bluuebunny/crossref_metadata_2025 huggingface dataset:
The Relationship Between Sexual Activity and Urinary Incontinence in Older Women
Authors: Tannenbaum Cara , Corcos Jacques , Assalian Pierre
Published: July 2006

OBJECTIVES: To determine whether continence status is associated with sexual activity in older women.

DESIGN: Cross‐sectional postal survey.

SETTING: Random selection from a list of respondents to a Canada Post survey.

PARTICIPANTS: Community‐dwelling women aged 55 to 95.

MEASUREMENTS: The International Consultation on Incontinence Questionnaire Short Form measured the presence, severity, and type of incontinence. Sexual activity and marital status were assessed using single close‐ended questions. The Medical Outcomes Study 12‐item Short‐Form Health Survey was used to query physical and mental health status.

RESULTS: Data from 2,361 women (mean age 71) were available for analysis. Thirty‐nine percent reported urinary incontinence (UI), and 27% were sexually active. UI was associated with sexual activity in crude logistic analyses (odds ratio (OR)=0.82, 95% confidence interval (CI)=0.68–0.98) but not in multivariate models adjusted for physical and mental health. Marital status and age were the strongest predictors of sexual activity (OR 8.94, 95% CI=6.89–11.60 for married women; OR=3.09, 95% CI=2.57–3.73 for age ≤70), with significant relationships also observed with physical and mental health (OR=1.04, 95% CI=1.03–1.04 and OR=1.02, 95% CI=1.01–1.04, respectively). Frequency of UI was not related to being sexually active, although greater amounts of urine loss, stress incontinence, and nocturnal incontinence were independently associated with sexual activity (OR=0.53, 95% CI=0.33–0.85; OR=1.40 95% CI=1.01–1.94; and OR=0.24, 95% CI=0.10–0.61, respectively).

CONCLUSION: Many older women remain sexually active as they age regardless of continence status. Caution should be exercised in interpreting intervention studies aimed at improving sexual function in incontinent older women if marital status and physical and mental health are not considered.
Prevalence of Tuberculous Infection and Active Tuberculosis in Old Age Homes in Hong Kong
Authors: Chan‐Yeung Moira , Chan Felix H. W. , Cheung Amy H. K. , Dai David L. K. , Chu Leung‐Wing , Lam Wah‐Kit , Leung Chi‐Chiu , Kam Kai‐Man , Tam Cheuk‐Ming
Published: July 2006

OBJECTIVES: To assess the prevalence of tuberculous infection and active tuberculosis (TB) in old age homes in Hong Kong and to determine whether there is institutional transmission in these homes.

DESIGN: Cross‐sectional.

SETTING: Old age homes.

PARTICIPANTS: Total of 2,243 residents, representing 84.6% of all residents in 15 old age homes; 1,698 were women, and 545 were men, with an average age of 82.

MEASUREMENTS: All residents had a questionnaire‐based interview, medical record review, two‐stage tuberculin testing using two units purified protein derivative‐RT23, and a chest x‐ray. Those with radiological abnormalities had sputum examined for acid‐fast bacilli.

RESULTS: The estimated prevalence rate of active TB in this population was 669 per 100,000, significantly higher in men than in women (1,101 per 100,000 vs 530 per 100,000). The proportion with positive tuberculin reactivity (≥10 mm induration) after two‐stage testing was 68.6%, significantly higher in men than in women. There was no evidence of active transmission of disease in these old age homes, with restriction fragment length polymorphism (RFLP) analysis performed on five cases of active pulmonary TB in the home with the highest rate of TB showing unique RFLP patterns.

CONCLUSION: The rate of active TB and TB infection in old age homes in Hong Kong is still high. Because treatment for latent TB carries a high risk for liver dysfunction in this population, clinicians and other healthcare workers need a high index of suspicion and to diagnose and treat this disease as early as possible to prevent transmission.
Translating Evidence‐Based Falls Prevention into Clinical Practice in Nursing Facilities: Results and Lessons from a Quality Improvement Collaborative
Authors: Colón‐Emeric Cathleen , Schenck Anna , Gorospe Joel , McArdle Jill , Dobson Lee , DePorter Cindy , McConnell Eleanor
Published: July 2006

OBJECTIVES: To describe the changes in process of care before and after an evidence‐based fall reduction quality improvement collaborative in nursing facilities.

DESIGN: Natural experiment with nonparticipating facilities serving as controls.

SETTING: Community nursing homes.

PARTICIPANTS: Thirty‐six participating and 353 nonparticipating nursing facilities in North Carolina.

INTERVENTION: Two in‐person learning sessions, monthly teleconferences, and an e‐mail discussion list over 9 months. The change package emphasized screening, labeling, and risk‐factor reduction.

MEASUREMENTS: Compliance was measured using facility self‐report and chart abstraction (n=832) before and after the intervention. Fall rates as measured using the Minimum Data Set (MDS) were compared with those of nonparticipating facilities as an exploratory outcome.

RESULTS: Self‐reported compliance with screening, labeling, and risk‐factor reduction approached 100%. Chart abstraction revealed only modest improvements in screening (51% to 68%, P<.05), risk‐factor reduction (4% to 7%, P=.30), and medication assessment (2% to 6%, P=.34). There was a significant increase in vitamin D prescriptions (40% to 48%, P=.03) and decrease in sedative‐hypnotics (19% to 12%, P=.04) but no change in benzodiazepine, neuroleptic, or calcium use. No significant changes in proportions of fallers or fall rates were observed according to chart abstraction (28.6% to 37.5%, P=.17), MDS (18.2% to 15.4%, P=.56), or self‐report (6.1–5.6 falls/1,000 bed days, P=.31).

CONCLUSON: Multiple‐risk‐factor reduction tasks are infrequently implemented, whereas screening tasks appear more easily modifiable in a real‐world setting. Substantial differences between self‐reported practice and medical record documentation require that additional data sources be used to assess the change‐in‐care processes resulting from quality improvement programs. Interventions to improve interdisciplinary collaboration need to be developed.
Expression and function of Noxo1γ, an alternative splicing form of the NADPH oxidase organizer 1
Authors: Takeya Ryu , Taura Masahiko , Yamasaki Tomoko , Naito Seiji , Sumimoto Hideki
Published: July 2006

Activation of the superoxide‐producing NADPH oxidase Nox1 requires both the organizer protein Noxo1 and the activator protein Noxa1. Here we describe an alternative splicing form of Noxo1, Noxo1γ, which is expressed in the testis and fetal brain. The Noxo1γ protein contains an additional five amino acids in the N‐terminal PX domain, a phosphoinositide‐binding module; the domain plays an essential role in supporting superoxide production by NADPH oxidase (Nox) family oxidases including Nox1, gp91phox/Nox2, and Nox3, as shown in this study. The PX domain isolated from Noxo1γ shows a lower affinity for phosphoinositides than that from the classical splicing form Noxo1β. Consistent with this, in resting cells, Noxo1γ is poorly localized to the membrane, and thus less effective in activating Nox1 than Noxo1β, which is constitutively present at the membrane. On the other hand, cell stimulation with phorbol 12‐myristate 13‐acetate (PMA), an activator of Nox1–3, facilitates membrane translocation of Noxo1γ; as a result, Noxo1γ is equivalent to Noxo1β in Nox1 activation in PMA‐stimulated cells. The effect of the five‐amino‐acid insertion in the Noxo1 PX domain appears to depend on the type of Nox; in activation of gp91phox/Nox2, Noxo1γ is less active than Noxo1β even in the presence of PMA, whereas Noxo1γ and Noxo1β support the superoxide‐producing activity of Nox3 to the same extent in a manner independent of cell stimulation.
The role of electrostatic interactions in the antitumor activity of dimeric RNases
Authors: Notomista Eugenio , Mancheño José Miguel , Crescenzi Orlando , Di Donato Alberto , Gavilanes José , D'Alessio Giuseppe
Published: July 2006

The cytotoxic action of some ribonucleases homologous to bovine pancreatic RNase A, the superfamily prototype, has interested and intrigued investigators. Their ribonucleolytic activity is essential for their cytotoxic action, and their target RNA is in the cytosol. It has been proposed that the cytosolic RNase inhibitor (cRI) plays a major role in determining the ability of an RNase to be cytotoxic. However, to interact with cRI RNases must reach the cytosol, and cross intracellular membranes. To investigate the interactions of cytotoxic RNases with membranes, cytotoxic dimeric RNases resistant, or considered to be resistant to cRI, were assayed for their effects on negatively charged membranes. Furthermore, we analyzed the electrostatic interaction energy of the RNases complexed in silico with a model membrane. The results of this study suggest that close correlations can be recognized between the cytotoxic action of a dimeric RNase and its ability to complex and destabilize negatively charged membranes.
Interferon‐α induces sensitization of cells to inhibition of protein synthesis by tumour necrosis factor‐related apoptosis‐inducing ligand
Authors: Jeffrey Ian W. , Elia Androulla , Bornes Stéphanie , Tilleray Vivienne J. , Gengatharan Karthiga , Clemens Michael J.
Published: July 2006

Tumour cells are often sensitized by interferons to the effects of tumour necrosis factor‐α‐related apoptosis‐inducing ligand (TRAIL). We have demonstrated previously that TRAIL has an inhibitory effect on protein synthesis [Jeffrey IW, Bushell M, Tilleray VJ, Morley S & Clemens MJ (2002) Cancer Res62, 2272–2280] and we have therefore examined the consequences of prior interferon‐α treatment for the sensitivity of translation to inhibition by TRAIL. Interferon treatment alone has only a minor effect on protein synthesis but it sensitizes both MCF‐7 cells and HeLa cells to the downregulation of translation by TRAIL. The inhibition of translation is characterized by increased phosphorylation of the α subunit of eukaryotic initiation factor eIF2 and dephosphorylation of the eIF4E‐binding protein 4E‐BP1. Both of these effects, as well as the decrease in overall protein synthesis, require caspase‐8 activity, although they precede overt apoptosis by several hours. Interferon‐α enhances the level and/or the extent of activation of caspase‐8 by TRAIL, thus providing a likely explanation for the sensitization of cells to the inhibition of translation.
Role of asparagine 1134 in glucosidic bond and transglycosylation specificity of reuteransucrase from Lactobacillus reuteri 121
Authors: Kralj Slavko , Eeuwema Wieger , Eckhardt Tom H. , Dijkhuizen Lubbert
Published: July 2006

Glucansucrases from lactic acid bacteria convert sucrose into various α‐glucans that differ greatly with respect to the glucosidic bonds present (e.g. dextran, mutan, alternan and reuteran). This study aimed to identify the structural features of the reuteransucrase from Lactobacillus reuteri 121 (GTFA) that determine its reaction specificity. We here report a detailed mutational analysis of a conserved region immediately next to the catalytic Asp1133 (putative transition‐state stabilizing) residue in GTFA. The data show that Asn1134 is the main determinant of glucosidic bond product specificity in this reuteransucrase. Furthermore, mutations at this position greatly influenced the hydrolysis/transglycosylation ratio. Changes in this amino acid expands the range of glucan and gluco‐oligosaccharide products synthesized from sucrose by mutant GTFA enzymes.
Adenine nucleotides inhibit proliferation of the human lung adenocarcinoma cell line LXF‐289 by activation of nuclear factor κB1 and mitogen‐activated protein kinase pathways
Authors: Schäfer Rainer , Hartig Roland , Sedehizade Fariba , Welte Tobias , Reiser Georg
Published: July 2006

Extracellular nucleotides have a profound role in the regulation of the proliferation of diseased tissue. We studied how extracellular nucleotides regulate the proliferation of LXF‐289 cells, the adenocarcinoma‐derived cell line from human lung bronchial tumor. ATP and ADP strongly inhibited LXF‐289 cell proliferation. The nucleotide potency profile was ATP = ADP = ATPγS > > UTP, UDP, whereas α,β‐methylene‐ATP, β,γ‐methylene‐ATP, 2′,3′‐O‐(4‐benzoylbenzoyl)‐ATP, AMP and UMP were inactive. The nucleotide potency profile and the total blockade of the ATP‐mediated inhibitory effect by the phospholipase C inhibitor U‐73122 clearly show that P2Y receptors, but not P2X receptors, control LXF‐289 cell proliferation. Treatment of proliferating LXF‐289 cells with 100 µm ATP or ADP induced significant reduction of cell number and massive accumulation of cells in the S phase. Arrest in S phase is also indicated by the enhancement of the antiproliferative effect of ATP by coapplication of the cytostatic drugs cisplatin, paclitaxel and etoposide. Inhibition of LXF‐289 cell proliferation by ATP was completely reversed by inhibitors of extracellular signal related kinase‐activating kinase/extracellular signal related kinase 1/2 (PD98059, U0126), p38 mitogen‐activated protein kinase (SB203508), phosphatidylinositol‐3‐kinase (wortmannin), and nuclear factor κB1 (SN50). Western blot analysis revealed transient activation of p38 mitogen‐activated protein kinase, extracellular signal‐related kinase 1/2, and nuclear factor κB1 and possibly new formation of p50 from its precursor p105. ATP‐induced attenuation of LXF‐289 cell proliferation was accompanied by transient translocation of p50 nuclear factor κB1 and extracellular signal‐related kinase 1/2 to the nucleus in a similar time period. In summary, inhibition of LXF‐289 cell proliferation is mediated via P2Y receptors by activation of multiple mitogen‐activated protein kinase pathways and nuclear factor κB1, arresting the cells in the S phase.
Functional association of the AAA complex and the peroxisomal importomer
Authors: Rosenkranz Katja , Birschmann Ingvild , Grunau Silke , Girzalsky Wolfgang , Kunau Wolf‐H. , Erdmann Ralf
Published: July 2006

The AAA peroxins, Pex1p and Pex6p, are components of the peroxisomal protein import machinery required for the relocation of the import receptor Pex5p from the peroxisomal membrane to the cytosol. We demonstrate that Pex1p and Pex6p form a stable complex in the cytosol, which associates at the peroxisomal membrane with their membrane anchor Pex15p and the peroxisomal importomer. The interconnection of Pex15p with the components of the importomer was independent of Pex1p and Pex6p, indicating that Pex15p is an incorporated component of the assembly. Further evidence suggests that the AAA peroxins shuttle between cytosol and peroxisome with proper binding of the Pex15p–AAA complex to the importomer and release of the AAA peroxins from the peroxisomal membrane depending on an operative peroxisomal protein import mechanism. Pex4p‐deficient cells exhibit a wild‐type‐like assembly of the importomer, which differs in that it is associated with increased amounts of Pex1p and Pex6p, in agreement with a function for Pex4p in the release of AAA peroxins from the peroxisomal membrane.
Spatially Disaggregated Modelling of Voting Outcomes and Socio‐Economic Characteristics at the 2001 Australian Federal Election
Authors: STIMSON ROBERT , McCREA ROD , SHYY TUNG‐KAI
Published: July 2006

This study uses GIS and spatial modelling to relate voting outcomes at the 2001 federal election for polling booths across Australia with the socio‐economic characteristics of polling booth catchment areas. The data and analysis used are more detailed and comprehensive than previous studies. It is conducted at a fine level of spatial disaggregation across the whole nation to examine voting outcomes for both major and minor political parties. Because the aim of the paper is to distinguish voting outcomes between political parties rather than to predict voting outcomes for particular political parties, a discriminant analysis is used rather than regression analysis. The statistical discriminant analysis identifies two main socio‐economic dimensions that are able to predict polling booth outcomes with a relatively high degree of accuracy. That analysis shows how, at the 2001 federal election, the middle ground, in terms of socio‐economic characteristics, was being claimed by the Liberal Party, Country Liberal Party, The Greens, and, to a lesser extent, by the Australian Labor Party. However, the Australian Democrats, National Party and One Nation had more distinctive constituencies, with the National Party and One Nation Party competing for areas with similar socio‐economic characteristics. Using GIS mapping tools, examples of actual and predicted polling booth voting outcomes are given, along with selected socio‐economic characteristics of booth catchments.
Valuing the Arts: Theorising and Realising Cultural Capital in an Australian City
Authors: JOHNSON LOUISE
Published: July 2006

For those who make and admire artistic works, there is no question of their value. However, for others interested in economic development, the value of the arts is often more tangential, contested and questionable. While the post‐modern world of consumption and spectacle suggests to some academics and governments that the arts and cultural industries are the way of the future, others remain sceptical about their social and economic value. This is a theoretical as well as a practical issue this paper explores by offering a reconceptualisation of Pierre Bourdieu's concept of cultural capital as a way of re‐assessing the value of the arts. The paper then applies this framework to quantify and qualify the value of the arts in one regional city in Australia – Geelong in Victoria – focusing on the work of two artists. The aim is to describe the interconnected processes by which the arts generate cultural capital in the form of confidence, image, individual well‐being, social cohesion and economic viability. The analysis also highlights the ongoing power relations which prescribe artistic production, circulation and valuation. The implications of such a rethinking and application go well beyond one city and region to other places grappling with the relationship between artistic production and urban well being. By focusing on the broad‐ranging process by which artistic value is created for individuals, groups, professionals, communities and governments, a model becomes available for other places to use in realising their cultural capital.
Machismo sustains health and illness beliefs of Mexican American men
Authors: Sobralske Mary
Published: July 2006

Purpose: To inform nurse practitioners (NPs) about Mexican American men’s health and illness beliefs and the ways in which these are influenced by their masculine identity and how they view themselves as men in their culture.

Data sources: The data sources used were based on a selected review of the literature about Mexican American men’s health and illness beliefs and the concept of machismo. Several studies, including the author’s study on Mexican American men’s healthcare‐seeking beliefs and behaviors and experience in providing primary health care to men across cultures, contributed new data.

Conclusions: The meaning of manhood in the Mexican American culture is critical in understanding how men perceive health and illness and what they do when they are ill. Machismo enhances men’s awareness of their health because they have to be healthy to be good fathers, husbands, brothers, sons, workers, and community members. Pain and disability are motivating factors in finding ways to regain their health.

Implications for Practice: Men’s health beliefs across cultures need further investigation by nurse researchers and NPs. How culture influences healthcare delivery to men should be better understood. If NPs are aware of men’s views on masculinity, they are better prepared to understand and assist men in becoming more aware of their health status and to seek health care when appropriate.
Determining predictors of delayed recovery and the need for transitional cardiac rehabilitation after cardiac surgery
Authors: Anderson Jane A. , Petersen Nancy J. , Kistner Clara , Soltero Ernesto R. , Willson Pamela
Published: July 2006

Purpose: To examine the relationship between demographic and clinical characteristics of cardiac surgery patients with postoperative length of stay (PLOS) greater than 7 days and determine the demographic, social, and clinical predictors of the need for transitional cardiac rehabilitation (TCR) after cardiac surgery.

Data sources: A retrospective review of characteristics, clinical indices, caregiver availability, and patient status (whether living alone) was completed for 304 patients undergoing cardiac surgery over 24 consecutive months. Univariate analyses and multivariable logistic regression models were used to evaluate risk factor characteristics for PLOS greater than 7 days and to predict discharge disposition to TCR or home.

Conclusions: Older patients, those with preoperative comorbidities, and those without a caregiver at home experience delays in functional recovery and discharge and are more likely to need TCR services.

Implications for practice: Our findings support the addition of functional recovery and social support risk items to the preoperative cardiac surgery risk assessment.
Recombinant human erythropoietin and management of anemia in orthopedic surgery
Authors: COUVRET CLAUDE
Published: July 2006

Concerns regarding the safety, supply and cost of allogeneic blood transfusion have led to the development of recombinant human erythropoietin (rHuEPO) for anemic patients. rHuEPO safely increases preoperative red blood cell production and reduces allogeneic transfusion. During the preoperative period, expected blood loss and patient medical status need to be evaluated to select those patients who can benefit from this therapy. The appropriate dose of rHuEPO is determined according to the patient’s baseline hematocrit. This therapy must be part of an overall management strategy for anemia with appropriate iron supplementation. rHuEPO is used in combination with other blood‐conservation techniques in revision arthroplasties and spine surgery, depending on expected blood loss. The benefits, risks and costs of these blood‐conservation techniques must be compared with those of allogeneic transfusion. For the future, the use of rHuEPO must continue to be developed in anemic patients undergoing orthopedic surgery.
Indications for perioperative blood transfusion in orthopedic surgery
Authors: HABLER OLIVER
Published: July 2006

Today’s aging population has resulted in an increase in the number of major orthopedic surgical interventions in the elderly. High perioperative blood losses, together with a reduced tolerance to anemia, raise the likelihood of transfusion in this patient subgroup. The expected cost explosion in the transfusion system (cost‐intensive quality management, imbalance between the number of donors and recipients) as well as the remaining transfusion‐related risks of hemolysis, infection and immunosuppression demonstrate the high socioeconomical importance of developing institutional transfusion programs. This article summarizes (i) the pathophysiology of anemia compensation; (ii) the decision‐making process for transfusion in healthy patients and patients with cardiovascular disease; and (iii) current pre‐ and intraoperative techniques aimed at reducing allogeneic transfusion in orthopedic patients.
Red cell salvage in orthopedic surgery
Authors: MUÑOZ MANUEL , CAMPOS ARTURO , MUÑOZ ENCARNACIÓN , CARRERO ANTONIO , CUENCA JORGE , GARCÍA‐ERCE JOSÉ ANTONIO
Published: July 2006

The increasing number of surgical procedures has raised the demand for allogeneic blood to a level that often exceeds supply. Moreover, 10% of all transfusions are given in the orthopedic surgery setting, requiring the avoidance of liberal transfusion criteria to further reduce the risk of infection and other complications. As a result, a series of blood‐conservation measures have been developed. In this article, we review the use of autologous transfusion in orthopedic surgery, with a special focus on perioperative red cell salvage.

From data reviewed, it can be concluded that perioperative salvage of blood, either intraoperative cell salvage or postoperative cell salvage, seems to be an excellent source of functional and viable red cells, without many of the transfusion‐related risks and with few side effects. The effectiveness of perioperative cell salvage to reduce exposure to allogeneic blood is greatly enhanced by the implementation of a restrictive transfusion protocol and the association with other blood‐sparing strategies [preoperative autologous blood donation (PABD), erythropoietin, intravenous iron], especially in anemic patients. Moreover, perioperative cell salvage may reduce the number of required PABD units or render PABD unnecessary. Finally, although formal cost‐effectiveness studies on perioperative cell salvage are lacking, based on current allogeneic blood transfusion costs, it is generally accepted that the equivalent of at least one unit of blood needs to be recovered for these techniques to be cost‐effective. Therefore, these procedures should be used on a case‐by‐case basis.
Dynamics and (de)localization in a one-dimensional tight-binding chain
Authors: Šiber Antonio
Published: July 2006

A simple tight-binding model is used to illustrate how the time dependence of a state vector can be obtained from all the eigenvalues and eigenvectors of the Hamiltonian. The behavior of the eigenvalues and eigenvectors is studied for various parameters and allows us to study scatteringlike events, impurity states, and localization in disordered systems.
Einstein’s “little machine” as an example of charging by induction
Authors: Segers Danny , Uyttenhove Jos
Published: July 2006

Einstein, a theoretical physicist, also contributed to practical realizations, such as the little machine, his “Maschinchen.” The goal was to measure small electrical potentials. Although Einstein proposed it as “a new electrostatic method to measure small quantities of electricity”, the method was not new. As far as we know, three original copies of the Maschinschen still exist. Only one of the instruments was used in research. Because the physical principles on which the instrument is based have not been explained clearly, we discuss these principles in more detail. Simulation of the charge amplification is performed and the equilibration time of the instrument is estimated.
Finite-time thermodynamics of an instrumented drinking bird toy
Authors: Lorenz Ralph
Published: July 2006

The motion and temperature of a drinking bird toy is monitored by a variety of instruments to determine the quantitative history of its motion over long times and to determine the thermodynamic and mechanical constraints on its performance.
The effect of grading incentive on student discourse in Peer Instruction
Authors: James Mark C.
Published: July 2006

The use of Peer Instruction to enhance lectures in large enrollment introductory college science courses has become widespread. In this technique, learner responses to multiple choice questions posed by the instructor during lecture are recorded and displayed in real time by an electronic classroom response system (CRS). Peer Instruction takes place when learners are given time to discuss ideas with their neighbors before registering individual responses. Although much research has been done to study the impact of Peer Instruction on student learning and engagement, little is known about the dynamics of the peer discussions that occur just before students register responses to questions. The results of this study suggest that the grading incentive instructors adopt for incorrect question responses impacts the nature and quality of the peer discussions that take place. Two large enrollment college astronomy classes employing contrasting assessment strategies for CRS scores were observed. In the high stakes classroom where students received little credit for incorrect CRS responses, it was found that conversation partners with greater knowledge tended to dominate peer discussions and partners with less knowledge were more passive. In the low stakes classroom where students received full credit for incorrect responses, it was found that students engaged in a more even examination of ideas from both partners. Conversation partners in the low stakes classroom were also far more likely to register dissimilar responses, suggesting that question response statistics in low stakes classrooms more accurately reflect current student understanding and therefore act as a better diagnostic tool for instructors.
Development and assessment of research-based tutorials on heat engines and the second law of thermodynamics
Authors: Cochran Matthew J. , Heron Paula R. L.
Published: July 2006

We report on an investigation of student ability to apply the second law of thermodynamics to cyclic devices such as heat engines and refrigerators. Students enrolled in courses ranging from algebra-based introductory physics to a junior-level thermodynamics course were asked if certain specified processes could occur. Their responses revealed several conceptual difficulties, including the failure to recognize the relevance of the second law to various problems. These findings informed the development of two tutorials to supplement instruction in standard undergraduate courses. Student performance on examination questions indicates that both tutorials can help improve understanding.
The failure of the Tacoma Bridge: A physical model
Authors: Green Daniel , Unruh William G.
Published: July 2006

The cause of the collapse of the Tacoma Narrows Bridge has been a topic of much debate and confusion over the years. Many mischaracterizations of the observed phenomena have limited the understanding of the collapse even though there has always been an abundance of evidence in favor of a negative damping model. Negative damping, or positive feedback, is responsible for large amplitude oscillations in many systems, from musical instruments to the Tacoma Narrows Bridge failure. We discuss some of the more well known examples of positive feedback, and then show how the interaction of the wind with the oscillating bridge, especially the development of large scale vortices above and below the deck of the bridge, led to such a positive feedback instability. We support our model by computational, experimental, and historical data.
Comments on the tethered galaxy problem
Authors: Clavering William J.
Published: July 2006

In a recent paper Davis, Lineweaver, and Webb make the counterintuitive assertion that a galaxy held “tethered” at a fixed distance from our own could emit blueshifted light. This effect was derived from the simplest Friedmann-Robertson-Walker (FRW) spacetimes and the ΩM=0.3, ΩΛ=0.7 case, which is believed to be a good late time model of our universe. In this paper, we recover their results in a more transparent way, revise their calculations, and propose a formulation of the tethered galaxy problem based on radar distance rather than comoving “proper” distance. This formulation helps to remove the coordinate-dependent nature of the tethered galaxy problem and establishes consistency between the empty FRW model and special relativity. In the general case, we see that, although the radar distance tethering reduces the redshift of a receding object, it does not do so sufficiently to cause the blueshift as found by Davis, Lineweaver, and Webb. We also discuss some important issues raised by this approach relating to the interpretation of the redshift, velocity, and distance in relativistic cosmology.
THE THEORY OF THE METARECURSIVELY ENUMERABLE DEGREES
Authors: GREENBERG NOAM , SHORE RICHARD A. , SLAMAN THEODORE A.
Published: July 2006

Sacks [23] asks if the metarecursively enumerable degrees are elementarily equivalent to the r.e. degrees. In unpublished work, Slaman and Shore proved that they are not. This paper provides a simpler proof of that result and characterizes the degree of the theory as [Formula: see text] or, equivalently, that of the truth set of [Formula: see text].
INDECOMPOSABLE LINEAR ORDERINGS AND HYPERARITHMETIC ANALYSIS
Authors: MONTALBÁN ANTONIO
Published: July 2006

A statement of hyperarithmetic analysis is a sentence of second order arithmetic S such that for every Y⊆ω, the minimum ω-model containing Y of RCA0 + S is HYP(Y), the ω-model consisting of the sets hyperarithmetic in Y. We provide an example of a mathematical theorem which is a statement of hyperarithmetic analysis. This statement, that we call INDEC, is due to Jullien [13]. To the author's knowledge, no other already published, purely mathematical statement has been found with this property until now. We also prove that, over RCA0, INDEC is implied by [Formula: see text] and implies ACA0, but of course, neither ACA0, nor ACA 0+ imply it.

We introduce five other statements of hyperarithmetic analysis and study the relations among them. Four of them are related to finitely-terminating games. The fifth one, related to iterations of the Turing jump, is strictly weaker than all the other statements that we study in this paper, as we prove using Steel's method of forcing with tagged trees.
Illustrating the impossibility of crash-tolerant consensus in asynchronous systems
Authors: Freiling Felix C. , Völzer Hagen
Published: July 2006

This exercise shows how a simple restricted algorithm can be used to present an introductory discussion on the crash-tolerant consensus problem in asynchronous distributed systems. This text is intended to support teaching the consensus problem in courses on distributed systems.
Virtualization for high-performance computing
Authors: Mergen Mark F. , Uhlig Volkmar , Krieger Orran , Xenidis Jimi
Published: July 2006

The specific demands of high-performance computing (HPC) often mismatch the assumptions and algorithms provided by legacy operating systems (OS) for common workload mixes. While feature- and application-rich OSes allow for flexible and low-cost hardware configurations, rapid development, and flexible testing and debugging, the mismatch comes at the cost of --- oftentimes significant --- performance degradation for HPC applications.The ubiquitous availability of virtualization support in all relevant hardware architectures enables new programming and execution models for HPC applications without loosing the comfort and support of existing OS and application environments. In this paper we discuss the trends, motivations, and issues in hardware virtualization with emphasis on their value in HPC environments.
Right-weight kernels
Authors: Minnich Ronald G. , Sottile Matthew J. , Choi Sung-Eun , Hendriks Erik , McKie Jim
Published: July 2006

DOE has put forth a considerable effort into light-weight kernels for high performance computing, yet there has been a lack of acceptance and use, perhaps due to the limited support for hardware and software. The arguments for light-weight kernels have been based on the problem of
interference
, i.e. changes in application performance that occur when the operating system pre-empts the application. Nevertheless, using existing, well supported operating systems for HPC systems has been quite successful. The problems with the standard operating systems remain, however, although their impact on applications is still not quantified. At LANL, we have undertaken a research program to determine whether Linux and/or Plan 9 can be used to realize the benefits of light-weight kernels while maintaining the benefits of a full-featured operating system. Specifically, we are evaluating measures that quantify what is "good" in a Light-Weight Kernel. We are using this knowledge to modify Linux and Plan 9 to make them competitive with custom light weight operating systems, in essence, a Right-Weight Kernel. This paper represents both a summary of early results as well as a description of work in progress.
K42
Authors: Silva Dilma Da , Krieger Orran , Wisniewski Robert W. , Waterland Amos , Tam David , Baumann Andrew
Published: July 2006

K42 is an open-source scalable research operating system well suited to support systems research. The primary goals of K42's design that support such research include flexibility to allow a multitude of policies and implementations to be supported simultaneously, extensibility to allow new policies and implementations to be readily added, and scalability to enable good performance for both small and large applications on both small and large multiprocessor systems. The goals are accomplished via key features including an object-oriented structure that allows specialized resource management implementations and policies on a per-resource, per-application basis, implementation in user-level servers of much of the system functionality, and a sophisticated set of underlying services that provides a programming model for developing system software in a scalable and modular fashion.These characteristics make K42 an attractive framework for prototyping new operating system ideas. In addition, K42 has a sophisticated performance monitoring infrastructure allowing a thorough understanding of new ideas to be gained. The above framework combined with a consistent emphasis on scalability makes K42 well suited for high-end computing initiatives. In this paper, we describe the structure of K42 which contributes to the advantageous prototyping environment, and demonstrate how to utilize it by describing ongoing research efforts.
HPC-Colony
Authors: Chakravorty Sayantan , Mendes Celso L. , Kalé Laxmikant V. , Jones Terry , Tauferner Andrew , Inglett Todd , Moreira José
Published: July 2006

Traditional full-featured operating systems are known to have properties that limit the scalability of distributed memory parallel programs, the most common programming paradigm utilized in high end computing. Furthermore, as processor counts increase with the most capable systems, the necessary activity to manage the system becomes more of a burden. To make a general purpose operating system scale to such levels, new technology is required for parallel resource management and global system management (including fault management). In this paper, we describe the shortcomings of full-featured operating systems and runtime systems and discuss an approach to scale such systems to one hundred thousand processors with both scalable parallel application performance and efficient system management.
Performance evaluation of automatic checkpoint-based fault tolerance for AMPI and Charm++
Authors: Zheng Gengbin , Huang Chao , Kalé Laxmikant V.
Published: July 2006

As the size of high performance clusters multiplies, the probability of system failure grows substantially, posing an increasingly significant challenge for scalability. Checkpoint-based fault tolerance methods are effective approaches at dealing with faults. With these methods, the state of the entire parallel application is checkpointed to reliable storage. When a fault occurs, the application is restarted from a recent checkpoint. However, the application developer is required to write significant additional code for checkpointing and restarting. This paper describes disk-based and memory-based checkpointing fault tolerance schemes that automate the task of checkpointing and restarting. The schemes also allow the program to be restarted on a different number of processors. These schemes are based on self-checkpointable, migratable objects supported by the Adaptive MPI (AMPI) and Charm++ run-time and can be applied to a wide class of applications written using MPI or message-driven languages. We demonstrate the effectiveness of the strategies and evaluate their performance.
Optimal table lookup for reserved words in Ada
Authors: Trono John A.
Published: July 2006

Recently a colleague wanted to include a section on perfect hashing functions in the latest edition of a book [4], and after an on-line search brought up a reference of mine [8], he sent me an email asking if I could generate a minimal perfect hashing function (MPHF) for the set of reserved words in Ada 2005. This is a summary of the process that determined one.
Compiler and runtime support for efficient software transactional memory
Authors: Adl-Tabatabai Ali-Reza , Lewis Brian T. , Menon Vijay , Murphy Brian R. , Saha Bratin , Shpeisman Tatiana
Published: July 2006

Programmers have traditionally used locks to synchronize concurrent access to shared data. Lock-based synchronization, however, has well-known pitfalls: using locks for fine-grain synchronization and composing code that already uses locks are both difficult and prone to deadlock. Transactional memory provides an alternate concurrency control mechanism that avoids these pitfalls and significantly eases concurrent programming. Transactional memory language constructs have recently been proposed as extensions to existing languages or included in new concurrent language specifications, opening the door for new compiler optimizations that target the overheads of transactional memory.This paper presents compiler and runtime optimizations for transactional memory language constructs. We present a high-performance software transactional memory system (STM) integrated into a managed runtime environment. Our system efficiently implements nested transactions that support both composition of transactions and partial roll back. Our JIT compiler is the first to optimize the overheads of STM, and we show novel techniques for enabling JIT optimizations on STM operations. We measure the performance of our optimizations on a 16-way SMP running multi-threaded transactional workloads. Our results show that these techniques enable transactional memory's performance to compete with that of well-tuned synchronization.
Better extensibility through modular syntax
Authors: Grimm Robert
Published: July 2006

We explore how to make the benefits of modularity available for syntactic specifications and present
Rats!
, a parser generator for Java that supports easily extensible syntax. Our parser generator builds on recent research on parsing expression grammars (PEGs), which, by being closed under composition, prioritizing choices, supporting unlimited lookahead, and integrating lexing and parsing, offer an attractive alternative to context-free grammars. PEGs are implemented by so-called packrat parsers, which are recursive descent parsers that memoize all intermediate results (hence their name). Memoization ensures linear-time performance in the presence of unlimited lookahead, but also results in an essentially lazy, functional parsing technique. In this paper, we explore how to leverage PEGs and packrat parsers as the foundation for extensible syntax. In particular, we show how make packrat parsing more widely applicable by implementing this lazy, functional technique in a strict, imperative language, while also generating better performing parsers through aggressive optimizations. Next, we develop a module system for organizing, modifying, and composing large-scale syntactic specifications. Finally, we describe a new technique for managing (global) parsing state in functional parsers. Our experimental evaluation demonstrates that the resulting parser generator succeeds at providing extensible syntax. In particular,
Rats!
enables other grammar writers to realize real-world language extensions in little time and code, and it generates parsers that consistently out-perform parsers created by two GLR parser generators.
An experimental analysis of self-adjusting computation
Authors: Acar Umut A. , Blelloch Guy E. , Blume Matthias , Tangwongsan Kanat
Published: July 2006

Dependence graphs and memoization can be used to efficiently update the output of a program as the input changes dynamically. Recent work has studied techniques for combining these approaches to effectively dynamize a wide range of applications. Toward this end various theoretical results were given. In this paper we describe the implementation of a library based on these ideas, and present experimental results on the efficiency of this library on a variety of applications. The results of the experiments indicate that the approach is effective in practice, often requiring orders of magnitude less time than recomputing the output from scratch. We believe this is the first experimental evidence that incremental computation of any type is effective in practice for a reasonably broad set of applications.
Shared memory programming for large scale machines
Authors: Barton Christopher , Casçaval CĆlin , Almási George , Zheng Yili , Farreras Montse , Chatterje Siddhartha , Amaral José Nelson
Published: July 2006

This paper describes the design and implementation of a scalable run-time system and an optimizing compiler for Unified Parallel C (UPC). An experimental evaluation on BlueGene/L®, a distributed-memory machine, demonstrates that the combination of the compiler with the runtime system produces programs with performance comparable to that of efficient MPI programs and good performance scalability up to hundreds of thousands of processors.Our runtime system design solves the problem of maintaining shared object consistency efficiently in a distributed memory machine. Our compiler infrastructure simplifies the code generated for parallel loops in UPC through the elimination of affinity tests, eliminates several levels of indirection for accesses to segments of shared arrays that the compiler can prove to be local, and implements remote update operations through a lower-cost asynchronous message. The performance evaluation uses three well-known benchmarks --- HPC RandomAccess, HPC STREAM and NAS CG --- to obtain scaling and absolute performance numbers for these benchmarks on up to 131072 processors, the full BlueGene/L machine. These results were used to win the HPC Challenge Competition at SC05 in Seattle WA, demonstrating that PGAS languages support both productivity and performance.
SAFECode
Authors: Dhurjati Dinakar , Kowshik Sumant , Adve Vikram
Published: July 2006

Static analysis of programs in weakly typed languages such as C and C++ is generally not sound because of possible memory errors due to dangling pointer references, uninitialized pointers, and array bounds overflow. We describe a compilation strategy for standard C programs that guarantees that aggressive interprocedural pointer analysis (or less precise ones), a call graph, and type information for a subset of memory, are never invalidated by any possible memory errors. We formalize our approach as a new type system with the necessary run-time checks in operational semantics and prove the correctness of our approach for a subset of C. Our semantics provide the foundation for other sophisticated static analyses to be applied to C programs with a guarantee of soundness. Our work builds on a previously published transformation called Automatic Pool Allocation to ensure that hard-to-detect memory errors (dangling pointer references and certain array bounds errors) cannot invalidate the call graph, points-to information or type information. The key insight behind our approach is that pool allocation can be used to create a run-time partitioning of memory that matches the compile-time memory partitioning in a points-to graph, and efficient checks can be used to isolate the run-time partitions. Furthermore, we show that the sound analysis information enables static checking techniques that eliminate many run-time checks. Our approach requires no source code changes, allows memory to be managedexplicitly, and does not use meta-data on pointers or individual tag bits for memory. Using several benchmark s and system codes, we show experimentally that the run-time overheads are low (less than 10% in nearly all cases and 30% in the worst case we have seen).We also show the effectiveness of static analyses in eliminating run-time checks.