cssi/SciSciGPT-SciSciNet huggingface dataset:
Automated Physical Modeling of Nonlinear Audio Circuits for Real-Time Audio Effects—Part II: BJT and Vacuum Tube Examples

This is the second part of a two-part paper that presents a procedural approach to derive nonlinear filters from schematics of audio circuits for the purpose of digitally emulating musical effects circuits in real-time. This work presents the results of applying this physics-based technique to two audio preamplifier circuits. The approach extends a thread of research that uses variable transformation and offline solution of the global nonlinear system. The solution is approximated with multidimensional linear interpolation during runtime to avoid uncertainties in convergence. The methods are evaluated here experimentally against a reference SPICE circuit simulation. The circuits studied here are the bipolar junction transistor (BJT) common emitter amplifier, and the triode preamplifier. The results suggest the use of function approximation to represent the solved system nonlinearity of the K-method and invite future work along these lines.
Expression and Radiolabeling of Recombinant Proteins Containing a Phosphorylation Motif

Abstract Radiolabeled proteins are useful in basic and clinical research. Current methods available for radiolabeling proteins involve chemical derivatization, resulting in multiple additions of radionuclides at random sites. A method designed to specifically localize the radionuclide to a unique site will offer advantages of control and predictability in radiolabeling. We have studied the usefulness of a prokaryotic expression vector by incorporating the coding sequence of a consensus phosphorylation motif (Kemptide) for the cAMP-dependent protein kinase A immediately upstream to the multiple cloning site. This vector was used to express five different recombinant proteins with a phosphorylation site at the amino terminus. In addition, the phosphorylation motif was introduced into two other proteins and expressed in yeast. The genetically engineered proteins were purified to homogeneity by affinity chromatography and radiolabeled with [γ32P]ATPin vitro.All seven proteins used in this study could be expressed with the phosphorylation sequence at their amino terminus and specifically labeled without loss of biological activity. This strategy allows the option of labeling proteins to high or low specific radioactivity and holds potential forin vitrobinding andin vivolocalization studies.
Lipopolysaccharide sequestrants: structural correlates of activity and toxicity in novel acylhomospermines.

Lipopolysaccharides (LPS), otherwise termed “endotoxins”, are outer membrane constituents of Gram-negative bacteria. Lipopolysaccharides play a key role in the pathogenesis of “septic shock”, a major cause of mortality in the critically ill patient. Therapeutic options aimed at limiting downstream systemic inflammatory processes by targeting lipopolysaccharide do not exist at the present time. We have defined the pharmacophore necessary for small molecules to specifically bind and neutralize LPS and, using animal models of sepsis, have shown that the sequestration of circulatory LPS by small molecules is a therapeutically viable strategy. In this paper, the interactions of a series of acylated homologated spermine compounds with LPS have been characterized. The optimal acyl chain length for effective sequestration of LPS was identified to be C16 for the monoacyl compounds. The most promising of these compounds, 4e, binds LPS with an ED50 of 1.37 μM. Nitric oxide production in murine J774A.1 cells, as well...
Medical student self-assessment of performance on an obstetrics and gynecology clerkship

OBJECTIVE: The purpose of this study was to evaluate the accuracy of medical student self-assessment of performance on an obstetrics and gynecology clerkship and to assess the influence that demographic and temporal factors had on the accuracy of that assessment. STUDY DESIGN: From June 1990 to July 2000, 1152 students predicted examination and clerkship grades at the beginning and end of their obstetrics and gynecology clerkship. The effects of class rank, gender, rotation length, semester, prediction type, and timing on the accuracy of prediction were evaluated with logistic regression. RESULTS: Students more often correctly predicted clerkship than examination grades. Students with higher grades tended to underestimate their performance; the students who received lower grades tended to overestimate their performance. All factors had a significant effect on the outcome (all, P <.001). Odds ratios for the overestimation were greatest for the lower one third of the class compared with the upper one third of the class (odds ratio, 4.38) and for students who completed the 6-week clerkship compared with the 8-week clerkship (odds ratio, 3.61) CONCLUSION: Better performing medical students tend to underestimate their performance; poorer performing students tend to overestimate their performance. Below-average students have the potential to derive the most benefit from formal feedback.
Removal of Oil from Water by Inverse Fluidization of Aerogels

Surface-treated hydrophobic aerogel (Nanogel) granules of sizes between 500 and 850 μm, 1.7 and 2.3 mm, and 0.5 and 2.3 mm are fluidized by a downward flow of oil-contaminated water in an inverse fluidization mode. Aerogel particles are nanostructured, extremely light and porous, have a very large surface area per unit mass, and are sufficiently robust to be fluidized. Their hydrophobic surface gives them a strong affinity for oil and other organic compounds, with the exclusion of water. These desirable properties make them an ideal sorbent or filter media for the removal of oil from wastewater. The hydrodynamic characteristics of inverse fluidized beds of aerogel granules of different size ranges were studied by measuring the pressure drop and bed expansion as a function of superficial velocity. The oil removal efficiency and capacity of the aerogel granules in the inverse fluidized bed were found to depend mainly on the size of the granules, the initial height of the bed (amount of powder used), the voi...
Do Negative Emotions Mediate the Association between Socioeconomic Status and Health

: In this chapter, we examine the possibility that negative emotions contribute to the relationship between socioeconomic status (SES) and health. A model of the associations among SES, emotion, and health is presented first. We then review the evidence for this model, showing associations of SES with depression, hopelessness, anxiety, and hostile affect and cognition, and of these negative emotions with disease. Notably, most of the data supporting the model provide only indirect evidence that negative emotions serve as a key contributor to the proposed associations. We, therefore, conclude with recommendations for longitudinal research, especially in children, that will more directly and comprehensively examine negative emotions as possible mediators of the SES and health relationship.
Capillary electrophoresis of cationic random coil peptide standards: Effect of anionic ion-pairing reagents and comparison with reversed-phase chromatography

The present study compares a charge/hydrophobicity capillary electrophoresis (CE) approach to reversed-phase high-performance liquid chromatography (RP-HPLC) for the separation of three series of four synthetic, random coil peptide standards. Each series has peptides of the same positive charge (+1, +2 and +3 series) and length but differing in hydrophobicity. Complete resolution of the 12 peptides was achieved via a novel CE approach: a capillary zone electrophoresis (CZE) mode effected a separation of identically charged peptides; within each charged group of peptides, the addition of perfluorinated acid anionic ion-pairing reagents allowed resolution of the peptides through a mechanism based on peptide hydrophobicity which we have termed ioninteraction (II)-CZE. The peak capacity and peptide resolution of this CE approach was superior to that of RP-HPLC and stresses an important role for CE for peptide/proteomic applications.
POSTER: WinOver Enterprise Dark Data

Any persistent untagged, untapped and unclassified data can be termed as dark data. It has two common traits: first, it is not possible to determine its worth, and second, in most of the scenarios it is inadequately protected. Previous work and existing solutions are restricted to cater single node system. Moreover, they perform specialized processing of selected content, for example, logs. Further, there is total negligence of stakeholders and minimal focus on the data getting generated within the enterprise. From the perspective of an enterprise it is important to understand the distribution, nature and worth of dark data, as it helps in choosing right security controls, insurance or steps needed to pre-process a system before discarding it. In this paper we demonstrate a distributed system, called File WinOver, for File Lifecycle Management (FLM). The solution operates in a distributed environment where it identifies the dormant and active files on a system, filters them as per requirement and computes their fingerprint. Moreover, the content fingerprinting is utilized to detect closed user groups. After which, it classifies the content based on configured policies, and maps them with the stakeholders. This mapping is further used for valuating the risk exposure of the file. Thus, our system helps in identifying dark data and assigns quantitative risk value.
A model comparison in least squares collocation

The well known least squares collocation model (I) $$\ell = Ax + \left[ {\begin{array}{*{20}c} O \\ I \\ \end{array} } \right]^T \left[ {\begin{array}{*{20}c} s \\ {s' + n} \\ \end{array} } \right]$$ is compared with the model (II) $$\ell = Ax + \left[ {\begin{array}{*{20}c} R \\ I \\ \end{array} } \right]^T \left[ {\begin{array}{*{20}c} s \\ n \\ \end{array} } \right]$$ The basic differences of these two models in the framework of physical geodesy are pointed out by analyzing the validity of the equation $$s' = Rs$$ that transforms one model into the other, for different cases. For clarification purposes least squares filtering, prediction and collocation are discussed separately. In filtering problems the coefficient matrix R becomes the unit matrix and by this the two models become identical. For prediction and collocation problems the relation s′=Rs is only fulfilled in the global limit where s becomes either a continuous function on the earth or an intinite set of spherical harmonic coefficients. Applying Model (II), we see that for any finite dimension of s the operator equations of physical geodesy are approximated by a finite matrix relation whereas in Model (I) the operator equations are applied in their correct form on a continuous, approximate function $$\tilde s$$ .
The effects of shading on competition between purple loosestrife and broad-leaved cattail

Abstract Interspecific competition between Purple loosestrife ( Lythrum salicaria L.), and broad-leaved cattail ( Typha latifolia L.) was examined using a replacement series design (total density of five plants per pot) in a greenhouse experiment. First-year growth of plants in unshaded and shaded (40% of available sunlight) conditions was compared to determine the effects of shading on competition. In both light treatments and all planting ratios, the growth of T. latifolia was more affected by interspecific competition than was that of L. salicaria. T. latifolia per-plant biomass in the replacement series trials increased in a 1:1 ratio with T. latifolia planting density and varied inversely with L. salicaria density. In contrast, L. salicaria growth was more affected by intraspecific competition than by interspecific competition. L. salicaria per-plant biomass decreased in a 1:1 ratio with L. salicaria planting density and increased similarly with T. latifolia density. Shading did not influence density effects in either species, but the average biomass production of shaded plants was only about half that of their unshaded counterparts. An input/output ratio analysis of biomass production suggests local extinction of T. latifolia during competition with L. salicaria , regardless of initial densities.
Intradialytic Hypotension: Is Midodrine Beneficial in Symptomatic Hemodialysis Patients?

Symptomatic hypotension during hemodialysis is a disabling complication in end-stage renal disease (ESRD) patients, especially in certain groups of patients who are at higher risk for this problem. Autonomic dysfunction is thought to play a significant role. We evaluated the efficacy of midodrine, an oral agent with selective alpha-adrenergic agonist activity used in the treatment of neurogenic orthostatic hypotension, on 10 hemodialysis patients with persistent intradialytic hypotension. The patients were given a dose of midodrine (mean dose, 5.5 mg; range, 5 to 10 mg) 30 minutes before each hemodialysis session. We compared blood pressure, pulse, body weight, and laboratory values for 10 consecutive dialysis sessions off and on midodrine therapy. There was a statistically significant improvement in lowest intradialytic systolic blood pressure (from 96.6 to 114.7 mm Hg; P < 0.001), lowest intradialytic diastolic blood pressure (from 53.2 to 59.0 mm Hg; P = 0.002), lowest intradialytic mean arterial pressure (from 67.7 to 77.6 mm Hg; P < 0.001), posthemodialysis systolic blood pressure (from 116.5 to 127.1 mm Hg; P < 0.001), posthemodialysis diastolic blood pressure (from 66.6 to 69.7 mm Hg; P = 0.040), and posthemodialysis mean arterial pressure (from 83.2 to 88.8 mm Hg; P = 0.001) after patients were placed on midodrine. There also was a small but statistically significant decrease in intradialytic pulse rate (from 86.3 to 81 beats/min; P = 0.021) and posthemodialysis pulse rate (from 87.4 to 81.7 beats/min; P = 0.024) after initiation of midodrine therapy. There was no significant difference in any of the prehemodialysis blood pressure measurements or pulse rate off or on midodrine therapy. The improvements in intradialytic and posthemodialysis blood pressure were associated with a uniform subjective improvement in symptoms associated with dialysis hypotension, such as cramps, fatigue, dizziness, and weakness. Other than scalp paresthesia in one patient, no adverse effects were noted. Our results suggest that the administration of a single dose of midodrine before hemodialysis is an effective therapy for intradialytic hypotension. A prospective trial with adequate patient numbers and long-term follow-up would be useful to evaluate this drug's efficacy and safety profile in patients with ESRD.
Medical care utilization among older HMO members with and without hypertension.

OBJECTIVES: To compare hospital utilization, health status, and sociodemographic characteristics of older persons with and without hypertension and to examine the nature of the association of hypertension with medical care utilization. DESIGN: A retrospective, nonexperimental study. SETTING: A large health maintenance organization (HMO), located in the Portland, Oregon and Vancouver, Washington areas, that provides comprehensive, prepaid benefits to its members. PARTICIPANTS: Approximately 4200 older (≥65 years) members enrolled in the Social HMO Demonstration Project. MEASUREMENTS: The dependent variables were (1) whether a member was hospitalized (0 = no; 1 = yes) and (2) the number of hospitalizations during the 12-month period before the return of the Health Status Form, a mail questionnaire. The predictor variables were high blood pressure and other medical conditions, health status, and sociodemographic characteristics. Patients classified as hypertensive were those who self-reported high blood pressure and who received two or more dispensings for antihypertensive medications. RESULTS: Older hypertensives were more likely than older nonhypertensives to have been hospitalized (odds ratio (OR) = 1.14 (95% CI 1.01,1.27)), self-report their health as only good or fair (P < .001), self-report IADL functional limitations (P < .001), and to be younger than nonhypertensives (P < .001). Utilization differences were similar after controlling for patients' age and gender. Factors independently associated with an increased likelihood of hospitalization were: male gender (OR = 1.14 (1.00,1.31)), age (OR = 1.35 (1.00,1.81)), poor (OR = 1.32 (1.02,1.72)) or fair (OR = 1.20 (1.01,1.44)) self-rated health status, functional limitations in activities of daily living (OR = 1.74 (1.48,2.03), and self-reported heart trouble (OR = 1.50 (1.34,1.68)), stroke (OR = 1.37 (1.15,1.64)), or cancer (OR = 2.89 (1.72,4.84)). Factors independently associated with a decreased likelihood of hospitalization were excellent self-reported health (OR = 0.65 (0.47,0.90)), no physical impairments (OR = 0.59 (0.48,0.72)), and no circulation problems (OR = 0.85 (0.74,0.98)). CONCLUSIONS: Older hypertensive patients had poorer self-reported health, more functional limitations, used more hospital services, and were not as old as nonhypertensive older patients. To the extent that general health is improved by treatment of hypertension, appropriate treatment of high blood pressure may not only improve health, it may also reduce medical care utilization. Our findings offer further support for hypertension prevention, detection, and treatment programs designed to reduce or minimize hypertension's later medical complications and to reduce future utilization. J Am Geriatr Soc 43: 222–229, 1995.
An intelligent tool to aid students in learning second and subsequent programming languages

Abstract This paper reports on the design rationale and formative evaluation of an intelligent tool to aid intermediate and advanced student programmers, who already have knowledge of another programming language, in acquiring a working knowledge of key parts of the Ada programming language. Research on transfer between programming languages has shown that, while previous programming experience helps students to learn subsequent languages, it also can be a source of negative transfer. In particular, students have little trouble with the syntax of the new language, but they do have difficulty in planning a solution which takes advantage of the features of the new language. Our tool, ADAPT, applies existing artificial intelligence technologies to the pedagogical problem of transfer between programming languages, with emphasis on the problem of developing programming plans which are appropriate to Ada. ADAPT was designed based on the findings of research in the cognition of programming. A prototype of the tool was developed, and a formative evaluation was carried out to evaluate the cognitively-based design decisions guiding ADAPT.
Tumor motion prediction with the diaphragm as a surrogate: a feasibility study.

We have previously assessed the use of the diaphragm as a surrogate for predicting real-time tumor position with linear models built with training data extracted from the same treatment fraction (Cervino et al 2009 Phys. Med. Biol. 54 3529-41). However, practical use in the clinical setting requires the capability of predicting tumor position throughout the treatment course using a model built at the beginning of the course. We evaluate the inter-fraction applicability of linear models to predict superior-inferior tumor position based on diaphragm position using 21 fluoroscopic sequences from five lung cancer patients. Tumor position is predicted with models built during the first fluoroscopic sequence of each patient. Other fluoroscopic sets are registered to the first set with five different methods. The mean localization prediction error and maximum error at a 95% confidence level averaged over all patients are found to be 1.2 mm and 2.9 mm, respectively, for bony registration and 1.2 mm and 2.8 mm, respectively, for registration based on the mean position of the tumor in the first two breathing cycles. Other registration methods produce larger prediction errors. In the clinical setting, this prediction error could be added as a margin to the target volume. We therefore conclude that it is feasible to predict lung tumor motion with diaphragm with sufficient accuracy in the clinical setting.
Rapidity Correlations between the Negative Pions Produced in the K + p Interaction.

Dramatic behavior is observed in the correlation between ${\ensuremath{\pi}}^{\ensuremath{-}}'\mathrm{s}$ as a function of their rapidity separation $\ensuremath{\Delta}y$. At small $\ensuremath{\Delta}y$, the $\ensuremath{\pi}'\mathrm{s}$ are strongly positively correlated. At large $\ensuremath{\Delta}y$ the correlation length is measured to be 0.52\ifmmode\pm\else\textpm\fi{}0.03. Particle-production and particle-particle correlations are distinguished and studied.
Measurement and influence of surface charges in high-voltage phenomena

A discussion of the formation of the positive and negative charges left on the surface of insulation as a result of the electric discharge between a metal and a dielectric surface. Results of measurements with the rotating probe electrometer are given. This new method has opened up many experimental techniques for studying the influence of surface charges in high-voltage phenomena.
Oesophageal cancer incidence in the United States by race, sex, and histologic type, 1977–2005

In the United States, the rates and temporal trends of oesophageal cancer overall and for the two predominant histologic types – adenocarcinoma (ADC) and squamous cell carcinoma (SCC) – differ between Blacks and Whites, but little is known with regard to the patterns among Asians/Pacific Islanders or Hispanics. Using the Surveillance, Epidemiology, and End Results programme data, we analysed oesophageal cancer incidence patterns by race, sex, and histologic type for the period 1977–2005. Total oesophageal cancer incidence has been increasing among Whites only; the rates among all other race groups have declined. Moreover, rates among White men surpassed those among Blacks in 2004. Oesophageal SCC rates have been decreasing among virtually all racial/ethnic groups; rates among Hispanic and Asian/Pacific Islander men have been intermediate to those of Blacks and Whites, with rates among women being lower than those among Blacks or Whites. The ADC rates among Hispanic men may be rising, akin to the historical trends among Whites and Blacks. The sex ratios for these cancers also varied markedly. These observations may provide clues for aetiological research.
Fibrinogen interaction with platelets of diabetic subjects

Abstract Fibrinogen-platelet interaction was studied in suspensions of platelets obtained from patients with uncontrolled diabetes mellitus of long duration and from control individuals. Fibrinogen binding sites were exposed by stimulating platelets with ADP or with chymotrypsin. There was no significant difference in fibrinogen mediated aggregation between ADP-stimulated platelets of 80 control and 47 diabetic subjects. The Km values for fibrinogen mediated aggregation of ADP-stimulated platelets obtained from control and diabetic donors were 1.39 ± 0.13 × 10 −7 M and 1.44 ± 0.13 × 10 −7 M; the Vmax values (expressed in arbitrary-light transmission units) were 87.8 ± 3.14 and 92.8 ± 4.5 (mean ± S.E.M.). The analysis of variance showed no significant relationship between Km, Vmax, age and sex in control group; in patient group there was no significant relationship between Km, Vmax, age, sex, type of diabetes, presence of vascular complications and type of treatment (insulin and/or oral hypoglycemic agents). Fibrinogen mediated aggregation of chymotrypsin-treated platelets showed similar pattern in 25 control and in 25 diabetic donors. In 24 normal individuals and in 24 diabetic patients Scatchard analysis revealed 48,820 ± 5350 fibrinogen binding sites per one normal platelet (Kd = 4.7 × 10 −7 M) and 45,350 ± 4663 sites per one diabetic platelet (Kd = 3.5 × 10 −7 M). Our data suggest a normal pattern of interaction between fibrinogen and fully activated platelets of diabetic subjects.
Interaction of Mycobacterium avium with human monocyte-derived dendritic cells.

ABSTRACT The mechanism by which mycobacteria elicit class I-restricted T-cell responses remains undefined because these organisms have been shown to reside exclusively within membrane-bound vesicles in macrophages (Mφ), their primary host cells. We studied the interaction of M. avium with dendritic cells (DC) because they are the most potent antigen-presenting cells and are abundant atM. avium infection sites. We observed that both DC and Mφ, generated from human peripheral blood monocytes by short-term culture, internalized M. avium. The onset of programmed cell death and the percentage of apoptotic cells in infected DC and Mφ were comparable. However, following infection, DC secreted significantly larger amounts of interleukin-12, but not interleukin-1β, than infected autologous Mφ. Further analysis of infected cells showed that while phagosomes failed to acidify in bothM. avium-infected DC and Mφ, bacilli grew more slowly in DC. Electron microscopy studies revealed that M. aviumresided within endocytic vacuoles in both cell types. The vacuolar membrane surrounding some bacilli in approximately 10% of the vacuoles in DC possessed several breaks. The importance of this finding will have to be addressed in future studies.
Comparison of the radiated fields generated by the fracture of a circular crack and a circular asperity

Summary The ‘far-field’ velocity and acceleration pulses radiated by the fracturing of a circular crack and a circular asperity are compared to determine the differences in the fields radiated by them. The cases of constant velocity fracture propagation as well as spontaneous fracture propagation are studied. The circular crack and asperity studied are of the same size and have the same average stress drop, although the distribution of the stress drop on the circular areas is different due to the inherent differences between the two problems. Since the results presented are dimensionless, they can also be used to compare the radiated field due to a crack having a given average stress drop with the radiated field due to an asperity having, say, twice this average stress drop, simply by multiplying the asperity pulses by two, and so on for the other non-dimensionalizing parameters. For the spontaneous problem, a complex fracture process is found for both problems. Due to the differences in initial conditions, it is shown that an asperity must be relatively stronger than a crack to have the same average fracture speed. It is found that no simple relation exists between the slope of the velocity pulse due to asperity failure and the average stress drop as it does for the constant velocity crack problem. Comparison of velocity, acceleration and energy-flux pulse shapes show that there are clear differences in the details of the radiated fields of the crack and the asperity models, which could be used to distinguish between them. In particular, it is found that a spontaneous crack may radiate a higher peak ground velocity and acceleration than the corresponding asperity, in some directions from the source while in other directions it is the asperity that radiates higher peak velocity and acceleration. These directions depend on the details of the fracture process for each problem.
To the mountain....a practitioner's view of the Gaithersburg conference

I went to the Human Factors conference in Gaithersburg hoping to learn from the experts. And there were experts, knee deep and crowded into the maze that was the Bureau of Standards. The papers and, presumably the research that preceded them, were thorough and thoughtful.
Workflow Composition of Service Level Agreements

Service-oriented architectures enable an environment where businesses can expose services for use by their collaborators and their peer organizations. In such an environment, organizations may have long-standing cooperative agreements representing the existing services that they share. Furthermore, they may have service level agreements (SLAs) that assure the quality of service standards of the existing services. In an ad-hoc workflow scenario, a business may need to perform real-time composition of the existing services in response to consumer requests. In this work, we suggest that, in parallel to traditional Web service composition, the business must also compose the corresponding SLAs of the chosen services to generate a guaranteed service level to the consumer. In this paper, we introduce a process for composing SLAs associated with a workflow of Web services. This process results in the discovery of the best composite (i.e. workflow) capability while optimizing the underlying service-level attributes.
Modelling for Scanning Impedance Imaging

Scanning electrical impedance imaging (SII) is a previously-introduced high resolution imaging modality with the potential of imaging the electrical activities of biological tissues. In this paper, a detailed complex electrostatic model is derived to describe the physical phenomena of the SII system. This model reveals the relationship between the voltage measurement and impedance distribution and also shows how system parameters such as height affect the resolution of the impedance image. A numerical solution is developed for this model based on the finite difference method (FDM). A variation of classical FDM is used to solve the complicated boundary conditions introduced by the combination of the electrostatic field and the peripheral circuit. Good correspondence can be observed when comparing the model simulation with experimental data acquired during a line-scan. It can be seen that the model provides a good explanation for the experimental results and can assist in the design of the special dual-conductor impedance probe used in the SII system. A two-source improvement for the SII system which is motivated by the modelling work is implemented and the corresponding physical analysis is obtained. It can help the reduction of the current contribution from the shield to the tip so that higher resolution can be achieved
HIV Testing Patterns Among Urban YMSM of Color

The heightened level of risk for HIV infection among Black and Latino young men who have sex with men (YMSM) is driven by multilevel influences. Using cross-sectional data, we examined HIV testing patterns among urban YMSM of color in a high–HIV seroprevalence area (ages 16 to 21 years). Self-reported frequency of testing was high, with 42% of youth reporting testing at a greater frequency than recommended guidelines. There were no differences between less frequent and more frequent testers on sexual risk behaviors. Most (80%) youth cited reassurance of HIV-negative status as a reason for testing. Further, over half of the sample reported numerous other reasons for HIV testing, which spanned individual, partner, social, and structural levels of influence. Approximately half of respondents indicated that peers, family members, and counselors influenced their motivation to get tested. Of concern, their first HIV test occurred approximately 2 years after their first sexual experience with another male. These...
Effects of Sample Size on the Distribution of Selected Fit Indices: A Graphical Approach.

The purpose of the present study was to investigate the effects of sample size on the cumulative distribution of selected fit indices. Two models (i.e., a reduced and a complete model) and six (20, 50, 100, 200, 500, 1,000) sample sizes were used to investigate the effect on the cumulative distribution of the fit indices as sample size was varied. Generally, the comparative fit index (CFI) exhibited very stable patterns and was less influenced by sample size or data types than were other fit indices. In addition, the normed fit index performed similarly to the CFI.
The Ancestry Question and Ethnic Heterogeneity: The Case of Arab Americans

This article uses US Census data to investigate change over time in Arab American profiles. In 2000, a higher proportion of children (0 to 13 years of age), women, and those who lived in the Northeast identified with an Arab/non-Arab ancestry compared to an Arab-only ancestry. In 1980 and 2000, a higher proportion (~90%) of those who identified with an Arab/non-Arab ancestry was US born compared to only one-half of those who identified with an Arab-only ancestry. Those who identified with an Arab-only ancestry were more likely to not be US citizens than those who identified with an Arab/non-Arab ancestry. These findings suggest Arab Americans are a heterogeneous group. [ABSTRACT FROM AUTHOR]
BIOGENESIS OF ENDOPLASMIC RETICULUM MEMBRANES I. Structural and Chemical Differentiation in Developing Rat Hepatocyte

The development of the endoplasmic reticulum of rat hepatocytes was studied during a period of rapid cell differentiation, i.e., from 3 days before to 8 days after birth. Before birth, the ER increases in volume, remaining predominantly rough surfaced; after birth, the increase continues but affects mainly the smooth-surfaced part of the system. These changes are reflected in variations of the RNA/protein and PLP/protein ratios of microsomal fractions: the first decreases, while the second increases, with age. The analysis of microsomal membranes and of microsomal lipids indicates that the PLP/protein ratio, the distribution of phospholipids, and the rate of P32 incorporation into these phospholipids show little variation over the period examined and are comparable to values found in adult liver. Fatty acid composition of total phosphatides undergoes, however, drastic changes after birth. During the period of rapid ER development in vivo incorporation of leucine-C14 and glycerol-C14 into the proteins and lipids of microsomal membranes is higher in the rough-than in the smooth-surfaced microsomes, for the first hours after the injection of the label; later on (∼10 hr) the situation is reversed. These results strongly suggest that new membrane is synthesized in the rough ER and subsequently transferred to the smooth ER.
Left ventricular mass and function in primary hypertension

The Hypertension Optimal Treatment study is a prospective, randomized, clinical trial designed to challenge the J curve phenomenon in hypertension. A subpopulation of 665 patients from seven participating centers in the United States were enrolled to evaluate the prevalence of left ventricular mass and its relationship to systolic and diastolic function, as assessed by Doppler echocardiography, and to clinical events during the length of the study. Echocardiographic measurements followed stringent criteria and were rechecked in a core laboratory for accuracy. Baseline data revealed left ventricular hypertrophy in 62% of the patients. Left ventricular hypertrophy was more prevalent in women than in men (72% σ 57%, P < .0001). The hypertrophy was further characterized according to left ventricular geometry and found the concentric pattern as the predominant form of hypertrophy (46%). Indices of left ventricular systolic function, including fractional shortening, cardiac index, and ejection fraction, were normal or above-normal. Doppler interrogation of the mitral inflow demonstrated left ventricular diastolic dysfunction in 81% of patients. The constrictive physiology (inversion of the E/A ratio) was the most prevalent mitral flow pattern (79%). Regression of left ventricular hypertrophy, modification of mass index geometry, and alterations in mitral flow characteristics under optimal blood pressure control will be specifically compared with subsequent examinations.
Characterization of cluster/monomer ratio in pulsed supersonic gas jets

Combining femtosecond frequency-domain interferometry with time-integrated transverse interferometry and Rayleigh scatter, we completely characterize all parameters - cluster mass fraction, total atomic density and average cluster size - that influence high-intensity laser interactions with clustering gas jets.
Test of a bond-correction formula for ultrasonic velocity measurement

A formula for the shift of a resonance frequency induced by a bond of nonvanishing thickness is tested. Experiments are performed on a solid rod of polycrystalline nickel that is machined into three segments, representing specimen, bond, and transducer. Acoustic waves are launched and detected magnetostrictively. Measured patterns of frequency shift vs. frequency for various lengths and diameters of the bond exhibit satisfactory agreement with predictions. The patterns provided physical insight into the interaction between specimen, bond, and transducer, and they indicate the importance of assessing the full pattern to determine accurate values of velocity in continuous-wave ultrasound experiments. >
Pricing network resources for adaptive applications

The Differentiated Services framework (DiffServ) has been proposed to provide multiple Quality of Service (QoS) classes over IP networks. A network supporting multiple classes of service also requires a differentiated pricing structure. In this work, we propose a pricing algorithm in a DiffServ environment based on the cost of providing different levels of services, and on long-term average user resource demand of a service class. We integrate the proposed service-dependent pricing scheme with a dynamic pricing and service negotiation environment by considering a dynamic and congestion-sensitive pricing component. Pricing network services dynamically based on the level of service, usage, and congestion allows a more competitive price to be offered, allows the network to be used more efficiently, and provides a natural and equitable incentive for applications to adapt their service requests according to network conditions. We also develop the demand behavior of adaptive users based on a physically reasonable user utility function. Simulation results show that a congestion-sensitive pricing policy coupled with user rate adaptation is able to control congestion and allows a service class to meet its performance assurances under large or bursty offered loads, even without explicit admission control. Users are able to maintain a stable expenditure, and allowing users to migrate between service classes in response to price increases further stabilizes the individual service prices. When admission control is enforced, congestion-sensitive pricing still provides an advantage in terms of a much lower connection blocking rate at high loads.
Gold as an Acceptor in Germanium

Results are presented and discussed concerning the effects of gold in germanium, measured by means of Hall effect, resistivity, photoconductivity, diffusion, heat treatment, and other techniques. It is shown that gold is an acceptor having high-lying states unlike those of the ordinary impurity elements. Evidence is presented to show that each gold atom produces two such levels, one at 0.15 ev above the valence band, the other 0.2 ev below the conduction band. It is assumed that these are brought about through the formation of ${\mathrm{Au}}^{\ensuremath{-}}$ and ${\mathrm{Au}}^{\ensuremath{-}\ensuremath{-}}$. The implications of this model are discussed. Depending upon the relative proportions of gold atoms and other donors and acceptors, the gold-doped samples may be either high- or low-resistance, $p$- or $n$-type at 77\ifmmode^\circ\else\textdegree\fi{}K. The resistivity may be as high as ${10}^{8}$ ohm-cm at this temperature. The segregation coefficient, measured from the electrical properties, was about 1.5\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}5}$. The solubility of gold in germanium is about ${10}^{15}$ atoms/${\mathrm{cm}}^{3}$. Photoconductivity studies confirm several features of the model proposed. In particular, gold-doped germanium has been shown to be an infrared photoconductor with response out to about 8 micron. A number of interesting trapping phenomena have been observed with gold-doped germanium. The diffusion coefficient of gold into germanium was measured. It is about 4\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}9}$ ${\mathrm{cm}}^{2}$/sec at 900\ifmmode^\circ\else\textdegree\fi{}C, with activation energy of about 2.5 ev, the same as found for other elements. Gold-doped germanium has been studied as a function of heat-treatment (copper diffusion). Several anomalous results are discussed. Gold-doped germanium has also been studied at low temperatures, for the purpose of detecting scattering by doubly charged impurity ions. The results were inconclusive in deciding whether or not doubly charged ${\mathrm{Au}}^{\ensuremath{-}\ensuremath{-}}$ ions were present. Also results on the scattering of neutral gold atoms were obtained. The Fermi statistics for gold-doped germanium are considered, and theoretical curves have been obtained for the temperature variation of the Fermi level, and of the Hall coefficient, under various conditions of gold-doping. Agreement of experimental and theoretical results was found to be fair. A discussion is also given of the applications of gold-doped germanium to research on other problems.
Regioselective cross-linking of silica aerogels with magnesium silicate ceramics

Nanoporous monoliths with a typical aerogel core and a mechanically robust exterior ceramic layer were synthesized from silica aerogels cross-linked with polyacrylonitrile (X-PAN aerogels). Following supercritical drying, X-PAN aerogels were wrapped in Mg and heated to 850 °C in inert atmosphere to generate Mg-PAN monoliths. Mg penetrated 2–3 mm inside the monolith, reacted with the silica framework and formed a mechanically strong crust with a hardness of 28 MPa, a reduced Young modulus of 374 MPa and a surface area of 170 m2 g−1. The core of the monoliths maintained chemical and physical characteristics close to those of native silica aerogels with a hardness of 0.81 MPa, a modulus of 7.42 MPa and a surface area of 370 m2 g−1. The cross-linking crust was composed of forsterite (Mg2SiO4), enstatite (MgSiO3), cristobalite and magnesium oxide (MgO). SEM and TEM showed that the Mg silicates bridged between silica aggregates, thus realizing the first known example of ceramic cross-linking of aerogels. Control experiments showed that carbon from PAN was responsible for the crust formation. A thin, mechanically weak crust formed in all other samples and was composed of MgO and Mg2SiO4. EELS showed the presence of disordered, graphite-type carbon in Mg-PAN aerogels and traces of amorphous carbon in all other control samples. The role of PAN was confirmed by using masking techniques, whereas acrylonitrile was photopolymerized in selected regions of aerogel monoliths. The crust formed only in these exposed regions. The role of carbon in crust formation is discussed, as well as potential applications of our technique for the fabrication of anisotropic ceramics.
The AMPTE CCE Magnetic Field Experiment

The AMPTE CCE spacecraft carries a high-resolution Magnetic Field Experiment for the operational purpose of determining spacecraft attitude and to fulfill the scientific objectives of providing magnetic-field measurements necessary for the determination of particle pitch angles, identification of geospace boundaries, measurement of geomagnetic activity, and the study of magnetospheric current systems and plasma processes. This experiment includes a fluxgate-magnetometer system with the sensors mounted on a 2.3-m boom to reduce spacecraft-related measurement errors. Te experiment has 7 automatically switchable ranges from ±16 to ±65 536 nT (full scale) and resolutions commensurate with a 13-bit A/D converter in each range (±0.002-±8 nT). Approximately 8.6 vector-samples/s are acquired, with information on fluctuating fields in the 5-50-Hz range provided by a system of filters and peak detectors. This instrument was operated from the time of the launch of the CCE spacecraft and is presently working in all modes as designed. The details of this experiment and early data are presented in this paper.
Differential susceptibility of rhesus monkeys to high doses of endotoxin

We investigated susceptibility of rhesus monkeys (Macaca mulatta) to Escherichia coli endotoxin (ETX) in two ways. We infused 8 monkeys (group A) with various doses of ETX (1.0-7.5 mg/kg) to assess the effect of dose on shock severity; and we infused 6 monkeys (group B) with 1.0 mg ETX/kg to test biological variability to ETX challenge. Controls were 7 saline-infused monkeys. Systolic pressure, heart rate (HR), temperature, plasma ETX and inflammatory markers — tumor necrosis factor-α (TNF), interleukin-1 (IL-1) and IL-6 — were quantified before and at 1.5, 2.5, 6 and 26 h after infusion. The highest plasma concentrations of ETX (at 1.5 h) — < 8% that infused — correlated well with the infused doses. ETX elicited hypotension and increases in HR in all monkeys. Fever did not occur. The degree of hypotension and increase in HR and death did not correlate with ETX dose (or plasma ETX concentrations). The response of inflammatory cytokines to ETX was greater in nonsurvivors than in survivors. The observed low...
Numerical studies of the interaction of time-modulated multi-gigabit sequences with metamaterial structures at millimeter-wave frequencies

It is shown with time domain simulations using the finite integration technique (FIT) that a metamaterial that acts as an artificial magnetic conductor (AMC), i.e. a metamaterial which produces an in-phase reflection, exhibits a time delay before its intended response can occur. A millimeter-wave metamaterial AMC is obtained as a generalization of a successfully designed microwave frequency AMC block consisting of an array of capacitively loaded loops (CLLs). It is also shown that while this time delay does distort millimeter-wave frequency signals composed of time-modulated multi-gigabit sequences, it does not have a detrimental impact on the overall system performance when these multi-gigabit/s signals interact with this CLL-based AMC. This time delay behaviour is demonstrated for several different but common communication-based modulation schemes. The presence of peculiar spikes in the output waveforms is tied to the time domain behaviour of the currents on the CLLs in the metamaterial AMC. Copyright © 2006 John Wiley & Sons, Ltd.
Sungas Instead of Syngas: Efficient Coproduction of CO and H2 with a Single Beam of Sunlight.

The electrolytic coproduction of CO and H2 is achieved from air, water, and a single beam of sunlight rather than from fossil fuels. H2 and CO cosynthesis is driven by a single concentrator photovoltaic to simultaneously drive molten hydroxide and molten carbonate electrolyses. The carbon neutral process captures carbon without the need for the preconcentration of atmospheric carbon dioxide.
Experimental evidence for linkages between infaunal recruitment, disturbance, and sediment surface chemistry

In prior studies, we have argued that changes in sediment surface chemistry driven by biotic and physical disturbance affect recruitment decisions of infauna. Here, we provide additional data for oxygen concentrations and infaunal recruitment behavior and a time-dependent numerical model of oxygen concentration in disturbed sediments to further support our proposed linkage between disturbance, sediment chemistry, and recruitment decisions. We evaluated the recruitment responses of the polychaete Arenicola cristata and the bivalve Mercenaria mercenaria to sediments that were undisturbed, disturbed, and allowed to recover for a specified period of time. We also obtained fine-scale measurements of oxygen concentration in surficial sediments and profiles in the upper sediment layer that new recruits explore. Undisturbed sediments were characterized by high oxygen levels and were readily accepted by recruiting organisms. Disturbance caused dramatic changes in surface and subsurface oxygen concentrations and was accompanied by nearly complete rejection of habitats by new recruits. Oxygen concentrations in cores that were disturbed and allowed to recover are consistent with the time scales of recovery as predicted by a transport-reaction numerical model. In addition, organism responses to recovering cores varied with oxygen concentration in the surface and subsurface sediments of these cores. The rapid recovery of cores suggests that diagenetic transport-reaction processes that determine pore-water composition drive the acceptability of sediments to new recruits.