cssi/SciSciGPT-SciSciNet huggingface dataset:
Does Delaying Kindergarten Entrance Give Children a Head Start

Abstract The rising trend in the minimum entrance age for kindergarten in the US has been motivated by findings from cross-sectional studies that older entrants have more favorable school outcomes compared to younger entrants. However, these studies fail to account for endogeneity in entrance age resulting from parental choice, leading to biased estimates of the entrance age effect. This paper uses exogenous variation in birth dates and kindergarten entrance age policies to generate instrumental variable estimates of the effect of delaying kindergarten entrance on children's academic achievement. Both initial level differences and subsequent growth in test scores are examined. I find that entering kindergarten a year older significantly boosts test scores at kindergarten entry. More importantly, entering older implies a steeper test score trajectory during the first 2 years in school. Results also suggest that the benefits from delaying kindergarten entrance tend to be significantly larger for at-risk children.
Sharkey′s Example

Abstract A reinterpretation of Sharkey′s example of an empty core illustrates a remark of Scarf about the complications that arise in an economy in which there are increasing returns and leisure is valued by households. In such an economy larger output can be stymied from having a reasonable effect on the outcome so that the core is empty owing to strange preferences such as perfect complementarity between goods and leisure coupled to a peculiar initial endowment. Under more reasonable conditions there is a nonempty core. Journal of Economic Literature Classification Number: C7.
Genetic Association Analysis under Complex Survey Sampling: The Hispanic Community Health Study/Study of Latinos

The cohort design allows investigators to explore the genetic basis of a variety of diseases and traits in a single study while avoiding major weaknesses of the case-control design. Most cohort studies employ multistage cluster sampling with unequal probabilities to conveniently select participants with desired characteristics, and participants from different clusters might be genetically related. Analysis that ignores the complex sampling design can yield biased estimation of the genetic association and inflation of the type I error. Herein, we develop weighted estimators that reflect unequal selection probabilities and differential nonresponse rates, and we derive variance estimators that properly account for the sampling design and the potential relatedness of participants in different sampling units. We compare, both analytically and numerically, the performance of the proposed weighted estimators with unweighted estimators that disregard the sampling design. We demonstrate the usefulness of the proposed methods through analysis of MetaboChip data in the Hispanic Community Health Study/Study of Latinos, which is the largest health study of the Hispanic/Latino population in the United States aimed at identifying risk factors for various diseases and determining the role of genes and environment in the occurrence of diseases. We provide guidelines on the use of weighted and unweighted estimators, as well as the relevant software.
The Random Dialing Survey as a Tool for Community Consultation for Research Involving the Emergency Medicine Exception From Informed Consent

Study objective In 1996, the Food and Drug Administration and the Department of Health and Human Services enacted rules allowing a narrow exception from informed consent for critically ill patients enrolled in emergency research. These include requirements for community consultation prior to trial implementation. Previous studies have noted difficulty in engaging the community. We seek to describe the experience with random dialing surveys as a tool for community consultation across 5 metropolitan regions in the United States. Methods Random dialing surveys were used as part of the community consultation for an out-of-hospital clinical trial sponsored by the Resuscitation Outcomes Consortium. The survey method was designed to obtain a representative sample of the community according to population demographics and geography. Logistics of survey administration, role of the survey in community consultation, and survey results by population demographics are discussed. Results Random dialing surveys were conducted in 5 of 8 US Resuscitation Outcomes Consortium sites. Overall, 70% to 79% of respondents indicated they would be willing to be enrolled in this study. Support for the inclusion of children (aged 15 to 18 years) ranged from 52% to 71%. Respondents aged 18 to 34 years were more willing to participate in the trial than older age groups. Women and racial minorities were less likely to favor the inclusion of minors. Conclusion Random dialing surveys provide an additional tool to engage the community and obtain a sample of the opinion of the population about research conducted under the emergency exception from informed consent regulations. Similar results were obtained across 5 diverse communities in the United States.
The vacuolar nature of bone ground substance.

Abstract The palates of 1 day old mice were fixed by immersion in chilled 95% ethanol and buffered aqueous 2% osmium tetraoxide. Some osmium-fixed tissue was stained with 1% phosphotungistic acid (PTA) in 95% ethanol. All tissue was dehydrated in ethanol and embedded in methacrylate. Thin sections mounted on grids were demineralized in 1% PTA in 50% ethanol or in a saturated solution of disodium ethylene diamine tetracetate (EDTA). Sections demineralized in EDTA were stained with aqueous 2% osmium tetraoxide. After demineralization, submicroscopic vacuoles were apparent in bone inter-fibrillar ground substance. In relatively mature bone the vacuoles were approximately 20 mμ in diameter and their walls approximately 10 mμ regardless of the preparative reagents used. The vacuoles increased in diameter as newly formed bone matured. This change was interpreted as resulting from the removal of collagen from the ground substance during fibril development and growth.
Response Growth With Sound Level in Auditory-Nerve Fibers After Noise-Induced Hearing Loss

People with sensorineural hearing loss are often constrained by a reduced acoustic dynamic range associated with loudness recruitment; however, the neural correlates of loudness and recruitment are still not well understood. The growth of auditory-nerve (AN) activity with sound level was compared in normal-hearing cats and in cats with a noise-induced hearing loss to test the hypothesis that AN-fiber rate-level functions are steeper in impaired ears. Stimuli included best-frequency and fixed-frequency tones, broadband noise, and a brief speech token. Three types of impaired responses were observed. 1) Fibers with rate-level functions that were similar across all stimuli typically had broad tuning, consistent with outer-hair-cell (OHC) damage. 2) Fibers with a wide dynamic range and shallow slope above threshold often retained sharp tuning, consistent with primarily inner-hair-cell (IHC) damage. 3) Fibers with very steep rate-level functions for all stimuli had thresholds above approximately 80 dB SPL and ...
A potent and highly selective sulfotransferase inhibitor.

In the present work, we have used a newly developed, fluorescence-based assay to screen a library of >30 000 compounds as potential β-arylsulfotransferase-IV inhibitors. A total of 11 inhibitors we...
On the probability of existence of pure equilibria in matrix games

We examine the probability that a randomly chosen matrix game admits pure equilibria and its behavior as the number of actions of the players or the number of players increases. We show that, for zero-sum games, the probability of having pure equilibria goes to zero as the number of actions goes to infinity, but it goes to a nonzero constant for a two-player game. For many-player games, if the number of players goes to infinity, the probability of existence of pure equilibria goes to zero even if the number of actions does not go to infinity.
Non-Native Structural Properties of the Glaucoma-Associated Olfactomedin Domain of Myocilin Lead to Amyloid Fibrils

Approximately 4% of adult-onset and 10-33% of juvenile-onset primary open angle glaucoma cases are caused by mutations in the gene encoding for myocilin. The vast majority of mutations are within the 30 kDa C-terminal olfactomedin (OLF) domain. Disease-causing myocilin variants aggregate within human trabecular meshwork (HTM) cells instead of secretion to the extracellular matrix. This accumulation taxes the cells and leads to HTM cell death, resulting in increased intraocular pressure, and a hastening of glaucoma-associated vision loss. In spite of reports on the intracellular accumulation of myocilin in HTM cells and model organisms, these aggregates have not been structurally characterized. Our lab recently provided biophysical evidence for the hallmarks of amyloid fibrils in aggregated forms of WT and mutant myocilin localized to the C-terminal OLF domain (myoc-OLF). Under mildly destabilizing conditions, WT myoc-OLF has a distinct non-native structure capable of forming amyloid fibrils. In the case of disease-causing myocilin variants, this non-native structure is accessible under physiological conditions, leading to accelerated fibril growth. Building on the hypothesis that partial unfolding of myoc-OLF is necessary for fibril growth, this study also investigates the structural and biophysical effects of adding stabilizing agents, such as osmolytes and Ca2+, to the myoc-OLF domain as a strategy to prevent myoc-OLF amyloid aggregation. The results of this study suggest a novel protein-based hypothesis for glaucoma pathogenesis and the need for further testing in a clinical setting.
AIDS and the health crisis of the U.S. urban poor: The perspective of critical medical anthropology.

The social identity of HIV/AIDS in the U.S. has been shaped, for the most part, by two factors, the prevailing configuration of social relations across class, racial, gender, and sexual orientation, on the one hand, and the prevailing array of public health, especially epidemiological, categories of disease transmission, on the other. Focusing on the AIDS epidemic among inner city people of color, this paper challenges the distortions wrought in our understanding from both of these factors and instead develops an alternative perspective for AIDS research among medical anthropologists and health social scientists generally.
IMPACT OF COMPUTER ASSISTED DIAGNOSIS ON HOSPITAL STAY

A previous study demonstrated the capacity of a computer (MEDITEL) to assist in the diagnosis of difficult pediatric problems. A study was undertaken to determine if the use of a computer diagnosis would hasten the time of initial diagnosis and reduce laboratory studies. A total of 67 pts. were studied. Pts. were selected if at the time of admission a diagnosis was not clearly evident. In 34 pts. the computer list of differential diagnoses was placed on the chart for the use of the house officer, while 33 pts. served as controls and the print-out retained by the chief resident. Review at discharge revealed that the time from admission to diagnosis was the same for both the computer (2.1 days) and control groups (2.8 days); the total number of laboratory studies ordered was similar (13.7 vs. 13.6); as was the number of irrelevant laboratory studies (1.3 vs. 2.3). When pts. in the control group, in whom a diagnosis had not been made within 48 hours, were contrasted with those in the computer group, it was found that the days to diagnosis was longer (4.48 vs. 3.40) and the number of irrelevant laboratory studies larger (3.57 vs. 1.50). Based on these observations, it would appear that in a univ. hospital setting, the routine use of computer assisted diagnosis will not decrease hospitalization costs but can be of benefit in those pts. in whom a diagnosis has not been established within 2 days of admission.
Characterization of molecular transport in artificial kidneys

Transport characterizations of artificial kidneys require the use of multiple marker molecules of various sizes, including small solutes, middle molecules, and albumin. Previous approaches for evaluating hemodialyzer transport performance are reviewed. New data obtained from in vitro experiments comparing 5 low molecular weight proteins of approximately the same molecular size as markers for middle molecule transport also are described. Sieving coefficients for marker low molecular weight proteins may vary substantially for a given artificial kidney membrane. Furthermore, sieving coefficients for marker proteins that do not absorb significantly to the membrane are comparable to those for polydisperse dextrans. These observations suggest that other protein properties besides molecular size are important determinants of protein sieving coefficients across artificial kidney membranes. We conclude that low molecular weight proteins can behave differently from one another and generalizations about artificial kidney membrane transport from data obtained on a single protein may be problematic, and that both low molecular weight proteins and polydisperse dextrans are useful markers of middle molecular transport across artificial kidney membranes.
Phase separation in ZnSe1—xSx and Zn1−yMgySe1−xSx layers grown by molecular beam epitaxy

Abstract The occurence of phase separation in (100) ZnSe 1− x S x and Zn 1− y Mg y Se 1− x S x layers grown by molecular beam epitaxy was found by transmission electron microscopy. The direction of the phase separation is [011], and the period of the composition modulation ranges from 300 to 500 A. X-ray microanlysis of the two regions resulting from the phase separation showed one to be sulfur-rich and the other sulfur-deficient. The one-to-one correspondence of the wavy surface structure and the composition modulation suggests that the phase separation occurs via nonuniform incorporation of sulfur atoms into the wavy growth plane of the epilayer.
Ethanol differentially modulates the expression and activity of cell cycle regulatory proteins in rat aortic smooth muscle cells.

Abstract The aim of this study was to determine the effect of ethanol on cell cycle events during the G 1 and S phases in cultured vascular smooth muscle cells (VSMC). Flow cytometric analysis for the DNA content in rat aortic VSMC indicated that following ethanol treatment, the cell population in the G 0 /G 1 phase increased; 57.8±1.6% vs. 72.3±1.2%, concomitant with a decrease in cells in the S phase; 12.7±1.4% vs. 3.67±0.6%, for control vs. ethanol, respectively. Western blot analysis on VSMC lysates demonstrated that ethanol (10–160 mmol/l) dose-dependently inhibited serum-induced retinoblastoma (pRb) hyperphosphorylation. While having no effect on Cdk2 protein expression, ethanol dose-dependently decreased (IC 50 ∼60 mmol/l) Cdk2 activity, assessed by histone H1 phosphorylation. Furthermore, ethanol induced the expression of the cyclin-dependent kinase (Cdk) inhibitor p21 waf1/cip1 , and inhibited the induction of cyclin A. These data demonstrate that modulation of the expression and activity of key cell cycle regulatory molecules may be a mechanism by which ethanol inhibits VSMC proliferation. These actions of ethanol may be relevant to its cardiovascular protective effect in vivo.
Former military officers from the Republic of Vietnam now living in the united states (US): exploring their perceptions of the US healthcare system.

Few studies have focused on perceptions of healthcare among Vietnamese who came to the United States (US) as refugees. A 48-item survey that included information on demographics, health status, and satisfaction with healthcare [including the Patient Satisfaction Questionnaire-18 (PSQ-18)] was sent to 49 former Vietnamese military officers, who are now living in the US, based on their current geographic residence. A total of 22 of 49 delivered questionnaires were completed and returned, yielding a response rate of 45%. The survey was sent in Vietnamese and English, and all except one was completed in Vietnamese. In response to “Language barriers have prevented me from accessing health care when I need it,” 77% of respondents acknowledged that this was “sometimes” the case even today. Most respondents otherwise viewed the healthcare system favorably, but cost concerns were an issue: 28% strongly agreed or agreed with the statement, “I have to pay for more of my medical care than I can afford.” In contrast, only 9% described that they would have strongly agreed or agreed to this statement upon first arriving to the US. Write-in comments revealed themes that centered on language barriers, favorable impressions of healthcare in the US, financial concerns, and patriotism towards the US. Further study of this aging population of Vietnamese Americans might help shed light on concerns faced by other refugee populations who have arrived more recently.
Molecular force field and structure of water: Recent microwave results

Abstract Recently, microwave studies of the rotational spectra of water and its various isotopic species have been reported. These studies provide rotational constants and among others the quartic distortion constants, which depend on the quadratic part of the vibrational potential function. These data are collected and discussed, and the molecular force field and structure of water is considered in light of this recent microwave data. The quartic distortion data gives force constants which are very reasonable considering the difficulties in the distortion analysis of these light molecules, where as many as 22 parameters are being evaluated to fit the observed spectrum. The infrared and microwave data are combined within the theoretical framework of the small oscillations model and the results compare favorably with the true harmonic force field. The infrared and microwave valence bond force constants of H 2 O are (mdyn/A): ƒ r =7.746, ƒ θ =0.700, ƒ rr =−0.093, ƒ rθ =0.379 The results further confirm the usefulness of rotation-vibration data in the determination of force constans, and show that even for water with extremely large anharmonicity effects, a very representative force field can be obtained by combining ground state infrared and microwave data. Various molecular structures have been evaluated, and the average structures in the ground vibrational state for H 2 O, D 2 O and T 2 O are found to be: 〈r〉 〈θ O-H=0.9724 A HOH=104.50° O-D=0.9687 A DOD=104.35° O-T=0.9671 A TOT=104.26° A one-dimensional approximation to the anharmonicity effects is applied to determine the equilibrium molecular structure of H 2 O from the average structure data. The result is as follows: r e =0.9587 A and θ e =103.9°
Pharmacologic IKK/NF-κB inhibition causes antigen presenting cells to undergo TNFα dependent ROS-mediated programmed cell death

Monocyte-derived antigen presenting cells (APC) are central mediators of the innate and adaptive immune response in inflammatory diseases. As such, APC are appropriate targets for therapeutic intervention to ameliorate certain diseases. APC differentiation, activation and functions are regulated by the NF-κB family of transcription factors. Herein, we examined the effect of NF-κB inhibition, via suppression of the IκB Kinase (IKK) complex, on APC function. Murine bone marrow-derived macrophages and dendritic cells (DC), as well as macrophage and DC lines, underwent rapid programmed cell death (PCD) after treatment with several IKK/NF-κB inhibitors through a TNFα-dependent mechanism. PCD was induced proximally by reactive oxygen species (ROS) formation, which causes a loss of mitochondrial membrane potential and activation of a caspase signaling cascade. NF-κB-inhibition-induced PCD of APC may be a key mechanism through which therapeutic targeting of NF-κB reduces inflammatory pathologies.
Engineering decentralized autonomic computing systems

A central challenge of autonomic computing is to enable large-scale computing systems--and the self-managing elements of which they are composed--to manage themselves in accordance with high-level objectives specified by people [2]. From the earliest days of autonomic computing, utility functions have been promoted by many authors [1, 4, 5, 6, 7, 9] as a powerful and principled means for representing high-level objectives. Once a utility function has been elicited, a combination of modeling, optimization, and (sometimes) learning techniques may be applied to this explicit mathematical representation of the objectives to determine an optimal solution for the control variables [3]. Since autonomic systems are by their nature large, complex, and decentralized [8], issues of decentralization deeply affect every phase of the utility function approach: elicitation, modeling, optimization, learning, and sensing and actuation.I will describe several autonomic systems that my colleagues and I have built at IBM Research, some of which have been commercialized. Each has employed a different mechanism for coordinating the actions of multiple auto-nomic managers to realize a system-wide objective, or a collection of individual objectives. Our most recent efforts have centered around reducing energy consumption in data centers, a problem that requires us to consider not just energy, but performance, availability, and other management issues as well. While from a purely academic perspective it is very tempting to formulate data center management as a single centralized optimization, the reality is that the scale and heterogeneity of the physical and IT infrastructure, the wide range of relevant spatial and temporal scales, and the mixture of several types of management concerns renders a centralized approach completely impractical. I will detail two distinct decentralized approaches that we have explored, one based on a federation of semi-autonomous managers with some centralized computation, and the other based on a more strongly decentralized market economy of resource consumers and producers.The ultimate grand unified theory of autonomic computing still eludes us, but I will offer insights gleaned from our experiences, and conclude with thoughts about the many remaining challenges of engineering decentralized autonomic computing systems.
TRANSPLANT NEPHECTOMY AFTER ALLOGRAFT FAILURE IS ASSOCIATED WITH ALLO-SENSITIZATION

Objectives To evaluate the effect of transplant nephrectomy (TN) on the percentage of panel reactive antibody (%PRA) and donor-specific antibody (DSA) levels in patients with renal allograft failure. Methods The records of patients with failed kidney transplants, who had undergone TN from 2000 to 2007, were reviewed. The pre- and post-TN serum samples were available for analysis from 31 patients. Human leukocyte antigen typing and the %PRA was measured in these patients using standard serologic techniques. The pre- and post-TN patient serum samples were evaluated for DSA levels using solid phase assays and single antigen beads. The pre- and post-TN measurements of the %PRA and DSA levels were compared using the Wilcoxon signed rank test, and the associated clinical variables were identified on multivariate regression analysis. Results The mean %PRA increased from 33.4 to 75.6 for class I antigens ( P P = .002) for class II antigens in patients before and after TN, respectively. This increase was associated with an increase in the mean human leukocyte antigen class I and class II DSA levels from 33 518 molecular equivalents of soluble fluorochrome (MESF) to 121 457 MESF ( P P P P = .02). Conclusions The results of the present study have confirmed that the %PRA increases after TN in patients with renal allograft failure, and sensitization occurs after TN, with an increase in DSA levels. Rejection episodes and early TN after graft failure might result in a greater degree of sensitization.
Controls, Health Assessment, and Condition Monitoring for Large, Reusable, Liquid Rocket Engines

The Space Shuttle Main Engine (SSME) represents the state-of-the-art for application of controls, health assessment, and condition monitoring technology to large, reusable, liquid rocket engines. Advances in the technologies that form engine control system along with experience gained in the development and deployment of the SSME point to opportunities for significant improvement in current and future engines. Identification of current engine shortcomings, of future engine requirements, and how control systems technology may be applied to improve life and performance while reducing life cycle costs provides motive for control systems improvement. This paper will derive research and development needs from a survey of liquid rocket control systems technology. The prospects for advanced liquid rocket control systems will be illuminated through discussion of current NASA programs and efforts. Applicable literature is reviewed.
Constraints on Porosity and Mass Loss in O-star Winds from the Modeling of X-Ray Emission Line Profile Shapes

We fit X-ray emission line profiles in high resolution XMM-Newton and Chandra grating spectra of the early O supergiant ζ Pup with models that include the effects of porosity in the stellar wind. We explore the effects of porosity due to both spherical and flattened clumps. We find that porosity models with flattened clumps oriented parallel to the photosphere provide poor fits to observed line shapes. However, porosity models with isotropic clumps can provide acceptable fits to observed line shapes, but only if the porosity effect is moderate. We quantify the degeneracy between porosity effects from isotropic clumps and the mass-loss rate inferred from the X-ray line shapes, and we show that only modest increases in the mass-loss rate (40%) are allowed if moderate porosity effects (h∞ R∗) are assumed to be important. Large porosity lengths, and thus strong porosity effects, are ruled out regardless of assumptions about clump shape. Thus, X-ray mass-loss rate estimates are relatively insensitive to both optically thin and optically thick clumping. This supports the use of X-ray spectroscopy as a mass-loss rate calibration for bright, nearby O stars.
Test Equating: What, Why, How?

The purpose of this paper is to introduce test equating, including its concept, needs, and methods, to the field of physical education and exercise science. Both traditional and item response theory (IRT) equating methods, along with data collection designs, were described in detail, and the advantages and disadvantages of these methods were also introduced. In addition, equating errors and evaluation criteria, sample size, and related computer programs were introduced. Using an existing data set of sit-up tests, a test-equating application was illustrated through a step-by-step example. As a result, two sit-up tests were equated onto a common scale, and equating accuracy was evaluated using both equating and cross-validation samples. Finally, benefits and potential applications of test equating in assessing motor functions and skills, as well as future research challenges, were described.
Hidden Markov Model: case study

This paper focuses on concept of Hidden Markov Model and its practical applications, with the detailed description of HMM based algorithms used in Named Entity Recognition. This paper is comprised of 9 sections. Section 1 provides brief introduction about Hidden Markov Model, Section 2 describes HMM in detail by making use of a practical problem, Section 3 includes diagrammatic representation of Hidden Markov Model, Section 4 describes the formal parameters used for representing HMM mathematically, Section 5 discusses the existing algorithm's of HMM, Section 6 tells the applications of HMM along with brief description of each application, Section 7 gives the description two Hidden Markov Model based algorithms used in Named Entity Recognition, Section 8 is the conclusion and Section 9 gives the overview of work to be carried in future.
Model Identification and Operating Load Characterization for a Small Horizontal Axis Wind Turbine Rotor Using Integrated Blade Sensors

One of the primary challenges in diagnostic health monitoring and control of wind turbines is compensating for the variable nature of wind loads. Given the sometimes large variations in wind speed, direction, and other operational variables (like wind shear), this paper proposes a data-driven, online rotor model identification approach. A 2 m diameter horizontal axis wind turbine rotor is first tested using experimental modal analysis techniques. Through the use of the Complex Mode Indication Function, the dominant natural frequencies and mode shapes of dynamic response of the rotor are estimated (including repeated and pseudo-repeated roots). The free dynamic response properties of the stationary rotor are compared to the forced response of the operational rotor while it is being subjected to wind and rotordynamic loads. It is demonstrated that both narrowband (rotordynamic) and broadband (wind driven) responses are amplified near resonant frequencies of the rotor. Blade loads in the flap direction of the rotor are also estimated through matrix inversion for a simulated set of rotor blade input forces and for the operational loading state of the wind turbine in a steady state condition. The analytical estimates are shown to be accurate at frequencies for which the ordinary coherence functions are near unity. The loads in operation are shown to be largest at points mid-way along the span of the blade and on one of the three blades suggesting this method could be used for usage monitoring. Based on these results, it is proposed that a measurement of upstream wind velocity will provide enhanced models for diagnostics and control by providing a leading indicator of disturbances in the loads.Copyright © 2010 by ASME
Management of acute gastroenteritis in children

Abstract Acute gastroenteritis remains one of the leading causes of death in the under 5-age group in the developing world. Over 2 million deaths per year occur in this group which is much improved compared to the 1980's when there were in the region of 4.5 million deaths per year. In the UK, gastrointestinal illness is rarely fatal but in 2007, it accounted for almost 32,000 admissions to hospital in the under 5-age group and so is a major economic burden. There is still a huge variation in practice and the NICE guidelines were published in April 2009 to develop a more unified approach to the management of acute gastroenteritis. In this article, I have tried to identify some of the key points from the NICE guidelines with regard to history taking, assessment of dehydration and fluid management. The NICE guidelines also looked at therapeutic options such as probiotics and antiemetics but were unable to find evidence to recommend them. More recent references were sought for further proof of efficacy of these agents. Adherence to guidelines for acute gastroenteritis in the past has been poor and variation related to institution. Data on adherence to the NICE guidelines is limited.
Anti-vamming trust enforcement in peer-to-peer VoIP networks

With the increasing popularity of Voice over IP (VoIP) the threat of "vamming" or VoIP spam calls is looming large over the telecom industry. This threat arises out of the "openness" of the IP-based network such as the Internet, which enables anyone to join the network without proving reasonable trustworthiness. Although this problem could be solved satisfactorily in managed networks, it proves to be a nightmare in distributed, unmanaged peer-to-peer (p2p) networks. A possible approach to solve this problem, at least to a certain extent, is to associate some level of trust with each p2p entity. In this paper, we propose a trust enforcement framework consisting of computation and memory bound functions that associate trust implicitly to the p2p VoIP entities. Based on this trust, one can judiciously decide whether a call from a p2p VoIP entity could be accepted or not, thus implementing a preliminary screening mechanism for malicious callers.
Identification of a U8 snoRNA-specific Binding Protein

Eukaryotic nucleoli contain a large and diverse population of small nucleolar ribonucleoprotein particles (snoRNPs) that play diverse and essential roles in ribosome biogenesis. We previously demonstrated that U8 snoRNP is essential for processing of both 5.8 and 28 S rRNA. The RNA component of the U8 RNP particle is necessary but not sufficient for processing. Using an electrophoretic mobility sift assay, we enriched for U8-specific binding proteins fromXenopus ovary extracts. UV cross-linking reactions with partially purified fractions implicated a 29-kDa protein directly binding to U8 RNA. This protein interacted specifically and with high affinity with U8 snoRNA; it did not bind other snoRNAs and is probably not a common component of all snoRNPs. This is the first report of a protein component specific to an snoRNP essential for processing of the large ribosomal subunit in vertebrates.
The Effect of Delayed Incentives on Supply Chain Profits and Consumer Surplus

We examine the use of consumer cash mail-in rebates offered by a manufacturer in a Stackelberg game where the manufacturer is the leader and the retailer is the follower. Our analysis indicates that rebates are profitable for manufacturers if consumers are inconsistent in the sense that their rebate valuation when they make purchase decisions is independent of their redemption probabilities when they make redemption decisions. If the manufacturer keeps the wholesale price unchanged, then the rebate increases the retailer's profit by a larger amount than the increase in the manufacturer's profit. If the manufacturer jointly optimizes the wholesale price and rebate, then the increase in the manufacturer's profit is twice the increase in the retailer's profit. The retailer responds to rebates by increasing the retail price, which increases the margin paid by consumers who do not redeem the rebate. On average, consumer surplus decreases when it is optimal for manufacturers to offer rebates. We suggest incentive schemes that make it worthwhile for retailers to limit the price increase. In these incentive schemes, the manufacturer imposes a negative relationship between the rebate value and the retail price. We show that such incentives increase supply chain profits.
Fractionation of the stable isotopes of oxygen and carbon in carbon dioxide during the reaction of calcite with phosphoric acid as a function of temperature and technique

The fractionation factor (α) between the 18O/16O ratio in calcite and CO2 gas produced as a result of reaction with phosphoric acid has been determined as a function of temperature for two of the most widely used variations of the dissolution technique, reaction in a sealed vessel and reaction in an acid bath. Although these methods show approximately the same relationship between temperature and α, they are offset from one another by between 0.2 and 0.4% over the temperature range 25–90°C. There appears to be no temperature- or technique-dependent fractionation on carbon over the range of temperatures examined in this study. The difference between these two methods arises from three main processes: (1) isotopic exchange between the CO2, the phosphate polymers in the acid and water produced in the reaction; (2) dissolution of CO2 in the acid; and (3) incomplete removal of CO2 during the extraction process. Of these two methods the “acid bath” method probably provides the most accurate isotopic composition of the calcite. As a result of the fact the original fractionation factors were determined using the “sealed vessel” method, we have calculated our temperature [T (K)] - dependent fractionation factor (αT) taking into account the difference between the two methods at 25°C. For the “sealed vessel” method: (a) αT= [5.60 (± 0.33) × 102] T−2 + 1.003943 (± 0.000067). For the “common acid bath” technique: (b) αT = [5.25 (± 0.08) × 102] T −2 + 1.003970 (± 0.000034).
The Social Stakes of Interoperability

While recognizing the risks posed by and hurdles to implementing fully interoperable systems, Palfrey and Gasser argue that the potential benefits are well worth pursuing.
Solving vertical and horizontal well hydraulics problems analytically in Cartesian coordinates with vertical and horizontal anisotropies

Summary A new generalized three-dimensional analytical solution is developed for a partially-penetrating vertical rectangular parallelepiped well screen in a confined aquifer by solving the three-dimensional transient ground water flow differential equation in x – y – z Cartesian coordinates system for drawdown by taking into account the three principal hydraulic conductivities ( K x , K y , and K z ) along the x – y – z coordinate directions. The fully penetrating screen case becomes equivalent to the single vertical fracture case of Gringarten and Ramey (1973) . It is shown that the new solution and Gringarten and Ramey solution (1973) match very well. Similarly, it is shown that this new solution for a horizontally tiny fully penetrating parallelepiped rectangular parallelepiped screen case match very well with Theis (1935) solution. Moreover, it is also shown that the horizontally tiny partially-penetrating parallelepiped rectangular well screen case of this new solution match very well with Hantush (1964) solution. This new analytical solution can also cover a partially-penetrating horizontal well by representing its screen interval with vertically tiny rectangular parallelepiped. Also the solution takes into account both the vertical anisotropy ( a zx = K z / K x ) as well as the horizontal anisotropy ( a yx = K y / K x ) and has potential application areas to analyze pumping test drawdown data from partially-penetrating vertical and horizontal wells by representing them as tiny rectangular parallelepiped as well as line sources. The solution has also potential application areas for a partially-penetrating parallelepiped rectangular vertical fracture. With this new solution, the horizontal anisotropy ( a yx = K y / K x ) in addition to the vertical anisotropy ( a zx = K z / K x ) can also be determined using observed drawdown data. Most importantly, with this solution, to the knowledge of the author, it has been shown the first time in the literature that some well-known well hydraulics problems can also be solved in Cartesian coordinates with some additional advantages other than the conventional cylindrical coordinates method.
Outcome of different reperfusion strategies in patients with former contraindications to thrombolytic therapy: A comparison of primary angioplasty and tissue plasminogen activator

High-risk patients have been excluded from most thrombolytic trials because of concern over hemorrhagic complications or lack of efficacy. However, based on several recent studies suggesting that patients with relative thrombolytic contraindications may also benefit from reperfusion, recommendations have been made to broadly expand the eligibility criteria for thrombolytic therapy, despite higher absolute complication rates. Primary percutaneous transluminal coronary angioplasty (PTCA) may be an attractive alternative for patients presenting at appropriately equipped hospitals who would otherwise remain at high risk after thrombolytic therapy. In the Primary Angioplasty in Myocardial Infarction (PAMI) trial, 395 patients with acute myocardial infarction were randomized to tissue plasminogen activator (t-PA) or primary PTCA. Conditions were present In 151 patients (38%) which formerly would have contraindicated thrombolytic therapy (age >70 yr, symptom duration >4 hr, or prior bypass surgery). In-hospitality was 4.3-fold higher in patients with former thrombolytic contraindications compared to lytic-eligible patients (8.6% vs. 2.0%, P = .002). Lytic-eligible patients treated with t-PA and PTCA had similar in-hospital mortality (1.7% vs. 2.4%, P = NS). In contrast, both in-hospital (2.9% vs. 13.2%, P = .025) and 6-mo mortality (2.9% vs. 15.7%, P = .009) were significantly reduced in patients with former thrombolytic contraindications treated by primary PTCA compared to t-PA. By logistic regression analysis, treatment by PTCA rather than t-PA was the strongest predictor of survival in patients with former thrombolytic contraindications. We conclude that patients with conditions formerly contraindicating thrombolytic therapy constitute a high-risk group with significant morbidity and mortality after lytic reperfusion. Our data suggest that patients with former contraindications to thrombolytic therapy may benefit by preferential management with primary PTCA without antecedent thrombolysis. © 1996 Wiley-Liss, Inc.
The green flash.

It was luck I was there on a Sunday when Mr. H.’s son (the drunk, also my clinic patient) shouted at a nurse that his father was dead. I went to see (the nurse didn’t). H. was inanimate as a wind-up toy run-out in mid-stride, his foot sticking out from under the sheet barely warm and weirdly doughy. The son came in then (I think). There were other patients in the room. I was looking at H.’s face and saw a blue light evaporate off it. It was like a flame in bright sun, there for a definite second, then you can’t see it and want to pass your hand through to see if it’s hot. No one else reacted as if they’d seen. The only lovely thing about him had been the sea-blue eyes. That was the light? How corny! I thought, under-reacting (as usual), to the disturbing/moving supernatural sight of— what, the ascent of his soul? Defaulting, I said nothing until, weeks later, a woman I was charming said that once, in a trying time, she’d walked outside and found herself suddenly bathed in a shaft of light that warmed her soul and God etc. Maybe a cloud moved? I asked. Or maybe as the brain drops to lower valence its energy passes out through the eyeholes, lighting up the iris? I’d believe that, having stood at the Pacific watching the sun dissolve into the water and waiting for the green flash that’s supposed to be seeable. That I made much of— hooted when I maybe saw it, felt enraptured sort of, and told everyone, though it was subtle at best. Did she have a bigger vision or just a better attitude? I wasn’t looking for anything—and didn’t find it.
Quantitative CBV measurement from static T1 changes in tissue and correction for intravascular water exchange.

The steady-state (SS) approach has been proposed to measure quantitative cerebral blood volume (CBV). However, it is known that the CBV value in SS (CBVSS) is subject to error resulting from the effects of water diffusion from the intra- to extravascular space. CBVSS measurements were simulated in both fast- and no-water-exchange limits, and compared with measured CBVSS values to determine which limiting case is appropriate. Twenty-eight patients were scanned with a segmented Look-Locker echo-planar imaging (LL-EPI) sequence before and after the injection of 0.1 mmol/kg of a T1-shortening contrast agent. Signal changes and T1 values of brain parenchyma and the blood pool were measured pre- and postcontrast. These signal changes and T1 values, in combination with the simulated results, were used to estimate water-exchange rates. We found that the intra- to extravascular water-exchange rates in white matter (WM) and gray matter (GM) were 0.9 and 1.6 s–1, respectively. With these water-exchange rates, the fast-water-exchange limit of the CBV values showed good agreement with the simulation (r = 0.86 in WM, and 0.78 in GM). The CBV values with the correction for water-exchange effects were recalculated as 2.73 ± 0.44 and 5.81 ± 1.12 of quantitative cerebral blood water volume (%) in WM and GM, respectively. Magn Reson Med, 2006. © 2006 Wiley-Liss, Inc.
Histologic features of atherosclerosis and hypertension from autopsies of young individuals in a defined geographic population: the Bogalusa Heart Study

Histologic features of arterial intima have been quantified at autopsy by morphometric methods in 66 individuals aged 6-30 years, in whom cardiovascular risk factors had been measured prospectively prior to death. Measures of serum cholesterol were found to correlate significantly with the extent of foam cell infiltration seen in paraffin sections and the intensity of lipid staining in frozen sections of the abdominal and thoracic segments of the aorta. A similar correlation in the coronary arteries was weak and inconsistent. Blood pressure was significantly correlated with foam cells and stainable lipid in the abdominal but not the thoracic segment of the aorta. A similar correlation in the coronary arteries was significant, but only in males, and most consistently in the black males. Intimal thickness of the coronary arteries showed sporadic and weak correlations with blood pressure and lipids; however, a strong and consistent correlation was seen between coronary intimal thickness and hyalinization of renal arterioles. With many statistical tests carried out on a limited data set, some particular details are, no doubt, spuriously significant; however, some persistent patterns are beginning to emerge. The reproducible findings support the concept that prospective measurements of blood pressure and serum lipids are associated with a degree of structural characteristics present in children and young adults. Moreover, the observed structural characteristics, specifically the deposition of lipids in the intima of coronary arteries and aorta, are likely to reflect variations in the rates of progression of atherosclerosis.
Numerical Study of Pressure Fluctuations due to a Mach 6 Turbulent Boundary Layer

Direct numerical simulations (DNS) are used to examine the pressure fluctuations generated by a Mach 6 turbulent boundary layer with nominal freestream Mach number of 6 and Reynolds number of Re(sub t) approx. =. 464. The emphasis is on comparing the primarily vortical pressure signal at the wall with the acoustic freestream signal under higher Mach number conditions. Moreover, the Mach-number dependence of pressure signals is demonstrated by comparing the current results with those of a supersonic boundary layer at Mach 2.5 and Re(sub t) approx. = 510. It is found that the freestream pressure intensity exhibits a strong Mach number dependence, irrespective of whether it is normalized by the mean wall shear stress or by the mean pressure, with the normalized fluctuation amplitude being significantly larger for the Mach 6 case. Spectral analysis shows that both the wall and freestream pressure fluctuations of the Mach 6 boundary layer have enhanced energy content at high frequencies, with the peak of the premultiplied frequency spectrum of freestream pressure fluctuations being at a frequency of omega(delta)/U(sub infinity) approx. = 3.1, which is more than twice the corresponding frequency in the Mach 2.5 case. The space-time correlations indicate that the pressure-carrying eddies for the higher Mach number case are of smaller size, less elongated in the spanwise direction, and convect with higher convection speeds relative to the Mach 2.5 case. The demonstrated Mach-number dependence of the pressure field, including radiation intensity, directionality, and convection speed, is consistent with the trend exhibited in experimental data and can be qualitatively explained by the notion of "eddy Mach wave" radiation.