cssi/SciSciGPT-SciSciNet huggingface dataset:
Structure of Arnold tongues and the f(α) spectrum for period doubling: Experimental results

We study experimentally the detailed structure of resonances in forced Rayleigh-B\'enard convection in mercury. The resonances appear as Arnold tongues in the phase diagram of the system. We follow a particular tongue beyond the critical line where tongues start to overlap and find a period-doubling curve stretching over the entire tongue. Above this line there is a symmetry breaking with period-doubling cascades at the two sides of the tongue. We also observe a multitude of other periodic windows in this regime together with hysteresis effects caused by overlap of other tongues. We follow one of the period-doubling cascades and study the full scaling structure of the attractor at the onset of chaos by means of an f(\ensuremath{\alpha}) spectrum of scaling indices. The experimental spectrum is, within error, the same as the universal spectrum calculated theoretically.
Why voters fail information tests: Can the hurdles be overcome?

Renowned public opinion scholars have provided solid evidence that average voters generally make rational political choices. If this is correct, why have most recent studies that measured voter knowledge and learning of current information yielded appallingly low scores? The essay sheds light on this intriguing puzzle by showing that current tests of voter knowledge, which focus on rote memorization of names and factual details, underrate voters' election IQ. Moreover, knowledge scores could rise sharply if the mass media information supply were better tailored to the average voter's information needs. Major problems in the election information supply are an overemphasis on isolated facts and inappropriate message framing when it comes to the substance and format of news stories. Furthermore, many election stories are repetitive and uninteresting to voters. The general public's response to the “new” media presentations, which became popular during the 1992 presidential campaign, shows that it is possible ...
Radionuclide analysis of ejection time, peak ejection rate, and time to peak ejection rate: response to supine bicycle exercise in normal subjects and in patients with coronary heart disease

Using equilibrium radionuclide angiography, we evaluated the ejection time (ET), peak ejection rate (PER), and time to peak ejection rate (TTp) at test and during supine bicycle exercise in 39 subjects, divided into three groups: group 1 = 13 normal subjects; group 2 = 10 patients with a previous infarction (MI); and group 3 = 16 patients with coronary disease without a previous MI. Normal subjects had greater ejection fractions and PERs than the other two groups at rest or peak exercise (p less than 0.05). PER was no more useful than ejection fraction in identifying cardiac dysfunction at either rest or exercise. The time of its occurrence varied with the group studied, and was slightly but significantly later in systole in groups 2 and 3 when compared to normals (p less than 0.05), though substantial overlap between groups occurred. During exercise, absolute ET shortened in all groups, but actually increased as a function of the R-R interval. The time to peak ejection rate (normalized for the R-R interval) was greater in the noninfarct group (group 3) patients (p less than 0.05) when compared to the group 1 or group 2 individuals at peak exercise. In conclusion, equilibrium radionuclide angiography is a useful technique for the quantification and characterization of events during systole, and is capable of providing information on the timing of events during ejection. Tardokinesis, or the delay of ventricular ejection, is not seen in the response of global indices of left ventricular function to exercise stress. While global early systolic indexes may not detect regional dyssynchrony, their timing during stress may occasionally aid in discerning the presence of cardiac dysfunction.
Clinicoradiological score for predicting the risk of strangulated small bowel obstruction

BACKGROUND: Intestinal ischaemia as a result of small bowel obstruction (SBO) requires prompt recognition and early intervention. A clinicoradiological score was sought to predict the risk of ischaemia in patients with SBO. METHODS: A clinico-radiological protocol for the assessment of patients presenting with SBO was used. A logistic regression model was applied to identify determinant variables and construct a clinical score that would predict ischaemia requiring resection. RESULTS: Of 233 consecutive patients with SBO, 138 required laparotomy of whom 45 underwent intestinal resection. In multivariable analysis, six variables correlated with small bowel resection and were given one point each towards the clinical score: history of pain lasting 4 days or more, guarding, C-reactive protein level at least 75 mg/l, leucocyte count 10 x 10(9)/l or greater, free intraperitoneal fluid volume at least 500 ml on computed tomography (CT) and reduction of CT small bowel wall contrast enhancement. The risk of intestinal ischaemia was 6 per cent in patients with a score of 1 or less, whereas 21 of 29 patients with a score of 3 or more underwent small bowel resection. A positive score of 3 or more had a sensitivity of 67.7 per cent and specificity 90.8 per cent; the area under the receiver operating characteristic curve was 0.87 (95 per cent confidence interval 0.79 to 0.95). CONCLUSION: By combining clinical, laboratory and radiological parameters, the clinical score allowed early identification of strangulated SBO.
Interplanetary dust between 1 and 5 AU

Analyses of data from the Meteoroid Detection Experiment (MDE) and the Imaging Photopolarimeter (IPP) aboard Pioneer 10 and 11 have led to contradictory conclusions. While the MDE indicates a significant particle environment in the outer solar system (out to at least 5 AU), the IPP sees no zodiacal light (therefore implying no small particles) past 3.3 AU. These two results are reconciled by noting that the spectral index p (relating particle radius and particle concentration) is not a constant in the solar system but changes from less than 2 near 1 AU to more than 2.5 at 5 AU for particles in the range of 10 microns.
Asymptotic stability properties of linear Volterra integrodifferential equations.

The Liapunov stability properties of solution to a certain system of Volterra integrodifferential equations is studied. Various types of Liapunov stability are defined; the definitions are natural extensions of the corresponding notions for ordinary differential equations. Necessary and sufficient conditions, in general, for uniform stability and uniform asymptotic stability are obtained in the form of a theorem. Connections between the stability of the system studied and the stability properties of a related Volterra integrodifferential equation with infinite memory are examined. Sufficient conditions in order that the trivial solution to the system studied be stable, uniformly stable, asymptotically stable, or uniformly asymptotically stable are derived.
Monte Carlo simulation of retinal light absorption by infants

Retinal damage can occur in normal ambient lighting conditions. Infants are particularly vulnerable to retinal damage, and thousands of preterm infants sustain vision damage each year. The size of the ocular fundus affects retinal light absorption, but there is a lack of understanding of this effect for infants. In this work, retinal light absorption is simulated for different ocular fundus sizes, wavelengths, and pigment concentrations by using the Monte Carlo method. The results indicate that the neural retina light absorption per volume for infants can be two or more times that for adults.
Aryl-Containing Chelates and Amine Debenzylation to Afford 1,3-Di-2-pyridyl-2-azaallyl (smif): Structures of {κ-C,N,Npy2-(2-pyridylmethyl)2N(CH2(4-tBu-phenyl-2-yl))}FeBr and (smif)CrN(TMS)2

Aryl-bromide ligand precursors have been prepared with the potential to afford tetradentate chelates (2-pyridylmethyl)3−xN(CH2-2-Aryl)x (x = 1, 2) containing metal-aryl linkages that promise to impart stronger fields about first row transition metals. Oxidative addition to Ni(COD)2 afforded two diamagnetic Ni(II) complexes, {κ-C,N,Npy-(2-pyridylmethyl)N(CH2(4-tBu-phenyl-2-yl))(CH2(4-tBu-phenyl-2-Br))}NiBr (1-Ni) and {(κ-C,N,Npy2-(2-pyridylmethyl)2N(CH2(4-tBu-phenyl-2-yl))}NiBr (2-Ni) in 96% and 67% yield, respectively. Extending these synthetic efforts to iron provided {κ-C,N,Npy2-(2-pyridylmethyl)2N(CH2(4-tBu-phenyl-2-yl))}FeBr (2-Fe, X-ray) in 91% yield via reduction of an adduct, {κ-N,Npy2-(2-pyridylmethyl)2N(CH2(4-tBu-phenyl-2-Br))}FeBr2 (3-Fe). 5-Coordinate 2-Fe possessed a pseudo-tbp structure, and SQUID magnetometry showed it to be S = 2 with significant zero field splitting (ZFS). 2-Fe was initially prepared via oxidative addition to Fe{N(TMS)2}2(THF) upon disproportionation to “Fe(0)” and 2 Fe{N(...
A critical evaluation of ultrasonics in dentistry

Abstract Some dentists who have employed the ultrasonic method of preparing cavities and patients who have experienced its use express favorable comment. Pulps of vital permanent teeth appear to be unaffected, but operations on children's teeth should not be attempted until future research indicates no ill effects. The original cost of the unit, its size, and the fact that it is strictly an adjunct to the present armamentarium of the dentist will probably be a deterrent to its acceptance. Cleaning and attaching the tips, tuning the machine, and applying the correct load while operating are discouraging aspects to the beginner. The ultrasonic method of cutting carious or sound enamel, carious or sound dentine, and certain types of restorative materials does not approach the effectiveness that can be demonstrated with the ultra high-speed rotational instruments.
Applying efficiency measurement techniques to the measurement of productivity change

Deterministic frontier analysis (DFA), stochastic frontier analysis (SFA), and data envelopment analysis (DEA) are alternative analytical techniques designed to measure the efficiency of producers. All three techniques were originally developed within a cross-sectional context, in which the objective is to compare the efficiencies of producers. More recently all three techniques have been extended for use in a panel data context. In the latter context it is possible to measure productivity change, and to decompose measured productivity change into its sources, one of which is efficiency change. However when efficiency measurement techniques, particularly SFA, have been applied to panel data, it has infrequently been made clear what the objective of the analysis is: the measurement of efficiency, which may vary through time as well as across producers, or the measurement and decomposition of productivity change. In this paper I explore the use of each technique in a panel data context. I find DFA and DEA to have achieved a more satisfactory reorientation toward productivity measurement than SFA has.
Big Data and the Invisible, Social Dimensions of Science

In this paper, I describe the challenges of using Big Data approaches in assessing security threats from the life sciences.
A haystack full of needles: Scholarly access challenges in museum video archives

Editor's Summary Museums are increasingly turning to video as an easy and inexpensive method of documentation and of developing valuable primary resources, but numerous barriers interfere with scholars' use of the materials. While technical difficulties are diminishing and attitudes and traditions are shifting, issues of intellectual property rights and information retrieval remain. Publishing video content online first demands a comprehensive rights assessment and clearing. Even more challenging is dealing with information retrieval in time-based and visual-aural resources, which makes finding a specific bit of data in mounds of footage a daunting task. Transcription enables free text search but is costly, time consuming and not entirely effective, delivering only the verbal aspect of original content. Descriptive metadata can be tied to time codes, adding broad or granular indexing to support navigation and retrieval, but the same drawbacks apply. Possible solutions include crowdsourcing, software tools and collaborative initiatives, applying metadata standards yet to be established and adopted.
Furans in foods

Furan represent a class of compounds that have been reported in a wide variety of foods. Normally, they result from thermal decomposition reactions, and, as such, are important in foods. They also possess unique sensory properties and, thus, can significantly contribute to food flavor. This review shall attempt to summarize their food occurrences, organoleptic properties, and formation pathways.
Detection by low temperature photoluminescence of oxygen recoils in “through-oxide” arsenic implanted silicon☆

Abstract The technique of low-temperature photoluminescence is used to study the damage induced by arsenic implantations through SiO2 layers. The presence of an oxygen dependent damage center in only the “through-oxide” implanted samples and in none of the samples implanted into bare surfaces is interpreted as indicating the presence of oxygen recoils from the oxide. It is also seen that the in-diffusion of oxygen during thermal growth of the SiO2 is insufficient to produce detectable oxygen-dependent luminescence after irradiation.
Numerical experimentation on spherically symmetric one-dimensional magnetohydrodynamic (MHD) wave propagation

Radial propagation of one-dimensional magnetohydrodynamic (MHD) waves are analyzed numerically on the basis of the Implicit-Continuous-Fluid-Eulerian (ICE) scheme. Accuracy of the numerical method and other properties are tested through the study of MHD wave propagation. The three different modes of MHD waves (i.e., fast-, slow- and Alfven (transverse) mode) are generated by applying physically consistent boundary perturbations derived from MHD compatibility relations. It is shown that the resulting flow following these waves depend upon the relative configurations of the initial magnetic field and boundary perturbations.
Carbohydrate metabolism studies after one year of using an oral contraceptive containing gestodene and ethinyl estradiol.

Abstract The objective of the study is to evaluate the effects of a gestodene-containing oral contraceptive on carbohydrate metabolism. The design of the study is prospective. The setting is at University of South Florida Outpatient Unit. The patients consisted of twenty-three normal women desiring contraception. Serum glucose and insulin levels were measured during a three-hour glucose tolerance test at control time and after one year of drug use. Results: All of the one-year glucose values were significantly elevated as well as the fasting and three-hour insulin values. These changes were mostly confined to women over 26 years of age and not in the younger 18 to 23 year olds. An oral contraceptive containing 75μg of gestodene and 30 μg of ethinyl estradiol can significantly alter carbohydrate metabolism in older women.
Can Service Learning Reinforce Social and Cultural Bias? Exploring a Popular Model of Family Involvement for Early Childhood Teacher Candidates

Service learning is often used in teacher education as a way to challenge social bias and provide teacher candidates with skills needed to work in partnership with diverse families. Although some literature suggests that service learning could reinforce cultural bias, there is little documentation. In a study of 21 early childhood teacher certification candidates, engaged in service learning experience with families living in deep poverty, 16 candidates appeared to confront their own biases and construct practical theories of poverty that were more complex than their original concepts. However, five candidates appeared to avoid confronting their own biases. Of those five, three appeared to have biases confirmed. Those three candidates were quite different from one another in age, experience, and attitude toward the project. More research is needed to examine the relationship between candidates' understanding of social relationships and their approach to service learning experiences.
Critical review of international standards for respiratory protective equipment - II. Gas and vapor removal efficiency and fit testing.

The purpose of a Respiratory Protective Equipment (R.P.E.) standard is to assure that a minimum level of performance is reached by the respirator. Standards from a number of countries and standards organizations require that certain specifications are met in construction and that respirators be evaluated by specific performance tests. This is the second of three critical review papers related to respirator standards. We here summarize in tabular form, compare and critically review how the different countries or standards organizations test respirators designed for protection against gases and vapors for leakage due to improper fitting of the respirator facepiece and gas and vapor removal efficiency of the cartridge/canister. Two general aspects as they relate to removal capacity testing are discussed. The first issue deals with the selection of test gases and vapors that best represent the sorptive behavior of a class or group of compounds. The second issue deals with the extrapolation of laboratory testing under rigidly specified conditions to conditions of actual use. Fit testing varies from country to country. The fit testing conditions specified in the various standards are summarized along with a discussion of test material selection, the test panel selection, and the range of controlled test activities.
Endoscopic evaluation of chronic human immunodeficiency virus-related diarrhea: is colonoscopy superior to flexible sigmoidoscopy?

In patients with chronic human immuno-deficiency virus (HIV)-related diarrhea undergoing lower endoscopy, the decision to perform flexible sigmoidoscopy or colonoscopy is controversial. The purpose of this study is twofold: 1) to evaluate the diagnostic yield of colonoscopy in a large group of patients with chronic HIV-related diarrhea and negative stool studies, and 2) to determine whether colonoscopy is superior to flexible sigmoidoscopy in this setting. Methods: All HIV-infected patients with chronic diarrhea who were referred for diagnostic colonoscopy at Bellevue Hospital Center between January 1992 and December 1996 were identified. Patient charts, pathology reports, and endoscopy records were reviewed. Results: During the 5-yr study period, 317 consecutive patients with chronic unexplained diarrhea undergoing colonoscopy were identified. A potential cause of diarrhea was found in 116 patients (36.6%). Cytomegalovirus was the most common pathogen detected (24%). The yield of colonoscopy was significantly higher in patients with a CD4 count of <100 cells/mm3 than in those with higher CD4 counts (44.8% vs 6.4, p < 0.0001). Thirty percent of pathogens and 75% of lymphomas were identified only on biopsies taken from the proximal colon, well beyond the reach of the flexible sigmoidoscope. Importantly, 94% of the pathogens that were found only in the proximal colon were organisms for which effective therapy is currently available. Conclusions: Colonoscopy is superior to flexible sigmoidoscopy in HIV-infected patients with chronic unexplained diarrhea. If flexible sigmoidoscopy had been performed instead of colonoscopy, 30% of pathogens would have been missed and 75% of lymphomas would have escaped detection.
Conference paper selectivity and impact

STUDYING THE METADATA of the ACM Digital Library (http://www.acm.org/dl), we found that papers in low-acceptance-rate conferences have higher impact than those in high-acceptance-rate conferences within ACM, where impact is measured by the number of citations received. We also found that highly selective conferences—those that accept 30% or less of submissions—are cited at a rate comparable to or greater than ACM Transactions and journals.
Effects of optical pulse shape on THz wave generation in laser induced gas plasma

Effects of the optical pulse shape on THz wave generation from laser induced plasma was investigated using optical pulse shaping technique. Laser induced plasma is particularly suitable media for THz pulse shaping because of a large freedom of controllable Fourier components over 10 THz. Narrow band THz wave generation was demonstrated using a square wave phase pattern added to optical pulses for a wide tuning range from 2.5–7.5 THz. A combination of pulse shaping technique and adaptive control technique was used to optimize the terahertz wave generation from gas plasma, and 20–25% of power enhancement was achieved. Finally, two pulse sequences were used to generate THz wave form gas plasma, and the effect of the pre-excitation of gas molecule was investigated.
Mechanically evoked reflex electrogenic chloride secretion in rat distal colon is triggered by endogenous nucleotides acting at P2Y1, P2Y2, and P2Y4 receptors.

Mechanical activation of the mucosal lining of the colon by brush stroking elicits an intestinal neural reflex and an increase in short circuit current (Isc) indicative of electrogenic chloride ion transport. We tested whether endogenous nucleotides are physiologic regulators of mucosal reflexes that control ion transport. The brush stroking-evoked Isc response in mucosa and submucosa preparations (M-SMP) of rat colon was reduced by the P2Y1 receptor (R) antagonist 2′deoxy-N6-methyl adenosine 3′,5′-diphosphate diammonium salt (MRS 2179) and further blocked by tetrodotoxin (TTX). M-SMP Isc responses to serosal application of the P2Y1 R agonist 2-methylthioadenosine-diphosphate (2MeSADP) or the P2Y2/P2Y4 R agonist 5′uridine-triphosphate (UTP) were reduced but not abolished by TTX. The potency profile of nucleotides for increasing Isc was 5′adenosine-triphosphate (ATP; effective concentration at half maximal response [EC50] 0.65 × 104 M) ≅ UTP (EC50 1.0 × 10−4 M) ≅ 2MeSADP (EC50 = 1.60 × 10−4 M). Mucosal touch and distention-induced Ca2+ transients in submucous neurons were reduced by apyrase and prevented by blocking the P2Y1 R with MRS 2179 and TTX; denervation of the mucosa. It did not occur by touching a ganglion directly. 2MeSADP Ca2+ responses occurred in subsets of neurons with or without substance P (SP) responses. The potency profile of nucleotides on the neural Ca2+ response was 2MeSADP (5 × 10−7 M) > UTP (6 × 10−6 M) > ATP (9 × 10−5 M). The expression of P2Y R immunoreactivity (ir) in nerve cell bodies was in the order of P2Y1 R > P2Y4 R ≫ P2Y2 R. P2Y1R ir occurred in the cell somas of more than 90% of neuronal nitric oxide synthase, vasoactive intestinal peptide (VIP), calretinin, or neuropeptide Y (NPY)–ir neurons, 78% of somatostatin neurons, but not in calbindin or SP neurons. P2Y2 R ir was expressed in a minority of SP, VIP, NPY, vesicular acetylcholine transporter, and calcitonin gene-related peptide–ir varicose fibers (5–20%) and those surrounding calbindin (5–20%) neurons. P2Y4 ir occurred mainly in the cell somas of 93% of NPY neurons. Reverse transcriptase polymerase chain reaction of the submucosa demonstrated mRNA for P2Y1R, P2Y2, P2Y4, P2Y6, and P2Y12 Rs. Expression of P2Y1, P2Y2, and P2Y4 protein was confirmed by western blots. In conclusion, endogenous nucleotides acting at P2YRs transduce mechanically evoked reflex chloride ion transport in rat distal colon. Nucleotides evoke reflexes by acting primarily at postsynaptic P2Y1 Rs and P2Y4 R on VIP+/NPY+ secretomotor neurons, at P2Y2 Rs on no more than 2% of VIP+ secretomotor neurons, and 2Y2 Rs mainly of extrinsic varicose fibers surrounding putative intrinsic primary afferent and secretomotor neurons. During mucosal mechanical reflexes, it is postulated that P2Y1 R, P2Y2 R, and P2Y4 R are activated by endogenous ATP, UTP, and 5′uridine-diphosphate. J. Comp. Neurol. 469:16–36, 2004. © 2003 Wiley-Liss, Inc.
Forty-eight percent of dentate patients receive dental radiographs per year

Original Article Gilbert GH, Reems RA, Shelton BJ. Incidence of dental radiographic procedures during a 48-month population-based study of dentate adults. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2003;96:243-9. Level of Evidence 2c Question What is the incidence of various common dental radiographic procedures, and the interval between these procedures, in a community-based sample of patients? Source of Funding National Institutes of Health. Type of Study/Design Prospective descriptive study of dental radiographic use by a cohort of patients
Comparison of the background, needs, and expectations for genetic counseling of adults with experience with Down syndrome, Marfan syndrome, and neurofibromatosis†

We describe an analysis of the responses of 605 adults with experience with Down syndrome, Marfan syndrome, or neurofibromatosis (NF) to the BNE Scale, a scale specifically designed to assess the background, needs, and expectations (BNE) of genetic counseling patients. Significant group differences were found. Specifically, the respondents in the Down syndrome group reported more favorable beliefs about the condition and the availability of social support than the respondents in the other groups. Respondents in the NF group reported more unsureness about their condition and a greater need for genetic information than members of the other groups. Notably, having positive feelings about the condition was negatively correlated with support group interest for respondents of the Marfan syndrome group (r = −0.159, P < 0.01). Having an affected child was associated with interest in health provider input (t = −3.4; P = 0.001) and the desire to talk about psychosocial issues (t = −2.9; P = 0.004). However, previous experience with genetic counseling was not found to affect BNE. These results support the usefulness of the BNE Scale to compare the BNE of patient groups, as well as provide important insight into the BNE of individuals seeking counseling about Down syndrome, Marfan syndrome, and NF. © 2011 Wiley-Liss, Inc.
Spontaneous domain nucleation under in-plane fields in ultrathin films with Dzyaloshinskii-Moriya interaction

In this paper, we show that applying a hard axis field reduces the energy barrier for the spontaneous formation of a multi-domain state in magnetic ultrathin films sandwiched between a heavy metal and an oxide. This provides a simple technique to generate a metastable multi-domain state in magnetic films where the ground state is uniform. This approach could be particularly interesting in materials with strong Dzyaloshinskii-Moriya interaction as a means to realize metastable chiral textures.
Color-difference matches.

For a given pair of colors (i) and (j) of the same brightness, an observer generates in a visual colorimeter a third color (i,j) such that he perceives all three colors to be equally bright and the three differences between them to be of equal size. In color-perception space, the three colors form an equilateral triangle on a surface of constant brightness. The precision of setting the third color (i,j) can be characterized by ellipsoids in color space. Three observers take part in the experiment and over 30 pairs of colors (i) and (j) are presented to them. In approximately 50% of the cases a given observer will agree, within the uncertainty of his own data, with the mean color (i,j) of another observer. The corresponding color-difference-matching ellipses (cross sections of the ellipsoids) of the different observers show a satisfactory correlation. The experimental data presented may be used to test color-difference formulas and the chromaticity spacing in UCS diagrams.
The impact of microbial symbionts on host plant utilization by herbivorous insects

Herbivory, defined as feeding on live plant tissues, is characteristic of highly successful and diverse groups of insects and represents an evolutionarily derived mode of feeding. Plants present various nutritional and defensive barriers against herbivory; nevertheless, insects have evolved a diverse array of mechanisms that enable them to feed and develop on live plant tissues. For decades, it has been suggested that insect-associated microbes may facilitate host plant use, and new molecular methodologies offer the possibility to elucidate such roles. Based on genomic data, specialized feeding on phloem and xylem sap is highly dependent on nutrient provisioning by intracellular symbionts, as exemplified by Buchnera in aphids, although it is unclear whether such symbionts play a substantive role in host plant specificity of their hosts. Microorganisms present in the gut or outside the insect body could provide more functions including digestion of plant polymers and detoxification of plant-produced toxins. However, the extent of such contributions to insect herbivory remains unclear. We propose that the potential functions of microbial symbionts in facilitating or restricting the use of host plants are constrained by their location (intracellular, gut or environmental), and by the fidelity of their associations with insect host lineages. Studies in the next decade, using molecular methods from environmental microbiology and genomics, will provide a more comprehensive picture of the role of microbial symbionts in insect herbivory.
Plowing Friction in Dry and Lubricated Metal Sliding

Demonstration experimentale de la creation de sillons dans des conditions de glissement a sec ou avec lubrification, et obtention d'expressions analytiques pour le coefficient de frottement du a ce phenomene. Mise en evidence du fait que le coefficient de frottement theorique est une fonction du caractere aigu des asperites dures, des conditions de «frottement» interfaciales, et de la forme de la zone plastique. Comparaison entre resultats theoriques et experimentaux, et proposition d'un modele different dans le cas du glissement a sec donnant un bon accord avec les resultats experimentaux
Population Shape Regression From Random Design Data

Regression analysis is a powerful tool for the study of changes in a dependent variable as a function of an independent regressor variable, and in particular it is applicable to the study of anatomical growth and shape change. When the underlying process can be modeled by parameters in a Euclidean space, classical regression techniques are applicable and have been studied extensively. However, recent work suggests that attempts to describe anatomical shapes using flat Euclidean spaces undermines our ability to represent natural biological variability. In this paper we develop a method for regression analysis of general, manifold-valued data. Specifically, we extend Nadaraya-Watson kernel regression by recasting the regression problem in terms of Frechet expectation. Although this method is quite general, our driving problem is the study anatomical shape change as a function of age from random design image data. We demonstrate our method by analyzing shape change in the brain from a random design dataset of MR images of 89 healthy adults ranging in age from 22 to 79 years. To study the small scale changes in anatomy, we use the infinite dimensional manifold of diffeomorphic transformations, with an associated metric. We regress a representative anatomical shape, as a function of age, from this population.
Community- and landscape-level responses of reptiles and small mammals to feral-horse grazing in the Great Basin

Abstract We investigated species- and community-level responses of squamate reptiles and granivorous small mammals to feral-horse grazing in two elevational strata across nine mountain ranges of the western Great Basin, USA. Although mammal species richness did not differ between horse-occupied and horse-removed sites, occupied sites possessed less community completeness (biotic integrity) and 1.1–7.4 times greater deer mice (Peromyscus maniculatus) than removed sites. In opposite fashion, horse-removed sites possessed greater reptile species richness and tended towards greater abundance for seven of nine species, yet unequal species pools across sites dictated that community completeness did not differ statistically between horse-removed and -occupied sites.
Interaction fidelity in two-component signaling

Two component signal transduction systems and phosphorelays have been adapted and amplified by bacteria to respond to a multitude of environmental, metabolic and cell cycle signals while maintaining essentially identical structures for the domains responsible for recognition and phosphotransfer between the sensor histidine kinase and the response regulator. Co-crystal structures of these domains have revealed the variable residues at the interaction surface of the two components responsible for interaction specificity in signal transfer. This information has formed the basis for the development and validation of statistical methods to identify interaction residues and surfaces from compiled databases of interacting proteins and holds forth the promise of determining structures of multi-protein complexes and signaling networks.
Can Brief Interventions by Hand Surgeons Influence Medical Students Toward a Career in Hand Surgery

Purpose In 2004, the American Society for Surgery of the Hand and the American Association for Hand Surgery formed a joint task force to deal with the difficulty of promoting hand surgery as a career choice to medical students. The purpose of this study was to use a previously validated format to expose medical students to a brief intervention early in their medical education that might influence their perceptions of hand surgery as a career choice. Methods First-year medical students were asked to rank 11 items on a Likert scale from 1 (not important) to 5 (very important) regarding their beliefs about hand surgery as a career before and after a brief 1-hour presentation by a hand surgeon. Additional information about career choice and prior exposure to hand surgery was obtained before the intervention, and student interest in hand surgery was measured after the intervention. Results Of 110 first-year medical students, 72 (65%) students completed both the prelecture survey and the postlecture survey. Of the 72 students with matched responses, 8 (11%) ranked surgery as their first career choice, whereas 13 (18%) ranked a surgical subspecialty as their first choice. Thirty-nine (54%) students stated that the lecture raised their interest in hand surgery as a possible career, and 36 (50%) were interested in doing an elective in it while in medical school. Nonparametric tests showed improvement in knowledge after the lecture for length of training, technical aspects, intellectual challenge, and fellowship requirements. Conclusions A positive information-providing encounter with a hand surgeon may favorably influence the perceptions of first-year medical students toward hand surgery.
Mitochondrial Ribosomal RNA (rRNA) Methyltransferase Family Members Are Positioned to Modify Nascent rRNA in Foci near the Mitochondrial DNA Nucleoid

We have identified RNMTL1, MRM1, and MRM2 (FtsJ2) as members of the RNA methyltransferase family that may be responsible for the three known 2′-O-ribose modifications of the 16 S rRNA core of the large mitochondrial ribosome subunit. These proteins are confined to foci located in the vicinity of mtDNA nucleoids. They show distinct patterns of association with mtDNA nucleoids and/or mitochondrial ribosomes in cell fractionation studies. We focused on the role of the least studied protein in this set, RNMTL1, to show that this protein interacts with the large ribosomal subunit as well as with a series of non-ribosomal proteins that may be involved in coupling of the rate of rRNA transcription and ribosome assembly in mitochondria. siRNA-directed silencing of RNMTL1 resulted in a significant inhibition of translation on mitochondrial ribosomes. Our results are consistent with a role for RNMTL1 in methylation of G1370 of human 16 S rRNA. Background: Mitochondrial rRNAs contain site-specific modifications, including methylated residues, but few of the enzymes responsible for these modifications have been found. Results: RNMTL1, MRM1, and MRM2 are methyltransferase family members found associated with the mtDNA nucleoid and with the large ribosomal subunit. Conclusion: The association of putative RNA-modifying enzymes with nucleoids and ribosomes supports the model that assembly of mitochondrial ribosomes begins while rRNA transcription continues. Significance: This work advances understanding of the assembly of mitochondrial ribosomes necessary for biosynthesis of the respiratory chain.
Cofermentation of glucose, xylose, and arabinose by mixed cultures of two genetically engineered Zymomonas mobilis strains.

Cofermentation of xylose and arabinose, in addition to glucose, is critical for complete bioconversion of lignocellulosic biomass, such as agricultural residues and herbaceous energy crops, to ethanol. A factorial design experiment was used to evaluate the cofermentation of glucose, xylose, and arabinose with mixed cultures of two genetically engineered Zymomonas mobilis strains (one ferments xylose and the other arabinose). The pH range studied was 5.0-6.0, and the temperature range was 30-37°C. The individual sugar concentrations used were 30 g/L glucose, 30 g/L xylose, and 20 g/L arabinose. The optimal cofermentation conditions obtained by data analysis, using Design Expert software, were pH 5.85 and temperature 31.5°C. The cofermentation process yield at optimal conditions was 72.5% of theoritical maximum. The results showed that neither the arabinose strain nor arabinose affected the performance of the xylose strain; however, both xylose strain and xylose had a significant effect on the performance of the arabinose strain. Although cofermentation of all three sugars is achieved by the mixed cultures, there is a preferential order of sugar utilization. Glucose is used rapidly, then xylose, followed by arabinose.
Report of ganglion cyst in the anterior cruciate ligament of a 6-year-old child☆

article i nfo Background: Intra-articular ganglion cysts of the knee are extremely rare within the pediatric population. To our knowledge, only seven case reports have been published in the medical literature identifying pediatric patients with intra-articular cysts of the anterior cruciate ligament (ACL). Intra-articular cysts of the knee are a rare cause of knee discomfort and mechanical symptoms such as locking of the knee. To our knowledge, up until now the youngest patient reported in the medical literature with an intra-articular ganglion cyst of the ACL was a 7-year-old boy. Case report: We describe a 6-year-old boy who presented with a unilateral intra-articular ganglion cyst of the ACL in the right knee. In addition to the diagnostic work-up of radiographs and MRI, the cyst was successfully treated with arthroscopic resection and debridement to decompress the cyst. Clinical relevance: We provide a review of the proposed pathogenesis, diagnostic modalities, differential diag- nosis, treatment options, and complications of treatment for intra-articular cysts of the ACL. Level of evidence: Level V, case report.
Aspects of personality associated with irregular sleep habits in young adults

Studied psychological correlates of irregularity in chronic sleep routines. The California Psychological Inventory (CPI) and Cornell Medical Index (CMI) were administered to two groups of 18 male university students who were categorized as either irregular sleepers or control Ss. The control group was composed of persons who habitually slept from 12-8:00 A.M. Irregular sleepers were defined as those whose retiring and awakening times continuously varied by about 2 to 4 hours. Control Ss scored significantly higher than the irregular group on the CPI scales of Do (dominance), Sy (sociability), Sa (self-acceptance), Sc (self-control), Ac (achievement via conformance), and Ie (intellectual efficiency), but lower on the Fx (flexibility) scale. There were no significant differences between the groups in scores on the CMI or average sleep length recorded over 2 weeks. The present findings indicate that in young adults, personality functioning is related more closely to the regularity of nocturnal sleep routines than to differences in chronic sleep duration. It is postulated that stable or irregular sleeping patterns are largely dependent factors not only of the psychological characteristics that distinguished the groups, but as yet unspecified constitutional and sociocultural antecedents of the human sleep response.
The Criterion Validity of Omitted Client Information as an Indicator of Suicide Risk: A Partial Replication

The purpose of the research reported in this article was to replicate findings reported by Nugent and Williams-Hayes that suggested that there is a relationship between missing information on demog...
Hepatic vein Doppler studies: variability of flow pattern in normal children.

Background: Loss of triphasicity of hepatic venous flow on Doppler US has been correlated with hepatic parenchymal disease such as cirrhosis and graft rejection in adults. Objective: To document physiological variations of hepatic vein (HV) flow patterns in normal children of different age groups, the influence of age, sex, body position, site of measurements within a given vein, exercise and food intake. Also, to document the reproducibility of the Doppler US findings in the three major HVs, in order to establish the limits of normal flow against which to assess liver pathology giving rise to abnormal flow pattern. Materials and methods: Thirty-two children, divided into four age groups: less than 1 year, 1–5 years, 5–12 years and 12–16 years, with four boys and four girls in each group, underwent repeated US examinations of their HVs. The HV flow pattern was recorded as triphasic = 4, diphasic = 3, monophasic = 2 or uninterpretable = 1 at three sites in each vein: peripheral, middle and proximal in the supine position in the fasting state. One recording was then obtained in the midportion of each vein in the sitting position, another one after exercise, then after a meal and lastly one by a second radiologist. Statistical analysis of variance was done of each variable alone, in combination two by two and three by three. Results: HV flow pattern was different from one vein to another in the majority of the children, the right HV having the least triphasic flow. Age was highly significant, the HV flow being less triphasic in young children. Sex and position were significant for the right HV only, which was the most difficult to examine. Exercise and food intake did not change the triphasicity of flow. Conclusions: HV flow pattern differs with age and can differ from one HV to another within an apparently normal liver. Interpretation is generally reproducible from one radiologist to another. A difference of sex, seen mostly for the right HV, may be due to unfavourable Doppler angle and difficulty of interpretation. The site of measurements within a given vein, body position, exercise and food intake do not influence the triphasicity of HV flow.
Computational electrochemistry: aqueous one-electron oxidation potentials for substituted anilines

Semiempirical molecular orbital theory and density functional theory are used to compute one-electron oxidation potentials for aniline and a set of 21 mono- and di-substituted anilines in aqueous solution. Linear relationships between theoretical predictions and experiment are constructed and provide mean unsigned errors as low as 0.02 V over a training set of 13 anilines; the error rises to 0.09 V over a test set of eight additional anilines. A good correlation is also found between oxidation potential and a simple computed property, namely the energy of the highest occupied molecular orbital for neutral anilines in aqueous solution. For the particular case of the substituted anilines, a strong correlation between oxidation potential and pKa is found, and a still stronger correlation between oxidation potential and physical organic descriptors for aromatic substituents is also found, albeit over a reduced data set.
The three-dimensional structure of an arachidonic acid 15-lipoxygenase

In mammals, the hydroperoxidation of arachidonic acid by lipoxygenases leads to the formation of leukotrienes and lipoxins, compounds that mediate inflammatory responses. Lipoxygenases are dioxygenases that contain a nonheme iron and are present in many animal cells. Soybean lipoxygenase-1 is a single-chain, 839-residue protein closely related to mammalian lipoxygenases. The structure of soybean lipoxygenase-1 solved to 2.6 angstrom resolution shows that the enzyme has two domains: a 146-residue beta barrel and a 693-residue helical bundle. The iron atom is in the center of the larger domain and is coordinated by three histidines and the COO- of the carboxyl terminus. The coordination geometry is nonregular and appears to be a distorted octahedron in which two adjacent positions are not occupied by ligands. Two cavities, in the shapes of a bent cylinder and a frustum, connect the unoccupied positions to the surface of the enzyme. The iron, with two adjacent and unoccupied positions, is poised to interact with the 1,4-diene system of the substrate and with molecular oxygen during catalysis.
Flowfield measurements and flame stabilization of a premixed reacting jet in vitiated crossflow

Abstract Flow field characteristics and flame stabilization behavior are studied experimentally for a premixed ethylene-air jet injected into a vitiated hot crossflow composed of products of fuel lean combustion. The jet was injected perpendicular to the crossflow in a rectangular duct with jet-to-crossflow momentum flux ratios (J) ranging from 5 to 23. High speed chemiluminescence imaging was used to capture unsteady and average behavior of the reacting jet in cross flow (JICF). Time resolved particle image velocimetry measurements were taken to characterize the flow field of non-reacting and reacting jets injected into the vitiated crossflow. Power law correlations for non-reacting JICF trajectory from the literature were found to over-predict the experimental non-reacting jet trajectories due to the greater degree of confinement present in the experimental configuration compared to previous studies. New jet trajectory correlations were developed, to fit the experimental non-reacting and reacting trajectory data, including the effects of confinement. In the case of reacting JICF, the flame was found to have two separate stabilization points, one on either side of the jet centerline. The windward flame stabilization was characterized by three distinct behaviors: complete flame attachment, an unsteady lifted flame, and windward blowoff. The average windward flame edge was lifted for all momentum ratios tested and the liftoff height showed strong dependence on J. The leeward flame consistently stabilized above the jet exit. Experimental strain rates, flame propagation speeds, and ignition delay times were found at the instantaneous flame stabilization locations. Consistencies between strain rate and ignition delay time at the windward flame edge for varying J suggest auto-ignition dominated flame stabilization behavior.
On NSF “open questions,” some external properties of the brain as a learning system and an architecture for autonomous learning

The 2007 NSF workshop report titled “Future Challenges for the Science and Engineering of Learning” (http://www.cnl.salk.edu/Media/NSFWorkshopReport.v4.pdf) raises lots of questions about how the brain works and learns and they have important implications for the development of autonomous adaptive systems. The report also defines some general characteristics of biological learners that, in essence, impose constraints on any kind of learning systems that we call brain-like. This paper examines these general characteristics of biological learners, as defined in the NSF report, and relates them to a set of properties of brain-like learning defined as early as 1994 [12]. The paper also shows how a control theoretic architecture for autonomous learning systems mitigates or resolves many of the “open questions” posed by the NSF report. It also provides some recent evidence from neuroscience on the nature of learning in biological systems that support the notion that the brain has a control theoretic architecture.