bluuebunny/crossref_metadata_2025 huggingface dataset:
Methane yields from Brahman cattle fed tropical grasses and legumes
Authors: Kennedy P. M. , Charmley E.
Published: March 2012

In the national greenhouse inventory, methane emissions from the Australian tropical beef herd are derived from cattle fed two diets. In the experiments reported here, methane production was measured by open-circuit gas exchange from 13 Brahman cattle offered 22 diets from combinations of five tropical grass species and five legumes, with a minimum of three steers per diet. All diets were offered daily ad libitum, with the exception of three legume diets fed without grass and leucaena (Leucaena leucocephala) mixed with grass, which were offered at 15 g dry matter per kg liveweight. Diets were fed as long-chopped dried hay, with the exception of leucaena, which was harvested and fed within 2 days. For the data from cattle fed diets of grass and grass mixed with legumes, methane production could be predicted as 19.6 g/kg forage dry matter intake (residual standard deviation 12.3). Observed methane yields were not predictable from a stoichiometry, which used volatile fatty acid proportions in rumen fluid. Mean methane emission rates across all diets were equivalent to 8.6–13.4% of digestible energy intake, and 5.0–7.2% of gross energy intake. The latter values are comparable to IPCC (2006) recommendations (5.5–7.5%) for large ruminants fed low-quality crop residues and by-products. Methane yields per unit of ingested dry matter or digested organic matter were variable across diets but were related to digestibility and contents of fibre and protein. These results constitute a significant downward revision of the methane emissions attributable to the northern Australian beef herd grazing tropical pastures.
Eosinophil-derived leukotriene C4 signals via type 2 cysteinyl leukotriene receptor to promote skin fibrosis in a mouse model of atopic dermatitis
Authors: Oyoshi Michiko K. , He Rui , Kanaoka Yoshihide , ElKhal Abdallah , Kawamoto Seiji , Lewis Christopher N. , Austen K. Frank , Geha Raif S.
Published: March 2012

Atopic dermatitis (AD) skin lesions exhibit epidermal and dermal thickening, eosinophil infiltration, and increased levels of the cysteinyl leukotriene (cys-LT) leukotriene C4(LTC4). Epicutaneous sensitization with ovalbumin of WT mice but not ΔdblGATA mice, the latter of which lack eosinophils, caused skin thickening, collagen deposition, and increased mRNA expression of the cys-LT generating enzyme LTC4synthase (LTC4S). Skin thickening and collagen deposition were significantly reduced in ovalbumin-sensitized skin of LTC4S-deficient and type 2 cys-LT receptor (CysLT2R)–deficient mice but not type 1 cys-LT receptor (CysLT1R)-deficient mice. Adoptive transfer of bone marrow-derived eosinophils from WT but not LTC4S-deficient mice restored skin thickening and collagen deposition in epicutaneous-sensitized skin of ΔdblGATA recipients. LTC4stimulation caused increased collagen synthesis by human skin fibroblasts, which was blocked by CysLT2R antagonism but not CysLT1R antagonism. Furthermore, LTC4stimulated skin fibroblasts to secrete factors that elicit keratinocyte proliferation. These findings establish a role for eosinophil-derived cys-LTs and the CysLT2R in the hyperkeratosis and fibrosis of allergic skin inflammation. Strategies that block eosinophil infiltration, cys-LT production, or the CysLT2R might be useful in the treatment of AD.
Harmonization of gene/protein annotations: towards a gold standard MEDLINE
Authors: Campos David , Matos Sérgio , Lewin Ian , Oliveira José Luís , Rebholz-Schuhmann Dietrich
Published: March 2012

Motivation: The recognition of named entities (NER) is an elementary task in biomedical text mining. A number of NER solutions have been proposed in recent years, taking advantage of available annotated corpora, terminological resources and machine-learning techniques. Currently, the best performing solutions combine the outputs from selected annotation solutions measured against a single corpus. However, little effort has been spent on a systematic analysis of methods harmonizing the annotation results and measuring against a combination of Gold Standard Corpora (GSCs).

Results: We present Totum, a machine learning solution that harmonizes gene/protein annotations provided by heterogeneous NER solutions. It has been optimized and measured against a combination of manually curated GSCs. The performed experiments show that our approach improves the F-measure of state-of-the-art solutions by up to 10% (achieving ≈70%) in exact alignment and 22% (achieving ≈82%) in nested alignment. We demonstrate that our solution delivers reliable annotation results across the GSCs and it is an important contribution towards a homogeneous annotation of MEDLINE abstracts.

Availability and implementation: Totum is implemented in Java and its resources are available at http://bioinformatics.ua.pt/totum

Contact:  david.campos@ua.pt; rebholz@ebi.ac.uk

Supplementary information:  Supplementary data are available at Bioinformatics online.
IsoCor: correcting MS data in isotope labeling experiments
Authors: Millard Pierre , Letisse Fabien , Sokol Serguei , Portais Jean-Charles
Published: March 2012

Mass spectrometry (MS) is widely used for isotopic labeling studies of metabolism and other biological processes. Quantitative applications—e.g. metabolic flux analysis—require tools to correct the raw MS data for the contribution of all naturally abundant isotopes. IsoCor is a software that allows such correction to be applied to any chemical species. Hence it can be used to exploit any isotopic tracer, from well-known (13C, 15N, 18O, etc) to unusual (57Fe, 77Se, etc) isotopes. It also provides new features—e.g. correction for the isotopic purity of the tracer—to improve the accuracy of quantitative isotopic studies, and implements an efficient algorithm to process large datasets. Its user-friendly interface makes isotope labeling experiments more accessible to a wider biological community.

Availability: IsoCor is distributed under OpenSource license at http://metasys.insa-toulouse.fr/software/isocor/

Contact:  jean-charles.portais@insa-toulouse.fr
Cerebral Oxygen Saturation Measured by Near-infrared Spectroscopy and Jugular Venous Bulb Oxygen Saturation during Arthroscopic Shoulder Surgery in Beach Chair Position under Sevoflurane-Nitrous Oxide or Propofol-Remifentanil Anesthesia
Authors: Jeong Hyejin , Jeong Seongtae , Lim Hoi J. , Lee JongUn , Yoo Kyung Y.
Published: March 2012

Background

We examined the effects of different anesthetics on cerebral oxygenation and systemic hemodynamics in patients undergoing surgery in beach chair position (BCP). Jugular venous bulb oxygen saturation (SjvO2) and regional cerebral tissue oxygen saturation (SctO2) were determined while patients were placed from the supine to BCP. Whether SctO2 and SjvO2 are interchangeable in assessing the cerebral oxygenation was also examined.

Methods

Forty patients undergoing shoulder surgery in BCP were randomly assigned to receive sevoflurane-nitrous oxide (S/N) or propofol-remifentanil (P/R) anesthesia. Four patients taking angiotensin II receptor antagonists were excluded post hoc. Mean arterial pressure and heart rate, as well as SjvO2 and SctO2, were measured before (postinduction baseline in supine position) and after BCP.

Results

Mean arterial pressure decreased by BCP in both groups. It was, however, significantly higher in S/N (n = 19) than in P/R group (n = 17) at 7 to 8 min after the positioning. SjvO2 also significantly decreased after BCP in both groups, the magnitude of which was lower in S/N than in P/R group (11 ± 10% vs. 23 ± 9%, P = 0.0006). The incidences of SjvO2 <50% and mean arterial pressure less than 50 mmHg were lower in S/N group, but SctO2and the incidence of cerebral desaturation (more than 20% decrease from baseline) did not significantly differ between the groups. SctO2 and SjvO2 were only weakly correlated (β = 0.218, r2 = 0.133). Bland-Altman analysis showed a mean difference of -7.2% with 95% limit of agreement between -38.2% and 23.8%.

Conclusions

The margin of safety against impaired cerebral oxygenation is greater and SjvO2 is more preserved with S/N than with P/R anesthesia. SctO2 may not be reliable in detecting a low SjvO2 during the surgery in BCP.
RecA-Dependent DNA Repair Results in Increased Heteroplasmy of the Arabidopsis Mitochondrial Genome
Authors: Miller-Messmer Marie , Kühn Kristina , Bichara Marc , Le Ret Monique , Imbault Patrice , Gualberto José M.
Published: March 2012

Plant mitochondria have very active DNA recombination activities that are responsible for its plastic structures and that should be involved in the repair of double-strand breaks in the mitochondrial genome. Little is still known on plant mitochondrial DNA repair, but repair by recombination is believed to be a major determinant in the rapid evolution of plant mitochondrial genomes. In flowering plants, mitochondria possess at least two eubacteria-type RecA proteins that should be core components of the mitochondrial repair mechanisms. We have performed functional analyses of the two Arabidopsis (Arabidopsis thaliana) mitochondrial RecAs (RECA2 and RECA3) to assess their potential roles in recombination-dependent repair. Heterologous expression in Escherichia coli revealed that RECA2 and RECA3 have overlapping as well as specific activities that allow them to partially complement bacterial repair pathways. RECA2 and RECA3 have similar patterns of expression, and mutants of either display the same molecular phenotypes of increased recombination between intermediate-size repeats, thus suggesting that they act in the same recombination pathways. However, RECA2 is essential past the seedling stage and should have additional important functions. Treatment of plants with several DNA-damaging drugs further showed that RECA3 is required for different recombination-dependent repair pathways that significantly contribute to plant fitness under stress. Replication repair of double-strand breaks results in the accumulation of crossovers that increase the heteroplasmic state of the mitochondrial DNA. It was shown that these are transmitted to the plant progeny, enhancing the potential for mitochondrial genome evolution.
Structural polytypism and residual strain in GaAs nanowires grown on Si(111) probed by single-nanowire X-ray diffraction
Authors: Biermanns Andreas , Breuer Steffen , Davydok Anton , Geelhaar Lutz , Pietsch Ullrich
Published: March 2012

The structural composition, phase arrangement and residual strain of individual GaAs nanowires (NWs) grown on Si(111) have been investigated using NW-resolved high-resolution X-ray diffraction employing a focused synchrotron beam. It is found that even neighbouring NWs grown on the same sample under the same growth conditions differ significantly in their phase structure, most of them exhibiting small wurtzite segments embedded between larger zincblende sections. Moreover, using structurally sensitive Bragg reflections, residual strain is observed in the zincblende sections of the NWs, likely caused by an incomplete relaxation at the substrate interface.
Dispersive spread of virtual sources by asymmetric X-ray monochromators
Authors: Huang X. R. , Macrander A. T. , Honnicke M. G. , Cai Y. Q. , Fernandez Patricia
Published: March 2012

The principles of the virtual source spread (spatial broadening) phenomenon induced by angular dispersion in asymmetric X-ray Bragg reflections are illustrated, from which the virtual source properties are analyzed for typical high-resolution multiple-crystal monochromators, including inline four-bounce dispersive monochromators, back-reflection-dispersion monochromators and nondispersive nested channel-cut monochromators. It is found that dispersive monochromators can produce spread virtual sources of a few millimetres in size, which may prevent efficient microfocusing of the beam as required by inelastic X-ray scattering spectroscopy and other applications. Possible schemes to mitigate this problem are discussed. The analyses may provide important guidelines for designing and optimizing modern high-precision synchrotron X-ray optics and beamline instrumentation for spectroscopy, imaging and nanofocusing applications.
Completion of autobuilt protein models using a database of protein fragments
Authors: Cowtan Kevin
Published: March 2012

Two developments in the process of automated protein model building in theBuccaneersoftware are presented. A general-purpose library for protein fragments of arbitrary size is described, with a highly optimized search method allowing the use of a larger database than in previous work. The problem of assembling an autobuilt model into complete chains is discussed. This involves the assembly of disconnected chain fragments into complete molecules and the use of the database of protein fragments in improving the model completeness. Assembly of fragments into molecules is a standard step in existing model-building software, but the methods have not received detailed discussion in the literature.
Exploiting structure similarity in refinement: automated NCS and target-structure restraints inBUSTER
Authors: Smart Oliver S. , Womack Thomas O. , Flensburg Claus , Keller Peter , Paciorek Włodek , Sharff Andrew , Vonrhein Clemens , Bricogne Gérard
Published: March 2012

Maximum-likelihood X-ray macromolecular structure refinement inBUSTERhas been extended with restraints facilitating the exploitation of structural similarity. The similarity can be between two or more chains within the structure being refined, thus favouring NCS, or to a distinct `target' structure that remains fixed during refinement. The local structural similarity restraints (LSSR) approach considers all distances less than 5.5 Å between pairs of atoms in the chain to be restrained. For each, the difference from the distance between the corresponding atoms in the related chain is found. LSSR applies a restraint penalty on each difference. A functional form that reaches a plateau for large differences is used to avoid the restraints distorting parts of the structure that are not similar. Because LSSR are local, there is no need to separate out domains. Some restraint pruning is still necessary, but this has been automated. LSSR have been available to academic users ofBUSTERsince 2009 with the easy-to-use -autoncs and -target target.pdb options. The use of LSSR is illustrated in the re-refinement of PDB entries 5rnt, where -target enables the correct ligand-binding structure to be found, and 1osg, where -autoncs contributes to the location of an additional copy of the cyclic peptide ligand.
The experiences of medically fragile adolescents who require respiratory assistance
Authors: Spratling Regena
Published: March 2012

Aims.  To report a study of the experiences of medically fragile adolescents who require respiratory assistance.

Background.  The population of medically fragile adolescents has grown in recent decades because of the sequelae of prematurity, injuries and chronic or terminal illnesses. Medically fragile adolescents who require respiratory assistance are part of this unique population, yet as nurses, we know little about their experiences and the best approaches to use in caring for them.

Design.  A qualitative design, interpretive phenomenology was used in this study.

Methods.  Interpretive phenomenology was used to describe and interpret the experience of 11 medically fragile adolescents (ages 13–18 years old) who required respiratory assistances of tracheostomies, ventilator support and Bi‐level positive airway pressure. Between April 2010–September 2010, audiotaped semi‐structured interviews were conducted with the adolescents. Data analysis was completed using a stepped approach to identify themes.

Findings.  Five themes were identified from the interviews with the adolescents: ‘Get to know me’, ‘Allow me to be myself’, ‘Being there for me’, ‘No matter what, technology helps’ and ‘I am an independent person’.

Conclusions.  Medically fragile adolescents have a clear view of who they are as a person. They want nurses to view them as a person, not just a patient. The adolescents said that friends were there for them when they needed support. Technology had meanings that enhanced daily living and existed as a part of their day, not their whole day. The adolescents were actively engaging in activities and strategies to achieve their goals of independence.
Quantifying judicious use of health information technology
Authors: Tsang Sandro
Published: March 2012

Rationale, aims and objectives  Sufficient evidence suggests that health information technology (HIT) will soon become part of physician procedure. This paper poses that the outcome of using HIT is affected by the intentions of use. Note that ethical indoctrination is a crucial mechanism for monitoring physicians. Judicious and sufficient use of HIT is expected to be the prerequisite for deploying these technologies to help in delivering better care. This research paper, therefore, aims to define professional concerns and intent to use HIT, and identify their associations.

Methods  A survey study was conducted to collect data for developing a seven‐dimensional eHealth success measure. This paper focuses on deriving a structural equation model that can explain the associations among professional concerns and intent to use HIT. Statistical analyses were, therefore, only performed on the Intent to Use and Physician Attributes constructs.

Results  The statistical results show that altruism, autonomy, physician‐patient relationship and (subconscious) autonomy significantly associate with each other at least at P < 0.05. Only altruism shows to be a significant determinant of intent to use HIT (with P = 0.00005). Other professional concerns only associate with it indirectly through altruism.

Conclusions  Medicine has been a science‐using and compassionate practice. Medical practice including HIT use may only be reliably assessed from a sociotechnical perspective. Professional concerns show to be associated with intent to use HIT is an expected result. This research direction may contribute to deriving policies to deploy HIT for delivering better care through implementing sufficient and judicious HIT use.
Respecting dignity in forensic care: the challenge faced by nurses of maintaining patient dignity in clinical caring situations
Authors: GUSTAFSSON L.‐K. , WIGERBLAD Å. , LINDWALL L.
Published: March 2012

Accessible summary

This paper is based on group interviews with carers in psychiatric forensic care in Sweden, about the subject of respecting patient's dignity.

Respecting dignity is one of the basic topics in caring and is taken to its limits psychiatric forensic care, where the patients are placed into care involuntary.

The study illuminates the meaning of maintenance of patient dignity as protection and respect but also as showing brotherly humanity.

A deeper understanding of the meaning of maintenance and respecting of patient dignity in forensic care will enable nurses to plan and provide qualitative care for these patients.

We must recognize the importance of increased understanding for maintaining patient dignity to expand earlier formulated knowledge about caring ethics. Illuminations of this topic can create conditions for changing and developing care, as well as making caregivers' preservation of dignity evident. The aim was to illuminate the meaning of maintenance of patient dignity in forensic care. A qualitative design with a phenomenological–hermeneutic approach was used to analyse and interpret focus group interviews with nurses in forensic care. In the text the meaning of maintenance of patient dignity was protection and respect but also brotherly humanity. Protection was shown outwards to cover or screen the patient and to guard against danger. The inner form was described as protecting the patients' needs and arousing the patients' protection resources. Respect was shown outwards to take the patient seriously and to show others that patients are to be reckoned with, inwards in teaching patients to create respect and in teaching patients to expect respect from others. Meeting patients with human brotherhood was shown in doing ‘the little extra’ and demonstrating human similarity. The new understanding will enable nurses to plan and provide professional care, based on caring science.
Russian wheat aphids (Diuraphis noxia) in China: native range expansion or recent introduction?
Authors: ZHANG B. , EDWARDS O. R. , KANG L. , FULLER S. J.
Published: March 2012

In this study, we explore the population genetics of the Russian wheat aphid (RWA) (Diuraphis noxia), one of the world’s most invasive agricultural pests, in north‐western China. We have analysed the data of 10 microsatellite loci and mitochondrial sequences from 27 populations sampled over 2 years in China. The results confirm that the RWAs are holocyclic in China with high genetic diversity indicating widespread sexual reproduction. Distinct differences in microsatellite genetic diversity and distribution revealed clear geographic isolation between RWA populations in northern and southern Xinjiang, China, with gene flow interrupted across extensive desert regions. Despite frequent grain transportation from north to south in this region, little evidence for RWA translocation as a result of human agricultural activities was found. Consequently, frequent gene flow among northern populations most likely resulted from natural dispersal, potentially facilitated by wind currents. We also found evidence for the long‐term existence and expansion of RWAs in China, despite local opinion that it is an exotic species only present in China since 1975. Our estimated date of RWA expansion throughout China coincides with the debut of wheat domestication and cultivation practices in western Asia in the Holocene. We conclude that western China represents the limit of the far eastern native range of this species. This study is the most comprehensive molecular genetic investigation of the RWA in its native range undertaken to date and provides valuable insights into the history of the association of this aphid with domesticated cereals and wild grasses.
Loading mechanisms of ring helicases at replication origins
Authors: Soultanas Panos
Published: March 2012

Threading of DNA through the central channel of a replicative ring helicase is known as helicase loading, and is a pivotal event during replication initiation at replication origins. Once loaded, the helicase recruits the primase through a direct protein–protein interaction to complete the initial ‘priming step’ of DNA replication. Subsequent assembly of the polymerases and processivity factors completes the structure of the replisome. Two replisomes are assembled, one on each strand, and move in opposite directions to replicate the parental DNA during the ‘elongation step’ of DNA replication. Replicative helicases are the motor engines of replisomes powered by the conversion of chemical energy to mechanical energy through ATP binding and hydrolysis. Bidirectional loading of two ring helicases at a replication origin is achieved by strictly regulated and intricately choreographed mechanisms, often through the action of replication initiation and helicase‐loader proteins. Current structural and biochemical data reveal a wide range of different helicase‐loading mechanisms. Here we review advances in this area and discuss their implications.
Genetics of winter wheat response to two freezing treatments
Authors: Skinner Daniel Z.
Published: March 2012

With 1 figure and 3 tables

The inheritance of the ability of winter wheat (Triticum aestivum) plants to survive two kinds of freezing stress was investigated in a five‐parent diallel cross. Cold‐acclimated plants were frozen to damaging temperatures with or without a −3°C, 16‐h prefreezing (PF) period. Test temperatures were adjusted such that the overall mean survivals were the same under the two PF treatment conditions (−10 to −12°C without PF; −14.5 to −16.5°C with PF). Lines that survived freezing tests with PF as well or better than without PF developed significantly more freezing tolerance during the PF treatment and tolerated the lower test temperatures of the PF tests. Diallel analysis indicated most variation under either kind of freezing stress was because of additive genetic effects, but non‐additive effects were significant in two of the 20 crosses. It may be possible to combine additive and non‐additive effects to develop cultivars that are exceptionally tolerant of freezing episodes with or without an extended PF period.
Being a male nurse in Portugal during Salazar’s dictatorship (1940–70)
Authors: da Silva Helena
Published: March 2012

In several western countries, nursing was clearly seen as an occupation for women. With the creation of the first nursing schools, the gendering of the profession was accelerated. Male nurses’ contribution to the development of the profession was limited in comparison with women’s. However, the situation was slightly different in Portugal. This article aims at demonstrating a specific example of the gendering of the nursing profession, by simply copying the western model – considered the most developed – without questioning the consequences or even whether it was adapted to the country that had a different nursing tradition. Because the consequences of this gendering are still felt nowadays, this article opens a reflection on how complex it is to follow a foreign nursing model and on the issues associated with such a copy. Qualitative and quantitative analysis of several historical documents and interviews with several retired nurses contributed to an understanding of how men became nurses and how they worked in Portugal, despite gender discrimination, between 1940 and 1970. With different nursing training and job opportunities, Portuguese male nurses still managed to contribute, even beyond that of female nurses, to the improvement of the nursing profession.
A cohort evaluation of the Laryngeal Mask Airway‐Supreme™ in children
Authors: Jagannathan Narasimhan , Sohn Lisa E. , Chang Edwina , Sawardekar Amod
Published: March 2012

Objectives:  To assess the clinical performance of the laryngeal mask airway‐Supreme in children.

Aim:  The purpose of this prospective audit was to evaluate the feasibility of the laryngeal mask airway‐Supreme in clinical practice and generate data for future comparison trials.

Background:  The laryngeal mask airway‐Supreme is a new second‐generation supraglottic airway that was recently released in limited pediatric sizes (sizes 1, 2).

Methods:  One hundred children, ASA I‐III, newborn to 16 years of age, and undergoing various procedures requiring a size 1, 2, or 3 laryngeal mask airway‐Supreme were studied. Assessments included insertion success rates, airway leak pressures, success of gastric tube insertion, quality of airway, and perioperative complications.

Results:  The first‐time insertion success rate was 97%, with an overall insertion success rate of 100%. The mean initial airway leak pressure for all patients was 22.3 ± 6.6 cm H2O. Gastric tube placement was possible in 98% of patients. Complications were noted in six patients: coughing or laryngospasm (n = 3), sore throat (n = 1), and dysphonia (n = 2).

Conclusions:  The laryngeal mask airway‐Supreme was inserted with a high degree of success on the first attempt by clinicians with limited prior experience with the device. It was effectively used for a variety of procedures in children undergoing spontaneous and mechanical ventilation with minimal complications. The leak pressures demonstrated in this study, along with access for gastric decompression, suggest that the laryngeal mask airway‐Supreme may be an effective device for positive pressure ventilation in children.
Ideological Party Cohesion in Macro‐comparative Politics: The Nordic Social Democratic Parties from a Comparative Perspective
Authors: Jahn Detlef , Oberst Christoph
Published: March 2012

‘Party cohesion’ is a central concept in the analysis of agenda‐setting, veto players and coalition‐building as well as in the analysis of policy efficiency and party responsiveness. However, there is no indicator to measure party cohesion in a systematic manner over time and across parties. As a consequence, most established studies treat political parties as unitary actors although from an analytical point of view they should be considered collective actors. In order to overcome this deficiency, in this article a time‐variant and party‐specific index of party cohesion is developed which can be used in macro‐comparative statistical analysis. The concept of ‘ideological cohesion’ is developed along the Left–Right dimension. This index is applied in order to compare the party cohesion of Nordic social democratic parties (SDs) with their counterparts in 17 additional countries. The results show that the myth of the cohesion of Nordic SDs is only true for the golden age of the welfare state. Currently, most of the Nordic SDs actually have a lower party cohesion than their counterparts in many other countries.
Influencia sindical en la empresa industrial española
Authors: GARCÍA‐OLAVERRI Carmen , HUERTA Emilio
Published: March 2012

Los autores estudian las relaciones existentes en las empresas españolas entre la actividad sindical, por un lado, y las políticas de recursos humanos y la productividad, por otro. Analizan el concepto de influencia sindical y en qué aspectos del funcionamiento de la empresa se hace sentir, basándose en dos encuestas realizadas en 1996 y 2007 a establecimientos de más de cincuenta trabajadores. Investigan si la influencia sindical opera como dicen los discursos tradicionales de las organizaciones sindicales o hay diferencias importantes entre la retórica al uso y la realidad. Encuentran que la influencia sindical guarda relación con los salarios y con el absentismo.
Progreso económico y social en las redes productivas mundiales. Problemas teóricos y de medición
Authors: MILBERG William , WINKLER Deborah
Published: March 2012

El desarrollo económico es cada vez más sinónimo de «progreso económico» en el seno de las redes productivas mundiales (RPM). La relación entre éste y el crecimiento de la producción y el comercio internacionales se ha estudiado mucho, pero se ha reflexionado poco acerca del progreso en materia de salarios, condiciones de trabajo, derechos, igualdad entre los sexos y estabilidad de ingresos de los trabajadores de las RPM. Los autores analizan las maneras de calibrar el progreso económico y el social, principalmente en los países en desarrollo, y los nexos teóricos que hay entre uno y otro. Por último, extraen algunas enseñanzas para los programas políticos.
Ultrasonographic examination of the palmar aspect of the pastern of the horse: Sesamoidean ligaments
Authors: Carnicer D. , Coudry V. , Denoix J.‐M.
Published: March 2012

The suspensory apparatus is composed of the third interosseous muscle (TIOM) or suspensory ligament, the proximal sesamoid bones, palmar ligament and distal sesamoidean ligaments (DSL). Of these structures, the suspensory ligament is the most frequently implicated in conditions seen in race and sport horses; nevertheless, DSL lesions are not rare and often associated with other injuries that can modify patient prognosis and management. Ultrasonography has been shown to be valuable in the assessment of DSL desmitis. In contrast to the metacarpal area, the pastern region has been considered technically more difficult to scan because of the small and irregular contact surface and frequent artefacts. Advances in imaging techniques with adapted ultrasound probes and the use of magnetic resonance imaging (MRI) for equine lameness evaluation have revealed that distal sesamoidean ligament injuries are more frequently implicated in lameness than previously suspected.
Effect of Wall Compliance and Permeability on Blood-Flow Rate in Counter-Current Microvessels Formed From Anastomosis During Tumor-Induced Angiogenesis
Authors: Guo Peng , Fu Bingmei M.
Published: March 2012

Tumor blood-flow is inhomogeneous because of heterogeneity in tumor vasculature, vessel-wall leakiness, and compliance. Experimental studies have shown that normalization of tumor vasculature by antiangiogenic therapy can improve tumor microcirculation and enhance the delivery of therapeutic agents to tumors. To elucidate the quantitative relationship between the vessel-wall compliance and permeability and the blood-flow rate in the microvessels of the tumor tissue, the tumor tissue with the normalized vasculature, and the normal tissue, we developed a transport model to simultaneously predict the interstitial fluid pressure (IFP), interstitial fluid velocity (IFV) and the blood-flow rate in a counter-current microvessel loop, which occurs from anastomosis in tumor-induced angiogenesis during tumor growth. Our model predicts that although the vessel-wall leakiness greatly affects the IFP and IFV, it has a negligible effect on the intravascular driving force (pressure gradient) for both rigid and compliant vessels, and thus a negligible effect on the blood-flow rate if the vessel wall is rigid. In contrast, the wall compliance contributes moderately to the IFP and IFV, but significantly to the vessel radius and to the blood-flow rate. However, the combined effects of vessel leakiness and compliance can increase IFP, which leads to a partial collapse in the blood vessels and an increase in the flow resistance. Furthermore, our model predictions speculate a new approach for enhancing drug delivery to tumor by modulating the vessel-wall compliance in addition to reducing the vessel-wall leakiness and normalizing the vessel density.
The Magnitude of the Thermal Energy Stored in a Building Wall Adjacent to an Unglazed Transpired Solar Collector
Authors: Moaveni Saeed , Tebbe Patrick A. , Schwartzkopf Louis , Dobmeier Joseph , Gehrke Joseph , Simones Matthew
Published: March 2012

In this paper, we will present a method for estimating the stored thermal energy in a building wall that is adjacent to an unglazed transpired collector. We also discuss how this value should be incorporated in the collector efficiency calculations. An unglazed transpired collector is made of a relatively thin, dark, perforated metal wall that is installed approximately 14 inches (35.5 cm) away from a south facing building wall to create an enclosed plenum. Typically, the outside air is drawn into the collector by fans that are located on the top of the collector. These types of solar collectors are used to preheat the intake air using solar energy before the air enters existing HVAC systems. They are generally used in situations and buildings where large ventilation volume flow rates are required. Most of the studies related to unglazed transpired collectors deal with estimation of air temperature rise due to solar gain and recaptured heat loss from the adjoining building wall. In the past, studies have neglected the amount of thermal energy that is stored in the building wall. However, as shown in this study, the stored thermal energy is of significant amount, and if incorporated correctly in the collector efficiency calculations, it would lead to higher efficiency values.
AIMFAST: Initial Dish System Alignments Results Using Fringe Reflection Methods
Authors: Andraka Charles E. , Yellowhair Julius , Finch Nolan , Carlson Jeff , Francis Matt , Hunt Kirby , Raffa Carl , Kulaga Tom
Published: March 2012

The proper alignment of facets on a dish engine system is critical to the performance of the system. Improper alignment can lead to poor performance and shortened life, through excessively high flux on the receiver surfaces, imbalanced power on multicylinder engines, and intercept losses at the aperture. Alignment approaches used in the past are time consuming field operations, typically taking 4–6 hours per dish with 40–80 facets on the dish. Production systems will need rapid, accurate alignment implemented in a fraction of an hour. In this paper, we present an AIMFAST characterization of a Stirling Energy Systems dish, before and after implementing an alignment using the AIMFAST software. The results of the alignment are correlated with fluxmapper measurements of the dish, and the improvement in the flux pattern projected to an engine receiver is calculated using Sandia’s CIRCE 2 dish optical modeling tool. The alignment substantially reduced the peak fluxes on the flat fluxmapper targets as well as the projection onto the receiver. The fluxmap images correlate well with the CIRCE projections of measured facet normals. In addition, we implemented automated actuation of the facet during alignment, improving the response and accuracy of the system, resulting in total dish alignments with under 0.1 mrad RMS alignment error. We also implemented an adaptive alignment strategy that varied the alignment based on the AIMFAST-measured facet shape.
How to improve x‐ray scattering techniques to quantify bone mineral density using spectroscopy
Authors: Krmar M. , Ganezer K.
Published: March 2012

Purpose:

The purpose of this study was to develop a new diagnostic technique for measuring bone mineral density (BMD) for the assessment of osteoporosis, which improves upon the coherent to Compton scattering ratio (CCSR) method, which was first developed in the 1980s. To help the authors achieve these goals, they have identified and studied two new indices for CCSR, the forward scattered to backward scattered (FS‐BS) and the forward scattered to transmitted (FS‐T) ratios. They believe that, at small angles, these two parameters can offer a practicalin vivo determination of BMD that can be used to overcome the limitations of past CCSR systems, including high radiation dosages, costs, and examination durations.

Methods:

In previous CCSR studies, a high‐activity radioactive source with a long half‐live (usually241Am) and an expensive and bulky cryogenic HPGe detector were applied to both in vivo and in vitro measurements. To make this technique more suitable for clinical applications, the possibility of using a standard diagnostic x‐ray tube generating a continuous spectrum was investigated in this paper. Scattered radiation from trabecular bone‐simulating phantoms containing various mineral densities that span the normal range of in vivo BMD was collected in this study using relatively inexpensive noncryogenic CdTe or NaI detectors.

Results:

The initial results demonstrate that a modified version of CCSR can be successfully applied to trabecular bone assessment using a diagnostic x‐ray tube with a continuous spectrum in two variations, the FS‐BS and the FS‐T ratio. When FS‐BS is measured, intensity spectra in the forward and backward directions must be collected while FS‐T requires only the integral intensity of the scattered and transmitted (T) spectra in the energy region above 40 keV. For both of these methods, forward scattering angles less than or equal to 15° and backward scattering angles greater than or equal to (165°= 180° − 15°) are needed.

Conclusions:

The authors determined that FS‐T is more sensitive to changes in BMD than transmission or absorption alone and that the FS‐BS method can yield an absolute measurement of the mean atomic number of the scattering medium, after a correction for path‐dependent attenuation. Since this study determined that the FS‐T ratio is independent of the incident energy over a broad energy region, it will be possible to apply FS‐T to bone densitometry using inexpensive integral photon detectors. The authors believe that, by replacing the radionuclide source with an x‐ray tube and the cryogenically cooled HPGe detector with a single solid state CdTe, NaI, or silicon detector or an annular array of detectors, as suggested in this study, the past difficulties of CCSR concerning high radiation exposure, costs, and durations as well as lack of convenience can be overcome and that CCSR could eventually become popular in clinical settings.
On the use of the method of wave images to introduce students to acoustics
Authors: Ginsberg Jerry H.
Published: March 2012

A previous paper [Ginsberg, 2006, J. Acoust. Soc. Am. 119, 1954–1960] extended the d’Alembert solution of the one-dimensional wave equation to semi-infinite and finite length waveguides. The concept uses images of incident waves in order to describe reflection phenomena. Each image is algebraically related to an incident wave when the restriction to purely resistive terminations is met. The present paper extends the previous treatment from initial value problems to situations in which the particle velocity at a termination is specified. The discussion emphasizes the use of hand-drawn sketches as a method that will allow students at all levels to understand the basic processes of wave propagation and reflection. The number and complexity of the wave images is enhanced in a bounded waveguide, so simple numerical algorithms for evaluating the response of such systems also are discussed. The wave image technique is applied to a sequence of increasingly complicated systems. Suggestions are given regarding what material should be presented to students at various levels, and what students can be expected to garner from each case. The recommendation is that this solution method should be used to introduce students at all levels to basic acoustical phenomena.
Cornu’s spiral in the Fresnel regime studied using ultrasound: A phase study
Authors: Hitachi Akira
Published: March 2012

A simple experimental technique for measuring the phase and amplitude of diffracting ultrasound wave [A. Hitachi and M. Takata, Am. J. Phys. 78, 678 (2010)] has been applied to diffracting objects with straight edges as a demonstration of the Cornu spiral. Babinet’s principle is studied observing the ultrasound field behind a slit and a complementary strip obstacle and is verified directly by comparing vectors (phasors) in the complex plane. The phase of the diffracted wave observed in the geometrical shadow of the straight screen has the form of a cylindrical wave originating at the edge of the straight screen as the boundary diffraction wave proposed by Young. In addition, the incident wave has a phase delay of π/4 behind the wave passing through on the center line of the slit, the plane of symmetry, has been observed as predicted by Huygens-Fresnel diffraction theory.
Reflections and recommendations on writing textbooks in the course of a career in academia
Authors: Ginsberg Jerry H.
Published: March 2012

The genesis of this paper was notification to the author that he would receive the 2010 Rossing Prize in Acoustics Education, which carried the responsibility of giving a lecture at a meeting of the Acoustical Society of America. He decided to draw on his remembrances of writing several textbooks during a 40 year career as a professor to discuss the facets of writing that a faculty member might encounter. This paper is an expanded version of that lecture [J. H. Ginsberg, J. Acoust. Soc. Am. 128, 2389 (2010)]. An opening section elucidating the author’s experiences as an author is followed by a discussion intended to motivate and encourage those who are undecided about taking on this activity. Suggestions are offered as to how to organize and proceed through a writing project as well as what elements should be included. An explanation of the author’s role in the process of producing a printed textbook is provided. Guidance is offered as to how one can focus on writing a book in the face of teaching, research, and personal responsibilities. The closure discusses current trends that endanger the ongoing flow of high quality textbooks.
Educational demonstration of a spherically propagating acoustic shock
Authors: Muhlestein Michael B. , Gee Kent L. , Macedone Jeffrey H.
Published: March 2012

Exploding gas-filled balloons are common chemistry demonstrations. They also provide an entertaining and educational means to experimentally verify nonlinear acoustical theory as described by the Earnshaw solution to the lossless Burgers equation and weak-shock theory. This article describes the theory, the demonstration, and the results of a propagation experiment carried out to provide typical results. Data analysis shows that an acetylene–oxygen balloon produces an acoustic shock whose evolution agrees well with weak-shock theory. On the other hand, the pressure wave generated by a hydrogen–oxygen balloon also propagates nonlinearly, but does not approach N-wave-like, weak-shock formation over the propagation distance. Overall, the experiment shows that popular demonstrations of chemical reactions can be extended from chemistry classrooms to a pedagogical tool for the student of advanced physical acoustics.
Overview of a university course on acoustics and noise
Authors: Kessissoglou Nicole J.
Published: March 2012

The Bachelor of Mechanical Engineering at the University of New South Wales in Sydney, Australia is a four year degree program. In their fourth and final year, students can choose from a range of technical elective courses, one of those being in acoustics. The acoustics course entitled “Fundamentals of Noise” can also be taken as a postgraduate coursework subject as part of a Masters by Coursework degree. The course covers fundamental topics in acoustics, noise, noise measurement, and noise control. This paper outlines the topics covered in the course, the range of assessment activities conducted by the students, and the use of invited industry guest speakers, all of which aim to maximize student knowledge, interest, and performance in the course.
Dictums for problem solving and approximation in mathematical acoustics: Examples involving low-frequency vibration and radiation
Authors: Pierce Allan D. , Thiam Amadou G.
Published: March 2012

A sequence of dictums for mathematical acoustics is given representing opinions intended to be regarded as authoritative, but not necessarily universally agreed upon. The dictums are presented in the context of the detailed solution for a class of problems involving the forced vibration of a long cylinder protruding half-way into a half-space bounded by a compliant surface (impedance boundary) characterized by a spring constant. One limiting case corresponds to a cylinder vibrating within an infinite rigid baffle, and another limiting case corresponds to a vibrating cylinder on the compliant surface of an incompressible fluid. The second limiting case is identified as analogous to that of a floating half-submerged cylinder whose vibrations cause water waves to propagate over the surface. Attention is focused on vibrations at very low frequencies. Difficulties with insuring a causal solution are pointed out and dictums are given as to how one overcomes such difficulties. Various approximation techniques are described. The derivations involve application of the theory of complex variables and the method of matched asymptotic expansions, and the results include the apparent entrained mass in the near field of the cylinder and the radiation resistance per unit length experienced by the vibrating cylinder.
A ray model of sound focusing with a balloon lens: An experiment for high school students
Authors: Dean Cleon E. , Parker Kendez
Published: March 2012

A weather balloon filled with carbon dioxide gas is used as a positive spherical acoustic lens. High frequency but audible sound from a circular loudspeaker ensonifies the balloon and produces increased sound pressure levels in a region along the principal axis according to a ray acoustics model. This enhancement was measured experimentally and was found to agree with theory. The possibility that interference from reflected sound off walls or the floor could mask or mimic the expected focusing was countered by calculating and measuring within a “shadow zone” in which only direct rays or rays refracted by the balloon exist by the method of Fresnel volumes. The experiment described in this paper would be a suitable learning experience for junior high and high school students showing how rays and Snell’s law apply to sound as well as light and giving them a measurable predicted focal region for enhanced sound pressure levels.