cssi/SciSciGPT-SciSciNet huggingface dataset:
On Twitter Purge: A Retrospective Analysis of Suspended Users

Abuse and spam in Twitter have long been a pressing issue, and in response, Twitter regularly purges (i.e., suspends in mass) accounts that violate Twitter Rules. However, there is no available information about the characteristics and activities of these regularly purged users. We have developed a novel and comprehensive measurement mechanism to identify millions of purged Twitter users and collect their tweets. We have identified 2.4M purged users and collected 1M tweets made by them over eight months. Using our dataset, we perform a retrospective analysis to characterize their account properties and behavioral activities. We analyze their tweet content to identify their role and abuse strategy over-time. Our analysis shows that the abuse on Twitter is pervasive globally and not confined in mere spamming. Alarmingly, more than 60% of the purged users survived on Twitter for more than two years. We observe that politics is a major theme among the purged users irrespective of language and location, and these politically motivated users spread controversial content consistently over time. However, the spammers reorient their agenda across time to participate in multiple marketing campaigns. We also discover interaction and associated communities among purged users. Our analysis sheds new light on the evolving nature of abuse in Twitter that can help researchers understanding the characteristics and behavior of emerging malicious users to develop an effective defense system.
The New "Essential": Rethinking Social Goods in the Age of Covid-19

The Covid-19 crisis has laid bare the fragility of social insurance systems in the United States and the lack of income security and basic benefits for many workers and residents. The pandemic has had a particularly grave impact on people of color and low-income individuals, while also affecting a wide array of tenants, students, and health care, service and “gig” workers. One consequence for law and policy is that addressing the social dislocations caused by the pandemic might lead to profound changes in what Americans consider essential goods for a sustainable society. This chapter examines government efforts to buttress the social infrastructure in response to the pandemic in the area of family and sick leave, employment discrimination, unemployment insurance and income security, and housing and utilities (including broadband access). The chapter considers the promise and the limitations of this emerging response. It then provides a practical guide to key legal and policy changes relevant to tenants, workers, students, and low-income individuals.
A spatiotemporal analysis of the impact of COVID-19 on child abuse and neglect in the city of Los Angeles, California.

Abstract Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2; COVID-19) has created an urgent need to identify child abuse and neglect (CAN) and efficiently allocate resources to improve the coordination of responses during a public health crisis. Objective To provide unique insights into the spatial and temporal distribution of CAN in relation to COVID-19 outcomes and identify areas where CAN has increased or decreased during the pandemic. Participants Children under 18 years old reported to the Los Angeles Police Department for CAN. Setting CAN incidents in the city of Los Angeles. Methods Negative binomial regression was used to explore associations between the implementation of social distancing protocols and reported CAN during COVID-19. Spatiotemporal analysis identified locations of emerging hot and cold spots during the pandemic. Associations between neighborhood structural factors (e.g., school absenteeism, poverty, unemployment, housing insecurity and birth assets) and hot and cold spot patterns were explored. Results There was a statistically significant decline in reports of CAN during the COVID-19 pandemic but no significant trends following the implementation of social distancing measures (e.g. safer at home orders, school closures). Compared to consecutive cold spots, severe housing burden, the number of assets children have at birth, poverty, school absenteeism and labor force participation were significantly associated with new and intensifying hotspots of CAN during the COVID-19 pandemic. Conclusions Our findings reinforce the utility of developing intervention strategies that minimize harm to children by targeting resources to specific challenges facing families enduring the COVID-19 experience.
Physiology of cardiomyocyte injury in COVID-19

Abstract COVID-19 affects multiple organs. Clinical data from the Mount Sinai Health System shows that substantial numbers of COVID-19 patients without prior heart disease develop cardiac dysfunction. How COVID-19 patients develop cardiac disease is not known. We integrate cell biological and physiological analyses of human cardiomyocytes differentiated from human induced pluripotent stem cells (hiPSCs) infected with SARS-CoV-2 in the presence of interleukins, with clinical findings, to investigate plausible mechanisms of cardiac disease in COVID-19 patients. We infected hiPSC-derived cardiomyocytes, from healthy human subjects, with SARS-CoV-2 in the absence and presence of interleukins. We find that interleukin treatment and infection results in disorganization of myofibrils, extracellular release of troponin-I, and reduced and erratic beating. Although interleukins do not increase the extent, they increase the severity of viral infection of cardiomyocytes resulting in cessation of beating. Clinical data from hospitalized patients from the Mount Sinai Health system show that a significant portion of COVID-19 patients without prior history of heart disease, have elevated troponin and interleukin levels. A substantial subset of these patients showed reduced left ventricular function by echocardiography. Our laboratory observations, combined with the clinical data, indicate that direct effects on cardiomyocytes by interleukins and SARS-CoV-2 infection can underlie the heart disease in COVID-19 patients. One Sentence Summary Cardiomyocytes derived from human induced pluripotent stem cells treated with interleukins and infected with SARS- CoV- 2 in cultures, show increased release of troponin, disorganization of myofibrils, and changes in beating mirroring specific pathologies in some COVID-19 patients.
Value of Data Sharing to Advance Drug Development: A Regulatory Perspective

New tools are needed to evaluate and predict the efficacy and safety of medical products. However, the development of such tools requires collaboration and effective data sharing. In this issue of Therapeutic Innovation & Regulatory Science, scientists from the Critical Path Institute (C-Path) discuss their experiences using patient-level data to facilitate innovation in drug development. We share our perspective on the issues discussed in the C-Path paper and offer suggestions on future efforts.
Near Optimal Control in Ride Hailing Platforms with Strategic Servers

Motivated by applications in online marketplaces such as ride-hailing, we study how strategic servers impact the system performance. We consider a discrete-time process in which, heterogeneous types of customers and servers arrive. Each customer joins their type's queue, while servers might join a different type's queue depending on the prices posted by the system operator and an inconvenience cost. Then the system operator, constrained by a compatibility graph, decides the matching. The objective is to design an optimal control (pricing and matching scheme) to maximize the profit minus the expected waiting times. We develop a general framework that enables us to analyze a broad range of strategic behaviors. In particular, we encode servers' behavior in a properly defined \emph{cost function} that can be tailored to various settings. Using this general cost function, we introduce a novel probabilistic fluid problem. The probabilistic fluid model provides an upper bound on the achievable net profit. We then study the system under a large market regime in which the arrival rates are scaled by $\eta$ and present a probabilistic two-price policy and a max-weight matching policy which results in a net profit-loss of at most $O(\eta^{1/3})$. In addition, under a broad class of customer pricing policies, we show that any matching policy has net profit-loss of at least $\Omega(\eta^{1/3})$. To show generality of our framework, we present multiple extensions to our model and analysis. We conclude the discussion by presenting numerical simulations comparing different cost models and analyzing performance of the proposed pricing and matching policies.
Telemedicine during COVID-19: who gets left behind?

Objectives: COVID-19 resulted in rapid implementation of telemedicine. It is critical to explore patient factors that drive telemedicine use to recognize any disparities in healthcare access that may emerge with remote healthcare. Our objective was to compare the characteristics and subsequent health care utilization of gynecologic oncology patients who had a scheduled telemedicine visit from 3/23/20-5/18/20. Methods: We conducted a retrospective study of women whose scheduled in-person office visits were converted to telemedicine. Video visits were encouraged and telephone visits were the default option. We compared patient factors between women who cancelled versus those who completed their telemedicine visits. Subsequent health care utilization included in-person office appointments, emergency department (ED) or operative care was compared between those who cancelled versus completed telemedicine visits. We also evaluated patient differences in completion of video vs telephone visits. Cancellation rates were compared to a historical control of in-person gynecologic oncology office visits (3/23- 5/18/19). Multivariate logistic regression analyses were performed to assess odds of completing a telehealth appointment. Results: Of the 185 women with scheduled telemedicine visits, 158 (85%) completed and 27 (15%) cancelled. Telemedicine had significantly higher cancellations compared to office visits a year ago, 15% vs. 3% (p Download : Download high-res image (58KB) Download : Download full-size image Conclusions: Telemedicine implementation faces ongoing challenges. High cancellation rates and patient's reluctance to use video or activate their electronic patient portals may limit a durable telemedicine platform. No patient characteristics were associated with the successful completion of telemedicine visits, and completion of telemedicine visits was not associated with subsequent healthcare utilization. More in-depth studies of patient engagement with telemedicine are needed to optimize healthcare delivery beyond the COVID-19 pandemic.
The Expanding Array of Human Service Personnel

This paper assesses the impact upon social work and the social welfare services of the various types of personnel being produced by the expanding human service education programs that have recently appeared in colleges and universities throughout the country. It also considers some possible responses by the social work profession, by social work education, and by the social welfare field to these developments. Many new kinds of human service education programs are being developed at the community college, baccalaureate, and graduate levels.* The titles of the new programs are quite diverse and include community psychology, applied behavioral sciences, family therapy, and social services. The graduates of these programs are moving into human service agencies in increasing numbers where they are playing a variety of roles. Since they are relatively new phenomena, the nature and purposes of these programs are not widely known or understood. However, their graduates appear to share some common purposes and characteristics with social workers while, at the same time, the potential for competition or conflict exists. The purpose of this paper is to examine the potential impact of the graduates of the emerging human service programs on social work and the social services and to consider some possible responses by social work to these developments. * For more detailed descriptions of these programs and discussion of their particular significance for social work education, see the author's previous works (Brawley, 1981a; 1981b).
Energy Harvesting using Thermoelectric Materials

This article introduces the concepts of harvesting energy from ambient thermal gradients using thermal electric generators. The basic concepts are presented and a few simple examples are given. The focus here is on the use of thermal energy harvesting to run small electronic components of the type that are used in wireless structural health monitoring applications. Following the basic concepts, simple design formulas are presented. Examples are then given and some simple comparisons to other forms of harvesting are presented (solar and vibration based harvesting). Keywords: thermal electric generator; energy harvesting
Construction experience with Fermilab-built full length 50mm SSC dipoles

Fourteen full length SSC dipole magnets are being built and tested at Fermilab. Their purpose is to verify the magnet design as well as transfer the construction technology to industry. Magnet design is summarized. Construction problems and their solutions are discussed. Topics include coil winding, curing and measuring, collaring, instrumentation, end clamp installation, yoking and electrical and mechanical interconnection.
The problem with evolutionary art is ...

Computational evolutionary art has been an active practice for at least 20 years. Given the remarkable advances in that time in other realms of computing, including other forms of evolutionary computing, for many a vague feeling of disappointment surrounds evolutionary art. Aesthetic improvement in evolutionary art has been slow, and typically achieved in ways that are not widely generalizable or extensible. So what is the problem with evolutionary art? And, frankly, why isn't it better? In this paper I respond to these questions from my point of view as a practicing artist applying both a technical and art theoretical understanding of evolutionary art. First the lack of robust fitness functions is considered with particular attention to the problem of computational aesthetic evaluation. Next the issue of genetic representation is discussed in the context of complexity and emergence. And finally, and perhaps most importantly, the need for art theory around evolutionary and generative art is discussed, and a theory that stands typical evolutionary art on its head is proposed.
Fabrication of the APS storage ring radio frequency accelerating cavities

Specification, heat treatment, strength, and fatigue life of the Advanced Photon Source (APS) Storage Ring 352-MHz radio frequency (RF) accelerating cavity copper is discussed. Heat transfer studies, including finite element analysis, and configuration of water cooling is described. Requirements for and techniques of machining are considered. Braze and electron beam joint designs are compared. Vacuum considerations during fabrication are discussed. >
A New 20 µm upper Limit for SGR A

We have made 20.0 µm imaging array observations of the core of the Sgr A West complex in an attempt to detect emission from Sgr A*. An improved upper limit at 20 µm further constrains models for the emission mechanism and structure of Sgr A* (e.g. Zylka et al. 1992). Simple visual inspection of the 20 µm array image shows no indication of any 20 µm point source at the position of Sgr A*. In this case establishing an upper limit is complicated by the fact that Sgr A* is not located in blank sky, but lies in a region of weak emission on the edge of the extended ridge known as the “east-west bar” where the 20.0 µm image brightness is 1.2 Jy arcsec-2 (4 times the 1σ noise level). An additional concern is that if Sgr A* lies behind the ridge along the line-of-sight, extinction by dust in the intervening ridge could introduce an additional small correction factor.
Growth of Clostridium perfringens in Food Proteins Previously Exposed to Proteolytic Bacilli

Proteolytic sporeforming bacteria capable of surviving processing heat treatments in synthetic or fabricated protein foods exhibited no antagonistic effects on growth of Clostridium perfringens, but instead shortened the lag of subsequent growth of C. perfringens in sodium caseinate and isolated soy protein. Bacillus subtilis A cells were cultured in 3% sodium caseinate or isolated soy protein solutions. The subsequent effect on the lag time and growth of C. perfringens type A (strain S40) at 45 C was measured by colony count or absorbance at 650 nm, or both. B. subtilis incubation for 12 h or more in sodium caseinate reduced the C. perfringens lag by 3 h. Incubation of 8 h or more in isolated soy protein reduced the lag time by 1.5 h. Molecular sieving of the B. subtilis-treated sodium caseinate revealed that all molecular sizes yielded a similar reduced lag time. Diethylaminoethyl-Sephadex ion exchange fractionation and subsequent amino acid analysis indicated that the lag time reduction caused by B. subtilis incubation was not related to charge of the peptides nor to their amino acid composition. Apparently the shortened C. perfringens lag in these B. subtilis-hydrolyzed food proteins was a result of the protein being more readily available for utilization by C. perfringens.
An approximate solver for symbolic equations

This paper describes a program, called NEWTON, that finds approximate symbolic solutions to parameterized equations in one variable. NEWTON derives an initial approximation by solving for the dominant term in the equation, or if this fails, by bisection. It refines this approximation by a symbolic version of Newton's method. It tests whether the first Newton iterate lies closer to the solution than does the initial solution. If so, it returns this iterate; otherwise, it chooses a new initial solution and tries again.
Temporal Change and Disturbance in a Mixed Hardwood Forest in Blood Mountain Wilderness Area

The objectives of the current analysis are to examine potential successional trajectories in a second growth southern Appalachian mixed-hardwood forest, with particular focus on the influence of lowintensity disturbances, such as surface wildfire and gap creation, on the differential success of individual species in the vertical forest strata.
Maternal/fetal dehydration: prolonged effects and responses to oral rehydration

Dehydration induces marked alterations in maternal-fetal fluid homeostasis and accompanying fetal endocrine responses. We sought to determine if the increase in fetal plasma arginine vasopressin (AVP) levels during maternal dehydration is mediated by fetal plasma hypovolemia in addition to hyperosmolality and to examine maternal and fetal plasma atrial natriuretic factor (ANF) responses to maternal dehydration and oral rehydration. Seven pregnant ewes (127 +/- 1 day) were water deprived for 72-96 h, and five of these were orally rehydrated. Dehydration induced significant increases in maternal plasma osmolality (pOSM) (300 +/- 2 to 325 +/- 8 mosmol/kg) and AVP (3.0 +/- 0.4 to 18.9 +/- 4.0 pg/ml), and decreases in plasma ANF levels (28.1 +/- 3.1 to 19.7 +/- 3.1 pg/ml). Fetal pOSM (293 +/- 3 to 314 +/- 4 mosmol/kg), AVP (2.5 +/- 0.6 to 8.1 +/- 4.8 pg/ml), and urinary fractional sodium excretion increased significantly, whereas plasma ANF and fetal blood volume did not change. After maternal water access maternal plasma AVP decreased rapidly in comparison to the gradual decrease in maternal pOSM. Fetal plasma AVP levels did not change significantly and fetal pOSM decreased more slowly than maternal pOSM. Fetal plasma ANF increased in association with increased urine flow and glomerular filtration rate after maternal rehydration. These data indicate marked differences in fetal and maternal plasma ANF and AVP responses with dehydration-induced increases in fetal plasma AVP being secondary to plasma hyperosmolality, rather than hypovolemia. Rapid suppression of maternal plasma AVP may contribute to the slower equilibration of fetal pOSM during oral, as compared with intravenous, maternal rehydration.
Cross-linking of the δ Subunit to One of the Three α Subunits Has No Effect on Functioning, as Expected if δ Is a Part of the Stator That Links the F1 and F0 Parts of the Escherichia coli ATP Synthase

A mutant of the Escherichia coliF1F0-ATPase has been generated (αQ2C) in which the glutamine at position 2 of the α subunit has been replaced with a cysteine residue. Cu2+ treatment of ECF1from this mutant cross-linked an α subunit to the δ subunit in high yield. Two different sites of disulfide bond formation were involved,i.e. between Cys90 (or the closely spaced Cys47) of α with Cys140 of δ, and between Cys2 of α and Cys140 of δ. Small amounts of other cross-linked products, including α-α, δ internal, and α-α-δ were obtained. In ECF1F0, there was no cross-linking between the intrinsic Cys of α and Cys140. Instead, the product generated between Cys2 of α and Cys140 of δ was obtained at near 90% yield. Small amounts of α-α and δ internal were present, and under high Cu2+ concentrations, α-α-δ was also formed. The ATPase activity of ECF1 and ECF1F0 was not significantly affected by the presence of these cross-links. When Cys140 of δ was first modified with N-ethylmaleimide in ECF1F0, an α-δ cross-link was still produced, although in lower yield, between Cys64 of δ and Cys2 of α. ATP hydrolysis-linked proton pumping of inner membranes from the mutant α2QC was only marginally affected by cross-linking of the α to the δ subunit. These results indicate that Cys140 and Cys64 of the δ subunit and Cys2 of the α subunit are in close proximity. This places the δ subunit near the top of the α-β hexagon and not in the stalk region. As fixing the δ to the α by cross-linking does not greatly impair either the ATPase function of the enzyme, or coupled proton translocation, we argue that the δ subunit forms a portion of the stator linking F1 to F0.
Characterization of a family 45 glycosyl hydrolase from Fibrobacter succinogenes S85

Fibrobacter succinogenes is one of the most active cellulolytic bacteria ever isolated from the rumen, but enzymes from F. succinogenes capable of hydrolyzing native (insoluble) cellulose at a rapid rate have not been identified. However, the genome sequence of F. succinogenes is now available, and it was hoped that this information would yield new insights into the mechanism of cellulose digestion. The genome has a single family 45 beta-glucanase gene, and some of the enzymes in this family have good activity against native cellulose. The gene encoding the family 45 glycosyl hydrolase from F. succinogenes S85 was cloned into Escherichia coli JM109(DE3) using pMAL-c2 as a vector. Recombinant E. coli cells produced a soluble fusion protein (MAL-F45) that was purified on a maltose affinity column and characterized. MAL-F45 was most active on carboxymethylcellulose between pH 6 and 7 and it hydrolyzed cellopentaose and cellohexaose but not cellotetraose. It also cleaved p-nitrophenyl-cellopentose into cellotriose and p-nitrophenyl-cellobiose. MAL-F45 produced cellobiose, cellotriose and cellotetraose from acid swollen cellulose and bacterial cellulose, but the rate of this hydrolysis was much too low to explain the rate of cellulose digestion by growing cultures. Because the F. succinogenes S85 genome lacks dockerin and cohesin sequences, does not encode any known processive cellulases, and most of its endoglucanase genes do not encode carbohydrate binding modules, it appears that F. succinogenes has a novel mechanism of cellulose degradation.
Aerothermodynamic Analysis of Commercial Experiment Transporter (COMET) Reentry Capsule

An aerothermodynamic analysis of the Commercial Experiment Transporter (COMET) reentry capsule has been performed using the laminar thin-layer Navier-Stokes solver Langley Aerothermodynamic Upwind Relaxation Algorithm. Flowfield solutions were obtained at Mach numbers 1.5, 2, 5, 10, 15, 20, 25, and~27.5. Axisymmetric and 5, 10, and 20~degree angles of attack were considered across the Mach-number range, with the Mach 25 conditions taken to 90 degrees angle of attack and the Mach 27.5 cases taken to 60 degrees angle of attack. Detailed surface heat-transfer rates were computed at Mach 20 and 25, revealing that heating rates on the heat-shield shoulder can exceed the stagnation-point heating by 230 percent. Finite-rate chemistry solutions were performed above Mach 10, otherwise perfect gas computations were made. Drag, lift, and pitching moment coefficients are computed and details of a wake flow are presented. The effect of including the wake in the solution domain was investigated and base pressure corrections to forebody drag coefficients were numerically determined for the lower Mach numbers. Pitching moment comparisons are made with direct simulation Monte Carlo results in the more rarefied flow at the highest Mach numbers, showing agreement within two-percent. Thin-layer Navier-Stokes computations of the axial force are found to be 15 percent higher across the speed range than the empirical/Newtonian based results used during the initial trajectory analyses.
The serine/threonine phosphatase inhibitor calyculin A induces rapid degradation of IκBβ. Requirement of both the N- and C-terminal sequences

Signal-initiated activation of the transcription factor NF-kappaB is mediated through proteolysis of its cytoplasmic inhibitory proteins IkappaBalpha and IkappaBbeta. While most NF-kappaB inducers trigger the degradation of IkappaBalpha, only certain stimuli are able to induce the degradation of IkappaBbeta. The degradation of IkappaBalpha is targeted by its site-specific phosphorylations, although the mechanism underlying the degradation of IkappaBbeta remains elusive. In the present study, we have analyzed the effect of phosphatase inhibitors on the proteolysis of IkappaBbeta. We show that the serine/threonine phosphatase inhibitor calyculin A induces the hyperphosphorylation and subsequent degradation of IkappaBbeta in both human Jurkat T cells and the murine 70Z-3 preB cells, which is associated with the nuclear expression of active NF-kappaB. The calyculin A-mediated degradation of IkappaBbeta is further enhanced by the cytokine tumor necrosis factor-alpha (TNF-alpha), although TNF-alpha alone is unable to induce the degradation of IkappaBbeta. Mutational analyses have revealed that the inducible degradation of IkappaBbeta induced by calyculin A, and TNF-alpha requires two N-terminal serines (serines 19 and 23) that are homologous to the inducible phosphorylation sites present in IkappaBalpha. Furthermore, the C-terminal 51 amino acid residues, which are rich in serines and aspartic acids, are also required for the inducible degradation of IkappaBbeta. These results suggest that the degradation signal of IkappaBbeta may be controlled by the opposing actions of protein kinases and phosphatases and that both the N- and C-terminal sequences of IkappaBbeta are required for the inducible degradation of this NF-kappaB inhibitor.
Interrelationship between controlling arrival and service in queueing systems

In this paper, the interrelationship between the F-Policy problem and the truncated N-Policy problem is considered. The F-Policy problem deals with the issue of controlling arrivals to a queueing system. The N-Policy problem involves a queueing system in which the server leaves the system (for alternative jobs) when it becomes empty and returns when the queue builds up to a predetermined level. The steady state probability distribution and expressions for the measures of effectiveness for these two systems are obtained. The complementarity relationships between these two queueing systems are established. These relationships provide insight into these queueing problems and facilitate the solution to any one of the problems given the solution to the other. Through a series of propositions, other relationships between these queueing systems are also established.
Die Beziehungen zwischen dem Lipasegehalt und der neurotoxischen Wirkung des Serums nach experimenteller Leherschädigung

1. Etwa am 4. Tage nach Leberschadigung durch Unterbindung der Gallenoder Pankreasgange erscheinen im Blute Substanzen, die im Reagensglasversuch zerstorend auf Rattenruckenmark einwirken. Diese Toxine sind nicht identisch mit den gleichzeitig vermehrten Lipasen; sie sind hitzebestandig und sie konnen noch nach mehreren Wochen nachgewiesen werden, wenn die Lipasen zur Norm zuruckgekehrt sind. 2. Diese Toxine werden durch den Plexus chorioideus in die Ventrikel des Gehirns ausgeschieden, oder sie verteilen sich, von den Gefasen ausgehend, in der Rinde. Ihre Wirkung ist am ausgepragtesten am Orte der Ausscheidung und grosten Konzentration. Sie erzeugen hier in einzelnen Fallen eine spongiose Gewebsnekrose in den Ventrikelwanden oder Lichtungs- und Entmarkungsherde in dem Rindenmark. Eine ausgebreitete Ganglienzellerkrankung wurde in allen Fallen beobachtet. Gleichzeitig setzt eine aktive Gliavermehrung ein unter Bildung dichter Faserfilze in den Entmarkungsherden. Das Mesenchym ist nicht aktiv beteiligt.
Central Arctic Ocean paleoceanographic interpretations based on Late Cenozoic calcareous dinoflagellates

Abstract Four calcareous dinoflagellate morphotypes, interpreted to represent a single species, Thoracosphaera arctica n. sp., occur in upper Miocene to Holocene sediments of the central Arctic Ocean. The calcareous fossils generally are rare except during one interval, that of the latest Pliocene to late Pleistocene. During this interval the fossil dinoflagellates were alternately abundant and rare in approximate coordination with greater and lesser times of foraminifera productivity. Dinoflagellates and foraminifera generally are rare during times of accumulation of abundant coarse textured ice-rafted sediment during this interval. The life cycle of the dinoflagellate that produces the Arctic Ocean calcareous fossil is unknown but the fossils probably are either resting cysts, motile vegetative cells or hypnozygotes. A vegetative cell origin better explains the co-occurrence of foraminifera as well as the negative correlation with ice-rafting. This tentative interpretation leads to the conclusion that during the interval 2.0 to 0.7 m.y. b.p., the Arctic Ocean had relatively productive surface waters with very thin or even periodic absence of pack-ice alternating with conditions more like that of the present. During periods before 2.0 m.y. and since 0.7 m.y., the Arctic Ocean probably was ice-covered, with oceanographic conditions similar to that of the modern ocean. These conclusions differ from previous interpretations that the Arctic was continually ice-covered, had no surface productivity or was covered by a giant, Antarctic-like ice-cap.
Uropharmacology: XI. Adrenergic-blocking agents and drugs affecting catecholamine binding and release

In 1906 Sir Henry Dale’ published a detailed report describing the inhibitory effects of an extract of the fungus ergot on some visceral and circulatory responses induced by circulating epinephrine and by sympathetic nerve stimulation. The ergot alkaloids were the first adrenergic blocking drugs to be disc0vered.l Ahlquist and others2-4 proposed the terms alpha and beta to designate adrenoceptive sites on smooth muscles where catecholamines produce excitation and inhibition, respectively. This classification of receptors has been substantiated by the observations that certain drugs, for example, phenoxybenzamine, are capable of selective blockade at alpha-receptor sites of the effects which occur after adrenergic neuronal stimulation or after injection of sympathomimetic agents, whereas other agents such as practolol or butoxamine produce selective blockade of beta-l and beta-2 adrenergic receptors, respectively, and their associated functions. We include a discussion of the uropharmacology of various alphaand beta-blocking drugs as well as agents which interfere with activation of the release of norepinephrine from adrenergic nerves. Interest in these drugs has increased recently as better understanding of the role of bladder and its outlet has evolved. This understanding has evolved from recent investigations which have shown the presence and selective distribution of the alpha and beta receptors in the bladder and bladder outlet.5-7 Alpha receptors are predominant in the outlet of the bladder where they mediate contraction of the smooth muscle of the outlet and therefore
A new CT prostate segmentation for CT-based HDR brachytherapy

High-dose-rate (HDR) brachytherapy has become a popular treatment modality for localized prostate cancer. Prostate HDR treatment involves placing 10 to 20 catheters (needles) into the prostate gland, and then delivering radiation dose to the cancerous regions through these catheters. These catheters are often inserted with transrectal ultrasound (TRUS) guidance and the HDR treatment plan is based on the CT images. The main challenge for CT-based HDR planning is to accurately segment prostate volume in CT images due to the poor soft tissue contrast and additional artifacts introduced by the catheters. To overcome these limitations, we propose a novel approach to segment the prostate in CT images through TRUS-CT deformable registration based on the catheter locations. In this approach, the HDR catheters are reconstructed from the intra-operative TRUS and planning CT images, and then used as landmarks for the TRUS-CT image registration. The prostate contour generated from the TRUS images captured during the ultrasound-guided HDR procedure was used to segment the prostate on the CT images through deformable registration. We conducted two studies. A prostate-phantom study demonstrated a submillimeter accuracy of our method. A pilot study of 5 prostate-cancer patients was conducted to further test its clinical feasibility. All patients had 3 gold markers implanted in the prostate that were used to evaluate the registration accuracy, as well as previous diagnostic MR images that were used as the gold standard to assess the prostate segmentation. For the 5 patients, the mean gold-marker displacement was 1.2 mm; the prostate volume difference between our approach and the MRI was 7.2%, and the Dice volume overlap was over 91%. Our proposed method could improve prostate delineation, enable accurate dose planning and delivery, and potentially enhance prostate HDR treatment outcome.
A Ge(Li) Concentric Duode Spectrometer for Compton Suppression

A Ge(Li) Compton sum coincidence spectrometer which greatly reduces the Compton continuum and essentially eliminates the Compton edges for low energy gammas has been fabricated. This spectrometer was made from a single cylinder of germanium in which lithium was drifted to form two separate and equal depth concentric detectors. An event in the full energy peak is recorded only if the total energy deposition occurs as the result of multiple events, with each detector sharing in the absorption process. Several types of gamma-ray spectra are presented which show the reduction of the Compton continuum. For the case of the 1275 keV gamma from 22Na the ratio of the full energy peak to Compton edge (in this case a multiple Compton event edge) increases from 2.8 to 1, when the device is used as the sum of two single spectrometers, to 13.5 to 1 when it is used in the sum coincidence mode with a decrease of efficiency of a factor of five. This ratio for the 511 keV line from 22Na increases from 3.6 to 1, to 18 to 1. Other spectra are shown and a discussion of efficiency is presented.
Stability analysis of the Luttinger liquid fixed-point in metallic nanotubes

We study the stability of a Luttinger liquid in a metallic single-walled nanotube against generic backscattering and Umklapp perturbations. Analizing the renormalization group equations we identify nontrivial particular solutions that lay in the same universality class of the Luttinger liquid. We describe in detail the mechanism of instability generation in that electron liquid and discuss under which conditions it governs the physical properties in the presence of low frequency or temperature cutoffs.
A comprehensive model for AP-based composite propellant ignition

A comprehensive model and numerical solutions for ignition of AP-based composite solid propellants are presented. The analysis simulates the ignition process of a propellant sample, located in a stagnation region, under rapid pressure loading conditions. Specific features considered in the model include: 1) detailed chemical kinetics information for the ignition of AP-based composite propellants, 2) two-dimensional (axisymmetric) geometry for the composite propellant, and 3) rapid pressurization of the gas phase. An implicit finite difference scheme is used to solve the set of transient, second-order, coupled, inhomogeneous, nonlinear, governing partial differential equations. Numerical solutions reveal a number of important events occurring during the ignition sequence, including: igniter gas penetration to the region near the sample surface, combustion of unburned species upon arrival of compression waves, heat transfer to the propellant, pyrolysis of the oxidizer and fuel, and gas-phase reactions leading to ignition. The model correctly predicts the experimental observation that the ignition delay time decreases as the pressurization rate is increased. The various ignition criteria considered show the same trend as that measured experimentally.
Beta-ray dose in tissue-equivalent material immersed in a radioactive cloud

The radioactive-cloud immersion problem for beta-radiation has been treated schematically by assuming a semi-infinite air medium (source region) located adjacent to a semi-infinite water medium (tissue-equivalent target). The source region has been assumed to contain a uniform concentration of beta- emitting radionuclide, and calculations have been made of the absorbeddose distribution (depth dose) in the water target. A leakage correction has also been made to estimate the reduction of absorbed dose that would occur if the target had lateral dimensions small compared to the beta-particle range in air. Depth-dose calculations have been carried out for various source spectra (including beta-ray as well as discrete electron spectra) for /sup 83m/Kr, /sup 85m/Kr, /sup 85/Kr, /sup 87/Kr, /sup 88/Kr, /sup 88/Rb, /sup 131m/Xe, /sup 133m/ Xe /sup 133/Xe, /sup 135/Xe, /sup 137/Xe, /sup 137/Cs /sup 138/Xe and /sup 138/ Cs, being rare gases emitted by nuclear power plants into the atmosphere, and for /sup 3/H, /sup 14/C, /sup 35/S, /sup 125/I, /sup 24/Na, /sup 32/P, /sup 42/K, / sup 90/Y, /sup 60/Co, /sup 89/Sr, /sup 90/Sr, /sup 131/I, being comm only used radionuclides. (auth)
Adaptive expansion of the maize maternally expressed gene (Meg) family involves changes in expression patterns and protein secondary structures of its members

Background: The Maternally expressed gene (Meg) family is a locally-duplicated gene family of maize which encodes cysteine-rich proteins (CRPs). The founding member of the family, Meg1, is required for normal development of the basal endosperm transfer cell layer (BETL) and is involved in the allocation of maternal nutrients to growing seeds. Despite the important roles of Meg1 in maize seed development, the evolutionary history of the Meg cluster and the activities of the duplicate genes are not understood. Results: In maize, the Meg gene cluster resides in a 2.3 Mb-long genomic region that exhibits many features of non-centromeric heterochromatin. Using phylogenetic reconstruction and syntenic alignments, we identified the pedigree of the Meg family, in which 11 of its 13 members arose in maize after allotetraploidization ~4.8 mya. Phylogenetic and population-genetic analyses identified possible signatures suggesting recent positive selection in Meg homologs. Structural analyses of the Meg proteins indicated potentially adaptive changes in secondary structure from α-helix to β-strand during the expansion. Transcriptomic analysis of the maize endosperm indicated that 6 Meg genes are selectively activated in the BETL, and younger Meg genes are more active than older ones. In endosperms from B73 by Mo17 reciprocal crosses, most Meg genes did not display parent-specific expression patterns. Conclusions: Recently-duplicated Meg genes have different protein secondary structures, and their expressions in the BETL dominate over those of older members. Together with the signs of positive selections in the young Meg genes, these results suggest that the expansion of the Meg family involves potentially adaptive transitions in which new members with novel functions prevailed over older members.
An abbreviated form of the WISC‐R: Is it valid?

The completed WISC-Rs of 76 white urban children (6–0 to 15–9) were rescored utilizing the Satz and Mogel criteria for an abbreviated intelligence measure. Extremely high correlations for IQs (.96 – .98) and subtests (.66 – .95) were found. However, when mean differences between complete WISC-R and the shortened form were examined, significant differences between administrations were found. Furthermore, one-third of the subjects showed changes in intelligence classification levels when the abbreviated form was used. Thus, two of the three criteria previously suggested for a valid abbreviated intelligence test of: (a) a significantly high correlation between administration forms; (b) nonsignificant t-tests between the abbreviated and standard form mean IQ; and (c) low percentage of IQ classification change with the administration of the short form, were not met. It was concluded, however, that the abbreviated WISC-R may be appropriate when intelligence is a question relative to candidacy for therapy or as a noncritical, general indication of intelligence when IQ classification is not important and/or assessment time is limited.
Oral Communication Skills of Children Who Are Hard of Hearing

Forty children with mild to severe hearing losses were administered a battery of speech and language tasks. The children’s speech was characterized by misarticulation of affricates and fricatives, ...
Parametric analysis of proton exchange membrane fuel cell performance by using the Taguchi method and a neural network

This study proposes a novel parameter optimization method, capable of integrating the neural network and the Taguchi method for parametric analysis of proton exchange membrane fuel cell (PEMFC) performance. Numerous parameters affecting the PEMFC performance are analyzed, such as fuel cell operating temperatures, cathode and anode humidification temperatures, operating pressures, and reactant flow rate. In the traditional design of experiments, the Taguchi method has been popularly utilized in engineering. However, the parameter levels selected to form the orthogonal array in the Taguchi method are discrete, preventing the estimation of the real optimum. This study used the Taguchi method to acquire the primary optimums of the operating parameters in the PEMFC. Each row in the orthogonal array together with its relative responses was used to establish a set of training patterns (input/target pair) to the neural network. The neural network can then construct relationships between the control factors and responses in the PEMFC. The actual optimums of the operating parameters in the PEMFC were obtained by the trained neural network. Experimental results are presented for identifying the proposed approach, which is useful in improving performance for PEMFC and developing electrical system on advanced vehicles and ships.
Are the energy poor also income poor? Evidence from India

Abstract The energy poverty line is defined as the threshold point at which energy consumption begins to rise with increases in household income. This approach is applied to cross-sectional data from a comprehensive 2005 household survey representative of both urban and rural India. The objective is to determine if the energy poor are also income poor and whether and how energy policies help reduce energy poverty, independent of income. The findings suggest that in rural areas some 57% of households are energy poor, versus 22% that are income poor. But in urban areas the energy poverty rate is 28% compared to 20% that are income poor. That is, energy policies are expected to play some roles in mitigating energy poverty. We find that reducing energy poverty requires not only support for rural electrification, but also more use of modern cooking fuels such as LPG. While income growth matters, a combination of energy related programs can play an independent and substantial role in reducing energy poverty.
Why Are There No Terminal Oxo Complexes of the Late Transition Metals? or The Importance of Metal–Ligand π Antibonding Interactions

Abstract π antibonding interactions result from the overlap of a filled π symmetry ligand orbital with a filled metal d orbital. This antibonding plays an important role in the chemistry of π donor ligands such as oxo and alkoxide. It is in large part responsible for the lack of late transition metal complexes with terminal oxo ligands, and can explain some of the unusual chemistry of late metal alkoxide complexes.
Relationship between acute physiologic derangement and risk of death

Abstract Initial evidence from 481 acutely ill patients with 12 major life-threatening diseases suggests a consistent relationship between the magnitude of physiologic derangement and the patient's risk of death. These results were found in postoperative and nonoperative diseases, including gastrointestinal bleeding, intracranial bleeding, pneumonia, congestive heart failure, trauma and hemorrhagic shock. There appear to be substantial differences in the inherent risk of these diseases, but within each diagnosis, the impact of incremental increases in physiologic derangement on mortality appears to be similar. The existence of a uniform relationship in a variety of diagnoses could have important implications for the researcher and clinician wishing to evaluate outcome from intense medical care. It would allow more reproducible and precise stratification of patients by risk of death prior to therapy, thereby improving our understanding of the efficacy of new and existing treatments.
The use of prophylaxis in patients undergoing diagnostic tests for suspected venous thromboembolism.

ObjectivesThe purpose of this study was to describe the use of pharmacological and mechanical prophylaxis and clinical outcomes of patients undergoing diagnostic tests for suspected venous thromboe...
Prescription Sharing, Alcohol Use, and Street Drug Use to Manage Pain Among Veterans

Abstract Context Efforts to promote awareness and management of chronic pain have been accompanied by a troubling increase in prescription medication abuse. At the same time, some patients may misuse substances in an effort to manage chronic pain. Objectives This study examines self-reported substance misuse for pain management among veterans and identifies the contributing factors. Methods We analyzed cross-sectional data from the Help Veterans Experience Less Pain study. Results Of 343 veterans, 35.3% reported an aberrant pain management behavior (24% reported using alcohol, 11.7% reported using street drugs, and 16.3% reported sharing prescriptions to manage pain). Poorer mental health, younger age, substance use disorders (SUDs), number of nonpain symptoms, and greater pain severity and interference were associated with aberrant pain management behaviors. In multivariate analysis, SUDs (odds ratio [OR]: 3.9, 95% confidence interval [CI]: 2.3–6.7, P P =0.006) were associated with using alcohol or street drugs to manage pain; SUDs (OR: 2.4, 95% CI: 1.3–4.4, P =0.006) and pain interference (OR: 1.1, 95% CI: 1.0–1.2, P =0.047) were associated with prescription sharing; and SUDs (OR: 3.6, 95% CI: 2.2–6.1, P P =0.031) were associated with any aberrant pain management behavior. Conclusion Veterans with a history of SUDs, greater pain interference, more nonpain symptoms, and mental health concerns should be carefully managed to deter substance misuse for pain management.