cssi/SciSciGPT-SciSciNet huggingface dataset:
Volunteering as an Equalizer: A Quasi-Experimental Study Using Propensity Score Analysis

Introduction Formal volunteering in later life is beneficial for both physical and psychological well-being. However, research points to potential selection bias because older adults with key advantages, such as wealth, are more likely to volunteer and reap its benefits. Accordingly, this study addresses this selection bias by considering the characteristics of volunteers and nonvolunteers using the inverse probability of treatment weighting. It also examines whether volunteering has differential impacts between the highest and lowest wealth quintiles using inverse probability of treatment weighting. Methods Data were analyzed from the 2004–2016 waves of the Health and Retirement Study (N=90,881). The weights, created using a machine learning method, were incorporated in the analysis to estimate the treatment effects along with relevant covariates. Analyses were conducted in 2020. Results Volunteering enhanced self-reported health and reduced depressive symptoms in the full sample. Furthermore, those in the lowest wealth quintile experienced significantly better self-reported health from volunteering than their wealthy counterparts. Volunteering was associated with fewer depressive symptoms regardless of wealth status. Conclusions The study enhances the understanding of formal volunteering and health while suggesting that volunteers with low wealth may benefit more from volunteering in terms of their health. Hindrances to volunteering among the least wealthy, such as financial distress, discrimination, or lack of organizational support, may attenuate the benefits of voluntary activity.
Potentially Traumatic Events and the Association Between Gender Minority Stress and Suicide Risk in a Gender-Diverse Sample

Transgender and gender diverse (TGD) individuals are at an elevated risk of trauma exposure and other negative mental and physical health outcomes. The present study examined the interaction between minority stressors, reported potentially traumatic events (PTEs), and suicide risk (i.e., ideation and behavior) in a TGD sample. A convenience sample of 155 self-identified TGD individuals completed questionnaires assessing distal (e.g., gender-related discrimination) and proximal (e.g., internalized transphobia) gender identity-related stressors, lifetime PTE history, and suicide risk. The results of a mediation analysis demonstrated that proximal stressors partially mediated the association between distal stressors and suicide risk, B = 1.12, t(152) = 3.72, p < .01, 95% CI [0.53, 1.72], and the results of a moderated mediation analysis showed that the interaction term was not significant, and that the number of PTEs did not moderate the mediation model that examined proximal stressors as a mediator of the association between distal stressors and suicide risk, F(3, 151) = 18.74, MSE = 0.75, R2 = 0.27, B = 0.07, t(151) = 0.89, p = .371, 95% CI [-0.08, 0.21]. These findings suggest that minority stressors may contribute to suicide risk in a TGD population above and beyond the impact of trauma exposure. Risk reduction efforts for suicide risk may be enhanced by attending to minority stressors in addition to PTEs.
Neurexin 1 (NRXN1) Splice Isoform Expression During Human Neocortical Development and Aging

Neurexin 1 (NRXN1), a presynaptic cell adhesion molecule, is implicated in several neurodevelopmental disorders characterized by synaptic dysfunction including autism, intellectual disability and schizophrenia. To gain insight into NRXN1's involvement in human cortical development we used quantitative real-time PCR to examine the expression trajectories of NRXN1, and its predominant isoforms, NRXN1-α and NRXN1-β, in prefrontal cortex from fetal stages to aging. In addition, we investigated whether prefrontal cortical expression levels of NRXN1 transcripts are altered in schizophrenia or bipolar disorder in comparison with non-psychiatric control subjects. We observed that all three NRXN1 transcripts were highly expressed during human fetal cortical development, markedly increasing with gestational age. In the postnatal dorsolateral prefrontal cortex, expression levels were negatively correlated with age, peaking at birth until ~3 years of age, after which levels declined markedly to be stable across the lifespan. NRXN1-β expression was modestly but significantly elevated in the brains of patients with schizophrenia compared with non-psychiatric controls, whereas NRXN1-α expression was increased in bipolar disorder. These data provide novel evidence that NRXN1 expression is highest in human dorsolateral prefrontal cortex during critical developmental windows relevant to the onset and diagnosis of a range of neurodevelopmental disorders, and that NRXN1 expression may be differentially altered in neuropsychiatric disorders.
Public Infrastructure Investment, Renewed Economic Growth, and the U.S. Fiscal Position

We show that large-scale debt-financed public infrastructure spending, in addition to (a) generating growth and employment on a similarly large scale and (b) significantly reducing inefficiency-generated public and private costs economy-wide, will also (c) be substantially “self-financing” by dint of the revenue gains that it likewise will generate. Not to pursue such projects now, moreover, with (a) labor, material, and financing costs at historic lows, and (b) cost-acceleration set to kick-in in the very near future, will itself occasion large-scale implicit costs. Insofar as these investments are agreed by all to be necessary at some point, now is that point.
Calibration and Vector Error Correction

Modern vector network analyzer (VNAs) can measure signals of high and low power with better precision than any other power sensor, and they can measure the gain across frequency of an electronic device with a performance traceable to measurements of physical dimensions. VNAs provide correction for both magnitude and phase responses, which is commonly called vector error correction. The VNA error correction process consists of two steps: the first step, called calibration, is to measure known standards to determine the systematic VNA error terms. This might be formally called error correction acquisition. The second step is measuring the device‐under‐test and applying the error correction algorithms to obtain a corrected result. This might be formally called error correction application. Correction of systematic errors of S‐parameter measurements in VNAs has been available for decades; the details of how the systematic errors affect the measurement results of a 2‐port S‐parameter measurement are presented.
The New Culture of Security Studies

The Culture of National Security: Norms and Identity in World Politics Edited by Peter J. Katzenstein
Active resource management for the differentiated services environment

This paper presents a mechanism for active resource management (ARM) in a differentiated services environment.. While the differentiated services architecture and the bandwidth broker agent provide a mechanism for QoS management through resource reservation, this mechanism is based on a static provisioning of resources. As bandwidth requirements are typically dynamic, such a static reservation approach can either lead to wasted bandwidth or leave applications resource-starved. The active resource management approach presented in this paper addresses this problem by dynamically, reallocating resources based on current network state and applications requirements. An implementation and evaluation of ARM using the NS-2 simulation toolkit is also presented.
Kinetics of silicalite-1 crystallization

Abstract Growth rates of silicalite-1 in combination with thermodynamic aspects of the aqueous chemistry of silica are used to evaluate two zeolite growth models. Analysis of a nanoparticle growth model indicates that, in its current state, the model does not adequately predict the effect of ionic strength and pH on growth rates. Preliminary studies of a monomer addition model based on solution chemistry, indicate the model is capable of quantitatively calculating growth rates as a function of temperature, pH, silica concentration, and ionic strength.
LeVine, Robert A

Robert LeVine's first work among the Gusii in Kenya, part of Beatrice and John Whiting's Six Culture study, prepared him for a life of prodigious fieldwork and theory building. He has returned to Kenya multiple times, and that research has been followed by work in Nigeria, Mexico, Nepal, Zambia, and Venezuela. “Bob” LeVine (b. 1932) began his graduate career at the University of Chicago, but left there in 1953 when he found no one to support his interest in psychological anthropology. The Kardiner and Linton seminars at Columbia were ending, and so LeVine chose Harvard University where he studied anthropology under Fred Eggan and psychoanalysis under David M. Schneider. Keywords: anthropology; cross-cultural psychology; ethnography; personality
Microtechnique for Indirect Immunofluorescence

A microtechnique for staining preparations of cells grown in vitro for indirect immunofluorescence tests is described. Smaller amounts of materials, as well as less handling of cover slips, greatly facilitates the process.
The state of water in rhyolitic glasses: A deuterium NMR study

The first application of ^2H NMR to the study of water in glasses is reported. Naturally occurring volcanic glass (Los Posos rhyolite) was autoclaved with D_2O to yield samples with total “D_2O” contents ranging from 1.6–4.8 wt%. Infrared results show that, in concordance with results from proton-containing glasses, the ratio of molecular D_2O to OD groups increases with increasing total “D_2O” content. Variable-temperature deuterium NMR spectra obtained at 11.7 T, using composite-pulse quadrupolar-echo pulse sequences, indicate the presence of two species with differing motional behavior. The species that is rigid over the entire temperature range investigated (173–393 K) is assigned to OD groups, and yields a powder pattern governed by a distribution of nuclear quadrupole coupling constants (NQCCs) and with a peak-to-peak splitting of ca. 160 kHz. The species that undergoes thermally activated motional processes in this temperature range is assigned to molecular D_2O. At room temperature, this species gives rise to a powder pattern characterized by a reduced quadrupole coupling constant and an asymmetry parameter (η) close to one, indicating that the D_2O molecules undergo twofold rotations about the bisector axis on a lime scale faster than ca. 10^(−5) s. Separation of both spectral components on the basis of their different spin-lattice relaxation times yields reasonable agreement with the D_2O/OD ratio determined from infrared spectroscopy. Lineshape changes at elevated temperatures suggest the activation of additional motional processes; however, even at 375 K only a minor fraction of isotropically mobile species is observed, indicating that “pools” of liquid-water do not exist in significant amounts in these glasses. Low-temperature studies indicate a gradual freezing-out of D_2O motion on the NMR time scale (ca. 10^(−5) s), resulting in a broad lineshape at 173 K governed by a distribution of NQCCs. The well-established correlation between the NQCC and the O-D ··· O distance, a measure of the hydrogen bonding strength, can be used to simulate the low-temperature ^2H NMR spectrum from an assumed distribution of O-D ··· O bond distances. The resultant spectrum, based on a distribution function obtained from independent IR data, is characterized by a mean NQCC of 223 kHz and is in good agreement with the experimental lineshape.
Visualization of entry flow separation for oscillating flow in tubes

Neutrally buoyant helium-filled soap bubbles with laser illumination are used to document entry flow separation for oscillating flow in tubes. For a symmetric entry case, the size of the separation zone appears to mildly depend on Reynolds number in the acceleration phase, but is roughly Reynolds number independent in the deceleration phase. For the asymmetric entry case, the separation zone was larger and appeared to grow somewhat during the deceleration phase. The separation zones for both entry geometry cases remain relatively small throughout the cycle. This is different from what would be observed in all-laminar, oscillator flows and is probably due to the high turbulence of the flow, particularly during the deceleration phase of the cycle.
Positive and negative transcriptional elements of the human type IV collagenase gene

Proteolysis by type IV collagenase (T4) has been implicated in the process of tumor metastasis. The T4 gene is expressed in fibroblasts, but not in normal epithelial cells, and its expression is specifically repressed by the E1A oncogene of adenovirus. We present an investigation of the transcriptional elements responsible for basal, E1A-repressible, and tissue-specific expression. 5'-Deletion analysis, DNase I footprinting, and gel mobility shift assays revealed a strong, E1A-repressible enhancer element, r2, located about 1,650 bp upstream of the start site. This enhancer bound a protein with binding specificity very similar to that of the transcription factor AP-2. A potent silencer sequence was found 2 to 5 bp downstream of this enhancer. The silencer repressed transcription from either r2 or AP-1 enhancer elements and in the context of either type IV collagenase or thymidine kinase (tk) gene core promoters; enhancerless transcription from the latter core promoter was also repressed. Comprising the silencer were two contiguous, autonomously functioning silencer elements. Negative regulation of T4 transcription by at least two factors was demonstrated. mcf-7 proteins specifically binding both elements were detected by gel mobility shift assays; a protein of approximately 185 kDa that bound to one of these elements was detected by DNA-protein cross-linking. The silencer repressed transcription, in an r2 enhancer-tk promoter context, much more efficiently in T4-nonproducing cells (mcf-7 or HeLa) than in T4-producing cells (HT1080), suggesting that cell type-specific silencing may contribute to the regulation of this gene.
Backbiting and bloodshed in books: Short-term effects of reading physical and relational aggression in literature

The current research consisted of two studies examining the effects of reading physical and relational aggression in literature. In both studies, participants read one of two stories (containing physical or relational aggression), and then participated in one of two tasks to measure aggression. In Study 1, participants who read the physical aggression story were subsequently more physically aggressive than those who read the relational aggression story. Conversely, in Study 2, participants who read the relational aggression story were subsequently more relationally aggressive than those who read the physical aggression story. Combined, these results show evidence for specific effects of reading aggressive content in literature.
Characterization of the proto-oncogene pim-1: kinase activity and substrate recognition sequence.

Abstract The human pim -1 proto-oncogene was expressed in Escherichia coli as a glutathione- S -transferase (GST)-fusion protein and the enzymatic properties of its kinase activity were characterized. Likewise, a Pim-1 mutant lacking intrinsic kinase activity was constructed by site-directed mutagenesis (Lys 67 to Met) and expressed in E. coli . In vitro assays with the mutant Pim-1 kinase showed no contaminating kinase activity. The wild-type Pim-1 kinase-GST fusion protein showed a pH optimum of 7 to 7.5 and optimal activity was observed at either 10 m m MgCl 2 or 5 m m MnCl 2 . Higher cation concentrations were inhibitory, as was the addition of NaCl to the assays. Previous work by this laboratory assaying several proteins and peptides showed histone H1 and the peptide Kemptide to be efficiently phosphorylated by recombinant Pim-1 kinase. Here we examine the substrate sequence specificity of Pim-1 kinase in detail. Comparison of different synthetic peptide substrates showed Pim-1 to have a strong substrate preference for the peptide LysArgArgAlaSer ∗ GlyPro with an almost sixfold higher specificity constant k cat K m over that of the substrate Kemptide (LeuArgArgAlaSer ∗ LeuGly). The presence of basic amino acid residues on the amino terminal side of the target Ser/Thr was shown to be essential for peptide substrate recognition. Furthermore, phosphopeptide analysis of calf thymus histone H1 phosphorylated in vitro by Pim-1 kinase resulted in fragments containing sequences similar to that of the preferred synthetic substrate peptide shown above. Therefore, under optimized in vitro conditions, the substrate recognition sequence for Pim-1 kinase is (Arg/ Lys) 3 -X-Ser/Thr ∗ -X′, where X′ is likely neither a basic nor a large hydrophobic residue.
Skepticism and the Question of Community

Analyse de la notion de communaute interrogative et de la forme de scepticisme ironique qui engendre et maintient son existence, a la lumiere des definitions hermeneutique (Gadamer) et liberale (Rawls) de la vie communautaire, d'une part, et de la conception de l'hyperdialectique de Merleau-Ponty, fondee sur les notions de raison et d'etre, d'autre part
SECTION – a computer program for the graphic display of cross sections through a unit cell

SECTION is a 32-bit Microsoft Windows-based program that displays cross-sectional slices through a packed crystal structure. Unit-cell dimensions as well as the unique atomic positions and symmetry operations are read from SHELX instruction files.
Nonempirical ab initio MODPOT, VRDDO, and MODPOT/VRDDO calculations. X. The attack of the simplest ultimate carcinogen, CH3+, on guanine by a MERGE technique and a possible fundamental difference between methylating versus ethylating ultimate carcinogens

Ab initio MODPOT/VRDDO/MERGE SCF calculations have been carried out for the attack of CH3+ on O6 and N7 of guanine (for both planar and pyramidal CH3+). There are minima in the potential energy surfaces at about 3 bohr. As expected, there is a crossing of the potential energy surfaces for planar and pyramidal CH3+ attack at ca. 3.5–3.75 bohr, since at the dissociation asymptote CH3+ planar is more stable, but attached to guanine CH3+ pyramidal would be more stable. The most interesting and fundamental finding from our calculations was not anticipated in advance. CH3+ + guanine is an ion-molecule reaction. In ion-molecule reactions if the reactants A+ + B are higher in energy at the asymptote than A + B+, then there will be a crossing or avoided crossing of the potential energy surfaces of A+ + B and of A + B+. In our SCF calculations of CH3+ + guanine at about 5.0 bohr there began a mixing of electronic configurations. This indicated that the ionization potential of guanine (which had not previously been reported as measured experimentally) had to be lower than that of CH3+, 9.8 eV. Unpublished photoelectron spectra of Le Breton indicated that the ionization potential of guanine was ca. 8.3 eV. The ionization potential of the methyl radical is higher than that of all the DNA bases, and thus there will be mixing of potential energy surfaces. Only ab initio configuration interaction (or ab initio MODPOT/VRDDO/CI or ab initio MODPOT/VRDDO/MERGE/CI) calculations can properly describe such a reaction pathway. On the contrary, the ionization potential of the ethyl radical, 8.4 eV, is lower than that of thymine and cytosine, and about that of adenine and guanine. Thus, completely different sets of potential energy surfaces will be available to the Et+ + DNA base reactions. The first two Et+ + DNA base reactions might be able to proceed along a lowest-energy singlet single-determinant surface. The latter two will have strong configuration mixing. Again, only CI calculations can resolve these reaction pathways.
Mechanism of Membrane Binding of the Phospholipase D1 PX Domain

Abstract Mammalian phospholipases D (PLD), which catalyze the hydrolysis of phosphatidylcholine to phosphatidic acid (PA), have been implicated in various cell signaling and vesicle trafficking processes. Mammalian PLD1 contains two different membrane-targeting domains, pleckstrin homology and Phox homology (PX) domains, but the precise roles of these domains in the membrane binding and activation of PLD1 are still unclear. To elucidate the role of the PX domain in PLD1 activation, we constructed a structural model of the PX domain by homology modeling and measured the membrane binding of this domain and selected mutants by surface plasmon resonance analysis. The PLD1 PX domain was found to have high phosphoinositide specificity, i.e. phosphatidylinositol 3,4,5-trisphosphate (PtdIns-(3,4,5)P3) >> phosphatidylinositol 3-phosphate > phosphatidylinositol 5-phosphate >> other phosphoinositides. The PtdIns(3,4,5)P3 binding was facilitated by the cationic residues (Lys119, Lys121, and Arg179) in the putative binding pocket. Consistent with the model structure that suggests the presence of a second lipid-binding pocket, vesicle binding studies indicated that the PLD1 PX domain could also bind with moderate affinity to PA, phosphatidylserine, and other anionic lipids, which were mediated by a cluster of cationic residues in the secondary binding site. Simultaneous occupancy of both binding pockets synergistically increases membrane affinity of the PX domain. Electrostatic potential calculations suggest that a highly positive potential near the secondary binding site may facilitate the initial adsorption of the domain to the anionic membrane, which is followed by the binding of PtdIns(3,4,5)P3 to its binding pocket. Collectively, our results suggest that the interaction of the PLD1 PX domain with PtdIns(3,4,5)P3 and/or PA (or phosphatidylserine) may be an important factor in the spatiotemporal regulation and activation of PLD1.
Interrelation between variational principles for scattering amplitudes and generalized R-matrix theory

We establish a connection between the Kohn variational principle, with (complex) outgoing-wave boundary conditions, and the Kapur-Peierls form of the R-matrix theory. We show that the complex Kohn method, unlike the usual Kohn method, does not suffer from the problem of spurious singularities. We also discuss a generalization that allows the calculation of scattering cross sections over a continuous range of energies from a single diagonalization of the Hamiltonian. Several numerical examples are presented.
Tools for the direct observation and assessment of psychomotor skills in medical trainees: a systematic review

Context The Accreditation Council for Graduate Medical Education (ACGME) Milestone Project mandates programmes to assess the attainment of training outcomes, including the psychomotor (surgical or procedural) skills of medical trainees. The objectives of this study were to determine which tools exist to directly assess psychomotor skills in medical trainees on live patients and to identify the data indicating their psychometric and edumetric properties. Methods An electronic search was conducted for papers published from January 1948 to May 2011 using the PubMed, Education Resource Information Center (ERIC), Cumulative Index to Nursing and Allied Health Literature (CINAHL) and Web of Science electronic databases and the review of references in article bibliographies. A study was included if it described a tool or instrument designed for the direct observation of psychomotor skills in patient care settings by supervisors. Studies were excluded if they referred to tools that assessed only clinical or non-technical skills, involved non-medical health professionals, or assessed skills performed on a simulator. Overall, 4114 citations were screened, 168 (4.1%) articles were reviewed for eligibility and 51 (1.2%) manuscripts were identified as meeting the study inclusion criteria. Three authors abstracted and reviewed studies using a standardised form for the presence of key psychometric and edumetric elements as per ACGME and American Psychological Association (APA) recommendations, and also assigned an overall grade based on the ACGME Committee on Educational Outcome Assessment grading system. Results A total of 30 tools were identified. Construct validity based on associations between scores and training level was identified in 24 tools, internal consistency in 14, test–retest reliability in five and inter-rater reliability in 20. The modification of attitudes, knowledge or skills was reported using five tools. The seven-item Global Rating Scale and the Procedure-Based Assessment received an overall Class 1 ACGME grade and are recommended based on Level A ACGME evidence. Conclusions Numerous tools are available for the assessment of psychomotor skills in medical trainees, but evidence supporting their psychometric and edumetric properties is limited.
THE “SOCIAL QUESTION,” 1820–1920*

In 1921, John A. Ryan, a priest and professor at Catholic University in Washington, DC, and one of his students, the Reverend Raymond McGowan, published A Catechism of the Social Question. The first question in it reads, “What do we mean by the social question?” Answer: “A question denotes a problem or a difficulty which demands solution. A social question is one that concerns society, or a social group. The social question means certain evils and grievances affecting the wage-earning classes, and calling for removal or remedy.”
A Brief Review of Adolescents and Tobacco: What We Know and Don’t Know

Smoking among teenagers is a major public health problem, and the purpose of this article is to review the literature concerning etiological factors of teen smoking, effects of prevention programs on reducing rates of teenage smoking, and the efficacy of smoking cessation treatment. Peer, family, and intrapersonal factors all play a role in the continuum of initiation to regular use. Prevention programs focusing on social norms governing teenage smoking are particularly effective in reducing onset of smoking behavior. Finally, behavioral cessation programs have been shown to be effective in reducing teenage smoking. Future directions concerning prevention and cessation research are discussed.
Tectal plate glioma: lessons learned from a patient with hydrocephalus, Chiari malformation-1 and concomitant aqueductal stenosis.

Chiari malformation type I (CM-1) is characterized by a reduced olume in the posterior fossa and by the caudal displacement of he cerebellar tonsils through the foramen magnum. CM-1 is usully congenital, although rarely may be acquired. Since its initial escription in 1891, many clinical symptoms of brainstem, cereellar, and spinal cord pathology have been attributed to this isease. Hydrocephalus, in particular, has been noted in approxmately 4–18% of patients with CM-1 [1]. The exact pathogenesis s unknown, but the association between hydrocephalus and CM-1 s believed to be multifactorial. The standard treatment for CMis decompressive suboccipital craniotomy. Though short-term mprovements have been reported in up to 75–90%, there is a ubset of as many as 35% of CM-1 patients whom experience sympom recurrence years after surgery [2]. This subset of patients may epresent a symptom etiology that is not localized to the hindrain decompression, but rather one that is related to a separate athology. We report a case of an adult patient with hydrocephalus nd CM-1 that had symptom recurrence after surgical decomression following years of uneventful follow up. The patient was
Simultaneous PET and 3D Fluorescence Optical Tomography for Small Animal Imaging: In vivo Results and System Improvements

We have built a simultaneous positron emission tomography and three-dimensional fluorescence optical tomography system for small animal imaging, and performed in vivo experiments. System improvements and a new fluorescence scanning method are proposed.
Enzymic determination of cerebrospinal fluid lipid fractions

Abstract Colorimetric peroxidase-coupled procedures for the determination of several cerebrospinal fluid (CSF) lipid classes are described. These methods were modified to increase the effectiveness of each cerebrospinal fluid lipid assay by using the sample as the primary diluent for a highly concentrated reagent in an inverse concentration technique. Direct enzymic assays for the determination of CSF cholesterol (free and total), choline phospholipids, and triglycerides were adapted from existing assays to require less than 0.5 ml of sample per assay. This made determinations of the several lipid analytes possible even when samples were from pediatric specimens. In a study model, 51 pediatric CSF samples were analyzed for these lipid constituents. Mean values and standard deviations were determined. Within and between-run studies were performed by sampling from a pool of cerebrospinal fluid specimens. Within-run coefficients of variation for the several proposed procedures were less than 3% while the between-run findings for all of the procedures were less than 5%.
Hypermethylated myoblasts specifically deficient in MyoD autoactivation as a consequence of instability of MyoD

MyoD is one of a family of basic helix loop helix (bHLH) transcription factors acting as master switches of skeletal muscle differentiation. In addition to transcriptionally activating differentiation-specific genes, it autoactivates its own expression through a positive feedback loop. It was cloned following the observation that treatment with the DNA methylation inhibitor 5-azacytidine converts cultured fibroblasts into muscle, presumably through the activation of a transcriptionally silenced locus. In an attempt to experimentally recapitulate this phenomenon, I have stably transfected mouse C2C12 myoblasts with a selectable marker fused to the MyoD promoter/enhancer, treated the cells with methyldeoxycytidine triphosphate to promote genomic hypermethylation, and negatively selected for loss of activity from the MyoD promoter/enhancer. Several clones were recovered that had lost expression of MyoD and the ability to differentiate to myotubes, but could be reverted by treatment with 5-azacytidine. One clone ("C2G2") was studied in detail. C2G2 cells resume differentiation through the forced expression of exogenous MyoD, but paradoxically fail to autoactivate the endogenous MyoD, suggesting that they are deficient in the MyoD positive feedback circuit but otherwise competent in downstream events in myogenesis. The myogenic bHLH proteins in this clone exhibit nuclear instability. Both the nuclear stability of MyoD and resumption of the autoactivation circuit may be restored either through cell fusion with fibroblasts or by treatment of the cells with protease inhibitors. This suggests that the transcriptional silencing of a factor, not in itself necessary for muscle differentiation but governing the proteolytic stability of MyoD, is responsible for the decay of the autoactivation circuit in these cells. A theoretical analysis offers an explanation for how increased rates of MyoD turnover may result in the kinetic dissociation of autoactivation from the "cross-activation" of downstream genes and suggests a mechanism for the phenomenon of myogenic "memory."
A low energy electron diffraction study of the (100), (110) and (111) surfaces of gold

Abstract The technique of low energy electron diffraction has been used to determine the structure of (100), (110) and (111) surfaces of single crystals of gold. Following short periods of argon ion bombardment, 1 × 1 bulk type structures are generated on all three surfaces. Subsequent low temperature annealing or extended ion bombardment, without annealing, results in the formation of the anomalous structures, (100) 5 × 1 and (110) 1 × 2; no change is observed in the (111) surface structure. The anomalous structures were observed to transform reversibly as follows: 5×1 ⇄ 800°C 1×1(100) 1×2 ⇄ 600°C 1×1(110) Based on the assumption that these structures arise from the interaction of an impurity with the gold substrate, a surface dislocation model is proposed that qualitatively accounts for the superperiodic character of these structures. A theory which invokes impurity layer roughening (disordering) is advanced to account for the reversible transformations. Evidence is presented that suggests that the impurity is derived from the bulk of the crystals and is brought to the surface by a combination of selective sputtering, volume and surface diffusion processes. A second type of impurity structure, resulting in “ring” type diffraction features for all three orientations, is observed after extended high temperature annealing in vacuum. Results describing the thermal desorption of impurities from electropolished surfaces of gold are also presented.
A test of socioeconomic status as a predictor of initial marijuana use.

Abstract The current study examined the effects of socioeconomic status (SES) on adolescent marijuana use using data from a national longitudinal survey of subjects aged 11 to 17 (N = 1,725). Both direct and indirect measures of SES (e.g., Hollingshead's measure of SES, urbanicity, neighborhood problems) were used to determine the extent to which SES predicts marijuana use among adolescents. For males, our study found a nonlinear relationship between the Hollingshead measure and marijuana use that had not been identified in previous research. For females, the Hollingshead measure was nonsignificant when alcohol use and having friends who use marijuana were added to the model. This finding suggests that the effects of SES on marijuana use may be mediated by alcohol use and friends' use of marijuana. Weekly alcohol users were much more likely than nonusers to initiate marijuana use for both males (Odds ratio [OR] = 18.28, Confidence interval [CI] = 4.93 – 67.81) and females (OR = 11.75, CI = 3.22 – 42.86). Other significant variables for both sexes included having a job, having friends who use marijuana, and having used some alcohol in the past year. For males, grade point average (GPA), commitment to friends, urbanicity, time spent with friends, and peer strain were also significant predictors of initial marijuana use. For females, prior victimization and low school aspirations were significant. In sum, our findings suggest that psychosocial risk factors for marijuana use are substantially different for males than for females and that future researchers need to test for nonlinear relationships between SES and adolescent substance use.
Precambrian Sulphide Deposits

This book is dedicated to Howard S. Robinson, who was born and educated in the United States, but who spent his professional career in Canada with McIntyre Porcupine Mines, concentrating on Precambrian mineral deposits. Although his career in mineral exploration was distinguished, his major contribution to earth science was probably as one of the founders of the Geological Association of Canada, an institution to which he made a bequest in his will. With this background, the strong emphasis on Canadian Precambrian mineral deposits should come as no surprise; of the 23 papers in this book, 21 are solely or primarily devoted to Canadian deposits. The two exceptions—those describing the Balmat, N.Y., zinc mines (at times the largest zinc producer in the United States) and the Crandon, Wisconsin, volcanogenic zinc-copper massive-sulfide deposit (the largest deposit of its kind found in the 1970s)—are each within a couple of hundred kilometers of the Canadian border. Although the title of the book is more expansive than the actual topics discussed, Canada is rich in Precambrian rocks and ore bodies, and Canadian scientists have been especially alert to tectonic influences in the formation of mineral deposits. These features, plus the fact that the country contains a very well exposed expanse of Archean rocks which is the largest in the world, facilitate the study of early crustal evolution and make the book of particular interest to geophysicists.
Medical indigency and inner city hospital care: patient dumping, emergency care and public policy.

This paper discusses the growing lack of private for-profit hospital care for the medically indigent. The issues of patient dumping and emergency care are examined form both judicial and public policy perspectives. The paper concludes by noting that dumping may be viewed as a most serious form of neglect and more comprehensive laws and court decisions are needed to require all hospitals, regardless of ownership, to treat all patients who arrive at their doors if they have the appropriate medical staff and facilities.
Plunging Faraday Cup System and a Slit System for Use in the Zero Gradient Synchrotron Short Straight Sections

Each short straight section of the Zero Gradient Synchrotron (ZGS) contains mechanisms for positioning three beam detectors. The mechanisms are noteworthy because of their unique target fast stroke length adjustment capabilities. One detector consists of a solid plate containing a long, horizontal slit. Plate position is vertically adjustable over a wide range. Beam currents to the plate flow through a coaxial cable to a signal detecting circuit. The second detector is a vertical square bar that is plunged upward. The plunge distance and horizontal position of the bar are continuously adjustable over the whole aperture. A coaxial cable connected to the bar carries beam currents to a signal detecting circuit. The third device is a vertical segmented assembly of linearly arranged detectors that can be plunged downward. The plunge distance and the horizontal position of the segmented assembly are continuously adjustable over the whole aperture. Each insulated segment is connected to resistor networks that provide voltages proportional to the total current to the segments and to the weighted function of the current to each segment. The vertical position of the beam can be derived from these voltages.
Wave Characteristics and Vibration Control of Translating Beams by Optimal Boundary Damping

The transverse motion of a translating tensioned Euler-Bernoulli beam is controlled by passive or active damping applied at a boundary. Even for an undamped beam with a symmetric boundary configuration, the interaction between the translating continuum and the stationary or moving boundary leads to energy variation in free motion. With the time-varying energy chosen as a Lyapunov functional, boundary control laws are designed based on Lyapunov's second method. For various types of translating beams, energy dissipation by boundary damping is quantified using the method of traveling waves. The optimal value of damping, maximizing the energy dissipation, is also explicitly represented by system parameters. The analytical results are compared with numerical simulations using the finite difference scheme.
Injectable polymerized high internal phase emulsions with rapid in situ curing.

Polymerized high internal phase emulsions (polyHIPEs) have been utilized in the creation of injectable scaffolds that cure in situ to fill irregular bone defects and potentially improve tissue healing. Previously, thermally initiated scaffolds required hours to cure, which diminished the potential for clinical translation. Here, a double-barrel syringe system for fabricating redox-initiated polyHIPEs with dramatically shortened cure times upon injection was demonstrated with three methacrylated macromers. The polyHIPE cure time, compressive properties, and pore architecture were investigated with respect to redox initiator chemistry and concentration. Increased concentrations of redox initiators reduced cure times from hours to minutes and increased the compressive modulus and strength without compromising the pore architecture. Additionally, storage of the uncured emulsion at reduced temperatures for 6 months was shown to have minimal effects on the resulting graft properties. These studies indicate that...
Timing of Parenthood and Experiences of Gay Fathers: A Life Course Perspective

How have men become gay fathers and how have their decisions about parenthood shaped their experiences? In this study of 739 gay fathers from across the United States, we explored generational changes in timing of parenthood and its association with identity development, sexual orientation disclosure, and social support. In this sample, most men over 50 years of age, but only a minority of younger men, reported that they had fathered children in the context of heterosexual relationships. In contrast, few of those over 50, but most of the younger men, reported that children joined their family in the context of a same-sex relationship. Moreover, timing of parenthood was the strongest predictor of the fathers’ experiences of sexual identity development, disclosure, and social support. The findings are consistent with the idea that a generational shift is underway and that this shift has important implications for gay fathers’ experiences.
The Gulf of Alaska coastal ocean as an atmospheric CO2 sink

Abstract A new data set of directly measured surface seawater carbon dioxide partial pressures (pCO 2 ) was compiled for the Gulf of Alaska (GOA) coastal ocean. Using this information, along with reconstructed atmospheric pCO 2 data, we calculate sea–air CO 2 fluxes over two interconnected domains: the coastal ocean defined by the Surface Ocean CO 2 Atlas (SOCAT) Continental Margin Mask, and the continental margin shoreward of the 1500 m isobath. The continental margin in this region lies within the coastal ocean. Climatological sea–air CO 2 fluxes were calculated by constructing monthly climatologies of sea–air pCO 2 difference (ΔpCO 2 ), sea surface temperature, salinity, and CO 2 solubility, coupled with the monthly second moment of wind speeds from the Scatterometer Climatology of Ocean Winds (SCOW; http://cioss.coas.oregonstate.edu/scow ). Climatological sea–air CO 2 fluxes showed instances of atmospheric CO 2 uptake and outgassing in both domains for nearly all months; however, uptake dominated from April through November, with distinct spring and autumn peaks that coincided with periods of strong winds and undersaturated surface seawater pCO 2 with respect to atmospheric levels. Atmospheric CO 2 uptake during the spring and autumn peaks was stronger on the continental margin compared with the coastal ocean. Annual mean area-weighted fluxes for the coastal ocean and continental margin were −2.5 and −4 mmol CO 2 m −2 d −1 , respectively. Scaling these annual means by the respective surface areas of each domain resulted in estimates of substantial atmospheric CO 2 uptake between 34 and 14 Tg C yr −1 . This region is a large sink for atmospheric CO 2 , which impacts the current view of weak net CO 2 emission from coastal waters surrounding North America.
Peripheral retinal albinotic spots.

The pigment epithelium of the retina is one of the most reactive structures of the eye, and alternations in it are commonly seen in diseases and degenerative processes in the eye. The purpose of this report is to record the observation of a retinal pigment epithe­ lial abnormality noted in the Eye Pathology Laboratory of The Johns Hopkins Hospital. The abnormality was noted during the routine processing of autopsy eyes. One eye was from a 59-year-old white man who died of squamous-cell carcinoma of the esopha­ gus, while the other eye was from a 64-yearold white man who died from complications of atherosclerosis. After the eyes were opened, it was noted that a round area of hypopigmentation was located inferonasally at the equator in one eye, and inferotemporally at the equator in the other. In each case, the fellow eye did not show similar abnormali­ ties. The involved areas were characterized by a loss of pigmentation, a more distinct choroidal pattern, and by fairly well demar­ cated borders (Fig. 1). There was no juxta­ posed area of pigmentary hyperplasia as is usually seen in old chorioretinal scars. In each eye, only a single area was so in­ volved. The spot measured 4 mm in diameter in one eye, and 4.5 mm in diameter in the other. Except for peripheral cystoid degen­ eration in both of the eyes and cobblestone degeneration in one eye, no other gross ab­ normalities were noted. On microscopic examination of the in­ volved areas, the cells of the retinal pigment epithelium were slightly flatter than in the uninvolved areas, as were the nuclei of the involved cells. These flattened cells had lost
Effect of high spontaneous polarization on defect structures and orientational dynamics of tilted chiral smectic freely suspended films

The director structure around topological defects and in $2\ensuremath{\pi}$ walls in the two-dimensional orientation field of thin freely suspended films of tilted chiral smectic liquid crystal is observed to minimize splay of the spontaneous polarization. Concentric ring patterns in the director field unwind more slowly in higher polarization films. These experiments confirm that polarization space charge increases the effective elasticity of static polarization-splay distortions and that it attracts ionic charge, leading to an increase in the effective orientational viscosity of the director field.
Exploring conformational changes coupled to ionization states using a hybrid Rosetta‐MCCE protocol

A hybrid protocol combining Rosetta fullatom refinement and Multi-Conformation Continuum Electrostatics (MCCE) to estimate pK(a) is applied to the blind prediction of 94 mutated residues in Staphylococcal nuclease (SNase), as part of the pK(a)-cooperative benchmark test. The standard MCCE method is limited to sidechain conformational changes. The Rosetta refinement protocol is used to add the backbone conformational changes in pK(a) calculations. The non-electrostatic energy component from Rosetta and the electrostatic energy from MCCE are combined to weight the calculated ionization states. Of 63 measured pK(a)s, the root mean squared deviation (RMSD) between the calculated pK(a)s and the measured values is 4.3, showing an improvement compared to the RMSD of 6.6 in the standard MCCE calculations, using a low protein dielectric constant of 4. The breakdown of pK(a) shift from the solution values (ΔpK(a)) shows that the desolvation energy contributes the most in the standard MCCE calculations. Lowering desolvation penalties and optimizing electrostatic interactions with the Rosetta/MCCE protocol reduces the ΔpK(a) to favor the charged states. Analysis also showed that the Rosetta/MCCE protocol samples conformations with pK(a)s close to the solution values. The question remains whether the correct conformational changes coupled to the ionization changes are found here. Nevertheless, a challenge emerges to accurately estimate the reorganization energy, which is not directly measured from the electrostatic environment of the site of interest. Possible improvements to the protocol are also discussed.
Urinary free cortisol and childhood trauma in cocaine dependent adults.

Objective: To examine whether childhood trauma may have a relationship to hypothalamic-pituitary-adrenal (HPA) axis function as an adult. Methods: Forty-six withdrawn cocaine dependent patients participated in 24-h urine collections for determination of urinary-free cortisol (UFC) and completed the Childhood Trauma Questionnaire (CTQ). Results: Patients with a mean UFC output below the median had significantly higher CTQ scores for childhood sexual abuse than patients with UFC outputs above the median. Multiple regression analysis showed that both childhood emotional neglect and sexual abuse were independently associated with UFC outputs. Conclusion: These cross sectional data, in a sample of middle-aged cocaine dependent patients, suggest the possibility that childhood trauma may have an effect on HPA axis function and thus predispose to psychiatric disorders. Further studies are needed in different samples.