cssi/SciSciGPT-SciSciNet huggingface dataset:
Optimal Throughput&#8211;Delay Scaling in Wireless Networks&#8212;Part II: Constant-Size Packets

In Part I of this paper, the optimal throughput-delay tradeoff for static wireless networks was shown to be D(n)=Theta(nT(n)), where D(n) and T(n) are the average packet delay and throughput in a network of n nodes, respectively. While this tradeoff captures the essential network dynamics, packets need to scale down with the network size. In this "fluid model, " no buffers are required. Due to this packet scaling, D(n) does not correspond to the average delay per bit. This leads to the question whether the tradeoff remains the same when the packet size is kept constant, which necessitates packet scheduling in the network. In this correspondence, this question is answered in the affirmative by showing that the optimal throughput-delay tradeoff is still D(n)=Theta(nT(n)), where now D(n) is the average delay per bit. Packets of constant size necessitate the use of buffers in the network, which in turn requires scheduling packet transmissions in a discrete-time queuing network and analyzing the corresponding delay. Our method consists of deriving packet schedules in the discrete-time network by devising a corresponding continuous-time network and then analyzing the delay induced in the actual discrete network using results from queuing theory for continuous-time networks.
Infliximab therapy in pediatric Crohn's pouchitis

Objective: We describe the prolonged clinical benefit of murine chimeric antitumor necrosis factor (TNF)–alpha monoclonal antibody, infliximab, on pediatric patients with Crohn’s disease and ileal pouch anal anastomosis (IPAA). Methods: A retrospective review of patients originally diagnosed with ulcerative colitis, status post colectomy and IPAA, who developed findings compatible with Crohn’s disease was undertaken. Refractory pouchitis developed in all patients as well as protracted symptoms of diarrhea, abdominal pain, joint pain, and incontinence. All patients received infliximab. Results: Four pediatric patients (2 males and 2 females) with mean age of 14.5 years (range 11–18 years) were studied. The development of perianal fistulas in 2 patients, granuloma on biopsy in 1 patient and perianal skin tag in 1 patient, led to a diagnosis change of CD. After failure to respond to antibiotics, aminosalicylates and immunomodulators such as azathioprine and 6-mercaptopurine (6-MP), all patients were treated with infliximab. Patients received infliximab infusions at a dose of 5 mg/kg, initially at weeks 0, 2 and 6 and subsequently at 8 weeks intervals in combination with an immunomodulator drug. All patients showed marked improvement clinically, endoscopically, and histologically. Conclusion: Infliximab can be used successfully for the treatment of pediatric patients with Crohn’s disease and IPAA who are refractory to conventional therapies.
Crosstalk between HIV and hepatitis C virus during co-infection

An estimated one-third of individuals positive for HIV are also infected with hepatitis C virus (HCV). Chronic infection with HCV can lead to serious liver disease including cirrhosis and hepatocellular carcinoma. Liver-related disease is among the leading causes of death in patients with HIV, and individuals with HIV and HCV co-infection are found to progress more rapidly to serious liver disease than mono-infected individuals. The mechanism by which HIV affects HCV infection in the absence of immunosuppression by HIV is currently unknown. In a recent article published in BMC Immunology, Qu et al. demonstrated that HIV tat is capable of inducing IP-10 expression. Further, they were able to show that HIV tat, when added to cells, was able to enhance the replication of HCV. Importantly, the increase in HCV replication by tat was found to be dependent on IP-10. This work has important implications for understanding the effect HIV has on the outcome of HCV infection in co-infected individuals. The findings of Qu et al. may inform the design of intervention and treatment strategies for co-infected individuals.
Advantages of a polycentric approach to climate change policy

Lack of progress in global climate change negotiations has revamped interest in polycentric approaches – sub-global mechanisms to reduce greenhouse gas emissions. It is still unclear why these mechanisms might achieve better outcomes than global negotiations. This Perspective outlines themain advantages of polycentric approaches over a global one by reviewing significant theoretical, empirical, and experimental evidence. Lack of progress in global climate negotiations has led scholars to reconsider polycentric approaches to climate policy. Several examples of subglobal mechanisms to reduce greenhouse-gas emissions have been touted, but it remains unclear why they might achieve better climate outcomes than global negotiations alone. Decades of work conducted by researchers associated with the Vincent and Elinor Ostrom Workshop in Political Theory and Policy Analysis at Indiana University have emphasized two chief advantages of polycentric approaches over monocentric ones: they provide more opportunities for experimentation and learning to improve policies over time, and they increase communications and interactions — formal and informal, bilateral and multilateral — among parties to help build the mutual trust needed for increased cooperation. A wealth of theoretical, empirical and experimental evidence supports the polycentric approach.
Differential Locus Expansion Distinguishes Toxoplasmatinae Species and Closely Related Strains of Toxoplasma gondii

ABSTRACT Toxoplasma gondii is a human obligate intracellular parasite that has infected over 20% of the world population and has a vast intermediate host range compared to those of its nearest relatives Neospora caninum and Hammondia hammondi . While these 3 species have highly syntenic genomes (80 to 99%), in this study we examined and compared species-specific structural variations, specifically at loci that have undergone local (i.e., tandem) duplication and expansion. To do so, we used genomic sequence coverage analysis to identify and curate T. gondii and N. caninum loci that have undergone duplication and expansion (expanded loci [ELs]). The 53 T. gondii ELs are significantly enriched for genes with predicted signal sequences and single-exon genes and genes that are developmentally regulated at the transcriptional level. We validated 24 T. gondii ELs using comparative genomic hybridization; these data suggested significant copy number variation at these loci. High-molecular-weight Southern blotting for 3 T. gondii ELs revealed that copy number varies across T. gondii lineages and also between members of the same clonal lineage. Using similar methods, we identified 64 N. caninum ELs which were significantly enriched genes belonging to the SAG-related surface (SRS) antigen family. Moreover, there is significantly less overlap (30%) between the expanded gene sets in T. gondii and N. caninum than would be predicted by overall genomic synteny (81%). Consistent with this finding, only 59% of queried T. gondii ELs are similarly duplicated/expanded in H. hammondi despite over 99% genomic synteny between these species. IMPORTANCE Gene duplication, expansion, and diversification are a basis for phenotypic differences both within and between species. This study represents the first characterization of both the extent and degree of overlap in gene duplication and locus expansion across multiple apicomplexan parasite species. The most important finding of this study is that the locus duplications/expansions are quantitatively and qualitatively distinct, despite the high degree of genetic relatedness between the species. Given that these differential expansions are prominent species-specific genetic differences, they may also contribute to some of the more striking phenotypic differences between these species. More broadly, this work is important in providing further support for the idea that postspeciation selection events may have a dramatic impact on locus structure and copy number that overshadows selection on single-copy genes.
Dietary tryptophan and the selection of ethyl alcohol in different strains of rats.

Rats of three different strains were tested systematically for their selection of water or ethanol offered in a two-choice situation. In order that preference-aversion curves could be derived, the concentrations of ethanol were increased in strength from 3 to 30% over an 11 or 12 day test sequence. l-tryptophan was added to the rat's diet in 1% or 3% mixtures for a predetermined interval beginning before or during a test for ethanol preference. Given to female hooded rats of the Royal Victoria strain, excess tryptophan elevated the ethanol preference threshold and significantly increased ethanol intake according to the dose administered. However, in male hooded rats of the Long-Evans strain, tryptophan augmented only slightly the selection of ethanol. Male Sprague-Dawley rats, an albino strain, were unaffected by the addition of this essential amino acid to their diet. Although tryptophan may exert its effect on ethanol intake through an alteration in the metabolism of cerebral serotonin, such an effect seems to be dependent upon the strain of rat tested.
Valued voices: Students’ use of Engagement in argumentative history writing

Abstract In this study, we explore rhetorical moves used by students in argumentative, analytical writing in a college-level world history course. Drawing on the system of Engagement within the Appraisal framework from Systemic Functional Linguistics, we investigate differences between higher-graded and lower-graded essays in the combinations and patterns of resources used to expand and contract dialogic space while building an argument. The results show that while both higher-graded and lower-graded essays made use of some of the same moves, the higher-graded essays did so in a way that consistently furthered an argument. In addition, the higher-graded essays showed a recurring pattern of Engagement resources used for including and interpreting source texts. These findings illustrate that beyond simply including Engagement resources, students need to learn how to use these resources in purposeful and strategic ways.
Stimulus artifact reduction in nerve conduction.

Abstract Techniques recommended to reduce stimulus artifact (SA) include modifications of electrodes, electrode contact, and stimulus circuitry. Twenty-two subjects were studied to evaluate two electrode positioning techniques to reduce the SA in sensory nerve conduction velocity recordings. In 16 normal subjects, rotating the stimulator anode around the cathode 70–105° flattened the baseline and permitted recording a clear take-off of the sural evoked response. In the remaining six subjects, other angles were optimal. Reconfiguring location of the reference and ground electrodes to increase common mode rejection was not consistently effective in reducing the SA in the eight patients tested. Isopotential lines produced by the stimulator electric dipole are described to explain the findings. This technique is simple and effective in reducing SA.
Building interoperable data systems in the Gulf of Mexico: a case study

Data collection in oceanography is undergoing a paradigm shift. We are moving from month-long shipboard surveys and mooring deployments with annual data recoveries to persistent adaptive observatories using networked, distributed and, sometimes, autonomous sensor systems returning data in near real-time. Real-time data have value that delayed-mode data do not (e.g., for rapid response to reduce impacts to ecosystems from oil spills). The challenge is automating the conversion and integration of sensor data to an analysis-ready state. The U.S. Integrated Ocean Observing System data management group identified the core elements, including data discovery, access, and transport, that are required to build interoperable systems. In practice, these require adoption of standards for vocabularies, data models, and Web Services. The Gulf of Mexico Coastal Ocean Observation System (GCOOS) began as a regional collaboration of eleven nonfederal sub-regional observatories whose data systems had evolved independently and were not interoperable. Grants allowed us to deploy a service-oriented architecture consisting of OPeNDAP transports and standards-based Open Geospatial Consortium Sensor Observation Service web interfaces with Observation and Measurement encodings in each of the observatories. We constructed and deployed a common vocabulary based on the NetCDF Climate and Forecast Metadata Conventions and Climate and Forecast standard names. The observatories host XML files, listing their active sensors, that are compiled into catalogs of available assets. Our regional data portal aggregates data from the observatories and constructs data products for stakeholder groups. These capabilities were available during and following the Deepwater Horizon oil spill. The GCOOS-built capability for interoperability made the data and products readily available to the incident command centers in hours instead of months.
Infrared spectroscopy of mass-selected metal carbonyl cations

Abstract Metal carbonyl cations of the form M ( CO ) n + are produced in a molecular beam by laser vaporization in a pulsed nozzle source. These ions, and their corresponding rare gas atom “tagged” analogs, M ( CO ) n ( RG ) m + , are studied with mass-selected infrared photodissociation spectroscopy in the carbonyl stretching region and with density functional theory computations. The number of infrared-active bands, their frequency positions, and their relative intensities provide distinctive patterns allowing determination of the geometries and electronic structures of these complexes. Cobalt penta carbonyl and manganese hexacarbonyl cations are compared to isoelectronic iron pentacarbonyl and chromium hexacarbonyl neutrals. Gold and copper provide examples of “non-classical” carbonyls. Seven-coordinate carbonyls are explored for the vanadium group metal cations (V+, Nb+ and Ta+), while uranium cations provide an example of an eight-coordinate carbonyl.
Couples treatment of agoraphobia

The results of 14 agoraphobic women treated in small groups and accompanied by their husbands were compared to the results of 14 agoraphobic women treated in an identical fashion without the presence of their husbands. Treatment consisted of cognitive restructuring and self-initiated exposure exercises. Results at posttest indcated a substantial advantage to the spouse group, when compared to the nonspouse group, on measures of agoraphobia. Ratings of social, work, and family functioning also improved more quickly in the spouse group, although this comparative advantage had disappeared at posttest. The overall results of this graduated, self-initiated, exposure-based treatment seem superior to more intensive therapist- or drug-assisted in vivo exposure when one considers attrition rates. However, the failure to confirm the role of between-session practice as a predictor of successful outcome suggested that variables in addition to exposure may play a major role in treatment.
Reversal of Procaine Conduction Blockade by Adenine Nucleotides in Vivo and in vitro

The effect of the adenine nucleotides on procaine-induced conduction block in rats was investigated in vivo and in vitro. Both adenine and cyclic nucleotides significantly shortened the duration of sciatic nerve blocks in rats without affecting the frequency, degree of block or time of onset. Adenosine 5'-triphosphate (ATP) and N6, O2' dibutyryl 3':5'-monophosphate (db-cyclic AMP) were most effective. In isolated sciatic nerve preparations, the adenine nucleotides (ATP, adenosine 5'diphosphate (ADP), adenosine 5'monophosphate (AMP)) rapidly reversed procaine-induced depression of the action potential. These results suggest that local anesthetic effects may be mediated through interference with the physiological functions of the nucleotides.
Utilization of Automatically Assigned Retention Indices for Computer Identification of Mass Spectra

Abstract A computer program which provides retention indices for the entire gas chromatogram has been applied to assist in the identification of components of mixtures using a GC-MS-Computer system. As one example, the identification of drugs and metabolites in body fluids is discussed and it is shown that retention indices, in combination with mass spectral data, allow a most efficient, unambiguous and readily automated identification of components of the relatively complex mixtures which result from the extraction of body fluids.
Significance of oxygen on interstitial ordering in tantalum (the Ta64C artifact)

Although the absence of equilibrium carbide precipitates on Ta/sub 64/C is explained by the particular polishing technique used, the observed diffraction and contrast effects are due to a different artifact. The alloys were prepared by evaporating thin layers of carbon onto pure tantalum sheet followed by a diffusion anneal at temperatures between 1000 and 2000/sup 0/C in a vacuum of 10/sup -4/ Pa. Annealing times were between 2 and 48h. According to published data, 0.1 mm sheets of tantalum can absorb 1 atm(unit) from an oxygen atmosphere at 10/sup -4/Pa in 3 h at 1700/sup 0/C by reaction. In water vapor, the same amount of oxygen is absorbed in 9h. The evaporated carbon film will initially react with residual gases at the vacuum/carbon interface and dissolve in the tantalum at the Ta/C interface. After the carbon layer has been removed, the oxygen that is adsorbed on the surface will then either go into solution, or react with the dissolved carbon to form carbon monoxide. Since the latter reaction is controlled by the slow diffusion of carbon to the tantalum surface, the solution of oxygen will be faster. These effects are found to be kinetically, thermodynamically, and structurally consistent with themore » ordered Ta/sub 12/O phase formed by oxygen contamination during the preparation of the alloys. 2 figures.« less
The role of retinal photoreceptors in the regulation of circadian rhythms

The circadian clock is an evolutionarily, highly conserved feature of most organisms. This internal timing mechanism coordinates biochemical, physiological and behavioral processes to maintain synchrony with the environmental cycles of light, temperature and nutrients. Several studies have shown that light is the most potent cue used by most organisms (humans included) to synchronize daily activities. In mammals, light perception occurs only in the retina; three different types of photoreceptors are present within this tissue: cones, rods and the newly discovered intrinsically photosensitive retinal ganglion cells (ipRGCs). Researchers believe that the classical photoreceptors (e.g., the rods and the cones) are responsible for the image-forming vision, whereas the ipRGCs play a key role in the non-image forming vision. This non-image-forming photoreceptive system communicates not only with the master circadian pacemaker located in the suprachiasmatic nuclei of the hypothalamus, but also with many other brain areas that are known to be involved in the regulation of several functions; thus, this non-image forming system may also affect several aspects of mammalian health independently from the circadian system.
Concepts in the Prevention of Adenocarcinoma of the Distal Esophagus and Proximal Stomach

For decades, the incidence rates for squamous cell carcinoma of the esophagus and adenocarcinoma of the distal stomach have been declining while the rates for adenocarcinomas of the esophagus and gastric cardia have increased profoundly. Recent studies have shown that the gastroesophageal junction (GEJ) is regularly exposed to concentrated gastric acid and to a variety of nitrosating species, noxious agents that may contribute to carcinogenesis in this region. For adenocarcinomas that straddle the GEJ, it can be difficult to determine whether the tumor originated in the esophagus or in the gastric cardia. This classification problem hampers studies on the epidemiology and pathogenesis of GEJ tumors. Current concepts in the prevention of cancers of the distal esophagus and proximal stomach have emerged from advances in our understanding of the specific molecular events that occur during the evolution of these tumors. This report reviews those events and focuses on current concepts in the prevention of adenocarcinomas at the GEJ. The similarities and differences in risk factors, molecular pathogenesis, and in preventive strategies for adenocarcinomas of the esophagus and gastric cardia are highlighted.
The relationships among time, distance, and intensity as determinants of motion discrimination

The threshold stimulus for visual motion discrimination was analyzed into the constituent parameters of velocity, i.e., time and distance, with both of these primary variables subject-determined. It was found that, given a constant stimulus luminance, motion threshold was characterized generally by a “trade-off” or inverse power relationship between time and distance of movement. Earlier reports of energy constancy at threshold (R. H. Brown, 1955, 1957, 1958), implying threshold relationships incompatible with these, were confirmed only for the atypical conditions of high-velocity/low-Iuminance stimuli and were attributed to absolute visibility requirements. Under more general and representative conditions, threshold was relatively insensitive to luminance. The present results were also contrasted with earlier findings (Graham. 1968) of distance or “displacement” constancy at threshold, pertaining to movement between stationary start and stop positions.
Dependence of electron mobility on spacer thickness and electron density in modulation-doped Ga0.47In0.53As/Al0.48In0.52As heterojunctions

Modulation-doped Ga0.47In0.53As/Al0.48In0.52As heterojunctions were grown by molecular beam epitaxy. Electron mobilities were measured at room temperature and 77 K as a function of undoped Al0.48In0.52As spacer layer thickness and sheet carrier concentration. Enhanced mobilities were as high as 10 900 cm2V−1s−1 at room temperature and 55 500 cm2V−1s−1 at 77 K in these samples with sheet carrier concentrations at 1 33 × 1012 cm−2 (room temperature) and 1.26 × 1012 cm−12 (77 K).
Precursors and pathogenesis of ovarian carcinoma

The ultimate goal of defining cancer specific precursors is to facilitate early detection and intervention before the development of invasive malignancy. Unlike other malignancies involving the female genital tract such as cervical or endometrial carcinomas, precursor lesions of ovarian carcinomas have not been well characterised, resulting in a failure to develop effective screening programs. Recent clinicopathological and molecular studies have provided new insight into the origin and pathogenesis of ovarian carcinomas. It has been shown that ovarian cancer is comprised of different tumour types differing not only in morphology, but also in pathogenesis, molecular alterations and clinical progression. A dualistic model of ovarian carcinogenesis has been proposed. Type I tumours which include low grade serous, low grade endometrioid, clear cell, mucinous carcinomas and Brenner tumours, are generally indolent and tend to be genetically stable, although clear cell carcinoma would probably belong to an intermediate category. They demonstrate a step-wise progression from a benign precursor such as a benign to borderline tumour or endometriosis and are characterised by genetic aberrations targeting specific cell signalling pathways. Type II tumours comprise high grade serous, high grade endometrioid, and undifferentiated carcinomas as well as malignant mixed mesodermal tumours. They are clinically aggressive and exhibit high genetic instability with frequent p53 mutations. Mounting evidence suggests that many high grade serous carcinomas originate from the epithelium of the distal fallopian tube, and that serous tubal intraepithelial carcinoma (STIC) represents the putative precursor of these neoplasms. Low grade serous carcinomas arise via transformation of benign and borderline serous tumours, thought to be derived from inclusion cysts originating from the ovarian surface or tubal epithelium. Recently it has been suggested that papillary tubal hyperplasia may be a putative precursor lesion for serous borderline tumours. Both endometrioid and clear cell carcinomas develop from endometriosis, via alterations affecting different genetic pathways. The origin of mucinous and transitional cell neoplasms is not well characterised, although new data suggest a possible origin from transitional cell nests present at the tubal-mesothelial junction. Likewise, the pathogenesis of carcinosarcomas is also not well established because of their rarity but there is accumulating evidence that the carcinomatous component determines the course of the disease and gives rise to the malignant mesenchymal component. This review discusses recent developments in the pathogenesis of ovarian carcinoma, with particular emphasis on the putative precursor lesions that give rise to the major histological subtypes. Recognition of these lesions is not only important in improving the understanding of ovarian carcinogenesis, but it will also influence our approach to prevent, detect and treat these tumours.
Ruminant Utilization of Silage in Relation to Hay, Pellets, and Hay Plus Grain. I. Composition, Digestion, Nitrogen Balance, Intake, and Growth

Abstract Two 4×4 Latin-square experiments were conducted using fistulated Holstein heifers. Experiment 1 compared silage, hay, pelleted hay, and hay plus grain. Experiment 2 compared direct-cut silage and hay harvested from the same source. The silage of Experiment 1 contained more acid detergent fiber than the hay. In Experiment 2, the silage was more highly lignifled than the hay and contained more total nitrogen relative to calories. The silage nitrogen was more soluble. Compared to the hay, the silage of Experiment 1 resulted in a lower digestion of dry matter, organic matter, neutral detergent fiber, and nitrogen. In Experiment 2, the ad libitum feeding of silage resulted in less nitrogen retained when expressed as grams per day, per cent of that fed, or per cent of that digested than the feeding of hay. In a companion growth trial conducted on the forages of Experiment 2, the silage-fed animals had a lower energy intake, lower gain, and required more energy above maintenance per unit gain. The amount of nitrogen retained per unit weight gain indicated that the lower utilization of nitrogen on the silage ration was first caused by the lower energy relative to nitrogen.
Neural network and fuzzy logic models for pacific halibut recruitment analysis

Abstract Time series based neural network and fuzzy logic models were developed for fish recruitment analysis using fish stock–recruitment data incorporating environmental information. Data from the Pacific halibut stock with the Pacific Decadal Oscillation (PDO) index as the environmental variable was used for the model development. The neural network model was developed based on the multi-layer feed-forward neural network model with back-propagation learning algorithm. The fuzzy logic model was developed based on the fuzzification of the PDO index into two fuzzy sets denoted as “positive” and “negative” regimes. We compared the performance of these models to the traditional Ricker stock–recruitment model and the Ricker model with PDO as covariate. All four models showed significant residual time series structure in the form of first order autocorrelation. To account for this time series structure, an autoregressive component was added to each model. It was demonstrated that the fuzzy logic model outperformed the traditional Ricker stock–recruitment model, the Ricker model with PDO as covariate and the neural network model as measured by several diagnostic criteria. In addition, the simple Ricker stock–recruitment model corrected with the autoregressive time series residuals outperformed the Ricker model with PDO as covariate, neural network model and fuzzy logic model ignoring the time series residuals. The importance of the PDO to halibut recruitment is discussed in terms of developing a harvest policy.
Effect of InAlAs emitter on the microwave performance of InAlAs/InGaAs abrupt npn heterojunction bipolar transistor

Npn InAIAs/InGaAs abrupt heterojunction bipolar transistor (HBT) structures were grown on InP substrates, by the molecular beam epitaxy (MBE). Transistors were fabricated by using a non-self-aligned technology which uses a selective wet etching to reach the base layer. DC measurement showed that the base current was dominated by the depletion region recombination in the base-emitter junction. CV measurement showed a lot of defects in the heavily compensated InAIAs emitter. The collector current densities for the different layers correlated with the CV measurement results. The microwave measurements on the 4 ?m x 5 ?m emitter InAIAs /InGaAs HBT resulted in ft and fmax of 47 GHz and 27 GHz, respectively. The bias scan and the S-parameter measurement showed that the microwave performance of the device was limited by the parasitic resistance in the emitter, which was much bigger than the emitter contact resistance. This extra emitter resistance was due to the undepleted and heavily compensated InAIAs emitter. A physical small signal circuit model showed that in the absence of this extra emitter resistance, f{ would become more than 70 GHz. A much better performance is expected with a higher InAIAs emitter dopings, such as 1x1018 cm-3, which reduces the extra parasitic resistance in the InAIAs emitter significantly.
A visual aproach to enhance discrete-event simulation model interoperability

Summary form only given. With the continued advance of discrete-event simulation technology, various software packages have evolved that greatly facilitate the development and analysis of discrete-event simulation models. However, each of these applications uses different approaches and terminology for representing the behavior of the systems being studied. As a result of this disparity in implementations, models developed in different applications cannot interact with other models. Also, the disparity makes it more difficult for humans to understand the models. In this work, a visual modeling approach is proposed that allows the modeler, and those not expert in simulation, to create conceptual models that are independent of the implementation application. The approach uses eight common simulation elements. This approach facilitates the model interactions at the model formulation stage and at the application stage
Fatigue strength of a single crystal in the gigacycle regime

Abstract The objective of this work is to investigate the fatigue behavior of a single crystal nickel-based superalloy in the gigacycle regime. Testing from 10 6 to 10 9 cycles at 593 °C was performed using an ultrasonic fatigue system operating at 20 kHz. Multiple tests were performed at stresses near the fatigue limit to determine the variability in fatigue life in this regime. Endurance limit results were compared to similar data generated on conventional servohydraulic test systems to determine if there are any frequency effects. Scanning electron microscopy was then used to determine the initiation sites and the failure mechanisms. Initial results indicate little or no frequency effect on the fatigue strength or failure mechanisms of PWA 1484 at 593 °C.
Ultrasounds emitted by female rats during agonistic interactions: effects of morphine and naltrexone

Ultrasonic vocalizations may be an expression of the affective pain response in laboratory rodents. The present experiment compared morphine's effects on high (33–60 kHz) and low (20–32 kHz) frequency ultrasonic vocalizations to its effects on a range of unconditioned behavioral responses to aversive stimuli; the influence of estrous cyclicity on morphine sensitivity was also investigated. In experiment 1, naive female Long-Evans rats, selected during estrus or diestrus, received cumulative morphine (1, 3, 6, 10 mg/kg SC) or saline, and in experiment 2, rats were pretreated with naltrexone (0.1 mg/kg IP) 5 min before morphine (17, 30, 60, 100 mg/kg SC). The following endpoints were measured 20–25 min post-injection: (1) tail flick latency; (2) ultrasonic and audible vocalizations; (3) the behavioral response to aggressive attack; and (4) locomotor activity. Following a brief exposure to an attack, rats were threatened by an aggressor but protected from further attack by a wire mesh cage (30×21.5×20 cm), thereby allowing for continued behavioral and vocal measurement without the risk of physical injury; video and audio recordings were made of the attack encounter and a subset of the protected encounter (1 min). The endpoint most potently and specifically modulated by morphine was high frequency ultrasounds. The rate of high frequency calling varied as a function of the estrous cycle, supporting gonadal hormone modulation of ultrasonic vocalizations. Low frequency ultrasounds, by contrast, were relatively insensitive to opiate manipulation and were less influenced by estrous cyclicity. High frequency vocalizations may be a more sensitive indication of the affective response to an attacking conspecific than low frequency calls. The attenuation of high frequency ultrasonic calls at doses that do not affect any other behavioral or vocal responses may correspond to human descriptions of morphine analgesia, in which the affective component to pain is more potently modulated than the sensory component.
Seven-transmembrane-spanning receptors and heart function

Understanding precisely how the heart can recognize and respond to many different extracellular signalling molecules, such as neurotransmitters, hormones and growth factors, will aid the identification of new therapeutic targets through which cardiovascular diseases can be combated. In recent years, we have learned more about the complex interactions that occur between the receptors and the signalling pathways of the heart and its environment. Most of these discoveries have focused on the most common type of cardiac receptor - the seven-transmembrane-spanning receptor or G-protein-coupled receptor.
In vivo measurement of normal rat intracellular pyruvate and lactate levels after injection of hyperpolarized [1-13C]alanine ☆

Hyperpolarized technology utilizing dynamic nuclear polarization has enabled rapid and high-sensitivity measurements of 13C metabolism in vivo. The most commonly used in vivo agent for hyperpolarized 13C metabolic imaging thus far has been [1-13C]pyruvate. In preclinical studies, not only is its uptake detected, but also its intracellular enzymatic conversion to metabolic products including [1-13C]lactate and [1-13C]alanine. However, the ratio of 13C-lactate/13C-pyruvate measured in this data does not accurately reflect cellular values since much of the [1-13C]pyruvate is extracellular depending on timing, vascular properties, and extracellular space and monocarboxylate transporter activity. In order to measure the relative levels of intracellular pyruvate and lactate, in this project we hyperpolarized [1-13C]alanine and monitored the in vivo conversion to [1-13C]pyruvate and then the subsequent conversion to [1-13C]lactate. The intracellular lactate-to-pyruvate ratio of normal rat tissue measured with hyperpolarized [1-13C]alanine was 4.89±0.61 (mean±S.E.) as opposed to a ratio of 0.41±0.03 when hyperpolarized [1-13C]pyruvate was injected.
The hydrolysis of phosphoenol pyruvate catalyzed by rabbit liver fructose-1,6-diphosphatase.

Abstract Fructose-1,6-diphosphatase isolated from rabbit liver has been found to catalyze the hydrolysis of phosphoenol pyruvate (PEP). Hydrolysis of either fructose diphosphate (FDP) or PEP is dependent on the presence of Mn++ or Mg++ and is inhibited by AMP.The hydrolysis of PEP is inhibited by FDP. The Km for PEP is 1.1 x 10−3 M and the Vmax is 2–4% of that observed with FDP. Some implications of this activity of fructose diphosphatase are mentioned.
“Constrained Geometry” Dialkyl Catalysts. Efficient Syntheses, C−H Bond Activation Chemistry, Monomer−Dimer Equilibration, and α-Olefin Polymerization Catalysis

This contribution reports an efficient synthesis of the “constrained geometry” group 4 dibenzyl complexes Me2Si(η5-Me4C5)(tBuN)MR2 (CGCMR2, where R = CH2Ph; M = Ti (1), Zr (2)), as well as the substantially different reaction patterns in the cocatalytic activation of the R = CH2Ph and Me complexes with B(C6F5)3, PBB (tris(2,2‘,2‘‘-perfluorobiphenyl)borane), and Ph3C+B(C6F5)4-. The resulting cationic complexes are highly but not equivalently active for α-olefin polymerization and copolymerization catalysis. The reaction of the neutral free ligand CGCH2 with Ti(CH2Ph)4 in aromatic or saturated hydrocarbon solvents at 60 °C cleanly affords 1 in 90% yield, while the corresponding reaction with Zr(CH2Ph)4 produces 2 in lower yield. When activated with Ph3C+B(C6F5)4- at low temperatures, 2 generates cationic CGCZrCH2Ph+ B(C6F5)4- (4). However, unlike the corresponding metallocene dibenzyl, the cationic derivative of which (Cp2ZrCH2Ph+B(C6F5)4- (3)) can be isolated in quantitative yield, the reaction of 1 with B...
Libraries, Churches, and Schools: The Literate Lives of Mothers and Children in a Homeless Shelter:

This article addresses the question,“How do mothers and children in a homeless shelter interact with literacy?” We drew on the theoretical framework of social literacy practices in which cultural context is foregrounded. Data for this qualitative study included participant observation in one homeless shelter and interviews with one shelter’s residents and other stakeholders, including teachers, administrators, shelter staff at various shelters, and homelessness experts across Los Angeles County, California. While examining the literacy practices of women and children living in one transitional shelter, we identified three institutions that were part of their lives (a) the public library, in which choice was a major factor; (b) the church, which focused on reading the Bible; and (c) schools, where literacy was tied to evaluative outcomes. Although families were overwhelmingly positive about their participation in each of these institutions and all three were referred to as places for learning, children’s t...
Congenital Diaphragmatic Hernia: Real Improvements in Survival

After completing this article, readers should be able to: 1. List the anomalies associated with congenital diaphragmatic hernia (CDH). 2. Delineate methods of determining the severity of CDH. 3. Review the roles of exogenous surfactant, extracorporeal membrane oxygenation, inhaled nitric oxide, sildenafil, and gentle ventilation in the management of CDH. 4. Describe the surgical repair undertaken in CDH. Congenital diaphragmatic hernia (CDH) is an intellectually fascinating and challenging birth defect that too often results in tragic loss for the child and family. Frequently diagnosed ultrasonographically at 20 weeks’ gestation, the diagnosis can overwhelm affected parents who never knew the condition existed and seldom can understand it adequately. Affected newborns face myriad potential issues, including pulmonary insufficiency, pulmonary hypertension, hemodynamic instability, associated cardiac defects, eventual feeding difficulties, and significant risk of dying or of surviving with substantial morbidity. Well-meaning but often inadequately informed physicians and caregivers too frequently view the situation as either hopeless or requiring dramatic but completely unproven prenatal interventions. However, improvements in understanding of CDH physiology coupled with expanding recognition of the negative effects of previously standard postnatal therapies have led to dramatic improvements in CDH survival in many centers. Some argue that the impact on overall CDH survival from these “advances” has been nil, but this is, in large part, due to continued significant rates of pregnancy termination with this diagnosis, rapid adoption of adjuvant CDH treatments, and slower penetration of fundamental changes in CDH therapy. This review examines what is known of the etiology of CDH, details the factors that affect the severity of the condition, describes the pathophysiology facing affected newborns, defines the physiologic basis of modern treatment, and provides examples of the improved survival and outcome experienced at centers that have embraced certain fundamental concepts. A relatively common birth defect, CDH is estimated to occur once in every …
Impaired Tracheobronchial Clearance of Bacteria in Calves Infected with Mycoplasma dispar

Infection of tracheal organ cultures with Mycoplasma dispar results in degeneration of respiratory epithelial cells with loss of ciliary activity. To assess the effect of these changes on the clearance of bacteria from the respiratory tract, the tracheobronchial clearance of a suspension of Serratia marcescens was determined in calves before and after infection with M. dispar. Tracheobronchial samples were obtained at various times after deposition of the marker bacteria. Clearance of S. marcescens was significant by 3 h after inoculation and only few colonies were detected 4 h after challenge. By contrast, in the same animals 5 days after intratracheal exposure to M. dispar, clearance of S. marcescens did not decrease significantly 4 h after inoculation. Histopathological and scanning electron microscopy (SEM) studies of infected lungs revealed that, as a result of infection with M. dispar, areas of degeneration and destruction of the respiratory ciliated epithelium occur in intermediate and small airways. These lesions may be responsible for the altered clearance observed in these mycoplasma-exposed calves.
Modelling relationships between job stressors and injury and near-miss outcomes for construction labourers

Construction work is an inherently dangerous occupation and exposure to additional job stressors is likely to exacerbate the level of danger, increasing workers’ risk for injury. Thus, it is important to identify and then reduce worker exposure to extraneous job stressors. This study examines the relationships between a variety of job stressors and injury or near-miss outcomes among construction workers. Self-reported questionnaire data collected from 408 construction labourers (male and female) via telephone interview were analysed using structural equation modelling. A theoretical model was tested whereby work stressors, classified into three groups, could be related, either directly or indirectly through the mediating effects of physical or psychological symptoms/strain, to self-reported injuries and near misses. Ten of the 12 work-related stressors were found to be directly related to either injury or near misses, including: job demands, job control, job certainty, training, safety climate, skill unde...
A heuristic method for solving reverse logistics vehicle routing problems with time windows

Vehicle routing problems with simultaneous pickup and delivery with time windows are studied in this paper. In a closed-loop logistics network, vehicles visiting customers for pickup and delivery may be only allowed for certain time intervals. A mixed integer programming model of the problem is presented. It has been known that solving vehicle routing problems with time windows is NP-hard. A heuristic solution procedure is developed to solve the problem. The proposed heuristic is tested on a number of numerical examples based on modified benchmark problems in the literature.
Sucrose‐derived exopolysaccharides of Streptococcus mutans V403 contribute to infectivity in endocarditis

We used an isogenic mutant of Streptococcus mutans V403, which differs from the wild-type V403 in genes involved in glucan and fructan production, to examine the importance of these exopolysaccharides as factors affecting infectivity in endocarditis. Rats inoculated with V403 developed endocarditis more frequently than animals inoculated with the mutant strain which produced neither glucan nor fructan (58% versus 12%, P < 0.01). In phagocytosis assays, both strains were found to be associated with the human granulocytes but a greater number of live V403 than of mutant organisms could be recovered. Colony counts recovered from fibrin plates incubated with the mutant were lower than those incubated with V403. These experiments indicate that exopolysaccharides produced by Streptococcus mutans contribute to its infectivity in endocarditis.
Quaternion wave equations in curved space-time

The quaternion formulation of relativistic quantum theory is extended to include curvilinear coordinates and curved space-time. This provides a promising framework for further exploration of a unified quantum/gravity theory.
Two approaches to discovering and developing new drugs for Chagas disease

This review will focus on two general approaches carried out at the Sandler Center, University of California, San Francisco, to address the challenge of developing new drugs for the treatment of Chagas disease. The first approach is target-based drug discovery, and two specific targets, cytochrome P450 CYP51 and cruzain (aka cruzipain), are discussed. A "proof of concept" molecule, the vinyl sulfone inhibitor K777, is now a clinical candidate. The preclinical assessment compliance for filing as an Investigational New Drug with the United States Food and Drug Administration (FDA) is presented, and an outline of potential clinical trials is given. The second approach to identifying new drug leads is parasite phenotypic screens in culture. The development of an assay allowing high throughput screening of Trypanosoma cruzi amastigotes in skeletal muscle cells is presented. This screen has the advantage of not requiring specific strains of parasites, so it could be used with field isolates, drug resistant strains or laboratory strains. It is optimized for robotic liquid handling and has been validated through a screen of a library of FDA-approved drugs identifying 65 hits.
Improved methods of simulating RLC coupled and uncoupled transmission lines based on the method of characteristics

This paper describes new techniques for simulating lossy (RLC) transmission lines based on the method of characteristics. For uncoupled lossy transmission lines a method is presented which speeds up the simulation time by a factor of two compared with existing techniques. A method is also presented for the transient analysis of coupled lossy lines in an inhomogeneous medium. Previously, simulation techniques were limited to coupled lossy lines in a homogeneous medium.
Epigenomics and the Microbiota

The mammalian gastrointestinal tract is home to trillions of commensal microorganisms that collectively make up the intestinal microbiota. These microbes are important environmental factors that regulate homeostasis, and alterations in the composition of the microbiota have been associated with several diseases, including inflammatory bowel disease, diabetes, and cancer. New research is beginning to uncover epigenomic pathways that may regulate this relationship with the microbiota. Epigenomic modifications alter the structure of the chromatin and therefore regulate the transcriptional program of a cell. These modifications are maintained by the dynamic activity of various modifying and demodifying enzymes, the activities of which can be influenced by metabolites and other environmental cues. Histone deacetylases (HDACs) are a class of epigenomic-modifying enzymes that are regulated by both endogenous and exogenous factors, and recent studies have suggested that host HDAC expression is important for regulating communication between the intestinal microbiota and mammalian host cells.