cssi/SciSciGPT-SciSciNet huggingface dataset:
Reaction path of protein farnesyltransferase at atomic resolution

Protein farnesyltransferase (FTase) catalyses the attachment of a farnesyl lipid group to numerous essential signal transduction proteins, including members of the Ras superfamily1. The farnesylation of Ras oncoproteins, which are associated with 30% of human cancers, is essential for their transforming activity2. FTase inhibitors are currently in clinical trials for the treatment of cancer2,3,4. Here we present a complete series of structures representing the major steps along the reaction coordinate of this enzyme. From these observations can be deduced the determinants of substrate specificity and an unusual mechanism in which product release requires binding of substrate, analogous to classically processive enzymes. A structural model for the transition state consistent with previous mechanistic studies was also constructed. The processive nature of the reaction suggests the structural basis for the successive addition of two prenyl groups to Rab proteins by the homologous enzyme geranylgeranyltransferase type-II. Finally, known FTase inhibitors seem to differ in their mechanism of inhibiting the enzyme.
Night-time observations of snow using visible imagery

Consideration is given to the possibility of increasing the frequency of satellite snow cover observations in the visible range by using the light reflected off the moon as an illumination source for nighttime observations. Images obtained at night by DMSP satellites orbiting in the noon-midnight plane are presented which were obtained at various phases of the moon. It is concluded that DMSP visible imagery can be used to detect snow cover during those periods when the moon is over the local horizon and is between the first quarter phase and the last quarter phase, which amounts to around five additional days a month allowing for cloud cover. The high frequency of observation of a given area provided by a light-sensitivity imager would be an important feature of a dedicated water-resources satellite.
CYTOKININ- AND GIBBERELLIC ACID-INDUCED EFFECTS ON THE STRUCTURE AND METABOLISM OF SHOOT APICAL MERISTEMS IN OPUNTIA POLYACANTHA (CACTACEAE)

The dormant axillary buds of Opluntia polyacanithla can be activated by either cytokinins or gibberellic acid. Under the influence of benzylaminopurine (BAP), the axillary bud meristem increases greatly in size and becomes mitotically active. The primordia produced by the meristem develop as normal photosynthetic leaves. Gibberellic acid (GA) also causes the meristem to become mitotically active, but the meristem does not increase in size. The primordia produced under the influence of GA develop as normal cactus spines. Leaf-producing meristems and spine-producing meristems have the same zonation, despite the differences in size. The meristems are composed of a uniseriate tunica, a central mother cell zone, peripheral zone, and a pith rib meristem. The mitotic activity of each of the zones in the leaf-producing meristem differs significantly from the mitotic activity of the corresponding zones in the spineproducing meristeni.
Characterization of polygalacturonase from the brown-rot fungus Postia placenta

Two extracellular isoenzymes of polygalacturonase, isolated from the brown-rot fungus Postia placenta, were purified 342-fold by Mono S cation-exchange chromatography. The temperature optimum ranged from 25 °C to 37 °C, and the pH optimum ranged from 3.2 to 3.9. Apparent pI values of the isoenzymes (3.2 and 3.4) were lower than any previously reported. The estimated molecular mass from a single band on sodium dodecyl sulfate/polyacrylamide gel electrophoresis (PAGE) was 34 kDa. Isoenzymes of polygalacturonase in native PAGE and isoelectric focusing gels were identified by substrate/ agar overlays (zymograms). Comparison of viscosity reduction rates with release of reducing sugars indicated that the enzyme from P. placenta is endo-acting. The objective of this study was to isolate polygalacturonase from the brown-rot fungus P. placenta and characterize the properties of the enzyme.
Receptor mechanisms in increased sensitivity to serotonin agonists after dihydroxytryptamine shown by electronic monitoring of muscle twitches in the rat

Muscle twitches and autonomic changes were induced by systemic injections of L-5-hydroxytryptophan (5-HTP) or the serotonin agonist 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) in rats previously lesioned with intracranial 5,7-dihydroxytryptamine (5,7-DHT) after desmethylimipramine. Movements were recorded sensitively and continuously by an electronic activity monitor. Spontaneous locomotor activity was strongly reduced after 5-HTP in both intact and lesioned rats, so that electronically recorded activity correlated very closely with disordered jerking movements scored by a behavioral rating scale. This myoclonus was dependent on the doses of 5-HTP and of 5,7-DHT and was strongly inhibited by serotonin antagonists. In lesioned rats, myoclonus occurred with unaltered activity of monoamine oxidase (MAO) and after only small increases in serotonin levels after 5-HTP, but even large increases in availability of serotonin in intact rats, or strong inhibition of serotonin uptake failed to induce myoclonus unless MAO was first inhibited. The response to 5-HTP in lesioned rats was attenuated by repeated injections of 5-HTP or 5-MeO-DMT. This decreased response was in turn blocked by repeated doses of a serotonin antagonist, but appeared not to be due to altered metabolism of 5-HTP or of serotonin; repeated pretreatment with cyproheptadine potentiated the myoclonic response to 5-HTP after DHT. Changes in postsynaptic receptors may be important in the behavioral supersentivity following 5,7-DHT, and restitution of serotonin or stimulation of its receptors after presynaptic denervation may suppress an evolving supersensitivity at receptive postsynaptic membranes.
Anastomotic calculus formation after side-to-side ureteroureterostomy in a patient with complete ureteral duplication.

Complete ureteral duplication, either unilateral or bilateral, occurs in approximately 1 of 334 individuals.1, 2 Hydronephrosis may occur with either moiety and is usually secondary to reflux into the lower pole moiety, while upper moiety obstruction is caused by urethral ectopia or a ureterocele. Surgical options for obstruction or reflux with complete ureteral duplication include common sheath reimplantation for functional renal segments and partial nephrectomy for nonfunctional segments. Ipsilateral end-to-side ureteroureterostomy is also an acceptable surgical modality in select patients. 3 We report on a patient who underwent ipsilateral ureteroureterostomy using a side-to-side anastomosis with subsequent calculus development at the anastomotic site. CASE REPORT
The suggestive properties of quantum mechanics without the collapse postulate

Everett proposed resolving the quantum measurement problem by dropping the nonlinear collapse dynamics from quantum mechanics and taking what is left as a complete physical theory. If one takes such a proposal seriously, then the question becomes how much of the predictive and explanatory power of the standard theory can one recover without the collapse postulate and without adding anything else. Quantum mechanics without the collapse postulate has several suggestive properties, which we will consider in some detail. While these properties are not enough to make it acceptable given the usual standards for a satisfactory physical theory, one might want to exploit these properties to cook up a satisfactory no-collapse formulation of quantum mechanics. In considering how this might work, we will see why any no-collapse theory must generally fail to satisfy at least one of two plausible-sounding conditions.
Designing a performance measurement system for a high technology virtual engineering team – a case study

Discusses the process and issues involved in developing a performance measurement system for a virtual engineering team working within a high technology environment. This team consists of members from many different sites across the world with a unique role in maintaining standardized manufacturing processes at the lowest possible cost. As a result, they faced many challenges including communication barriers, culture differences, as well as different reporting structures within each individual site. To help address these issues, a performance measurement system was developed to focus the team on the key actions affecting performance instead of the issues getting in the way. A measurement system was developed that linked the team’s objectives to its mission and identified the critical actions associated with each objective.
On the improvement of creep strength and ductility of Ni-20 pct Cr by small zirconium additions

The creep and fracture properties of high-purity Ni-20 pct Cr and Ni-20 pct Cr-0.11 pct Zr alloys are compared at 1073 K in vacuum. The Ni-20 pct Cr alloy cavitates at the grain boundaries and fractures intergranularly after strains of typically 20 pct. The observed cavity growth rates are in keeping with those predicted. Alloying with zirconium substantially increases the creep strength and ductility. Creep rupture associated with dynamic recrystallization occurs, and voids are observed only in heavily necked parts of the samples. In addition to Ni5Zr and ZrO2 inclusions, a Zr4C2S2 carbo-sulfide was identified. Thus, the sulfur-gettering effect of zirconium even at very low residual sulfur levels (20 wt ppm) was confirmed. The zirconium-induced increase in the creep strength is discussed, and the inhibition of creep cavitation by zirconium is examined within the framework of thermal cavity nucleation. Lowering of the grain boundary diffusivity and the grain boundary free energy as well as dynamic recrystallization are likely to reduce cavity nucleation and growth rates in Ni-Cr-Zr and will thus increase its ductility. Finally, the results are used to illustrate the critical importance of minor alloying additions in constructing and using fracture mechanism maps.
Association analysis of 33 lipoprotein candidate genes in multi-generational families of African ancestry.

African ancestry individuals have a more favorable lipoprotein profile than Caucasians, although the mechanisms for these differences remain unclear. We measured fasting serum lipoproteins and genotyped 768 tagging or potentially functional single nucleotide polymorphisms (SNPs) across 33 candidate gene regions in 401 Afro-Caribbeans older than 18 years belonging to 7 multi-generational pedigrees (mean family size 51, range 21–113, 3,426 relative pairs). All lipoproteins were significantly heritable (P 0.10), but the heritability for LDL cholesterol (LDL-C) was higher (P < 0.05) in men than in women (men, 0.79 ± 0.21, P < 0.01; women, 0.39 ± 0.12, P < 0.01). The top 14 SNPs that passed the false discovery rate threshold in the families were then tested for replication in an independent population-based sample of 1,750 Afro-Caribbean men aged 40+ years. Our results revealed significant associations for three SNPs in two genes (rs5929 and rs6511720 in LDLR and rs7517090 in PCSK9) and LDL-C in both the family study and in the replication study. Our findings suggest that LDLR and PCSK9 variants may contribute to a variation in LDL-C among African ancestry individuals. Future sequencing and functional studies of these loci may advance our understanding of genetic factors contributing to LDL-C in African ancestry populations.
Gender differences in HIV risk behaviors in an adult emergency department in New York City

Background The human immunodeficiency virus (HIV) epidemic in the US increasingly involved urban heterosexual adults, particularly women, belonging to ethnic minority groups. An understanding of gender-based differences in HIV risk behaviors within these groups would be of value in the ongoing struggle to limit HIV transmission in metropolitan centers.
Energy metabolism in rat hippocampus during and following seizure activity.

The hippocampus exhibits a post-ictal phenomenon in which it is unresponsive to further stimulation. It has been suggested that this loss of excitability is the basis of post-seizure amnesia. The biochemical events associated with this phenomenon are unclear. In the present study, energy metabolites were measured in the stratum oriens, stratum pyramidale and stratum radiatum in rat hippocampus, and correlated with field potential recordings. Wistar rats were anesthetized and the calvarium removed. Following removal of the cortex by aspiration, the hippocampus was covered with oil, and stimulating and recording electrodes were placed. Stimulation consisted of a train of stimuli at 100 Hz (10–20 m Amps). This stimulation was found to be effective in evoking self-sustaining after-discharges and post-ictal depression. Tissues for metabolite analysis were taken from a series of controls, from animals during active self-sustaining seizures, and from animals which were totally unresponsive to further electrical stimulation. Hippocampal tissue for metabolite analysis was obtained by pouring liquid N2 on the exposed tissue, then removing the frozen tissue. Glucose, ATP, and phosphocreatine were measured in hippocampal layers of CA1 using fluorescence techniques and enzymatic cycling. Results showed that during seizure activity, glucose, ATP, and phosphocreatine were all decreased from 40–80% in the three layers of the hippocampus, whereas from 60 seconds after the onset of hippocampal shutdown, energy metabolites had returned toward normal. Thus, at a time when the hippocampus was unresponsive, energy metabolites were at control levels. These data suggest that the shutdown phenomenon occurs in the presence of adequate energy stores.
Sex chromosomes of a pygopodid lizard, Lialis burtonis

Es wird erstmals uber den Karyotyp einer Eidechse der Familie Pygopodidae,Lialis burtonis mit dem GeschlechtschromosomensystemX 1 X 2 Y berichtet. Die diploide Chromosomenzahl des Mannchens ist 33 und diejenige des Weibchens 34. Morphologisch scheint der Karyotyp eine Ahnlichkeit mit demjenigen der Geckoniden zu besitzen.
Computerized characterization of breast masses using three-dimensional ultrasound images

Breast ultrasound can potentially increase the accuracy of computerized discrimination of malignant and benign masses. Newly developed 3D ultrasound techniques provide statistically richer information than conventional 2D ultrasound, and may therefore be better-suited for computerized statistical classification techniques. In this study, we investigated the feasibility of classifying solid breast masses using features extracted from 3D ultrasound images. Our data set consisted of seventeen biopsy-proven masses. Eight of the masses were malignant and nine were benign. The masses were identified by an experienced breast radiologist in the 3D volume, and a 3D ellipsoid containing the mass was defined. Spatial gray level dependence features were extracted from 2D slices in three regions, which were (1) the interior of the ellipse; (2) a disk-shaped region at the upper periphery of the ellipse; and (3) a disk-shaped region at the lower periphery of the ellipse. 2D analysis was performed by evaluating the classification accuracy of the features extracted from each slice. 3D analysis was performed by first averaging feature values from different slices into a single 3D feature, and then evaluating the classification accuracy. The best texture feature in this study achieved a classification accuracy of Az equals 0.97 for both 3D and 2D analysis. Our results indicate that the performance of 3D analysis is comparable to that of 2D analysis using the best available slice. Since the best 2D slice for texture analysis may not be known a-priori, this preliminary study suggests that 3D ultrasound may be beneficial for computerized breast mass characterization.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
The neurobiology of impulse control disorders

OBJETIVO: Revisar os artigos sobre substratos neurobiologicos dos transtornos do controle dos impulsos. O jogo patologico e o foco central desta revisao na medida em que a maioria dos estudos biologicos dos formalmente classificados como transtornos do controle dos impulsos examinou este transtorno. METODO: Foi feita uma busca no banco de dados Medline de artigos publicados de 1966 ate o presente para identificar aqueles relevantes para serem revisados neste artigo. DESFECHOS: Estudos pre-clinicos sugerem que a neuromodulacao das monoaminas cerebrais esta associada a tomada de decisoes impulsivas e aos comportamentos de risco. Os estudos clinicos implicam diversos sistemas de neurotransmissores (serotoninergico, dopaminergico, adrenergico e opioide) na fisiopatologia do jogo patologico e de outros transtornos do controle dos impulsos. Estudos de neuroimagem preliminares tem indicado o cortex pre-frontal ventromedial e o estriato ventral como atuantes na fisiopatologia do jogo patologico e de outros transtornos do controle dos impulsos. As contribuicoes geneticas para o jogo patologico parecem substanciais e os estudos iniciais tem relacionado esse transtorno a polimorfismos alelicos especificos, ainda que os achados de varredura genomica ainda tenham que ser publicados. CONCLUSAO: Mesmo que tenham sido logrados avancos significativos em nossa compreensao sobre os transtornos do controle dos impulsos, mais pesquisas sao necessarias para ampliar o conhecimento existente e traduzir esses achados em avancos clinicos.
New cytotoxic acridine alkaloids from two deep water marine sponges of the family

Abstract Fused ring alkaloids having the pyridol[4,3,2- mn ]acridine skeleton comprise a new class of marine natural products. 1a–h Their biological activity 1e and challenging structure elucidation make them an interesting group of compounds. In this paper we report the identification of four new cytotoxic and structurally related alkaloids: nordercitin ( 1 ), dercitamine ( 2 ), dercitamide ( 3 ), and cyclodercitin ( 4 ).
Influence of Three Concentrations of DL-Methionine or Methionine Hydroxy Analog on Milk Yield and Milk Composition

Sixty-eight Holstein cows were fed diets consisting of 60% concentrate and 40% forage, dry basis. Diets were supplemented with DL-methionine or methionine hydroxy analog at either 0, .1, .2, or .3% of the concentrate. Dietary protein averaged 14% of total dry matter on all diets except for a positive control diet, which was 19% crude protein. Data were collected beginning 4 d postpartum and continued through 116 d postpartum. Milk yield was not influenced by either DL-methionine or methionine hydroxy analog. Supplementation with DL-methionine resulted in a quadratic response in milk fat percentage (3.34, 3.58, 3.72, 3.42) at 0, .1, .2, and .3% of the concentrate, respectively. Milk fat percentage increased linearly (3.34, 3.64, 3.60, 3.73) with supplementation of methionine hydroxy analog at 0, .1, .2, and .3%, respectively.
Intraluminal calcium hydroxyapatite crystals in breast carcinoma: an ultrastructural study.

Sixty-three breast carcinomas were examined by electron microscopy to determine the frequency of calcium hydroxyapatite (apatite) within tumor lumina. Twenty-one adenocarcinomas contained apatite in intracytoplasmic and/or intercellular lumina. Well-differentiated tumors exhibited a higher incidence of apatite (44%), while only 20% of the poorly differentiated tumors contained apatite (7 = +.22). There was no apparent correlation between the presence of apatite and a positive estrogen receptor assay. Ninety-eight adenocarcinomas of other than breast origin (previously processed for electron microscopy) were examined, revealing 2 cases containing apatite in the appropriate locations. The tissue of origin in one case was determined to be ovarian, while the origin of the second case remains undetermined. The ultrastructural finding of apatite in lumina of adenocarcinoma appears to be unusual in that it has only been observed in breast carcinomas and certain ovarian tumors. The presence of apatite within the ...
Studies on sweating and bacterial ecology in Juvenile Plantar Dermatosis

Summary The role of sweating and the surface bacterial flora were studied in 34 patients with Juvenile Plantar Dermatosis (JPD), and in 51 control patients. In 11 patients with JPD the spatial distribution of active sweat ducts was abnormal. Affected areas on the big toes of children with JPD were hypohidrotic and the number of visible sweat duct openings was Reduced, Sweating was studied quantitatively in 26 patients with JPD and 20 normal controls. No increase or decrease in sweat retention could be demonstrated in JPD patients compared to controls. No difference was found in bacterial counts from the plantar surfaces of the big toes in any of three groups—34 JPD Patients, six patients with atopic eczema (with normal feet) and 21 normal controls. It is unlikely that the hypohidrosis seen in affected areas of the feet of patients with JPD is due to miliaria induced by occlusive footwear, but probably is a phenomenon which results from the dermatosis itself.
Ab Initio Study of Polycyclic Aromatic Hydrocarbons in Their Ground and Excited States

Both ground- and excited-state ab initio calculations are reported for four polycyclic aromatic hydrocarbons (PAHs): pyrene, benzo(a)pyrene, fluoranthene, and benzo(b)fluoranthene. Ground-state geometries, IR frequencies, excitation energies, changes in excited-state electron distributions, excited-state geometries, and excited-state frequencies are calculated and quantitatively compared to experimental data. Overall agreement with experiment is quite good, with the largest discrepancies occurring when predicting the excitation energies of the molecules. Changes in electron density correlate with changes in the excited-state geometry, with all PAHs lengthening along their axis of polarization upon excitation. These calculations are also used to examine characteristic differences between the alternant (pyrene and benzo(a)pyrene) and nonalternant (fluoranthene and benzo(b)fluoranthene) PAHs. Relative to their alternant isomers, nonalternant PAHs tend to possess higher ground-state energies, lower relative ...
Searching for build debt: experiences managing technical debt at Google

With a large and rapidly changing codebase, Google software engineers are constantly paying interest on various forms of technical debt. Google engineers also make efforts to pay down that debt, whether through special Fixit days, or via dedicated teams, variously known as janitors, cultivators, or demolition experts. We describe several related efforts to measure and pay down technical debt found in Google's BUILD files and associated dead code. We address debt found in dependency specifications, unbuildable targets, and unnecessary command line flags. These efforts often expose other forms of technical debt that must first be managed.
Recognition, evaluation, and treatment of anaphylaxis in the child care setting.

Background Anaphylaxis can occur anywhere. Many young children with a history of allergic reactions or anaphylaxis spend considerable time in child care centers. However, little is known about the centers' knowledge of, experience with, and capability to manage anaphylaxis. Objective To evaluate the ability of child care centers to recognize, evaluate, and treat anaphylactic episodes in children aged 1 to 6 years. Methods Eighty-five child care centers in the suburbs of Chicago were randomly selected. They were contacted by telephone and asked to participate in a study by completing an initial questionnaire. Center directors and teachers were then offered an allergy seminar addressing anaphylaxis avoidance, recognition, evaluation, and treatment. Center directors completed a questionnaire after the seminar. Results Forty-four of the 85 centers contacted agreed to participate. Forty-two surveys were completed before the seminar and 39 after the seminar. On average, each center has up to 7 children with an identifiable food allergy. Information provided by the parents was the most commonly reported source of education concerning allergies. Before seminar completion, only 24% of child care centers would administer intramuscular epinephrine for a severe allergic reaction. After the seminar, 77% of centers stated that they would administer intramuscular epinephrine ( P Conclusions There is a need for greater anaphylaxis education among child care providers. Our intervention significantly increased the ability of child care staff to recognize, evaluate, and treat anaphylaxis.
TGFβ2 and TGFβ3 Have Separate and Sequential Activities during Epithelial–Mesenchymal Cell Transformation in the Embryonic Heart

Heart valve formation is initiated by an epithelial-mesenchymal cell transformation (EMT) of endothelial cells in the atrioventricular (AV) canal. Mesenchymal cells formed from cardiac EMTs are the initial cellular components of the cardiac cushions and progenitors of valvular and septal fibroblasts. It has been shown that transforming growth factor beta (TGFbeta) mediates EMT in the AV canal, and TGFbeta1 and 2 isoforms are expressed in the mouse heart while TGFbeta 2 and 3 are expressed in the avian heart. Depletion of TGFbeta3 in avian or TGFbeta2 in mouse leads to developmental defects of heart tissue. These observations raise questions as to whether multiple TGFbeta isoforms participate in valve formation. In this study, we examined the localization and function of TGFbeta2 and TGFbeta3 in the chick heart during EMT. TGFbeta2 was present in both endothelium and myocardium before and after EMT. TGFbeta2 antibody inhibited endothelial cell-cell separation. In contrast, TGFbeta3 was present only in the myocardium before EMT and was in the endothelium at the initiation of EMT. TGFbeta3 antibodies inhibited mesenchymal cell formation and migration into the underlying matrix. Both TGFbeta2 and 3 increased fibrillin 2 expression. However, only TGFbeta2 treatment increased cell surface beta-1,4-galactosyltransferase expression. These data suggest that TGFbeta2 and TGFbeta3 are sequentially and separately involved in the process of EMT. TGFbeta2 mediates initial endothelial cell-cell separation while TGFbeta3 is required for the cell morphological change that enables the migration of cells into the underlying ECM.
Self-Perceived Development Needs of Today's Middle Managers.

The need to develop new skills among middle managers has been increasing since the early 1990s. This need arises from the changes in the workplace environment associated with the realities of downsizing, the quality movement, and the increased use of teams. This article reports on the experience of one downsized, quality‐conscious, team‐based organization in identifying the development needs of its middle managers. The process used by the case study organization to identify the development needs among its middle managers is outlined. This process can be seen as an example of how development needs can be identified. The findings from the identification process within the case study organization present an initial list of development needs among today’s middle managers. Recommendations on training courses for middle management development are proposed. These recommendations provide initial guidance to organizations interested in developing their middle management assets.
Sexual health of homeless youth: prevalence and correlates of sexually transmissible infections

Background: The study examined risk factors for having ever contracted sexually transmissible infections (STI) among a high-risk sample in midwestern USA. Methods: A cross sectional survey was conducted among 428 homeless youth aged 16–19 years. Assessed correlates included child maltreatment, street exposure, sexual histories, street experiences and substance use. Results: Multivariate analyses revealed that males were 86% less likely to have had STI compared with females (adjusted odds ratio [AOR] = 0.14; 95% confidence interval [CI] = 0.06–0.31). Blacks were almost four times more likely (AOR = 3.71; 95% CI = 1.80–7.63) and other races were over two times more likely (AOR = 2.25; 95% CI = 1.08–4.67) to have had STI compared with whites. For every one unit increase in the number of times youth ran away, there was a 3% increase in the likelihood of ever having had an STI (AOR = 1.03; 95% CI = 1.01–1.06). For every one unit increase in frequency of condom use there was a 61% decrease in the likelihood of an STI (AOR = 1.39; 95% CI = 1.10–1.76). Finally, youth who traded sex were approximately 2.5 times more likely to have had STI compared with youth who did not trade sex (AOR = 2.36; 95% CI = 1.04–5.34). None of the remaining correlates approached multivariate significance. Conclusions: The amount of time youth spend on the street, their sexual practices, and their subsistence strategies are important correlates of STI and females and non-whites are particularly vulnerable among this high-risk population.
Photoluminescence in Analysis of Surfaces and Interfaces

Photoluminescence (PL) is the spontaneous emission of light from a material under optical excitation. The excitation energy and intensity are chosen to probe different regions and excitation concentrations in the sample. PL investigations can be used to characterize a variety of material parameters. PL spectroscopy provides electrical (as opposed to mechanical) characterization, and it is a selective and extremely sensitive probe of discrete electronic states. Features of the emission spectrum can be used to identify surface, interface, and impurity levels and to gauge alloy disorder and interface roughness. The intensity of the PL signal provides information on the quality of surfaces and interfaces. Under pulsed excitation, the transient PLintensity yields the lifetime of nonequilibrium interface and bulk states. Variation of the PL intensity under an applied bias can be used to map the electric field at the surface of a sample. In addition, thermally activated processes cause changes in PL intensity with temperature. PL analysis is nondestructive. Indeed, the technique requires very little sample manipulation or environmental control. Because the sample is excited optically, electrical contacts and junctions are unnecessary and high-resistivity materials pose no practical difficulty. In addition, time-resolved PL can be very fast, making it useful for characterizing the most rapid processes in a material. The fundamental limitation of PL analysis is its reliance on radiative events. Materials with poor radiative efficiency, such as low-quality indirect bandgap semiconductors, are difficult to study via ordinary PL. Similarly, identification of impurity and defect states depends on their optical activity. Although PL is a very sensitive probe of radiative levels, one must rely on secondary evidence to study states that couple weakly with light.
The effects of textual enhancement type on L2 form recognition and reading comprehension in Spanish

Previous research investigating the effectiveness of textual enhancement as a tool to draw adult second language (L2) learners’ attention to the targeted linguistic form has consistently produced m...
Detritivory in neotropical fish communities

Fish communities of major river systems in South America contain a high proportion of detritivorous fishes in the families Prochilodontidae and Curimatidae. These families include important fish stocks that in some regions comprise over 50 percent of the community ichthyomass. As a group, detritivores have anatomical-physiological adaptations for collection and digestion of detritus, but the actual mechanisms of these presumed adaptations have to-date only been inferred. Dietary requirements have not been identified. Behavioral adaptation is implied by feeding habitat selection but its nutritional significance is unknown. Because many of these species have commercial importance, and because ongoing construction of impoundments threatens to disrupt seasonal migrations between spawning and feeding areas, an understanding of the feeding biology of detritivores is important.
Sculpting the Bacterial Cell

Prokaryotes come in a wide variety of shapes, determined largely by natural selection, physical constraints, and patterns of cell growth and division. Because of their relative simplicity, bacterial cells are excellent models for how genes and proteins can directly determine morphology. Recent advances in cytological methods for bacteria have shown that distinct cytoskeletal filaments composed of actin and tubulin homologs are important for guiding growth patterns of the cell wall in bacteria, and that the glycan strands that constitute the wall are generally perpendicular to the direction of growth. This cytoskeleton-directed cell wall patterning is strikingly reminiscent of how plant cell wall growth is regulated by microtubules. In rod-shaped bacilli, helical cables of actin-like MreB protein stretch along the cell length and orchestrate elongation of the cell wall, whereas the tubulin-like FtsZ protein directs formation of the division septum and the resulting cell poles. The overlap and interplay between these two systems and the peptidoglycan-synthesizing enzymes they recruit are the major driving forces of cylindrical shapes. Round cocci, on the other hand, have lost their MreB cables and instead must grow mainly via their division septum, giving them their characteristic round or ovoid shapes. Other bacteria that lack MreB homologs or even cell walls use distinct cytoskeletal systems to maintain their distinct shapes. Here I review what is known about the mechanisms that determine the shape of prokaryotic cells.
Effects of decomposition and storage conditions on the δ13C and δ15N isotope values of killer whale (Orcinus orca) skin and blubber tissues

Several different factors in the collection and preservation of whale skin and blubber samples were examined to determine their effect on the results obtained by stable nitrogen and carbon isotope (δ15N and δ13C) analysis. Samples of wet killer whale skin retained their original stable isotope values for up to 14 d at 4°C or lower. However, decomposition significantly changed the δ15N value within 3 d at 20°C. Storage at −20°C was as effective as −80°C for the preservation of skin and blubber samples for stable isotope analysis for at least a year. By contrast, once a skin sample had been freeze-dried and lipid extracted, the stable isotope values did not change significantly when it was stored dry at room temperature for at least 12 mo. Preservation of whale skin samples for a month in DMSO-salt solution, frozen or at room temperature, did not significantly change the δ15N and δ13C values of lipid extracted tissues, although the slight changes seen could influence results of a study if only small changes are expected.
Borderline low conus medullaris on infant lumbar sonography: what is the clinical outcome and the role of neuroimaging follow-up?

Isolated borderline low conus medullaris is a frequent finding on screening lumbar sonography of unknown significance that often prompts further imaging and clinical follow-up. To determine the clinical outcome and utility of follow-up neuroimaging in infants with isolated borderline low conus on lumbar sonography. We reviewed 748 consecutive spinal sonograms identifying infants with conus terminating between L2-L3 disc space and mid-L3 level without other findings of tethered cord. We excluded infants with conditions associated with developmental delay and those who passed away, and compared the age of gross motor milestone achievement to normal ranges. Follow-up imaging was reviewed. Isolated borderline low conus was found in 90 of 748 infants (12%) on sonography. Seventy of those infants met inclusion criteria. Follow-up imaging in 11 children (10 MRI, 1 sonogram), showed change in conus position to “normal” level in 10, no change in 1, and no new findings within lumbar spine. Clinical follow-up was available in 50 of 70 (71%) children meeting inclusion criteria, with normal motor milestones met in all 50 children. Isolated borderline low conus is a common finding in infants who meet normal developmental milestones suggesting that follow-up evaluation has little utility and is likely unwarranted.
Morphine Decreases Enteric Neuron Excitability via Inhibition of Sodium Channels

Gastrointestinal peristalsis is significantly dependent on the enteric nervous system. Constipation due to reduced peristalsis is a major side-effect of morphine, which limits the chronic usefulness of this excellent pain reliever in man. The ionic basis for the inhibition of enteric neuron excitability by morphine is not well characterized as previous studies have mainly utilized microelectrode recordings from whole mount myenteric plexus preparations in guinea pigs. Here we have developed a Swiss-Webster mouse myenteric neuron culture and examined their electrophysiological properties by patch-clamp techniques and determined the mechanism for morphine-induced decrease in neuronal excitability. Isolated neurons in culture were confirmed by immunostaining with pan-neuronal marker, β-III tubulin and two populations were identified by calbindin and calretinin staining. Distinct neuronal populations were further identified based on the presence and absence of an afterhyperpolarization (AHP). Cells with AHP expressed greater density of sodium currents. Morphine (3 µM) significantly reduced the amplitude of the action potential, increased the threshold for spike generation but did not alter the resting membrane potential. The decrease in excitability resulted from inhibition of sodium currents. In the presence of morphine, the steady-state voltage dependence of Na channels was shifted to the left with almost 50% of channels unavailable for activation from hyperpolarized potentials. During prolonged exposure to morphine (two hours), action potentials recovered, indicative of the development of tolerance in single enteric neurons. These results demonstrate the feasibility of isolating mouse myenteric neurons and establish sodium channel inhibition as a mechanism for morphine-induced decrease in neuronal excitability.
The Simian Virus 40 Core C Enhancer-like Element Is a Positive Regulator in the Rat α1BAdrenergic Receptor Gene Proximal Promoter

Abstract Transcription of the rat α1Badrenergic receptor (α1BAR) gene is controlled by three promoters (P1, P2, and P3), which generate 2.3-, 2.7-, and 3.3-kb transcripts, respectively. The expression of the 2.3-kb mRNA species is tissue-specific. To explore the underlying mechanism, the P1 promoter was analyzed. DNase I footprinting of the P1 promoter yielded three protected regions: P1f1(−49 to −62); P1f2 (−73 to −90), and P1f3 (−95 to −115). Sequence analysis of P1f3 revealed the presence of an SV40 core C enhancer-like element. In gel mobility shift assays, P1f3 was found to bind a sequence specific protein, which was competed away by a SV40 core C enhancer consensus oligonucleotide. Mutations of this enhancer-like core sequence within P1f3 significantly reduced specific protein binding to P1f3 and inhibited P1 promoter activity. The distribution of the protein which binds to P1f3 is restricted. These findings suggest that the P1 promoter is controlled by a cell-type-specific transcription factor, which may account for the tissue-specific expression of 2.3-kb rat α1BAR mRNA species.
Highly elliptical orbit satellites better at observing high-latitude CO2

Boreal forests have a significant influence on the global carbon cycle. Arctic permafrost holds about twice the amount of carbon as the Earth's atmosphere. Since the boreal and Arctic region (50°N–90°N) has experienced the largest temperature increases in recent decades, understanding its influence on the global carbon cycle will become increasingly important as the climate continues to warm.
Flow during droplet separation

Abstract Flow patterns inside a separating droplet were measured by following the motion of particles which wore suspended within the droplet. For the four systems investigated, the velocity was independent of radial position and there was no internal circulation during separation. The magnitude of the velocity of the suspended particles relative to the velocity of the apex of the droplet showed that internal fluid motion probably has little influence on the shape of the profile during separation. The experimental velocity curves were approximated by an exponential function using a non-linear least squares analysis.
Soil Permittivity Response to Bulk Electrical Conductivity for Selected Soil Water Sensors

Bulk electrical conductivity (σ a ) can dominate the low frequency dielectric loss spectrum in soils, causing changes in the permittivity and errors in estimated water content. We examined the dependence of measured apparent permittivity ( K a ) on σ a in contrasting soils using time-domain reflectometry (TDR), a digital time-domain transmission (TDT) sensor, and a capacitance sensor (5TE) during near saturated solute displacement experiments. Sensors were installed in columns packed with fine sand or a clay loam soil. Displacement experiments were completed by first equilibrating columns with 0.25 dS m −1 CaCl 2 , introducing a step pulse of ∼4.7 dS m −1 CaCl 2 and, after equilibration, displacing the resident solution with 0.25 dS m −1 CaCl 2 . Using TDR, measured K a increased with increasing σ a ; however, the slope of this response averaged 3.47 m dS −1 for clay loam compared with 0.19 m dS −1 for sand. The large response in the clay loam was attributed to relaxation losses that narrowed the effective bandwidth from 821 to an estimated 164 MHz. In contrast, the effective frequency in sand averaged 515 MHz. Permittivity measured using the TDT probe exhibited little or no sensitivity to σ a ( −1 ) in both media. Measured K a using the 5TE probe declined with increasing σ a up to 1 to 1.8 dS m −1 and then increased thereafter with net negative responses for sand (Δ K a /Δσ a = −3.1 m dS −1 ) and net positive responses for the clay loam (Δ K a /Δσ a = 2.9 m dS −1 ). Consideration of the K a –σ a response is required for accurate soil water content estimation (±0.03 m 3 m −3 ) in the presence of solution EC variations using TDR in fine-textured soils or the 5TE sensor in all media. Large differences in the sampling volumes between 5TE-measured bulk EC and permittivity confounded the K a –σ a response in the presence of a concentration gradient.
Growth and characterization of germanium and boron doped silicon epitaxial films

The epitaxial growth and characterization of in-situ germanium and boron (Ge/B) doped Si epitaxial films is described. As indicated by secondary ion mass spectroscopy and spreading resistance measurements, the total and electrically activated B concentrations are essentially identical and independent of Ge incorporation. The B and Ge concentrations are uniformly distributed in these Ge/B doped films. A slight enhancement of Hall mobility is obtained, possibly due to the stress relief induced by Ge counterdoping. Carrier conduction in these films is due to the activated B with an activation energy of 0.04 eV as revealed by conductivity versus temperature measurements. Ge atoms appear to be isoelectronic with Si atoms in these films. A slight degradation of minority carrier diffusion length is observed. Electrical characterization of PN diodes on these Ge/B doped films do not reveal any anomaly. SiO2 on these Ge/B doped films has similar oxide fixed charge density, interface state density and dielectric breakdown strength compared to silicon dioxide on boron doped epitaxial films. Electron injection reveals a different transport mechanism of the SiO2 grown on these Ge/B doped films.
On Ulm’s method using divided differences of order one

We provide new sufficient convergence conditions for the semilocal convergence of Ulm’s method (Tzv Akad Nauk Est SSR 16:403–411, 1967) in order to approximate a locally unique solution of an equation in a Banach space setting. We show that in some cases, our hypotheses hold true but the corresponding ones in Burmeister (Z Angew Math Mech 52:101–110, 1972), Kornstaedt (Aequ Math 13:21–45, 1975), Moser (1973), and Potra and Ptak (Cas Pest Mat 108:333–341, 1983) do not. We also show that under the same hypotheses and computational cost, finer error bounds can be obtained. Some error bounds are also shown to be sharp. Numerical examples are also provided further validating the results.
Postnatal growth of the sheep lung: A morphometric study

Stereologic methods were used to study lung development in sheep from 2 to 171 days of age. Most growth occurs within the first 2 months when there is a threefold increase in lung volume, but allometric relationships show that this increase does not keep pace with body weight. Alveolar and capillary surface areas increase as lung volume to a power only slightly larger than 1, suggesting a modest increase in complexity; this is confirmed by only a two- to threefold increase in total alveolar number. Allometric power functions are essentially unchanged even during the first 30 days so that throughout development, the surface for gas exchange is added at a fairly constant rate. A slight increase in septal volume during the first 30 days is probably due to relative increase in capillary luminal volume through a progressive distension of capillaries. The results suggest that the active newborn lamb requires an alveolar lung, but in the postnatal period functional needs increase only moderately. In contrast, other mammals, such as the rat, are helpless as newborns and have a primitive saccular lung that must undergo considerable morphogenesis to meet the demands of the active adult.
Diagnosis of amyotrophic lateral sclerosis

This review of the differential diagnosis of amyotrophic lateral sclerosis focuses on two themes. The first is practical, how to establish the diagnosis based primarily on clinical findings buttressed by electrodiagnosis. The main considerations are multifocal motor neuropathy and cervical spondylotic myelopathy. The second theme is the relationship of motor neuron disease to other conditions, including benign fasciculation (Denny-Brown, Foley syndrome), paraneoplastic syndromes, lymphoproliferative disease, radiation damage, monomelic amyotrophy (Hirayama syndrome), as well as an association with parkinsonism, dementia and multisystem disorders of the central nervous system.
Stable carbon isotope biogeochemistry of a shallow sand aquifer contaminated with fuel hydrocarbons

Abstract Ground-water chemistry and the stable C isotope composition (δ 13 C DIC ) of dissolved inorganic C (DIC) were measured in a sand aquifer contaminated with JP–4 fuel hydrocarbons. Results show that ground water in the upgradient zone was characterized by DIC content of 14–20 mg C/L and δ 13 C DIC values of −11.3‰ to −13.0‰. The contaminant source zone was characterized by an increase in DIC content (12.5 mg C/L to 54 mg C/L), Ca, and alkalinity, with a significant depletion of 13 C in δ 13 C DIC (−11.9‰ to −19.2‰). The source zone of the contaminant plume was also characterized by elevated levels of aromatic hydrocarbons (0 μg/L to 1490 μg/L) and microbial metabolites (aromatic acids, 0 μg/L to 2277 μg/L), non-detectable dissolved O 2 , NO 3 and SO 4 . Phospholipid ester-linked fatty acid analyses suggest the presence of viable SO 4 -reducing bacteria in ground water at the time of sampling. The ground-water chemistry and stable C isotope composition of ground-water DIC are interpreted using a chemical reaction model involving rainwater recharge, contributions of CO 2 from soil gas and biodegradation of hydrocarbons, and carbonate dissolution. The major-ion chemistry and δ 13 C DIC were reconciled, and the model predictions were in good agreement with field measurements. It was concluded that stable C isotope measurements, combined with other biogeochemical measures can be a useful tool to monitor the dominant terminal electron-accepting processes in contaminated aquifers and to identify mineralogical, hydrological, and microbiological factors that affect δ 13 C of dissolved inorganic C.