlike ethylene film is found to be layered by the graphite substrate well above ${T}_{t}$. The layer critical point ${T}_{c}$(m), the high-temperature limit where a film of m-1 layers coexists with that of m layers, is found to decrease towards ${T}_{t}$ with increasing m. The monolayer-bilayer layer-critical-point transition is found to be two-dimensional Ising-like. The isotopic effects in two-dimensional orientational, melting, and liquid-vapor transitions were also studied in this experiment.
Simulation studies on the origin of the limiting conversion phenomenon in hybrid miniemulsion polymerization

Abstract Hybrid systems of acrylic monomers are studied as they undergo miniemulsion free radical polymerization in the presence of unsaturated alkyd resins. The goal of such polymerizations is to induce grafting between the acrylic and alkyd components, which would retard microdomain phase separation, and produce materials with the crosslinking capability of alkyd coatings (normally applied from a solvent system) with the environmental and cost benefits of an aqueous system. In this paper, the observed limiting monomer conversion phenomenon will be explored via simulation studies. Two mathematical models describing the kinetics of bulk hybrid polymerization of an alkyd–acrylate system were developed. The first was a homogenous model in which the kinetics of retardive chain transfer was used to attempt to simulate the observed phenomenon of limiting conversion. The second model was a core–shell model in which polymerization takes place in an acrylic-rich shell, while the alkyd-rich core serves as a reservoir for acrylic monomer and alkyd. Based on the results from these models, the cause of limiting conversion was attributed to the combined role of the glass effect and the partitioning effect of the monomer into a core–shell system and its subsequent entrapment. Retardive chain transfer was not capable of producing the observed limiting conversion.
The Pharmacogenomics Journal: the official journal of the International Society of Pharmacogenomics (ISP)

The Pharmacogenomics Journal : the official journal of the International Society of Pharmacogenomics (ISP)
A dynamic approach to diffusion and permeation measurements

A dynamic method for investigating the mechanism of permeation and diffusion through polymers has been explored. The permeation cell consists of two compartments separated by the membrane. The permeant (gas, vapor, or liquid) is introduced into one compartment; a carrier gas (helium) flows at constant rate through the other and sweeps the permeant which diffuses through the membrane to the thermal conductivity detector. Both compartments are at atmospheric pressure; thus no or little membrane support is required, and leakage problems are minimal. Moreover, the same membrane can be used over a wide temperature range and for diverse permeants. The detector signal is at any instant proportional to the permeation rate. A simple mathematical formalism for deriving the diffusion coefficient from the transient permeation rates has been developed. The measured diffusion and permeability coefficients of CO2, O2, and N2 through low-density polyethylene closely agree with literature values. Permeation of hexane and benzene through polyethylene follows a complex diffusion law, and the rate depends on the thermal history of the system. The dynamic method is particularly suited to the study of transitions in polymers. Changes in permeation rates, usually occurring at transition points, can easily be discovered by slow temperature scanning of the system.
PEA APHID–PARASITOID INTERACTIONS: HAVE PARASITOIDSADAPTED TO DIFFERENTIAL RESISTANCE?

In insect host-parasitoid systems, successful immune responses of the host kill the parasitoid, and successful development of the parasitoid will kill the host. Thus, hosts and their parasitoids can exert strong selection on each other that may lead to the coevolution of host defense traits and parasitoid counter-defenses. In upstate New York, pea aphids (Acyrthosiphon pisum) specialized on alfalfa are, on average, two times more physiologically resistant to parasitism by Aphidius ervi parasitoids than pea aphids spe- cialized on clover. There is genetic variation within populations of Aphidius ervi in the ability to overcome pea aphid resistance; thus an evolutionary response to the differences in aphid resistance is possible. Here, I document that pea aphid populations that are more resistant to parasitism in laboratory assays exhibit lower rates of parasitism in the field, suggesting that the genetically based differences in aphid resistance may influence rates of successful parasitism. I found that the difference in resistance between pea aphids spe- cialized on alfalfa or on clover in New York is present in additional populations of pea aphids assayed over several years and is present in Maryland as well as New York. However, despite the potentially large difference in selective regimes due to differences in aphid resistance, parasitoids collected from alfalfa fields and clover fields do not differ in their ability to overcome pea aphid resistance. There is no evidence that they are adapted to aphids from their home crop, or locally adapted to aphids from their home field. The mobility of this parasitoid, and its relatively recent introduction to North America as a biological control agent, may contribute to the lack of adaptation.
Learning topics and related passages in books

The number of books available online is increasing, but user interfaces may not be taking full advantage of advances in machine learning techniques that could help users navigate, explore, discover and understand interesting and useful content in books. Using a group of ten students and over one thousand crowdsourced judgments, we conducted multiple user studies to evaluate topics and related passages in books, all learned by topic modeling. Using ten books, selected from humanities (e.g. Plato's Republic), social sciences (e.g. Marx's Capital) and sciences (e.g. Einstein's Relativity), and four different evaluation experiments, we show that users agree that the learned topics are coherent and important to the book, and related to the automatically generated passages. We show how crowdsourced evaluations are useful, and can complement more focused evaluations using students who have studied the texts. This work provides a framework for (1) learning topics and related passages in books, and (2) evaluating those learned topics and passages, and moves one step toward automatic annotation to support topic navigation of books.