cssi/SciSciGPT-SciSciNet huggingface dataset:
Thyristor model development for low impedance load pulse generator simulation

Many thyristor models exist that are either impractical to implement in a SPICE simulator, or do not model transient turn-on performance accurately. An empirical SPICE model is developed for thyristors to model turn-on performance. Silicon Power's CCS SC 14N40 is selected for simulation. The process of model determination is detailed and simulation results are compared to experiments.
Metastatic Colorectal Cancer to the Small Bowel—an Uncommon Cause of Obscure GI Bleeding: a Three-Case Experience with Review of the Literature

Metastatic colorectal cancer to the small intestine is a rare condition presenting with nonspecific symptoms such as obscure gastrointestinal bleeding (OGIB). We report our experience with the use of capsule endoscopy (CE) and double-balloon enteroscopy (DBE) to identify and diagnose the metastatic colorectal cancer to the small bowel. The aim was to demonstrate the approach to the diagnosis of metastatic colorectal cancer to the small bowel including literature review. This is a retrospective case series from an academic tertiary referral center. Three patients with a history of colorectal cancer referred for OGIB underwent CE and subsequent DBE. All patients underwent evaluation including esophagogastroduodenoscopy and colonoscopy prior to referral. In each case, CE was performed revealing the source of bleeding which was confirmed as metastatic colorectal cancer to the small bowel by DBE. Significant lag time was noted from the initial diagnosis of colorectal cancer to the onset of symptomatic small bowel metastasis in this series (1.3–7 years). We found the incidence of metastatic colorectal cancer to the small intestine of those with small intestine tumors to be 6%. Clinicians should be suspicious of this condition in any patient with OGIB and prior history of colorectal cancer. The approach to this diagnosis is varied but one algorithm includes the combined use of CE for tumor localization and balloon-assisted enteroscopy for confirmation.
The Content of Their Character

Deep down, all of us have prejudices, and physicians are not immune. Almost 45 years after Dr. Martin Luther King Jr. wished that his children—and ours—would be judged by the content of their chara...
Hydrogen pressure-composition isotherms for Ti45Zr38Ni17 amorphous and quasicrystal powders produced by mechanical alloying

Pressure-composition isotherms (PCTs) for amorphous and icosahedral (i) quasicrystal powders produced by mechanical alloying of Ti 45 Zr 38 Ni 17 powder mixtures were measured at temperatures of 473 K and 523 K at low-hydrogen pressures, lower than 0.1 MPa. Sloping plateau-like features on PCTs were observed at equilibrium hydrogen pressures lower than 1 kPa, below an H/M (hydrogen to metal atom ratio) 1.2 and 1 for the amorphous and i-phase powders respectively. The plateau-like region for the i-phase powder was steeper and narrower than that for the amorphous powder, implying some small differences between the local structures of the i-phase and the amorphous phase. After the PCT measurements, an increase in the nearest-neighbor atom spacing and an expansion of the quasilattice were observed for the amorphous and i-phase powders respectively. Impurities from some unsynthesized elemental material and a Ti 2 Ni type phase were also present. These also absorbed hydrogen, shown by an expansion of their crystal lattices. However, no crystal hydride formation was observed in any of the powders.
Dental Implant Outcomes may Vary in Patients With a History of Periodontal Disease

Article Title and Biographical Information Systematic review of implant outcomes in treated periodontitis subjects. Ong CTT, Ivanoski S, Needleman IG, Retzepi M, Moles DR, Tonetti MS, et al. J Clin Periodontol 2008;35:438-62. Reviewer Clark Stanford, DDS, PhD Purpose/Question To determine the effect of a past history of periodontitis on survival and success of dental implants in partially edentulous patients. Source of Funding Self-funded/university institutional support. Type of Study/Design Systematic review. Level of Evidence Level 2: Limited-quality patient-oriented evidence Strength of Recommendation Grade Grade B: Inconsistent or limited-quality patient-oriented evidence
Cosmic Abundance of Iron and Nature of Primitive Material in Meteorites

Comparison of solar abundance data with bulk analyses of type-I carbonaceous meteorites and microprobe analyses of type-I phyllosilicates. The comparison seems to lend support to Kerridge's (1971) hypothesis that the apparently primitive chemistry of such meteorites may be the result of a major component dominating the analysis and that this component may be unaltered solar system condensate.
New Tools for Online Information Literacy Instruction

This article investigates the new landscape of online information literacy tools, such as embedding resources into course management software and specific academic organizations' web sites and using podcasts, screencasts, blogs, Web-based board games, and virtual three-dimensional environments. This article also explores the influence these methods have on information literacy skills of undergraduate students.
Meta-analysis of venous thromboembolism prophylaxis in medically Ill patients.

Abstract Background: Venous thromboembolism (VTE) prophylaxis in medically ill patients has received a level 1A recommendation in previously published clinical guidelines. Pharmacologic prophylaxis for VTE includes unfractionated heparin (UFH), low-molecular-weight heparin (LMWH), and fondaparinux. Few direct comparisons between anticoagulants exist in medically ill patients. Objective: This meta-analysis was conducted to assess UFH and LMWH (including the selective factor Xa inhibitor fondaparinux) in the reduction of in-hospital VTE in unselected medically ill patients. Methods: We searched MEDLINE, EMBASE, and the Cochrane Controlled Trials Registry databases from January 1981 through September 2007 (English language) for randomized controlled trials using the following terms: dalteparin, enoxaparin, fondaparinux, nadroparin, and heparin . References of included articles and key review papers for additional studies were also searched. Data from studies were included in the analysis if the studies included medically ill patients with risk factors for VTE who had been followed up for 7 to 21 days. Results: A total of 12,391 patients (of whom 8357 were in placebo-controlled trials) from 9 studies were included. Mean age for the entire cohort was 72.8 years; mean (SD) body mass index, 25.6 kg/m2; and mean (SD) actual body weight, 68.2 kg. Deep vein thrombosis (DVT) was significantly reduced with the addition of an LMWH compared with placebo (odds ratio [OR], 0.60; 95% CI, 0.47-0.75; P ≤ 0.001), but rates of DVT were similar when comparing LMWH with UFH (OR, 0.92; 95% CI, 0.56-1.52). No significant differences in pulmonary embolism (PE) or death were found among the UFH, LMWH, and placebo groups. LMWH was associated with a significant increased risk for minor bleeding compared with placebo (OR, 1.64; 95% CI, 1.18-2.29; P=0.003). However, no significant difference was found between LMWH and UFH (OR, 0.68; 95% CI, 0.27-1.70). Major bleeding events were similar among all groups: LMWH/fondaparinux versus placebo, OR, 1.65 (95% CI, 0.8-3.4); LMWH/fondaparinux versus UFH, OR, 0.69 (95% CI, 0.29-1.68); LMWH/fondaparinux versus UFH or placebo, OR, 1.16 (95% CI, 0.66-2.04). Conclusions: This analysis suggests that VTE prophylaxis with an LMWH (including fondaparinux) or UFH is effective in reducing the rate of DVT, but this benefit did not extend to enhanced protection against PE. Additionally, LMWH and UFH had similar bleeding outcomes.
Genetic diversity within a threatened, endemic North American species, Euphorbia telephioides (Euphorbiaceae)

The southeastern United States and Florida support an unusually large number of endemic plant spe- cies, many of which are threatened by anthropogenic habitat disturbance. As conservation measures are under- taken and recovery plans designed, a factor that must be taken into consideration is the genetic composition of the species of concern. Here we describe the levels, and par- titioning, of genetic diversity in 17 populations of the rare and threatened Florida endemic, Euphorbia telephioides (telephus spurge). Species-wide genetic diversity was high (Ps = 91%, APs = 3.81, As = 3.57 and Hes = 0.352) as was mean population genetic diversity (Pp = 81%, APp = 2.98, Ap = 2.59 and Hep = 0.320) which ranks it among the highest 10% of plant species surveyed. Partitioning of genetic variation (Gst = 0.106) was low compared to other herbaceous outcrossing perennials indicating high histori- cal gene flow across its limited geographic range. Among population Gst values within the three Florida counties in which it occurs, Gulf (0.084), Franklin (0.059) and Bay Counties (0.033), were also quite low. Peripheral popula- tions did not generally have reduced genetic variation although there was significant isolation by distance. Rare- faction analysis showed a non-significant relationship between allelic richness and actual population sizes. Our data suggest that E. telephioides populations were probably more continuously distributed in Bay, Gulf and Franklin Counties and that their relative contemporary isolation is a recent phenomenon. These results are important for developing a recovery plan for this species.
The DREAM: An Integrated Photonic Thresholder

We propose a novel all-optical integrated thresholder called the dual resonator enhanced asymmetric Mach-Zehnder interferometer (DREAM). Unlike prior integrated photonic devices, the DREAM exhibits properties of stable binary decision making, outputting a constant “one” power value for signals above a certain power level and “zero” for signals of lower powers. This thresholding shape arises from the interference of complementary nonlinear effects of two microring resonators (MRR), one in each arm of a Mach-Zehnder interferometer (MZI). The proposed device performs several orders of magnitude better in size, decision latency, energy efficiency, and stability compared to fiber-based methods of optical thresholding. It is best suited for application in densely integrated systems where rapid conversion between analog and digital signal domains is ubiquitous, such as hybrid analog-digital and neuromorphic processing architectures. We derive analytical steady-state solutions to the nonlinear MRR, which enable design simulation, optimization, and automation of a continuous signal thresholder about three orders of magnitude faster than with numerical simulation. Additional numerical simulations indicate the possibility of a 50 GHz pulse thresholder with a 380 pJ switching threshold in a silicon-on-insulator (SOI) platform. The proposed circuit design techniques are potentially applicable to a wide range of materials, waveguide platforms, and resonator types, but for concreteness, we limit the focus of this paper to MRRs in SOI.
TH-D-342-02: Advanced CT Applications and Their Impact On Clinical Practice

Physicians from nearly every medical specialty rely on CT for its ability to rapidly and reliably define anatomic morphology. The tremendous advances in CT technology over the past decade have allowed many new techniques to move into mainstream clinical use. CardiacCT,CTangiography,CT enterography and CT colonography have, in many cases, become accepted replacements for invasive alternatives such as catheter angiography or endoscopy. The use of 3‐ or 4‐D image displays allows a more intuitive demonstration of imaging findings to the referring physician and the patient, resulting in more than 100% growth per year in the numbers of exams using these techniques. The use of 4D CT joint kinematics may allow for the assessment of orthopedic motion abnormalities, just as 4D cardiacimaging allows for the assessment of cardiac motion abnormalities. New interventional CT procedures allow for outpatient spine fracture stabilization, tumor ablation, and complicated biopsies. CT perfusion exams in oncology patients may allow assessment of the therapeutic effect of anti‐angiogenic drugs. And, material composition information is becoming available with the reintroduction of dual‐energy CT. Dual energy CT has been shown to provide > 93% accuracy for the identification of uric acid kidney stones; to be able to differentiate gout from calcium pyrophosphate dihydrate deposits; to facilitate rapid bone removal from CTangiographydata sets; and to be able to remove iodine from contrast‐enhanced data sets. Clinical adoption of these and other dual‐energy applications is anticipated to increase as more commercial dual‐energy CT products are brought to the marketplace. In spite of these and other advances in CT capabilities, the pressure to keep patient dose as low as possible (consistent with the imaging task) remains. Dose management strategies are thus a necessary consideration for the development and clinical implementation of any new CTimaging capability. The participant will learn about these and other new CT clinical applications.
Incremental maintenance of recursive views using relational calculus/SQL

Views are a central component of both traditional database systems and new applications such as data warehouses. Very often the desired views (e.g. the transitive closure) cannot be defined in the standard language of the underlying database system. Fortunately, it is often possible to incrementally maintain these views using the standard language. For example, transitive closure of acyclic graphs, and of undirected graphs, can be maintained in relational calculus after both single edge insertions and deletions. Many such results have been published in the theoretical database community. The purpose of this survey is to make these useful results known to the wider database research and development community.There are many interesting issues involved in the maintenance of recursive views. A maintenance algorithm may be applicable to just one view, or to a class of views specified by a view definition language such as Datalog. The maintenance algorithm can be specified in a maintenance language of different expressiveness, such as the conjunctive queries, the relational calculus or SQL. Ideally, this maintenance language should be less expensive than the view definition language. The maintenance algorithm may allow updates of different kinds, such as just single tuple insertions, just single tuple deletions, special set-based insertions and/or deletions, or combinations thereof. The view maintenance algorithms may also need to maintain auxiliary relations to help maintain the views of interest. It is of interest to know the minimal arity necessary for these auxiliary relations and whether the auxiliary relations are deterministic. While many results are known about these issues for several settings, many further challenging research problems still remain to be solved.
Chemical routes to ultra thin films for copper barriers and liners

Abstract Triruthenium dodecarbonyl and trimethylphosphine or triphenylphosphine were used in flowing hydrogen or argon at 575 K to explore the effect of changing the percentage of P on the amorphous character of the films and on the electrical properties of the films. Films as thin as 7 nm were grown. The films contained a carbon impurity that depended on the delivery gas and the alkylphoshphine source. The microstructure changed with the percentage P; amorphous films formed provided the percentage of P exceeded 15 at.%. Film resistivity was most sensitive to the carbon impurity and also changed with microstructure. A 15 nm thick, amorphous film containing ∼ 15 at.% P had a resistivity of 210 μΩ cm. Ion scattering studies reveal that ∼ 0.4 nm Cu films completely wet amorphous Ru–P alloy films. First-principles density-functional calculations are presented revealing the interaction of Ru with P, and predicting that the amorphous structure should be most stable above 20 at.% P.
CH4 uptake and N availability in forest soils along an urban to rural gradient

Abstract Concern about increases in atmospheric CH 4 concentrations has resulted in investigations of the magnitude of and the factors that control aerobic soils as a sink for CH 4 . N additions decrease CH 4 consumption in temperate forest, prairie and agricultural soils, suggesting that low rates of CH 4 consumption are associated with high concentrations of available N. We have observed the opposite pattern in a series of oak-dominated forest sites of similar age on similar soils located along an urban to rural land-use gradient. Low rates of CH 4 consumption were observed in urban forest sites with low amounts of available N relative to rural sites that had high concentrations of available N. In situ consumption rates ranged from 6.9 to 2.1 mg CH 4 m −2 d −1 . Mean rates of consumption were 30% lower in urban than in rural and suburban forest sites, suggesting that factors associated with urbanization may decrease rates of CH 4 consumption in temperate forest soils. We hypothesize that low consumption rates of CH 4 in urban forest sites are a product of low rates of organic matter degradation and nutrient cycling caused by air pollution (especially ozone) damage to forest tree leaves. Reduced rates of decomposition may result in lower rates of C and N flow from litter to soil microbial populations responsible for consumption of CH 4 .
Hypothetical inference and category structure

The present experiment considers whether the internal structure of statements plays a role in the way students reason about hypothetical domains. Students were asked to assign truth values to statements to form a consistent set of relations about hypothetical situations. The statements varied in degree of structure along two dimensions: across categories organization (generality) and within-categories organization (typicality). The results show that when generalities affirm a relation, they are readily accepted as defining a domain. The addition of within-categories structure makes only a marginal contribution to decisions. In contrast, there is a semantic structure effect for generalities that deny a relation. The findings accord with a two-stage process derived from a generality coding model.
Identification of novel antimicrobial resistance genes from microbiota on retail spinach

Drug resistance genes and their mobile genetic elements are frequently identified from environmental saprophytic organisms. It is widely accepted that the use of antibiotics in animal husbandry selects for drug resistant microorganisms, which are then spread from the farm environment to humans through the consumption of contaminated food products. We wished to identify novel drug resistance genes from microbial communities on retail food products. Here, we chose to study the microbial communities on retail spinach because it is commonly eaten raw and has previously been associated with outbreaks of bacterial infections. We created metagenomic plasmid libraries from microbiota isolated from retail spinach samples. We identified five unique plasmids that increased resistance to antimicrobial drugs in the E. coli host. These plasmids were identified in E. coli that grew on plates that contained ampicillin (pAMP), aztreonam (pAZT), ciprofloxacin (pCIP), trimethoprim (pTRM), and trimethoprim-sulfamethoxazole (pSXT). We identified open reading frames with similarity to known classes of drug resistance genes in the DNA inserts of all 5 plasmids. These drug resistance genes conferred resistance to fluoroquinolones, cephalosporins, and trimethoprim, which are classes of antimicrobial drugs frequently used to treat human Gram negative bacterial infections. These results show that novel drug resistance genes are found in microbiota on retail produce items. Here we show that microbiota of retail spinach contains DNA sequences previously unidentified as conferring antibiotic resistance. Many of these novel sequences show similarity to genes found in species of bacteria, which have previously been identified as commensal or saprophytic bacteria found on plants. We showed that these resistance genes are capable of conferring clinically relevant levels of resistance to antimicrobial agents. Food saprophytes may serve as an important reservoir for new drug-resistance determinants in human pathogens.
Fine-scale chemical fingerprinting of an open coast crustacean for the assessment of population connectivity

Chemical fingerprinting techniques recently have been used to track larval dispersal of estuarine species that bear calcified structures, but the applicability of this important approach may be limited on the open coast where chemical signatures may be less distinctive and for the many species that do not retain calcified structures throughout development. Externally brooded embryos of the porcelain crab, Petrolisthes cinctipes, and inductively coupled plasma mass spectrometry were used to determine whether fine-scale variation in trace-elemental composition occurred along an open coast. Embryos were collected from 16 sites from 37.8° to 39.5° north latitude along the Pacific Coast of California, USA during late January and early February 2003. Discriminant function analysis revealed that collection sites, many separated by only a few kilometers along an open coast, could be differentiated with an overall accuracy of 73%, and combining the sites into three regions increased the accuracy to 88%. Thus, distinctive elemental signatures can be detected in open coast species even at a fine scale raising the possibility that larval tags can be developed for many more species than previously thought possible.
Joining of components of complex structures for improved dynamic response

Abstract The goal of this work is to provide a method for choosing joining (e.g., bolt) locations for attaching structural reinforcements onto complex structures. The joining locations affect structural performance criteria such as the frequency response and the static compliance of the modified structure. One approach to finding improved/optimal joining locations is to place the joints such that the total amount of energy input into the structure (from external forces) is lowered/minimized, thus ensuring that the performance of the structure is least affected by the structural modifications. However, such an approach does not account for the stresses in the joints. Therefore, in this work, the amount of strain energy concentrated in the joints is also considered. The cost function for this optimization problem is then composed of two energies. These energies are different for the undamped and damped cases. Herein, the focus is on the (more realistic) damped case. The cost function is minimized by a modified optimality criteria method. This process is time consuming because it requires the calculation of sensitivities of the joint strain energy, which in turn requires the calculation of the displacements of all candidate joint locations by using the system-level mass and stiffness matrices and force vector (at each frequency in the range of interest). To address this issue, a series of complex algebraic manipulations and approximations are used to significantly reduce the computational cost. In addition, for the case where structural and geometrical variations are necessary, parametric reduced-order models are used to compute the cost function with further significant gains in computational speed. Numerical results for improved/optimal joining are presented for representative complex structures with structural variabilities.
Frequent HPRT mutations in paroxysmal nocturnal haemoglobinuria reflect T cell clonal expansion, not genomic instability.

Summary Paroxysmal nocturnal haemoglobinuria (PNH) results from acquired mutations in the PIG-A gene of an haematopoietic stem cell, leading to defective biosynthesis of glycosylphosphatidylinositol (GPI) anchors and deficient expression of GPI-anchored proteins on the surface of the cell's progeny. Some laboratory and clinical findings have suggested genomic instability to be intrinsic in PNH; this possibility has been supported by mutation analysis of hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene abnormalities. However, the HPRT assay examines lymphocytes in peripheral blood (PB), and T cells may be related to the pathophysiology of PNH. We analysed the molecular and functional features of HPRT mutants in PB mononuclear cells from eleven PNH patients. CD8 T cells predominated in these samples; approximately half of the CD8 cells lacked GPI-anchored protein expression, while only a small proportion of CD4 cells appeared to derive from the PNH clone. The HPRT mutant frequency (Mf) in T lymphocytes from PNH patients was significantly higher than in healthy controls. The majority of the mutant T lymphocyte clones were of CD4 phenotype, and they had phenotypically normal GPI-anchored protein expression. In PNH patients, the majority of HPRT mutant clones were contained within the Vβ2 T cell receptor (TCR) subfamily, which was oligoclonal by complementarity-determining region three (CDR3) size analysis. Our results are more consistent with detection of uniform populations of expanded T cell clones, which presumably acquired HPRT mutations during antigen-driven cell proliferation, and not due to an increased Mf in PNH. HPRT mutant analysis does not support underlying genomic instability in PNH.
Deprivation-induced strengthening of presynaptic and postsynaptic inhibitory transmission in layer 4 of visual cortex during the critical period.

Inhibition from fast-spiking (FS) interneurons plays a crucial role in shaping cortical response properties and gating developmental periods of activity-dependent plasticity, yet the expression mechanisms underlying FS inhibitory plasticity remain largely unexplored. In layer 4 of visual cortex (V1), monocular deprivation (MD) induces either depression or potentiation of FS to star pyramidal neuron (FS→SP) synapses, depending on the age of onset (Maffei et al., 2004, 2006). This reversal in the sign (− to +) of plasticity occurs on the cusp of the canonical critical period (CP). To investigate the expression locus behind this switch in sign of inhibitory plasticity, mice underwent MD during the pre-CP [eye-opening to postnatal day (p)17] or CP (p22–p25), and FS→SP synaptic strength within layer 4 was assessed using confocal and immunoelectron microscopy, as well as optogenetic activation of FS cells to probe quantal amplitude at FS→SP synapses. Brief MD before p17 or p25 did not alter the density of FS→SP contacts. However, at the ultrastructural level, FS→SP synapses in deprived hemispheres during the CP, but not the pre-CP or in GAD65 knock-out mice, had larger synapses and increased docked vesicle density compared with synapses from the nondeprived control hemispheres. Moreover, FS→SP evoked miniature IPSCs increased in deprived hemispheres when MD was initiated during the CP, accompanied by an increase in the density of postsynaptic GABAA receptors at FS→SP synapses. These coordinated changes in FS→SP synaptic strength define an expression pathway modulating excitatory output during CP plasticity in visual cortex.
Deducing Receptor Signaling Parameters from In Vivo Analysis: LuxN/AI-1 Quorum Sensing in Vibrio harveyi

Quorum sensing, a process of bacterial cell-cell communication, relies on production, detection, and response to autoinducer signaling molecules. LuxN, a nine-transmembrane domain protein from Vibrio harveyi, is the founding example of membrane-bound receptors for acyl-homoserine lactone (AHL) autoinducers. We used mutagenesis and suppressor analyses to identify the AHL-binding domain of LuxN and discovered LuxN mutants that confer both decreased and increased AHL sensitivity. Our analysis of dose-response curves of multiple LuxN mutants pins these inverse phenotypes on quantifiable opposing shifts in the free-energy bias of LuxN for occupying its kinase and phosphatase states. To understand receptor activation and to characterize the pathway signaling parameters, we exploited a strong LuxN antagonist, one of fifteen small-molecule antagonists we identified. We find that quorum-sensing-mediated communication can be manipulated positively and negatively to control bacterial behavior and, more broadly, that signaling parameters can be deduced from in vivo data.
An evaluation of flooding risks associated with giant reed (Arundo donax).

The presence of vegetation in a channel may influence water movement in the channel and the surrounding land in several ways. One hypothesis is that increased abundance of the invasive plant Arundo donax in a watercourse contributes to increased flooding risk. To test this hypothesis, we determined Manning's coefficient for A. donax and subsequently used it in the HEC-RAS model to estimate the impact that A. donax has on flooding risks at three sites within two moderately sized northern California rivers. The mean value for Manning's coefficient for A. donax was 0.066, and it varied from 0.019 to 0.121 (n = 37). Model simulations showed that A. donax within a stream channel had a direct effect on flooded area, causing increases up to 10% above baseline conditions, which represent cross sections with no A. donax present. Storm size also affected A. donax's impact on the size of the flooded area. Using the maximum value for Manning's n for A. donax in the simulations resulted in an increase in the flooded a...
An Index of Dynamic Density

The risk of a collision between aircraft is rising as the density of commercial air traffic increases. This trend, together with the overwhelming need to upgrade the National Airspace System, has motivated the Federal Aviation Administration to sponsor the development of metrics to evaluate "dynamic density"--a proxy for the likelihood of collision risk. This paper proposes and evaluates a mathematical index of dynamic density, D, that describes collision risk. Although the domain of investigation is aviation, the logic of D is applicable whenever objects move in limited spaces. A series of sensitivity analyses illustrate how D responds to frequently encountered air traffic conflict situations. A use of D is illustrated that characterizes pilot performance and efficiency in experimental simulations of free flight, and other human factors applications are suggested. This research could be applied immediately by the traffic management units of en-route air traffic control centers to reformulate the criterion for the critical capacity of sectors.
Population Dynamics of Bacteriophage and Bacillus Subtilis in Soil

The dynamics of the interaction of populations of Bacillus subtilis and a temperate bacteriophage in soil microorganisms were examined. The purpose of the study was to investigate these dynamics in a structured habitat approaching that of their natural habitat in soil, in contrast to previous investigations in broth or chemostats. We addressed three main questions. What are the population dynamics of a phage-bacteria interaction in soil? What role might the heterogeneity of the soil play in shaping the interaction? Are the dynamics controlled more by the population biology of the phage or of the bacteria? The phage used was isolated from Arizona desert soil in which B. subtilis is common. Phage and bacteria were grown separately or together in sterile soil microcosms consisting of autoclaved soil rich in organic material. Densities of phage and bacteria were estimated through repeated sterile sampling of the microcosms by spreading precise dilutions of sampled soil suspensions onto plates of microbiological media. The plates for estimation of phage densities contained in addition a lawn of host bacteria. While the principal focus is on temperate phage ecology, the dynamics of a single example of interaction between B. subtilis and virulent phage is also presented. In all cases an initial epidemic of phage occurred, followed by stable equilibria lasting weeks to months. A threshold host density for phage outbreak occurs at 5 x 106 colony-forming units per gram of soil. At equilibrium the phage, both temperate and virulent, were much less abundant than the bacteria. The temperate phage did not depress the equilibrium host density, while the virulent phage lowered it by a factor often. The acidic soil of these experiments caused rapid and permanent inactivation of free phage, making the continuous interaction of phage and host essential for persistence of phage. Low levels of phage resistance (superimmunity or genetic) were typical of host populations. Most properties of the interaction between B. subtilis and phage in soil are quite different from those observed with chemostat populations of Escherichia coli and virulent phages. Potential doubling times and rates of increase in soil for phage and B. subtilis were cal- culated. At equilibrium, soil slows the interaction of phage and host relative to population growth in broth culture, and possibly also makes it heterogeneous in space and time. The life-history features of B. subtilis and temperate phage are considerably more complex than those of non-sporeforming bacteria and virulent phage. The biotic relationship of temperate phage and host may be distinct from predation or parasitism. Patterns in the ecology and evolution of temperate and virulent phage were explored, leading to the expectation that temperate forms will be more common among the phages of soil bacteria.
Diversification of Transcription Factor Paralogs via Noncanonical Modularity in C2H2 Zinc Finger DNA Binding

SUMMARY A major challenge in obtaining a full molecular description of evolutionary adaptation is to characterize how transcription factor (TF) DNA-binding specificity can change. To identify mechanisms of TF diversification, we performed detailed comparisons of yeast C2H2 ZF proteins with identical canonical recognition residues that are expected to bind the same DNA sequences. Unexpectedly, we found that ZF proteins can adapt to recognize new binding sites in a modular fashion whereby binding to common core sites remains unaffected. We identified two distinct mechanisms, conserved across multiple Ascomycota species, by which this molecular adaptation occurred. Our results suggest a route for TF evolution that alleviates negative pleiotropic effects by modularly gaining new binding sites. These findings expand our current understanding of ZF DNA binding and provide evidence for paralogous ZFs utilizing alternate modes of DNA binding to recognize unique sets of noncanonical binding sites.
Voegelin, Heidegger, and Arendt: Two's a company, three's a crowd?

Abstract Hannah Arendt's political theory seemingly lends itself to both a “premodern” coupling with Eric Voegelin and a “postmodern” coupling with Martin Heidegger. Closer comparison between all three thinkers reveal not only that neither coupling is cogent, but that all three thinkers provide essential dimensions for a political theory which moves beyond such distinctions.
SGR activity and global characteristics

Of the over one thousand detected cosmic transient gamma-ray sources, only three are known to have exhibited recurrent activity. Apart from their recurrent nature, these events differ from the majority of bursts in that they are of much shorter duration and have relatively soft spectra. They can thus be considered as a distinct class of objects- the Soft Gamma Repeaters (SGRs). Their embryonic sky distribution suggests that they are galactic objects. The absence of detection of new sources in the 4.0 years of BATSE operation, together with the BATSE detection of the reactivation of two of the three already known SGRs, indicates that these objects are rare. We present here a short review of the overall SGR activity and their global characteristics.
Outcomes of laparoscopic herniorrhaphy without fixation of mesh to the abdominal wall.

Background: Recently there has been interest in performing laparoscopic herniorrhaphies without the use of staples or tacks to fix the mesh. Although mesh fixation has been linked to an increased incidence of nerve injury and involves increased operative costs, many surgeons feel that fixation is necessary to reduce the risk of hernia recurrence. This study evaluates the outcomes of laparoscopic herniorrhapies performed with and without mesh fixation at our institution. Methods: We retrospectively evaluated our last 172 laparoscopic herniorrhaphies, which span a period of conversion from staple fixation to nonfixation of total extraperitoneal herniorrhaphies using systematic chart review and follow-up self-administered questionnaires. The outcomes assessed were the incidences of postoperative neuralgia and hernia recurrence. Adjustment for important prognostic factors was achieved using Cox regression for estimating the risk of recurrence, and multiple logistic regression for estimating the risk of neuropathic complications. Results: Of 172 laparoscopic herniorrhaphies performed in 129 patients since July 1993, 105 were accomplished without mesh fixation, and 67 were performed with fixation of mesh to the abdominal wall. There were no significant differences in demographics between the two groups. A trend toward a higher incidence of neuropathic complications was observed in the mesh-fixation group (risk ratio [RR], 2.2; 95% CI, 0.5-10). A nonsignificant increased risk of hernia recurrence with fixation of mesh was observed (4.2 vs 1.6 per 100 hernia-years at risk; RR, 2.3; 95% CI, 0.4-13.10), but this finding may be associated with a selection bias with regard to giant hernia defects. Conclusions: Our data suggest that mesh fixation to the abdominal wall may be avoided in total extraperitoneal repairs without increasing the risk of hernia recurrence and neuropathic complications. The increased risk of recurrence observed with mesh fixation possibly results from selection bias. Large randomized controlled studies are needed to determine whether mesh fixation is truly related to neuropathic complications and the incidence of recurrence.
On the nonexistence of boundary branch points for minimal surfaces spanning smooth contours II

This is the second in a series of two papers discussing the elementary but beautiful and fundamental question (open for some eighty years) of whether or not a minimal surface spanning a sufficiently smooth curve, which is a local minimizer, is immersed up to and including the boundary. We show that Ck minimizers of energy or area cannot have nonexceptional boundary branch points.
Novel β-carotene ketolases from non-photosynthetic bacteria for canthaxanthin synthesis

We reported previously that the Rhodococcus erythropolis strain AN12 synthesizes the monocyclic carotenoids 4-keto γ-carotene and γ-carotene. We also identified a novel lycopene β-monocyclase in this strain. Here we report the identification of the rest of the carotenoid synthesis genes in AN12. Two of these showed apparent homology to putative phytoene dehydrogenases. Analysis of Rhodococcus knockout mutants suggested that one of them ( crtI) encodes a phytoene dehydrogenase, whereas the other ( crtO) encodes a β-carotene ketolase. Expression of the β-carotene ketolase gene in an Escherichia coli strain which accumulates β-carotene resulted in the production of canthaxanthin. In vitro assays using a crude extract of the E. coli strain expressing the crtO gene confirmed its ketolase activity. A crtO homologue (DR0093) from Deinococcus radiodurans R1 was also shown to encode a β-carotene ketolase, despite its sequence homology to phytoene dehydrogenases. The Rhodococcus and Deinococcus CrtO ketolases both catalyze the symmetric addition of two keto groups to β-carotene to produce canthaxanthin. Even though this activity is similar to the CrtW-type of ketolase activity, the CrtO ketolases show no significant sequence homology to CrtW-type ketolases. The presence of six conserved regions may be a signature for the CrtO-type of β-carotene ketolases.
Online courseware inspires it student consultants & IT staff

To provide consistent and in-depth training to The University of Montana's IT Central student help desk and to the Student Technology Assistants Program (STAP), we successfully implemented an on-line training program. UM has a population of over 16,000 students, faculty and staff. IT Central and STAP support the software computing needs of students and the desktop/software needs of departmental faculty and staff. While the student consultants have a diverse set of skills and knowledge, they need to provide consistent customer service for the software and systems we support. Since funding at our small university doesn't allow for staff to provide training to students on a regular basis each semester, we began researching online courseware options. We chose SkillSoft; the response has been enthusiastic. Using their curriculum, we designed a training program whereby student consultants progress from basic to advanced classes. Each consultant is responsible for completing a specific number of courses per semester, ranging from desktop support to network troubleshooting. At the end of each semester, they may be eligible for a raise based on their coursework completion and actual hours worked. When they complete several semesters of courseware, they are then prepared to take the Microsoft Desktop Certification Exam if they desire. Our primary goal is to improve customer service among our student consultants. Secondly, SkillSoft programs are also being utilized by IT staff and UM's Library and Residence Life technology assistants. In addition, we are pleased that there is significant interest in offering SkillSoft to other campus department personnel.
Ground-based Measurement of Millimetre-wavelength Emission by Upper Stratospheric O2

Measurements from ground level of 53 GHz radiation from molecular oxygen in the stratosphere, using a very precise radiometer, can be used to give stratospheric temperatures.
Thioltransferase (Glutaredoxin) Is Detected Within HIV-1 and Can Regulate the Activity of Glutathionylated HIV-1 Protease in Vitro

Abstract Previous studies have suggested that the two conserved cysteines of the HIV-1 protease may be involved in regulating protease activity. Here, we examined diglutathionylated wild type protease (Cys-67-SSG, Cys-95-SSG) and the monoglutathionylated protease mutants (C67A, Cys-95-SSG and C95A, Cys-67-SSG) as potential substrates for thioltransferase (glutaredoxin). Time-dependent changes in the extent of deglutathionylation of each protein were assayed by reverse phase-high performance liquid chromatography. Glutathione alone was not an effective reductant, whereas thioltransferase displayed differential catalysis toward the Cys-95-SSG and Cys-67-SSG sites. At low thioltransferase concentrations (5 nm), deglutathionylation occurred almost exclusively at Cys-95-SSG. With substantially more thioltransferase (100 nm) Cys-67-SSG was partially deglutathionylated but only at 20% of the rate of Cys-95-SSG reduction. Treatment of the diglutathionylated protease with thioltransferase not only restored protease activity but generated an enzyme preparation that had a 3- to 5-fold greater specific activity relative to the fully reduced form. Immunoblot analysis of HIV-1MN virus with an antibody to thioltransferase detected a band co-migrating with recombinant thioltransferase that persisted following subtilisin treatment, indicating the presence of thioltransferase within HIV-1. Our results implicate thioltransferase in the regulation and/or maintenance of protease activity in HIV-1 infected cells.
Early peer relations: Developmental significance and prognostic implications

The developmental and prognostic implications of early peer relations are considered. Evidence concerning peer difficulties as risk factors is reviewed along with research dealing with family relations and peer relations in social development. A conjunctive model is advanced to account for the manner in which troubled family relations are followed by troubled peer relations, problems with self-regard, narrowed alternatives in choosing friends, and manifestations of social deviance. The origins of these conjunctive cycles appear to exist in early childhood, hence requiring attention in program implementation and management for young children.
A Constitutive Formulation for Anisotropic Materials Suitable for Wave Propagation Computer Programs

The constitutive relationships for an anisotropic material are established for shock wave propagation computer programs, commonly referred to as hydrocodes. In this paper, stresses are formulated in terms of strains for two specific two-dimensional cases: orthotropic behavior in plane strain problems; and transversely isotropic behavior in axisymmetric problems. Additionally, the procedure for separating material nonlinear compressibility effects (equation of state) from strength effects is formulated which per mits the consistent calculation of stresses in the elastic regime, and allows the mean stress and pressure to be defined in accordance with their scalar interpretation. Further, this pro cedure permits the computation of inelastic response by scaling of deviatoric stresses, so the equivalent stress resides on a yield or failure surface, without changing the pressure. In conjunction with this constitutive development, a parallel experimental program was designed and conducted to explosively load fib...
The Influence of Fluid Management Policy and Operational Changes on Metalworking Fluid Functionality

This paper discusses the influence of metalworking fluid management policy and operational changes on metalworking fluid functionality in terms of lubricating and cooling ability. Several important pathways for metalworking fluid depletion are reviewed. Using an instrumented drilling-based test-bed, the effects of lubricating component depletion, microfiltration, and dilutant water hardness were assessed. It was observed that microfiltration had no effect on fluid functionality. Increases in dilutant water hardness were found to produce decreases in drilling forces and temperature. Additionally, increasing dilutant hardness decreased microfiltration flux, but this effect can be counteracted with the addition of a chelating agent.
Pericarditis complicating acute myocardial infarction: Incidence of complications and significance of electrocardiogram on admission

Abstract The records of 31 patients with pericarditis complicating acute myocardial infarction were reviewed and compared to a control group of 274 patients with infarction but without pericarditis. The cases of pericarditis all occurred within one week of myocardial infarction and were included only if a typical pericardial friction rub was heard by more than one observer. Sex distribution and age were similar in both groups. There was a higher incidence of anterior wall infarction in the group with pericarditis. The incidence of atrial arrhythmias was less than in controls, while the incidence of ventricular arrhythmias, significant congestive heart failure, and death was slightly greater in those with pericarditis. Maximum ST segment elevation on the day of admission in the group with pericarditis was compared with a control group. In those with anterior wall infarction and pericarditis, the average ST segment elevation in the anterior precordium was 5.6 mm. compared to 2.6 mm. in the controls. In those with inferior wall infarction and pericarditis, the average ST segment elevation was 3.6 mm. in Lead III compared to 1.7 mm. in a control group. It is concluded that patients who develop pericarditis within one week of acute myocardial infarction do not have an increased incidence of atrial arrhythmias. The incidence of ventricular arrhythmias, significant congestive heart failure, and death are slightly greater and may be due to more extensive myocardial infarction. The higher initial ST segment elevation in patients with pericarditis may indicate a greater amount of injury or may be a sign of pericardial involvement that is seen before clinical pericarditis is present.