cssi/SciSciGPT-SciSciNet huggingface dataset:
The Structure and Mechanism of myo-Inositol-1-Phosphate Synthase

The first and rate-limiting step in the biosynthesis of myo-inositol is the conversion of D-glucose 6-phosphate to 1L-myo-inositol 1-phosphate catalyzed by 1L-myo-inositol 1-phosphate synthase (MIP synthase). MIP synthase has been identified in a wide variety of organisms from bacteria to humans and is relatively well-conserved throughout evolution. It is probably homotetrameric in most if not all cases and always requires NAD+ as a cofactor, with NADH being reconverted to NAD+ in the catalytic cycle. This review focuses on the structure and mechanism of MIP synthase, with a particular emphasis on the mechanistic insights that have come from several recent structures of the enzyme. These include the structure of the enzyme from Saccharomyces cerevisiae, Archeoglobus fulgidus and Mycobacterium tuberculosis.
Feedback Designs in Information-Based Control

This paper reports a tight bound on the data capacity a feedback channel must provide in order to stabilize a right half-plane pole of a linear, time-invariant control system. The proof is constructive, and involves considering a general class of quantized control realizations of classical feedback designs. Even for the coarsest quantizations—with two-element control input sets, which we refer to as a binary realization—the bound is achievable in the scalar case. The open question of whether bounded trajectories in higher order systems could be produced by a binary realization is answered in the affirmative—again via an explicit construction for a system with two-dimensional state space. It is also shown how binary realizations of classical feedback designs organize the way in which the controller pays attention to different open-loop modes in the plant.
Cognitive Strategies to Reduce Stress in Competitive Athletic Performance

One of the most common problems each of us has to deal with day in and day out is stress. Some of us live with an ever-present, rather subdued, level all the time. We cannot associate it with any particular event so we think this is just the way we are! Other stress responses are much more overt, reflected in such signals as a racing heart, disrupted breathing patterns, sweaty palms, feelings of weakness, and so on. Many times we can associate this with the specific situation we anticipate or in which we find ourselves. Those who experience situationally-specific stress and tension are much more aware of the cause and are in a better position to do something about controlling it. Regardless of the cause of the stress, the more years we experience it at any level, the greater the cost. It is impossible to go through life without stress, nor would we wish to. Without it, we would not learn to cope or to control it.
Universal common ancestry, LUCA, and the Tree of Life: three distinct hypotheses about the evolution of life

Common ancestry is a central feature of the theory of evolution, yet it is not clear what “common ancestry” actually means; nor is it clear how it is related to other terms such as “the Tree of Life” and “the last universal common ancestor”. I argue these terms describe three distinct hypotheses ordered in a logical way: that there is a Tree of Life is a claim about the pattern of evolutionary history, that there is a last universal common ancestor is an ontological claim about the existence of an entity of a specific kind, and that there is universal common ancestry is a claim about a causal pattern in the history of life. With these generalizations in mind, I argue that the existence of a Tree of Life entails a last universal common ancestor, which would entail universal common ancestry, but neither of the converse entailments hold. This allows us to make sense of the debates surrounding the Tree, as well as our lack of knowledge about the last universal common ancestor, while still maintaining the uncontroversial truth of universal common ancestry.
Women and men, moms and dads: Leveraging social role change to promote gender equality

Abstract This chapter examines gender inequalities in work and family outcomes through the lens of identity construction with a focus on the power of the social context in driving identity conflict. Cultural scripts dictate normative expectations around how to fulfill the roles of mother, father, and worker. The content of the scripts generates greater identity conflict for women than men as they strive to succeed in both roles. This conflict is driven in part by a tighter connection between the role mom and the category women than between dad and the category men, and in part by greater overlap in the roles of dad and professional than mom and professional. Moreover, mothers as a category are viewed as higher in essentialism than fathers. These perceptions affect both perceivers’ judgments of how the genders ought to fulfill these roles, and the self-perceptions of young women and men, such that when women anticipate greater role conflict, they engage in identity shifting on an implicit self-association task, whereas men demonstrate identity stability. Women also intend to make greater accommodations to work hours due to children. Changing the content of these social roles through strengthening the tie between dads and men, promoting less gendered division of caretaking responsibilities, and changing normative scripts for young professionals are discussed as pathways for promoting greater gender equality in both work and family outcomes.
Resilient distributed state estimation with mobile agents: overcoming Byzantine adversaries, communication losses, and intermittent measurements

Applications in environmental monitoring, surveillance and patrolling typically require a network of mobile agents to collectively gain information regarding the state of a static or dynamical process evolving over a region. However, these networks of mobile agents also introduce various challenges, including intermittent observations of the dynamical process, loss of communication links due to mobility and packet drops, and the potential for malicious or faulty behavior by some of the agents. The main contribution of this paper is the development of resilient, fully-distributed, and provably correct state estimation algorithms that simultaneously account for each of the above considerations, and in turn, offer a general framework for reasoning about state estimation problems in dynamic, failure-prone and adversarial environments. Specifically, we develop a simple switched linear observer for dealing with the issue of time-varying measurement models, and resilient filtering techniques for dealing with worst-case adversarial behavior subject to time-varying communication patterns among the agents. Our approach considers both communication patterns that recur in a deterministic manner, and patterns that are induced by random packet drops. For each scenario, we identify conditions on the dynamical system, the patrols, the nominal communication network topology, and the failure models that guarantee applicability of our proposed techniques. Finally, we complement our theoretical results with detailed simulations that illustrate the efficacy of our algorithms in the presence of the technical challenges described above.
A study of pediatric cerebral arteriovenous malformations: clinical presentation, radiological features, and long-term functional and educational outcomes with predictors of sustained neurological deficits

OBJECTIVE Large experiences with the treatment of pediatric arteriovenous malformations (AVMs) remain relatively rare, with limited data on presentation, treatment, and long-term functional outcomes. Because of the expected long lifespan of children, caregivers are especially interested in outcome measures that assess quality of life. The authors' intention was to describe the long-term functional outcomes of pediatric patients who undergo AVM surgery and to identify predictors of sustained neurological deficits. METHODS The authors analyzed a 21-year retrospective cohort of pediatric patients with intracranial AVMs treated with microsurgery at two institutions. The primary outcome was a persistent neurological deficit at last follow-up. Secondary outcome measures included modified Rankin Scale (mRS) score and independent living. RESULTS Overall, 97 patients (mean age 11.1 ± 4.5 years; 56% female) were treated surgically for intracranial AVMs (mean follow-up 77.5 months). Sixty-four patients (66%) presented with hemorrhage, and 45 patients (46%) had neurological deficits at presentation. Radiologically, 39% of lesions were Spetzler-Martin grade II. Thirty-seven patients (38%) with persistent neurological deficits at last follow-up were compared with those without deficits; there were no differences in patient age, presenting Glasgow Coma Scale score, AVM size, surgical blood loss, or duration of follow-up. Multivariate analysis demonstrated that a focal neurological deficit on presentation, AVM size > 3 cm, and lesions in eloquent cortex were independent predictors of persistent neurological deficits at long-term follow-up. Overall, 92% of the children had an mRS score ≤ 2 on long-term follow-up. CONCLUSIONS Pediatric patients with AVMs treated with microsurgical resection have good functional and radiological outcomes. There is a high rate (38%) of persistent neurological deficits, which were independently predicted by preoperative deficits, AVMs > 3 cm, and lesions located in eloquent cortex. This information can be useful in counseling families on the likelihood of long-term neurological deficits after cerebral AVM surgery.
Predicting the Slide to Long-Term Homelessness: Model and Validation

In spite of numerous programs and interventions, homelessness remains a significant societal concern. Long-term homelessness is particularly problematic because it can be increasingly difficult to escape from, and because it represents a continuous drain on societal resources. This paper develops a model for predicting long-term homelessness in response to a simple question: if an individual becomes homeless, what influences the individual's slide to long-term homelessness? The data we analyze to answer the question comes from the City of Boston. The model points to race, veteran status, disability, and age as key factors that predict this slide. The paper describes and illustrates the model along with problems encountered in data preparation and cleansing, prior scholarly work that helped to shape our decisions, and collaboration with participants in the ecosystem for homeless care that complemented the model-building effort. The results are important because they point to possible policy interventions (programs and funding) and process improvements (at homeless shelters) to mitigate this slide.
United They Stand, Divided They Fall.

Cancer cells that leave their natural environment during metastatic spread must adapt to numerous stresses to survive. In this issue, Labuschagne et al. (2019) highlight one adaptive mechanism to overcome these stresses that involves cell clustering, which induces a hypoxic environment and metabolic rewiring to buffer oxidative stress.
Variable Phase and Electrochemical Capacitance of Electrospun MnOx Fibers Via Controlled Calcination

Supercapacitors have the potential to complement or replace batteries in many current and emerging applications. As inexpensive and environmentally benign capacitive materials, manganese oxides are promising electrode materials. Nanostructured oxides have high energy storage capacities owing to their increased surface-area-to-volume ratios as compared to bulk materials. By electrospinning precursor-containing polymer fibers and subsequently calcining, nanostructured MnOx fibers can be prepared with relative ease. Controlling calcination pressure and time provides a route for variable capacitance via modifying surface roughness and oxide phase. At moderate pressures and short calcination times, mixed-phase Mn2O3/Mn3O4 fibers with high surface roughness exhibit enhanced electrochemical specific capacitance.
2991 Planned Multidisciplinary Surgical Approach to Deep Infiltrating Endometriosis

Study Objective To describe a multidisciplinary minimally invasive approach to deep infiltrating endometriosis (DIE) with colorectal and gynecologic surgeons. Design A retrospective cohort study. Setting Between 2014-2018, all patients with suspected DIE and intestinal involvement were assessed by a team of minimally invasive gynecologic surgeons (MIGS) and colorectal surgeons at the University of North Carolina Hospitals. Perioperative data were abstracted from medical records and analyzed. Patients or Participants Women ≥18 years of age with suspected DIE. Interventions MIGS and colorectal surgical teams planned combined cases in patients with clinical suspicion, prior diagnosis or radiographical evidence of DIE. Preoperative work-up included imaging, predominately lower endoanal ultrasound or pelvic MRI. Interventions indicated by patient's goals and disease burden included variable combinations of gynecologic and colorectal procedures. Measurements and Main Results Thirty-three patients were included, with a mean age of 37 years and average BMI of 30.5. Most were African American (48.5%) or Caucasian (33.3%) and had a prior laparotomic (56.7%) or laparoscopic (90.9%) surgery. At the initial gynecologic consult, patients reported hematochezia (21.2%), constipation (45.5%), dyschezia (66.7%), and straining during bowel movement (21.2%). An endoanal ultrasound (54.6%) and/or pelvic MRI (39.4%) were obtained based on symptoms and exam for suspected DIE. Imaging findings suggestive of bowel disease were strongly correlated (80%), therefore all patients underwent a preoperative colorectal consult. Combined hysterectomy and bowel resection were performed in 18 cases (54.5%), excision of endometriosis and bowel resection for DIE in six cases (18.1%). Six excision of DIE cases required bowel adhesiolysis alone (18.1%) and one case needed no colorectal intervention (3%). One case required conversion to laparotomy (3%). Conclusion A planned multidisciplinary gynecological–colorectal approach for the management of DIE can be performed in a minimally invasive manner in patients with suspected colorectal disease. We recommend a stepwise approach of preoperative imaging and a colorectal consult to coordinate two surgical teams.
Looking to aquatic species for conservation farming success

Thousands of species worldwide are threatened with extinction due to human activities. For some animals, such as elephants, totoaba, and bluefin tuna, population declines are largely driven by hunting. High prices and large profits create a strong incentive for illegal hunting, even in the face of penalties and strict international restrictions against trade. One innovative solution to help reverse the declines of such species is to farm them to increase supply, thereby reducing prices and decreasing hunting incentives. However, this idea has been criticized as impractical, though some examples exist of successful implementation. Here, we evaluate the hurdles facing endangered species farming as a market‐based mechanism to reduce illegal harvest of wild populations and provide guidance on when it is most likely to be effective. Using a simple model, we show how farming costs and enforcement of anti‐poaching measures are key drivers of success for this solution. We also argue that many of the most promising candidates are aquatic species that have been largely overlooked. Thus, while conservation farming may not be a solution for all endangered species, it should be more seriously considered for species that could be produced quickly and cost‐effectively.
Smart Data Center

Recently, the increase in demand of online applications and services that are hosted at data centers, have increased the power consumption of the data centers tremendously. In this chapter, we have addressed the problem of minimizing the operational cost of the power consumption in the data center. We have presented a new idea to power up the data center from more than one Smart grid. The algorithm titled “Smart Data center” is also presented in the chapter that minimizes the operational cost of the data center. The algorithm operates on long term and real time price markets from the local grid, low cost surplus power from the remote grid, and the backup power in the batteries of Uninterrupted Power Supply (UPS). The performance of the algorithm in analyzed using theoretical analysis.
Tales from New York City, the pandemic epicenter: A case study of COVID-19 impact on clinical and translational research training at the Icahn School of Medicine at Mount Sinai

In the spring of 2020, New York City was at the epicenter of the COVID-19 pandemic in the USA, resulting in disruption of TL1 and KL2-mentored Clinical and Translational Science (CTS) research at the Icahn School of Medicine at Mount Sinai (ISMMS). The impact of the pandemic on trainees' research productivity and career plans was explored using a qualitative survey. Participant responses were analyzed using coding and categorization. Six key themes emerged: redirection of effort, reduced access to people, lack of access to resources, home as a workplace, future uncertainty, and stress and anxiety. Insight into participant experiences allows for the development of support strategies and resources to address trainee needs.
Case 7-2021: A 19-Year-Old Man with Shock, Multiple Organ Failure, and Rash

A Man with Shock, Multiple Organ Failure, and Rash A 19-year-old man was admitted to the pediatric ICU because of shock, multiple organ failure, and rash. Twenty hours before admission, abdominal p...
Access to Justice: Litigating Rights Before US Supreme Court

Whitford describes his experiences as a plaintiff in a U.S. Supreme Court case concerning partisan gerrymandering: Gill v. Whitford, 138 S. Ct. 1916 (2018). He emphasizes and details what is particular to the role of a named plaintiff, and attending an argument at the Supreme Court.
Significant Sparse Polygenic Risk Scores across 428 traits in UK Biobank

We present a systematic assessment of polygenic risk score (PRS) prediction across more than 1,600 traits using genetic and phenotype data in the UK Biobank. We report 428 sparse PRS models with significant (p < 2.5 x 10-5) incremental predictive performance when compared against the covariate-only model that considers age, sex, and the genotype principal components. We report a significant correlation between the number of genetic variants selected in the sparse PRS model and the incremental predictive performance in quantitative traits (Spearmans {rho} = 0.54, p = 1.4 x 10-15), but not in binary traits ({rho} = 0.059, p = 0.35). The sparse PRS model trained on European individuals showed limited transferability when evaluated on individuals from non-European individuals in the UK Biobank. We provide the PRS model weights on the Global Biobank Engine (https://biobankengine.stanford.edu/prs).
Managing Disease and Therapy-Related Complications in Patients with Central Nervous System Tumors

Treating patients with brain tumors can be divided into tumor-directed therapies, the management of tumor-related symptoms and complications and the psychosocial aspect of patient care. In this review, we will discuss the management of disease and treatment-related complications, which can negatively impact patient quality of life and functional status. Brain edema is a common complication or brain tumors and often causes more symptoms than the tumor itself. Treatment options are limited to the use of corticosteroids, which although effective have a plethora of side effects, so the goal should be the lowest dose that maximizes symptoms. Seizures are more common in lower grade brain tumors and treatment should be limited to patients who have seizures using agents that do not affect the metabolism of other drugs, especially chemotherapies. Blood clots are also common in patients and although there is a “fear” of tumoral bleeding, this is not a frequent occurrence; hence, using anticoagulants should be routinely used in patients who experience this complication.
Life Course Diversity Among Older Lesbians and Gay Men: A Study in Chicago

How much can we assume about the shared life experiences of older lesbians and gays? This article is broadly concerned with rethinking the significance of this question as it pertains to cultural images and stereotypes of “older gay and lesbian” identities in a large and diverse American city. In 1996, the authors completed a 10-month needs assessment study regarding the lives and needs (social and psychological), which must be addressed for older lesbians and gays in the city of Chicago. The authors take the approach that simply being of the same or similar age is insufficient to understand the meaning of people's sexual identities. They entered into this study aware of some stereotypes about older lesbians and gays, but like previous investigators, they were surprised at the range of diversity that they uncovered. They discovered not only the common denominators in their participants' experiences and their lives, but as some commentators have already suggested, they also discovered a great deal of variation. To address the issues, the authors describe conceptual problems that emerged in a recent needs assessment of older lesbians and gay men in Chicago.
Superfluidity in a Crystal

The phenomenon of nonclassical rotational inertia (NCRI), in which a body does not rotate with its rotating container, has long been thought to be peculiar to Bose-Einstein condensates of certain liquids and gases, in particular liquidHe. In his Perspective, [Leggett][1] discusses the experimental observation by [Kim and Chan][2] of similar behavior in solidHe. The new results are most naturally interpreted as showing that the crystalline solid phase ofHe displays NCRI below about 230 mK, although the fraction of the system that behaves in this way is very small. This experiment presents a major challenge to our current theoretical understanding of solid helium. [1]: http://www.sciencemag.org/cgi/content/full/305/5692/1921 [2]: http://www.sciencemag.org/cgi/content/short/305/5692/1941
Teaching software engineering practices with Extreme Programming

Extreme Programming (XP), one of many models for software development, has challenged some traditional software engineering practices while taking others to the extreme. The controversial practices raise questions about the role of XP in teaching undergraduate software engineering courses, especially capstone project courses. Can an XP model for software development be successfully used in teaching software engineering practices? Specific educational goals for the course are that 1) students recognize the strengths and weaknesses of XP as a model for software development and 2) that students evaluate XP practices in the larger context of other software engineering practices. Students should also complete a software development project while following a defined set of processes and practices.Students in a 4 credit, one-semester software engineering practices course used XP for their project. A survey of fifteen practices representing both XP and more traditional software engineering practices was given to students upon completion of the course to determine the students' perceptions and experiences.Overall, students were successful in using XP for their projects. Students liked pair programming, automated testing, and test-first and believed it contributed to their success. The XP practices of simple design and refactoring did not work well. XP's practices for embracing change accommodates changing requirements, design, and code but do not manage change well for the overall goals of the product. Survey results and anecdotal evidence suggests that students were aware of the strengths and weaknesses of XP and its relationship to more traditional software engineering practices.
Creating Value: Data Exploration, Multiple Objectives, and Real Options

One of the key tasks of decision analysis is to help a decision maker identify better decision opportunities than those that the decision maker started with. The use of data exploration and the adoption of multiple objectives can help a decision maker uncover such decision opportunities -- real options -- that are either future opportunities that the decision maker might not have recognized, additional alternatives for the current decision, or completely new decision opportunities. The concepts are illustrated via a fictional example from the pharmaceutical industry. Implications for information and decision support systems design are discussed in the conclusion.
Immigration and Ethnic Entrepreneurship: A Comparative Study in the United States

Using Singer's typology of different types of immigration gateways, this study mainly addresses how metropolitan area conditions impact ethnic labor force entrepreneurial choices across ethnicity and gender, within the contexts of different types of immigration gateways. Employing the 5 percent 2000 Integrated Public Usable Microdata Samples and a multilevel regression strategy, this study demonstrates that different types of immigration gateways have distinctive impacts on ethnic entrepreneurship. After controlling for both personal- and metropolitan-level characteristics, it is found that whites and blacks are more likely to own businesses in newer immigration gateways, while Hispanics and Asians are more likely to do so in the more established gateways. In addition, differences as to the interaction effects of gender and regional labor markets are the most significant for blacks and Asians. Such interaction effects reshape gender differences in business ownership across ethnic groups.
“Not Getting Any Because of Jesus”: The Centrality of Desire Management to the Identity Work of Gay, Celibate Christians

Drawing from semistructured interviews with gay, celibate Christians or “Side B” individuals, I explore the emotion of desire. I specifically attend to these questions: How do Side Bs interpret and communicate feeling rules connected to desire? How do these individuals manage desire? How might feeling rules and conceptualizations of this feeling serve as an important source of boundary heightening? Finally, how might shared feeling rules create connection with others who do not identify as Side B? By attending to these questions, I illustrate the relationship between the conceptualization of an emotion and a set of feeling rules and emotion management strategies. I also highlight how such rules and strategies can serve as a source of boundary heightening, or alternatively, as a bridge between seemingly disparate groups.
Metals in Metal Salts: A Copper Mirror Demonstration

A simple lecture demonstration is described to show the latent presence of metal atoms in a metal salt. Copper(II) formate tetrahydrate is heated in a round-bottom flask forming a high-quality copper mirror.
Reply to Bach and Neale

Parmi les remarques qu'ont suscitees sa critique des approches pragmatique et syntaxique du probleme de la restriction du domaine de quantification, l'A. repond a l'approche implicite de S. Neale selon laquelle l'A. n'aurait pas presente une conception comprehensive de toutes les analyses possibles du phenomene, d'une part, et repond au postulat des domaines variables propose par K. Bach dans son analyse des contextes de quantification, d'autre part.
Vertical expandable prosthetic titanium rib device insertion: does it improve pulmonary function?

Abstract Purpose Vertical expandable prosthetic titanium rib (VEPTR) insertion and expansion has been advocated to increase thoracic volume and pulmonary function in patients with thoracic insufficiency syndrome. We reviewed our experience with VEPTR implantation to determine if lung function and growth is augmented, to determine the children's functional status, and if the scoliosis is controlled. Methods From 2006 to 2010, 29 insertions and 57 expansions were performed in 26 patients at our institution. Demographic data were reviewed in conjunction with complications, scoliosis angles, pulmonary function tests (PFTs), and computed tomography–guided 3D reconstructions to determine lung volumes; and quality of life scores were determined using a modified Scoliosis Research Society (SRS) questionnaire preoperatively and postoperatively. The groups were also stratified by age (because of lung growth potential), disease (congenital or infantile scoliosis, Jeune syndrome, neuromuscular, other structural thoracic disorders), and sex. Analyses using SPSS (SPSS, Chicago, Ill) were performed with P Results Each patient underwent 3.03 ± 1.8 surgeries, spending 0.97 ± 1.8 days in the intensive care unit and 4.41 ± 6 days in the hospital for each procedure. Mean age was 90.7 ± 41 months. Of the 36 complications, most were because of infection (12), half requiring operative repair (hardware removal). The average PFT percent predicted values for forced expiratory volume in 1 second, forced vital capacity, and RV were 54.6 ± 22, 58.1 ± 24, and 145.3 ± 112, respectively, preoperatively and 51.8 ± 20, 55.9 ± 20, and 105.6 ± 31, respectively, postoperatively. The lung volumes measured by computed tomography when corrected for age do not increase significantly postoperatively. The mean Cobb measurement for the preoperative major curves was 64.7° and postoperatively was 46.1° for those curves measured preoperatively, for a 29% curve improvement. All postoperative curves had a mean of 56.4° and 58.1° at final follow-up, a 3% curve increase. The SRS scores for patients remained unchanged and no statistical difference was seen from preoperative to postoperative values. No statistically significant difference was seen in complications, PFT (forced expiratory volume in 1 second, forced vital capacity, RV), lung volumes, scoliosis angles, and SRS scores between sex, age, and disease categories. Conclusion There was mild improvement in scoliosis angles but no improvement in lung function and volume. Scoliosis Research Society scores indicate that the children have near normal function both before and after VEPTR placement. Pulmonary function, lung volume, and patient subjective assessments did not increase dramatically after VEPTR placement, although scoliosis angles improved.
Controlling gas-phase reactions for efficient charge reduction electrospray mass spectrometry of intact proteins

Charge reduction electrospray mass spectrometry (CREMS) reduces the charge states of electrospray-generated ions, which concentrates the ions from a protein into fewer peaks spread over a larger m/z range, thereby increasing peak separation and decreasing spectral congestion. An optimized design for a CREMS source is described that provides an order-of-magnitude increase in sensitivity compared to previous designs and provides control over the extent of charge reduction. Either a corona discharge or an α-particle source was employed to generate anions that abstract protons from electrosprayed protein cations. These desired ion/ion proton transfer reactions predominated, but some oxidation and ion-attachment reactions also occurred, leading to new peaks or mass-shifted broader peaks while decreasing signal intensity. The species producing these deleterious side-reactions were identified, and conditions were found that prevented their formation. Spectrometer m/z biases were examined because of their effect upon the signal intensity of higher m/z charge-reduced protein ions. The utility of this atmospheric pressure CREMS was demonstrated using a cell lysate fraction from E. coli. The spectral simplification afforded by CREMS reveals more proteins than are observed without charge reduction.
Heat Transfer From Combustion Gases to a Single Row of Closely Spaced Tubes in a Swirl Crossflow Stirling Engine Heater

This paper describes an experimental program to determine the heat-transfer characteristics of a combustor and heat-exchanger system in a hybrid solar receiver which utilizes a Stirling engine. The system consists of a swirl combustor with a crossflow heat exchanger composed of a single row of 48 closely spaced curved tubes. In the present study, heat-transfer characteristics of the combustor/heat-exchanger system without a Stirling engine have been studied over a range of operating conditions and output levels using water as the working fluid. Nondimensional heat-transfer coefficients based on total heat transfer have been obtained and are compared with available literature data. The results show significantly enhanced heat transfer for the present geometry and test conditions. Also, heat transfer along the length of the tubes is found to vary, the effect depending upon test condition.
The vanadate-stimulated oxidation of NAD(P)H by biomembranes is a superoxide-initiated free radical chain reaction

Abstract Rat liver microsomes catalyze a vanadate-stimulated oxidation of NAD(P)H, which is augmented by paraquat and suppressed by superoxide dismutase, but not by catalase. NADPH oxidation was a linear function of the concentration of microsomes in the absence of vanadate, but was a saturating function in the presence of vanadate. Microsomes did not catalyze a vanadate-stimulated oxidation of reduced nicotinamide mononucleotide (NMNH), but gained this ability when NADPH was also present. When the concentration of NMNH was much greater than that of NADPH a minimal average chain length could be calculated from 1 2 the ratio of NMNH oxidized per NADPH added. The term chain length, as used here, signifies the number of molecules of NMNH oxidized per initiating event. Chain length could be increased by increasing [vanadate]and [NMNH] and by decreasing pH. Chain lengths in excess of 30 could easily be achieved. The Km for NADPH, arrived at from saturation of its ability to trigger NMNH oxidation by microsomes in the presence of vanadate, was 1.5 μ m . Microsomes or the outer mitochondrial membrane was able to catalyze the vanadate-stimulated oxidation of NADH or NADPH but only the oxidation of NADPH was accelerated by paraquat. The inner mitochondrial membrane was able to cause the vanadate-stimulated oxidation of NAD(P)H and in this case paraquat stimulated the oxidation of both pyridine coenzymes. Our results indicate that vanadate stimulation of NAD(P)H oxidation by biomembranes is a consequence of vanadate stimulation of NAD(P)H or NMNH oxidation by O2−, rather than being due to the existence of vanadate-stimulated NAD(P)H oxidases or dehydrogenases.
An algorithm for estimating the parameters in multiple linear regression model with linear constraints

Abstract This paper develops an algorithm for estimating the parameters when the parameters are restricted by linear constraints in a general multiple regression model. The algorithm solves discrete approximation in the Φ error where Φ is a convex and symmetric function. These discrete approximations arise in fitting by polynomials, linear regression and goal programming. Discrete approximation problems in the L1 norm is a special case. The approaches to the solution of these approximation problems have a long history. The algorithm utilizes certain properties of the problem to significantly reduce the number of iterations to find the approximated solution.
STAT3 mediates bone marrow mesenchymal stem cell VEGF production

The mechanisms by which mesenchymal stem cells (MSCs) may protect native tissue are incompletely understood. Understanding the mechanisms by which these cells release factors such as vascular endothelial growth factor (VEGF), may lead to enhanced protection. We hypothesized that stress, in the form of hypoxia or TNF, activates MSCs to release VEGF by STAT3 and p38 MAPK dependent mechanisms. Mouse MSCs from wild type (WT) and STAT3 knockout mice (STAT3KO) were harvested and purified by a single-step method using adhesion. The release of VEGF was analyzed by using MSC conditioned media under hypoxia or TNF stimulation with or without p38 MAPK inhibition. Activation of STAT3 and p38 MAPK was determined by analysis of cell lysates. MSCs released VEGF under normoxia, which was associated with constitutive STAT3 activity. STAT3 deficiency resulted in decreased MSC production of VEGF. In response to hypoxia or TNF, MSCs produced more VEGF, which was correlated with hypoxia or TNF activated p38 MAPK and STAT3. The p38 MAPK inhibitor significantly decreased hypoxia-induced or TNF-stimulated VEGF production in WT. Additionally, STAT3 ablation neutralized hypoxia-induced MSC release of VEGF. No effect of p38 MAPK inhibitor alone was observed on MSC release of VEGF in WT. However, inhibition of p38 MAPK blocked release of VEGF in STAT3KO MSCs. MSCs are a potent source of VEGF, the production of which is mediated by STAT3 under normoxia partly; however, following hypoxia or TNF exposure, MSC release of VEGF is mediated by both STAT3 and p38 MAPK.
THE INSERTION AND EXTRUSION OF HETEROSULFUR BRIDGES. VII. DESULFURIZATION OF PHENANTHRO(4,5‐BCD)THIOPHENE BY MEANS OF METHANOL AND A MOLYBDENA CATALYST

Phenanthro[4,5-bcd]thiophene (1) is converted into phenanthrene (2) (50%) and a mixture of methylphenanthrenes (3) (12%) by means of methanol and a sulfided cobaltous oxide-molybdic oxide-aluminum oxide catalyst (CMA-1) at 450° in a flow system. Similarly, 2 gives 3; and 4-methylphenanthrene yields 2 plus 3 (main component 3-methylphenanthrene) under the same reaction conditions. Mechanisms of the reactions are discussed. A facile chromatographic separation for 1- and 4-keto-1,2,3,4-tetrahydrophenanthrenes is presented.
A Modified Huxley-Type Model that Simulates Activation-Dependent Rates of Tension Recovery

Many laboratories now estimate how quickly cross-bridges cycle in chemically permeabilized muscle preparations by measuring how quickly tension recovers to its steady-state after a rapid-shortening/re-stretch perturbation. Brenner, who developed this technique (PNAS, 85:3265-3269, 1988), showed that the rate of force development (ktr) increased with the level of Ca2+ activation. K.B. Campbell (no relation to the present author) developed an analytical model (Biophys J, 72:254-262, 1997) that attributed the activation-dependence of the rate constant to cooperative effects. The current work extends this approach by modifying a strain-dependent Huxley-type model (Prog Biophys Biophys Chem, 7:255-318, 1957) so that the proportion of binding sites that are available for cross-bridges to attach to (pon) depends on the prevailing Ca2+ concentration and the muscle's history of movement. Specifically, dpon/dt = (kon[Ca2+] + ψpon)(1-pon) - koff(pon-pbound), where kon and koff are rate constants, ψ is a scaling factor, and pbound is the proportion of binding sites that have myosin heads attached. During a rapid shortening/re-stretch maneuver, myosin heads are forcibly detached as they are pulled into configurations with high detachment rates. This increases the (pon-pbound) term above and the pon population thus declines. At high Ca2+ concentrations, this effect is short-lived and pon quickly returns to its steady-state value. ktr under these conditions is thus limited by the f and g rate functions. At low Ca2+ concentrations, dpon/dt is suppressed and ktr is dictated by how quickly binding sites become available for myosin heads to attach to. Initial calculations have shown that when this model is driven by a realistic length perturbation, the simulated force records accurately reproduce those measured in real experiments using rat myocardial preparations.
Multidisciplinary Design Optimization of a transonic strut-braced wing aircraft

The objective of this study was to use Multidisciplinary Design Optimization (MDO) to~investigate the use of truss-braced wing concepts in concert with other advanced technologies to obtain a significant improvement in the performance of transonic transport aircraft. To perform this study, a suite of approximate analysis tools was assembled into a complete, conceptual-level MD0 code. A typical mission of the Boeing 777-2001GW was chosen as the design mission profile. Several single-strut configurations were optimized for minimum takeoff gross weight, using eighteen design variables and seven constraints. The best single-strut configuration shows a 15% reduction in takeoff gross weight, a 29% reduction in fuel weight, a 28% increase in the lift-to-drag ratio, and a 41% increase in seat-miles per gallon relative to a comparable cantilever configuration. In addition to the MD0 work, an innovative arch-braced wing concept has been proposed. A plastic solid model of this configuration was created using the I-DEAS solid modeling software and the rapid prototyping hardware at Virginia Tech.
Growth and characterization of doped DTGS crystals for infrared sensing devices

Abstract Modified deuterated triglycine sulfate (DTGS) single crystals have been grown from the deuterated aqueous solution simultaneously doped with l -alanine and neodymium sulfate in the ferroelectric phase using temperature-lowering technique. The effects of these different dopants on the growth, dielectric and pyroelectric properties have been investigated. Doped crystals exhibited higher material figures of merit for pyroelectric infrared sensing devices and vidicons applications with wider operating temperature, compared with virgin DTGS crystals.
Storage protein in hereditary ceroid-lipofuscinosis contains S-methylated methionine

Abstract Hereditary ceroid-lipofuscinoses are neurodegenerative disorders characterized by the accumulation in numerous tissues of a storage material with lipofuscin-like fluorescence properties. Investigations were undertaken to determine the chemical nature of this storage material isolated from the cerebral cortex of human subjects with the late infantile form of the disease. The storage material was mainly protein that consisted of a mixture of polypeptides ranging in apparent molecular weight from 13 to 67 kDa. Protein-bound fluorophores apparently were largely responsible for the autofluorescence of the storage bodies. The disease-related storage body protein was rich in S-methylmethionine [(3-amino-3-carboxypropyl) dimethyl sulfonin ion], an amino acid that does not normally occur in animal proteins. Methylation of proteins to form this unusual charged amino acid may impair proteolytic degradation or other aspects of protein metabolism, and account for the accumulation of protein-filled inclusions in cells of individuals with ceroid-lipofuscinoses. Similar amino acid modifications that block proteolysis could be involved in age pigment accumulation.
In vitro efficacy of β-lactam/β-lactamase inhibitor combinations against bacteria involved in mixed infections

Mixed infections are usually caused by a relatively limited range of bacteria, with the anaerobes and opportunistic pathogens contributing to their severity. In order to make the best therapeutic choice for a patient with a life-threatening infection, which is probably of mixed etiology, clinicians must be aware of the organisms that are likely to be involved, and the fact that most of them will produce beta-lactamase. Of the options available for empiric therapy, the beta-lactam/beta-lactamase inhibitor combinations represent a good choice. Their antibacterial spectra include both aerobic and anaerobic pathogens. Five combinations are available in clinical practice: ampicillin-sulbactam, piperacillin-tazobactam, ticarcillin-clavulanic acid, amoxicillin-clavulanic acid, and cefoperazone-sulbactam. More strains of clinically important anaerobic bacteria are susceptible to ampicillin-sulbactam than to either piperacillin-tazobactam or ticarcillin-clavulanic acid, which are also available widely and suitable for more life-threatening infections. In addition, sulbactam itself has the highest intrinsic activity of the beta-lactamase inhibitors against the opportunistic pathogen, Acinetobacter baumannii. Thus, ampicillin-sulbactam could be considered a drug of choice for the empirical treatment of mixed infections where there is a reasonable possibility of the presence of A. baumannii.
Drugs Designed to Improve Endothelial Function: Effects on Erectile Dysfunction

Endothelial dysfunction (EtD) has emerged as a critical master pathway in the pathogenesis of both vascular disease and erectile dysfunction (ED). Drugs that have been developed for vascular diseases and/or found to have beneficial endothelial effects may be helpful in the management of ED. In this manuscript we summarize the current state of the art with respect to endothelial active drugs and discuss the evidence supporting their use in the management of ED. Pubmed query for the terms Endothelial dysfunction, erectile dysfunction, pharmaceuticals, "endothelium", "function", "pharmaceutical", "eNOS", "erectile dysfunction" and "erectile function" was conducted. Relevant articles were reviewed and summarized. A variety of cardiovascular medications have mechanisms of action that involve the endothelium. Examples include HMG-CoA Reductase inhibitors ("statins"), Angiotensin Converting Enzyme Inhibitors (ACEI), Angiotensin Receptor blockers (ARB), Endothelin Receptor Antagonists (ERA), certain beta blockers, and some oral hypoglycemics. Some of these drugs have been found to improve penile erection, although an endothelium dependent mechanism has not been conclusively demonstrated in all studies. Drugs that improve endothelial function in the cavernous arteries and the erectile tissues of the corpora cavernosa hold great promise in treating or at least minimizing the vascular damage that contributes to ED. ACEI and ARB appear to hold great promise in this regard, while statins and oral hypoglycemics may play a potentially useful role as adjunctive therapy for ED. Improvements in endothelial function may help reverse ED in some cases, which would be a marked improvement over management with currently available "on demand" ED therapies.
Amplified immunoperoxidase staining of isoelectrically focused human tumor markers

Avidin-biotin amplified immunoperoxidase staining of the human tumor marker, carcinoembryonic antigen (CEA) localized in malignant tissue by isoelectric focusing is described. CEA either in electrofocused aqueous tissue extracts or extracted and separated by direct tissue isoelectric focusing in agarose (IsoGel), was reacted with rabbit and anti-CEA antiserum and with enzyme conjugated swine anti-rabbit antiserum, or with avidin-biotin conjugated reagents, then with enzyme substrate. Avidin-biotin amplified immunoperoxidase staining of CEA gave more intense staining. Quantitation and characterization of tumor markers by direct tissue electrophoresis in isoelectric focusing media and enzyme amplification of anti-tumor marker antisera, make possible the study of their biological meaning and clinical usefulness.
COLONIAL PIPELINE ENOREE RIVER OIL SPILL: A CASE HISTORY1

ABSTRACT In December 1991, a pipeline ruptured near Fountain Inn, South Carolina, resulting in the release of approximately 13,000 barrels of No. 2 fuel oil to the inland surface water system. Over 18 miles of Durbin Creek and the Enoree River were seriously impacted by the spill, one of the largest inland oil discharges in the United States in 1991. As a result of the spill, primary water supply intakes for the towns of Clinton (population 8,500) and Whitmire (population 2,000) remained closed until the appropriate level of water quality for consumption could be restored. These towns are located about 30 miles and 50 miles respectively, from the site of the pipeline rupture. The Environmental Protection Agency Region IV on-scene coordinator and the U. S. Coast Guard Strike Team responded to the scene and directed the pipeline company's cleanup efforts over a five-day period, which resulted in recovery of more than 95 percent of the spilled product. This paper presents a case history of the spill response...
Variability of Treatments and Experimental Units in the Design and Analysis of Experiments

Abstract The design and analysis of experiments should take into account all of the major sources of variability that are expected to influence the responses. In this article a description is given of types of commonly used experimental plans that do not permit useful inferences to be made from the effects of treatment comparisons because they do not allow for the estimation of all major sources of variability that affect the treatment comparisons.