bluuebunny/crossref_metadata_2025 huggingface dataset:
Exigência de lisina digestível para frangos de corte machos de 1 a 42 dias de idade
Authors: Goulart Cláudia de Castro , Costa Fernando Guilherme Perazzo , Lima Neto Raul da Cunha , Souza Janete Gouveia , Silva José Humberto Vilar da , Givisiez Patrícia Emília Naves
Published: May 2008

Objetivou-se estimar as exigências nutricionais de lisina digestível de frangos de corte machos de 1 a 42 dias de idade. Utilizaram-se 1.950 pintos de corte Cobb (750 para a fase pré-inicial, 600 para a fase inicial e 600 para a fase de crescimento) com pesos iniciais de 45,1 ± 0,6; 160,5 ± 2,4 e 746,3 ± 10,7 g, respectivamente. As aves foram distribuídas em delineamento inteiramente casualizado, com seis tratamentos, cinco repetições de 25 pintos por unidade experimental na fase pré-inicial e 20 nas fases inicial e de crescimento. Como tratamentos, uma ração basal deficiente em lisina foi suplementada com L-lisina.HCL de modo a conter seis níveis de lisina digestível: 1,10; 1,16; 1,22; 1,28; 1,34 e 1,40% na fase pré-inicial; 0,92; 0,98; 1,04; 1,10; 1,16 e 1,22% na fase inicial e 0,815; 0,875; 0,935; 0,995; 1,055 e 1,115% na fase de crescimento, respectivamente. As variáveis avaliadas foram: consumo de ração (CR), ganho de peso (GP), conversão alimentar (CA), peso e rendimento de carcaça e de cortes nobres, peso absoluto e relativo das vísceras comestíveis e gordura abdominal. Nas três fases, verificaram-se efeito linear dos níveis de lisina digestível sobre o consumo de ração e efeito quadrático sobre o ganho de peso e a conversão alimentar. Não houve efeito significativo dos níveis de lisina sobre os pesos absolutos de carcaça, coração e gordura abdominal, os rendimentos de carcaça, peito, coxa e sobrecoxa e os pesos relativos de coração, fígado, moela e gordura abdominal. No entanto, verificou-se efeito quadrático sobre os pesos absolutos de peito, coxa, sobrecoxa e fígado. Recomenda-se para frangos de corte machos 1,286; 1,057 e 1,009% de lisina digestível para as fases pré-inicial, inicial e crescimento, respectivamente.
Valores nutricionais de milhos de diferentes qualidades para frangos de corte
Authors: Silva Cynthia Siqueira , Couto Humberto Pena , Ferreira Rony Antonio , Fonseca José Brandão , Gomes Augusto Vidal da Costa , Soares Rita da Trindade Ribeiro Nobre
Published: May 2008

Este trabalho foi realizado com o objetivo de determinar os valores nutricionais de milhos de quatro qualidades, obtidos por meio de estratificação em mesa densimétrica, para frangos de corte em diferentes idades. Os milhos foram designados como: MDA - milho de densidade alta; MDI - milho de densidade intermediária; MDB - milho de densidade baixa; e MDT - milho de densidade total, composto de 30% de MDA, 60% de MDI e 10% de MDB. Dois ensaios biológicos foram conduzidos utilizando-se o método tradicional de coleta total de excretas para determinação da energia metabolizável aparente corrigida (EMAn). O primeiro ensaio metabólico foi conduzido com pintos Cobb de 11 a 19 dias e o segundo, com pintos de 29 a 37 dias de idade. Foram realizadas análises químicas para determinação do perfil nutricional, classificação de grãos segundo a densidade e comparação por meio das estimativas de equações de predição do valor energético e de micotoxinas. Os perfis de aminoácidos digestíveis dos milhos foram estimados pelo NIR. Os valores da EMAn dos milhos de diferentes qualidades (MDA, MDI, MDB e MDT) determinados com frangos na fase inicial foram: 3.308; 3.121; 2.937 e 3.239 kcal/kg e, para a fase de crescimento: 3.413, 3.362, 3.174 e 3.348 kcal/kg, respectivamente. Esses valores comprovam as significativas perdas energéticas dos milhos de mais baixa qualidade e a eficiência da mesa densimétrica em estratificar os grãos. A diferença da EMAn entre as idades das aves sugere melhor eficiência de utilização da energia com o avanço da idade. As equações de predição podem ser utilizadas para estimar o valor energético de milhos, tanto por sua classificação como pela densidade. Entretanto, o erro sistemático associado a cada equação de predição pode comprometer a exatidão de seu valor nutricional. As contaminações por aflatoxinas e tricotecenos variam com a qualidade do milho estratificado, fator importante a ser considerado na alimentação de frangos de corte.
Consumo, digestibilidade e parâmetros ruminais em vacas gestantes alimentadas com silagem de rama de mandioca
Authors: Modesto Elisa Cristina , Santos Geraldo Tadeu dos , Zambom Maximiliane Alavarse , Damasceno Julio Cesar , Branco Antonio Ferriani , Vilela Duarte
Published: May 2008

O experimento foi conduzido para estudar os efeitos da substituição da silagem de milho pela silagem da rama de mandioca para vacas gestantes não-lactantes. Os níveis de substituição da silagem de milho pela silagem da rama de mandioca foram 0, 20, 40 e 60%. Foram avaliados o consumo e as digestibilidades de matéria seca (MS), matéria orgânica (MO), proteína bruta (PB), fibra em detergente neutro (FDN), carboidratos totais (CT) e carboidratos não-fibrosos (CNF), o pH e o nitrogênio amoniacal ruminal antes e 2, 4, 6 e 8 horas depois da alimentação da manhã. Foram utilizadas quatro vacas da raça Holandesa não-lactantes e no terço final de gestação, canuladas no rúmen, distribuídas em um quadrado latino 4 × 4. Não foi observado efeito do nível de substituição da silagem de milho pela silagem da rama de mandioca sobre o consumo, a digestibilidade dos nutrientes e os parâmetros ruminais, exceto a digestibilidade aparente de proteína bruta e as concentrações de nitrogênio amoniacal. Verificou-se efeito linear negativo para digestibilidade aparente da proteína à medida que a silagem de milho foi substituída pela de rama de mandioca. Também para o nitrogênio amoniacal foi observado efeito linear negativo 8 horas pós-prandial. A substituição da silagem de milho pela silagem da rama de mandioca, em todos níveis estudados, pode ser feita na alimentação de vacas gestantes não-lactantes, pois não modifica o consumo, os parâmetros ruminais e a digestibilidade da matéria seca e dos nutrientes, exceto proteína bruta e nitrogênio amoniacal no tempo de 8 horas pós-prandial.
Desenvolvimento de um compósito laminado híbrido com fibras natural e sintética
Authors: Da Silva R.V. , Aquino E.M.F. , Rodrigues L.P.S. , Barros A.R.F.
Published: May 2008

Compósitos poliméricos com fibras naturais vêm sendo bastante estudados nas duas últimas décadas com algumas aplicações já bem estabelecidas, principalmente no setor automotivo. No entanto, suas aplicações são limitadas pelo seu baixo desempenho mecânico e alta absorção de umidade, comparado aos compósitos com fibras sintéticas. Buscando minimizar estes problemas e ampliar o leque de aplicações, propõe-se neste trabalho desenvolver um compósito laminado híbrido associando fibras naturais (curauá) e sintéticas (vidro-E) em uma matriz de resina poliéster. Foi realizado um estudo comparativo das propriedades mecânicas em flexão do laminado híbrido e de dois outros laminados, um apenas com fibras de vidro e um apenas com fibras de curauá. Ensaios de absorção de água foram também realizados sendo obtidas as curvas de saturação para os três laminados. Por fim, foi analisada a influência da absorção de água nas propriedades mecânicas em flexão do laminado híbrido. As propriedades do laminado híbrido foram muito próximas do laminado de fibra de vidro, já o laminado de curauá teve um desempenho bastante inferior. Nos ensaios de absorção de água foi comprovada a eficiência da hibridização na redução do percentual de absorção de água do laminado apenas com fibra natural. O laminado híbrido vidro/curaua mostrou ser um promissor substituto para os laminados de fibra de vidro mesmo em aplicações de contato direto com água.
Tenacidade ao impacto de compósitos de tecido de juta reforçando matriz de polietileno reciclado
Authors: Camerini A.L. , Terrones L.A.H. , Monteiro S.N.
Published: May 2008

Compósitos ambientalmente corretos fabricados com tecido de juta, retirados de sacos de aniagem, reforçando matriz de polietileno reciclado estão sendo investigados como sucedâneos de materiais convencionais para painéis de construção e mobiliário. O presente trabalho avaliou a tenacidade ao impacto destes compósitos para diferentes frações, até 40% em peso, de tecido de juta. Corpos de prova com dimensões padronizadas foram preparados por moldagem a quente e ensaiados em pêndulo de impacto Charpy. As correspondentes fraturas foram analisadas por microscopia eletrônica de varredura, MEV. Constatou-se que a energia registrada nos ensaios aumenta com a fração de tecido de juta como reforço. Observações por MEV permitiram identificar os mecanismos do efeito do reforço que o tecido de juta acarreta para o aumento da tenacidade do compósito.
Terapia gênica, doping genético e esporte: fundamentação e implicações para o futuro
Authors: Artioli Guilherme Giannini , Hirata Rosário Dominguez Crespo , Lancha Junior Antonio Herbert
Published: May 2008

A busca pelo desempenho ótimo tem sido uma constante no esporte de alto rendimento. Para tanto, muitos atletas acabam utilizando drogas e métodos ilícitos, os quais podem ter importantes efeitos adversos. A terapia gênica é uma modalidade terapêutica bastante recente na medicina, cujos resultados têm, até o momento, indicado sua eficácia no tratamento de diversas doenças graves. O princípio da terapia gênica consiste na transferência vetorial de materiais genéticos para células-alvo, com o objetivo de suprir os produtos de um gene estruturalmente anormal no genoma do paciente. Recentemente, o potencial para uso indevido da terapia gênica entre atletas tem despertado a atenção de cientistas e de órgãos reguladores de esporte. A transferência de genes que poderiam melhorar o desempenho esportivo por atletas saudáveis, método proibido em 2003, foi denominado de doping genético. Os genes candidatos mais importantes para doping genético são os que codificam para GH, IGF-1, bloqueadores da miostatina, VEGF, endorfinas e encefalinas, eritropoetina, leptina e PPAR-delta. Uma vez inserido no genoma do atleta, o gene se expressaria gerando um produto endógeno capaz de melhorar o desempenho atlético. Assim, os métodos atuais de detecção de doping não são sensíveis a esse tipo de manipulação, o que poderia estimular seu uso indevido entre atletas. Além disso, a terapia gênica ainda apresenta problemas conhecidos de aplicação, como resposta inflamatória e falta de controle da ativação do gene. Em pessoas saudáveis, é provável que tais problemas sejam ainda mais importantes, já que haveria excesso do produto do gene transferido. Há também outros riscos ainda não conhecidos, específicos para cada tipo de gene. Em vista disso, debates sobre o doping genético devem ser iniciados no meio acadêmico e esportivo, para que sejam estudadas medidas de prevenção, controle e detecção do doping genético, evitando assim futuros problemas de uso indevido dessa promissora modalidade terapêutica.
Transgenic mice overexpressing GH exhibit hepatic upregulation of GH-signaling mediators involved in cell proliferation
Authors: Miquet Johanna G , González Lorena , Matos Marina N , Hansen Christina E , Louis Audreen , Bartke Andrzej , Turyn Daniel , Sotelo Ana I
Published: May 2008

Chronically elevated levels of GH in GH-transgenic mice result in accelerated growth and increased adult body weight. We have previously described that the GH-induced JAK2/STAT5-signaling pathway is desensitized in the liver of transgenic mice overexpressing GH. However, these animals present increased circulating IGF-I levels, increased hepatic GHR expression, and liver organomegaly due to hypertrophy and hyperplasia, which frequently progress to hepatomas as the animals age, indicating that action of GH on the liver is not prevented. In the present study, we have evaluated other GH-signaling pathways that could be activated in the liver of GH-transgenic mice. Upon GH administration, normal mice showed an important increment in STAT3 phosphorylation level, but transgenic mice did not respond to acute GH stimulation. However, STAT3 was constitutively phosphorylated in transgenic mice, whereas its protein content was not increased. GH-transgenic mice showed overexpression of c-Src, accompanied by an elevation of its activity. Other signaling mediators including focal adhesion kinase, epidermal growth factor receptor, Erk, Akt, and mammalian target of rapamycin displayed elevated protein and basal phosphorylation levels in these animals. Thus, GH-overexpressing transgenic mice exhibit hepatic upregulation of signaling mediators related to cell proliferation, survival, and migration. The upregulation of these proteins may represent GH-signaling pathways that are constitutively activated in the presence of dramatically elevated GH levels throughout life. These molecular alterations could be implicated in the pathological alterations observed in the liver of GH-transgenic mice.
Evaluation of contact exposure as a method for acclimatizing growing pigs to porcine reproductive and respiratory syndrome virus
Authors: Vashisht Kapil , Erlandson Keith R. , Firkins Lawrence D. , Zuckermann Federico A. , Goldberg Tony L.
Published: May 2008

Objective—To determine whether 6.5-week-old gilts that have not previously been exposed to porcine reproductive and respiratory syndrome (PRRS) virus can be acclimatized to an endemic strain of the virus by commingling with age-matched gilts inoculated with the endemic PRRS virus strain and whether 10.5-week-old gilts can be acclimatized by commingling with age-matched inoculated or contact-exposed animals.

Design—Randomized controlled longitudinal study.

Animals—80 gilts seronegative for PRRS on a farm in the Midwestern United States with a history of PRRS.

Procedures—20 gilts were inoculated with the endemic PRRS virus strain at 6.5 weeks of age (group 1) and were commingled with 20 gilts that were not inoculated (group 2). Four weeks later, the remaining 40 gilts (group 3) were commingled with gilts in groups 1 and 2. Presence of viral RNA in the tonsils, seroconversion rate, serum neutralizing antibody titers, interferon-γ-mediated cellular immunity, and reproductive outcomes were analyzed.

Results—Acclimatization of PRRS virus-naïve pigs was achieved by means of contact exposure at both 6.5 and 10.5 weeks of age. No differences were observed among the 3 groups with respect to development of anti-PRRS virus-specific immune responses or reproductive outcomes.

Conclusions and Clinical Relevance—Results suggested that contact exposure of 6.5- to 10.5-week-old pigs that had not previously been exposed to PRRS virus to pigs inoculated with endemic PRRS virus may be an efficient acclimatization strategy for controlling outbreaks on commercial farms on which PRRS is endemic.
Effect of a Prenatal Nutritional Intervention Program On Initiation and Duration of Breastfeeding
Authors: Léger-Leblanc Gisèle , Rioux France M.
Published: May 2008

Purpose: To evaluate initiation and duration of breastfeeding of infants born to mothers who participated in the Early Childhood Initiative (ECI) program. Factors affecting the initiation and the early cessation of breastfeeding were also explored.

Methods: Twenty-five pregnant women participating in the ECI program completed this prospective study. At 36 weeks’ gestation, a questionnaire was administered to assess socioeconomic status, intention to breastfeed and breastfeeding experience. When the infants were three and six months of age, feeding practices were assessed with a questionnaire.

Results: The breastfeeding initiation rate was 62.5%. At one and three months postpartum, exclusive breastfeeding rates were 39% and 4%, respectively. At six months, none of the women was exclusively breastfeeding. Primiparity, prenatal classes, having been breastfed and intention to breastfeed at 36 weeks’ gestation were positively associated with breastfeeding initiation. Father’s education, intention to breastfeed at 36 weeks’ gestation, no water or formula given to the infant during hospitalization and higher maternal hemoglobin level at 36 weeks’ gestation were positively associated with the duration of breastfeeding.

Conclusions: The rate of initiation and duration of breastfeeding for ECI participants were low. To achieve successful interventions, it is important to target modifiable factors known to influence the initiation and duration of breastfeeding within this population.
The Challenge of Skill Transfer: Dietitian Perspectives
Authors: Lordly Daphne
Published: May 2008

Purpose: The notion of transferable skills is part of the comprehensive education model for dietetic practice. Dietitians’ perspectives were collected to determine their understanding of the concept and which dietetic skills they considered transferable in long-term and acute care environments.

Methods: The study included a purposive sample of 14 dietitians representing long-term and acute care internship training and employment. The dietitians completed a questionnaire and were interviewed.

Results: All respondents demonstrated an understanding of the concept of transferability of skills. Results indicated that the majority believed dietetic entry-level competencies could be achieved in both long-term and acute care environments. While the majority believed competencies could be transferred from one environment to another, issues were raised about transfer from long-term care to acute care. These issues included limited client communication, fewer resources, and less opportunity for exposure to skill areas. Interpretation of the term “skill,” one-way transferability, and level of competence required for the particular working environment emerged as challenges to operationalization of the concept.

Conclusions: Transferability of skills within dietetic practice requires further investigation if it is to be fully understood and used to its full potential.
Decision-making in the Dairy Aisle: Maximizing Taste, Health, Cost and Family Considerations
Authors: Hammond Gail K. , Chapman Gwen E.
Published: May 2008

Purpose: To gain insight into the decision-making processes used by women when selecting dairy and dairy alternative foods, including examination of the role of bone health concerns.

Methods: Semi-structured, point-of-purchase interviews were conducted with a convenience sample of 30 female grocery shoppers. Constant comparative data analysis was used to generate themes on shoppers’ decision-making processes.

Results: Women considered multiple issues in their dairy and dairy alternative food choice strategies: taste was most often associated with the fat and sugar content of foods; health concerns were centred on achieving an acceptable body weight and preventing osteoporosis and cardiovascular disease, and women chose foods to satisfy other family members’ needs and preferences and to obtain “good food value.” Women prioritized their food choices by weighing the value of each issue, which led to a strategic process for “maximizing the value” of their food choices. The availability of a wide range of dairy and dairy alternative foods meant that in most instances, it was unnecessary for women to “trade off” one area of concern for another.

Conclusions: Dietitians and nutrition educators can help women make dietary changes by helping them identify foods that they perceive as meeting a variety of needs.
Outcomes of Screening And Nutritional Intervention Among Older Adults in Healthcare Facilities
Authors: Babineau Jolyne , Villalon Lita , Laporte Manon , Payette Hélène
Published: May 2008

A nutritional screening and early intervention program was administered to older adults in a subacute care facility. The study group was recruited among patients aged 65 or older, who were admitted to the geriatric and rehabilitation units of two hospitals. Two simple, reliable, and valid tools were used to screen subjects for the risk or presence of malnutrition. Those determined to be at high nutritional risk (n=62) were included in the study. Dietitians then conducted a full nutritional assessment and implemented a nutritional care plan for these subjects. Weekly follow-up was completed to measure oral intake, weight, and biochemical indices. A Short-Form 36 Health Survey was administered upon admission and discharge. Results showed significant increases in energy (p=0.0001) and protein (p=0.01) intakes, and in serum albumin (p=0.001), prealbumin (p=0.003), transferrin (p=0.024), and hematocrit (p=0.026) levels. There was also a significant increase in seven of the eight dimensions of the healthrelated quality of life questionnaire (p<0.05). Outcomes improve when older adults are screened for the risk or presence of malnutrition and receive an early nutritional care program.
Imaging Stem Cell Implant for Cellular-Based Therapies
Authors: Lee Zhenghong , Dennis James E. , Gerson Stanton L.
Published: May 2008

Stem cell–based cellular therapy represents a promising outlook for regenerative medicine. Imaging techniques provide a means for noninvasive, repeated, and quantitative tracking of stem cell implant or transplant. From initial deposition to the survival, migration and differentiation of the transplant/implanted stem cells, imaging allows monitoring of the infused cells in the same live object over time. The current review briefly summarizes and compares existing imaging methods for cell labeling and imaging in animal models. Several studies performed by our group using different imaging techniques are described, with further discussion on the issues with these current imaging approaches and potential directions for future development in stem cell imaging.
Endogenous Hedgehog Expression Contributes to Myocardial Ischemia-Reperfusion–Induced Injury
Authors: Bijlsma Maarten F. , Leenders Peter J. A. , Janssen Ben J. A. , Peppelenbosch Maikel P. , ten Cate Hugo , Spek C. Arnold
Published: May 2008

The developmentally important hedgehog (Hh) pathway is activated in ischemic tissue, and exogenously administered Sonic hedgehog (Shh) supports tissue repair after cardiac ischemia. Hence, it is currently assumed that the endogenous increase in Shh during ischemia serves a beneficial role in limiting cardiac tissue damage. To prove or refute this hypothesis, we treated mice with the smoothened (Smo) inhibitor cyclopamine to block the Hh pathway during myocardial ischemia and reperfusion. The experimental induction of myocardial ischemia resulted in activation of the Hh pathway and hallmark features of myocardial damage, such as left ventricular dilatation and reduced cardiac output. Unexpectedly, cyclopamine treatment ameliorated left ventricular dilatation and cardiac output. As the beneficial effect of exogenous Shh was suggested to depend on reduced apoptosis, increased vascularization, and reduced fibrosis, we subsequently assessed the effect of cyclopamine on these processes. Vascularization was similar in cyclopamine-treated and control-treated animals, but increased apoptosis and reduced fibrosis were observed in the cyclopamine-treated animals. Thus, Hh seems to exert a dualistic action in cardiac ischemia in which high exogenous levels are able to foster tissue repair and endogenous Hh seems to be deleterious.
Influence of Neuronal Nicotinic Receptors over Nicotine Addiction and Withdrawal
Authors: De Biasi Mariella , Salas Ramiro
Published: May 2008

Cigarette smoking represents an enormous, global public health threat. Nearly five million premature deaths during a single year are attributable to smoking. Despite the resounding message of risks associated with smoking and numerous public health initiatives, cigarette smoking remains the most common preventable cause of disease in the United States. Fortunately, even in an adult smoker, smoking cessation can reverse many of the potential harmful effects. The symptoms associated with nicotine withdrawal represent the major obstacle to smoking cessation. This minireview examines the roles of various nicotinic receptors in the mechanisms of nicotine dependence, discusses the potential role of the habenula-interpeduncular nucleus axis in nicotine withdrawal, and highlights nicotinic receptors containing the β4 subunit as a potential pharmacological target for smoking cessation strategies.
Upregulation of Telomerase Function During Tissue Regeneration
Authors: Elmore Lynne W. , Norris Michelle W. , Sircar Sohini , Bright A. Taylor , McChesney Patricia A. , Winn Richard N. , Holt Shawn E.
Published: May 2008

Telomerase plays a primary role in the maintenance of telomeres in immortal, germ, and tumor cells in humans but is lacking in most somatic cells and tissues. However, many species, including fish and inbred mice, express telomerase in most cells and tissues. Little is known about the expression of telomerase in aquatic species, although the importance of telomerase for longevity has been suggested. We compared telomerase activity and telomere lengths among a broad range of tissues from aquatic species and found telomerase at significant levels in both long- and short-lived aquatic species, suggesting constitutive telomerase expression has an alternative function. Telomere lengths in these aquatic species were comparable to those observed in normal human tissues and cell strains. Given that a host of aquatic species with short life spans have telomerase and a tremendous capacity to regenerate, we tested the hypothesis that telomerase upregulation is important for tissue regeneration. During regeneration, telomerase activity was upregulated and telomere lengths are maintained with the shortest telomeres being elongated, indicating the importance for maintaining telomere length and integrity during tissue regeneration. Thus, the expression of telomerase in aquatic animals is likely not related to longevity but to their ability to regenerate injured tissue.
Seismicity and deformation associated with ice-shelf rift propagation
Authors: Bassis Jeremy N. , Fricker Helen A. , Coleman Richard , Bock Yehuda , Behrens James , Darnell Dennis , Okal Marianne , Minster Jean-Bernard
Published: May 2008

Previous observations have shown that rift propagation on the Amery Ice Shelf (AIS), East Antarctica, is episodic, occurring in bursts of several hours with typical recurrence times of several weeks. Propagation events were deduced from seismic swarms (detected with seismometers) concurrent with rapid rift widening (detected with GPS receivers). In this study, we extend these results by deploying seismometers and GPS receivers in a dense network around the tip of a propagating rift on the AIS over three field seasons (2002/03, 2004/05 and 2005/06). The pattern of seismic event locations shows that icequakes cluster along the rift axis, extending several kilometers back from where the rift tip was visible in the field. Patterns of icequake event locations also appear aligned with the ice-shelf flow direction, along transverse-to-rift crevasses. However, we found some key differences in the seismicity between field seasons. Both the number of swarms and the number of events within each swarm decreased during the final field season. The timing of the slowdown closely corresponds to the rift tip entering a suture zone, formed where two ice streams merge upstream. Beneath the suture zone lies a thick band of marine ice. We propose two hypotheses for the observed slowdown: (1) defects within the ice in the suture zone cause a reduction in stress concentration ahead of the rift tip; (2) increased marine ice thickness in the rift path slows propagation. We show that the size–frequency distribution of icequakes approximately follows a power law, similar to the well-known Gutenberg–Richter law for earthquakes. However, large icequakes are not preceded by foreshocks nor are they followed by aftershocks. Thus rift-related seismicity differs from the classic foreshock and aftershock distribution that is characteristic of large earth quakes.
Improvement of a 2-D SIA ice-flow model: application to Glacier de Saint-Sorlin, France
Authors: Schäfer Martina , Le Meur Emmanuel
Published: May 2008

A number of improvements have been made to an existing two-dimensional ice-flow model applied to an alpine glacier. Analysis of the results of the existing model revealed several shortcomings. The first concerns the lack of mass conservation of the applied alternating-direction-implicit (ADI) scheme. A semi-implicit (SI) scheme is therefore proposed and the effects on mass conservation assessed by a comparison with the ADI scheme. The comparison is first carried out with a simple theoretical glacier for which the improvement is significant. Concerning the real case of Glacier de Saint-Sorlin, France, the initial deviation in mass conservation was much less pronounced such that the new scheme, although improving mass conservation, does not significantly change the modelled dynamics. However, other shortcomings that have a more profound impact on the modelling of glacier behaviour have been identified. The ice thickness may become negative over some gridpoints, leading to an inconsistency. The problem is partly resolved by incorporating extra checks on critical gridpoints at the glacier border. Finally, with the help of ice particle tracking, unrealistic ice settlement above the bergschrund has been identified as the main reason for spurious dynamic effects and has been corrected.
Thermal conditions at the bed of the Laurentide ice sheet in Maine during deglaciation: implications for esker formation
Authors: Hooke Roger LeB. , Fastook James
Published: May 2008

The University of Maine Ice Sheet Model was used to study basal conditions during retreat of the Laurentide ice sheet in Maine. Within 150 km of the margin, basal melt rates average ∼5 mm a−1 during retreat. They decline over the next 100 km, so areas of frozen bed develop in northern Maine during retreat. By integrating the melt rate over the drainage area typically subtended by an esker, we obtained a discharge at the margin of ~1.2 m3 s-1. While such a discharge could have moved the material in the Katahdin esker, it was likely too low to build the esker in the time available. Additional water from the glacier surface was required. Temperature gradients in the basal ice increase rapidly with distance from the margin. By conducting upward into the ice all of the additional viscous heat produced by any perturbation that increases the depth of flow in a flat conduit in a distributed drainage system, these gradients inhibit the formation of sharply arched conduits in which an esker can form. This may explain why eskers commonly seem to form near the margin and are typically segmented, with later segments overlapping onto earlier ones.
Glacier and lake variations in the Yamzhog Yumco basin, southern Tibetan Plateau, from 1980 to 2000 using remote-sensing and GIS technologies
Authors: Ye Qinghua , Zhu Liping , Zheng Hongxing , Naruse Renji , Zhang Xueqin , Kang Shichang
Published: May 2008

Glacier and lake variations in the Yamzhog Yumco basin in southern Tibet were studied by integrating series of spatial data from topographic maps and Landsat images at three different times: 1980, 1988/90 and 2000. The results indicate that the total glacier area has decreased from 218 km2 in 1980 to 215 km2 in 2000, a total reduction of 3 km2 (i.e. a 1.5% decrease). Glacier recession rates were clearly larger in the 1990s than the 1980s due to the warmer climate. The total lake area decreased by about 67 km2 during 1980–90 and increased by 32 km2 during 1990–2000. It is suggested that change of lake area in the basin was rapid and most likely caused primarily by the change in precipitation and evaporation in the basin, and secondarily by the increased water supply from melting glaciers.
The distribution and timing of tephra deposition at Siple Dome, Antarctica: possible climatic and rheologic implications
Authors: Gow Anthony J. , Meese Debra A.
Published: May 2008

Approximately 300 volcanic ash and dust layers were observed in the Siple Dome (Antarctica) ice core. Most of this tephra, deposited between 700 and 800 m depth, consisted primarily of glass shards with varying amounts of crystalline material and groundmass fragments. The pattern of distribution of tephra fallout closely replicates that found in the Byrd ice core, indicative of contemporaneous deposition at both locations. Peak fallout occurred approximately 19 500 years ago, based on methane tie points in the Siple Dome and Greenland Ice Sheet Project 2 (GISP2) ice cores. Mount Berlin was identified as a potential source of tephra, although other volcanoes in West and East Antarctica appear to have contributed ash and dust. Ice between 697 and 730 m, in which fine-grained tephra is concentrated, has undergone enhanced thinning compared to ice with a similar concentration of tephra deposited contemporaneously between 1300 and 1540 m at Byrd. It is speculated that this thinning has occurred in response to dynamic interaction between ice at Siple Dome and the two ice streams flanking it. A dramatic change to a shear fabric appears to be directly related to the higher concentration of volcanic particles in the ice between 700 and 800 m.
The influence of third shear stress invariant dependence in the isotropic viscous relation on the reduced model for ice-sheet flow
Authors: Morland L.W.
Published: May 2008

Ice-sheet flow solutions commonly adopt a simple isotropic viscous law, in which the deviatoric stress is coaxial with the strain rate, and the single response function depends on only one invariant, the second principal invariant of the deviatoric stress. This can be correlated with single-stress component tests, which cannot, however, verify the validity of the simplification. Morland (2007) has shown how combined compression and shear tests can verify and correlate a general quadratic isotropic viscous relation, or simply third invariant dependence, and there is evidence that at least third principal invariant dependence is required. Morland (2007) showed that a significant quadratic term changes the relative stress magnitudes in the reduced model for ice-sheet flow, that crucial simplifications are not achieved and formally noted that dependence on the third invariant in the coaxial relation also prevented the simplification. It is now shown that, provided the third invariant dependence does not dominate the isotropic relation, further asymptotic expansion does yield the reduced model simplification, and the influence of different weightings of third invariant dependence is illustrated by a comparison of steady radial flow solutions over a flat bed. It is found that the third invariant dependence does not have a large influence in these examples.
Recent evolution (1981–2005) of the Maladeta glaciers, Pyrenees, Spain: extent and volume losses and their relation with climatic and topographic factors
Authors: Chueca Javier , Julián Asunción , López-Moreno Juan Ignacio
Published: May 2008

Analysis of aerial photographs, GPS mapping and comparison of digital elevation models have been used to quantify the losses in extent and volume observed (1981–2005) in the glaciers of the Maladeta massif (Spanish Pyrenees). The data are examined in relation to different climatic (temperature, precipitation) and topographic factors that control glacial retreat both at the general and local scales. The evolution observed in the massif is characterized by the remarkable surface and volumetric shrinkage registered in all the glaciers: (1) glacial ice decreased in extent 35.7%, reducing from 240.9 ha to 155.0 ha; (2) losses in total ice volume reached 0.0137 km3 (75.6 m w.e.); (3) mean altitude of the studied glaciers increased 43.5 m. These changes seem to have been forced by climatic change (reduction in the snowfall contributions and increase in the maximum temperatures) during the past few decades in this Pyrenean region. In addition, local variables such as the orientation of each glacier, their altitude and their initial size seem to have induced significant spatial differences in the magnitude of the losses.
Intermittent thinning of Jakobshavn Isbræ, West Greenland, since the Little Ice Age
Authors: Csatho Bea , Schenk Toni , Van Der Veen C.J. , Krabill William B.
Published: May 2008

Rapid thinning and velocity increase on major Greenland outlet glaciers during the last two decades may indicate that these glaciers became unstable as a consequence of the Jakobshavn effect (Hughes, 1986), with terminus retreat leading to increased discharge from the interior and consequent further thinning and retreat. To assess whether recent trends deviate from longer-term behavior, we measured glacier surface elevations and terminus positions for Jakobshavn Isbræ, West Greenland, using historical photographs acquired in 1944, 1953, 1959, 1964 and 1985. These results were combined with data from historical records, aerial photographs, ground surveys, airborne laser altimetry and field mapping of lateral moraines and trimlines, to reconstruct the history of changes since the Little Ice Age (LIA). We identified three periods of rapid thinning since the LIA: 1902–13, 1930–59 and 1999–present. During the first half of the 20th century, the calving front appears to have been grounded and it started to float during the late 1940s. The south and north tributaries exhibit different behavior. For example, the north tributary was thinning between 1959 and 1985 during a period when the calving front was stationary and the south tributary was in balance. The record of intermittent thinning, combined with changes in ice-marginal extent and position of the calving front, together with changes in velocity, imply that the behavior of the lower parts of this glacier represents a complex ice-dynamical response to local climate forcings and interactions with drainage from the interior.
Combined oceanic and atmospheric influences on net accumulation on Devon Ice Cap, Nunavut, Canada
Authors: Colgan William , Sharp Martin
Published: May 2008

An annual net accumulation history of the high-elevation region of Devon Ice Cap, Nunavut, Canada, was reconstructed for the period 1963–2003 using five shallow firn cores. Annual net accumulation decreased significantly after 1989. To explain variability in the reconstructed annual net accumulation record, monthly and seasonal moisture-source probabilities were calculated for gridcells throughout the Arctic during 1979–2003. Seasonally, moisture-source probabilities reach a maximum in northern Baffin Bay in late summer/early fall and approach zero throughout the Arctic in winter. Late-summer/early-fall moisture-source probabilities were significantly higher around the North Open Water (NOW) Polynya during the 4 year period of highest annual net accumulation during the 1979–2003 period (1984–87), than during the 4 year period with the lowest annual net accumulation (1994–97). This is due to both a significant decrease in the sea-ice fraction and a significant increase in low-elevation atmospheric transport over the NOW area during the high net accumulation period. Anomalously low net accumulation and anomalously high firnification rates during the 1989–2003 period suggest that a change in ice dynamics, rather than a change in surface mass balance, may explain recent ice-cap thickening observed by laser altimetry.
Preparation, Characterization, and Application of L‐Cysteine Functionalized Multiwalled Carbon Nanotubes as a Selective Sorbent for Separation and Preconcentration of Heavy Metals
Authors: Liu Yue , Li Yan , Yan Xiu‐Ping
Published: May 2008

L‐cysteine functionalized multi‐walled carbon nanotubes (MWCNTs‐cysteine) are synthesized and characterized by XPS, FT‐IR, XRD, and TEM. The capability of MWCNTs‐cysteine for selective separation and preconcentration of heavy metal ions are statically and dynamically evaluated with Cd2+ as a model heavy metal ion. Unlike MWCNTs, the sorption of Cd2+ onto MWCNTs‐cysteine is not influenced by ionic strength in a wide range. The MWCNTs‐cysteine is demonstrated to be good column packings for on‐line microcolumn separation and preconcentration of Cd2+. Effective preconcentration of Cd2+ on the MWCNTs‐cysteine packed microcolumn is achieved in a pH range of 5.5 to 8.0. The retained Cd2+ is efficiently eluted with 0.5 mol L−1 HCl for on‐line flame atomic absorption spectrometric determination. The MWCNTs‐cysteine exhibit fairly fast kinetics for the adsorption of Cd2+, and offer up to 1600‐fold improvement of the tolerable concentrations of co‐existing metal ions over the MWCNTs for on‐line solid‐phase extraction of Cd2+. With a preconcentration time of 60 s at a sample loading flow rate of 5.0 mL min−1, an enhancement factor of 33 and a sample throughput of 36 h−1 along with a detection limit (3s) of 0.28 µg L−1 are obtained. The precision (RSD) for 11 replicate measurements is 1.6% at the 10 µg L−1 level. The developed method using the MWCNTs‐cysteine as sorbent is successfully applied to determination of trace cadmium in a variety of biological and environmental materials.
Inflammatory markers and secondhand tobacco smoke exposure among U.S. workers
Authors: Clark John D. , Wilkinson James D. , LeBlanc William G. , Dietz Noella A. , Arheart Kristopher L. , Fleming Lora E. , Lee David J.
Published: May 2008

Background

Self‐reported exposure to secondhand smoke (SHS) has been associated with elevated inflammatory markers in adults. The association between SHS indicated by serum cotinine and markers of inflammation has not been investigated in adult workers.

Methods

Using the subpopulation of employed participants (20 years and older) who were non‐smokers and denied home SHS exposure from the National Health and Nutrition Examination Survey (NHANES) 1999–2002, the association between serum cotinine and inflammatory markers (C‐reactive protein, fibrinogen, homocysteine, and white blood cells) was analyzed. Inflammatory marker values were log‐transformed and expressed as geometric means with 95% confidence intervals (CI). Serum cotinine was categorized as either no cotinine (below the detection limit), low cotinine (above the detection limit and <0.2 ng/ml), or high cotinine (≥0.2 and <15.0 ng/ml). The association between serum cotinine and inflammatory markers was analyzed using univariate and multivariate‐adjusted linear regression.

Results

Geometric mean serum cotinine was significantly higher among non‐smokers reporting SHS exposure in the workplace (0.17 vs. 0.10 ng/ml, P < 0.01). Workers exposed to low and high levels of cotinine had significantly higher homocysteine levels relative to non‐exposed workers; mean homocysteine differences remained significant in the multivariable model (i.e., 0.363 and 0.491 mg/dl increase, respectively).

Conclusion

Exposure to SHS as measured by serum cotinine may result in increased homocysteine levels among adult workers. These results provide further evidence in support of universal workplace smoking restrictions in order to protect worker health. Further research is required to determine the adverse effects of workplace SHS exposure on cardiovascular risk. Am. J. Ind. Med. 51:626–632, 2008. © 2008 Wiley‐Liss, Inc.
A new look at XXYY syndrome: Medical and psychological features
Authors: Tartaglia Nicole , Davis Shanlee , Hench Alison , Nimishakavi Sheela , Beauregard Renee , Reynolds Ann , Fenton Laura , Albrecht Lindsey , Ross Judith , Visootsak Jeannie , Hansen Robin , Hagerman Randi
Published: May 2008

XXYY syndrome occurs in approximately 1:18,000–1:40,000 males. Although the physical phenotype is similar to 47,XXY (tall stature, hypergonadotropic hypogonadism, and infertility), XXYY is associated with additional medical problems and more significant neurodevelopmental and psychological features. We report on the results of a cross‐sectional, multi‐center study of 95 males age 1–55 with XXYY syndrome (mean age 14.9 years), describing diagnosis, physical features, medical problems, medications, and psychological features stratified by age groups. The mean age of diagnosis was 7.7 years. Developmental delays and behavioral problems were the most common primary indication for genetic testing (68.4%). Physical and facial features varied with age, although hypertelorism, clinodactyly, pes planus, and dental problems were common across all age groups. Tall stature was present in adolescents and adults, with a mean adult stature of 192.4 cm (SD 7.5; n = 22). Common medical problems included allergies and asthma (>50%), congenital heart defects (19.4%), radioulnar synostosis (17.2%), inguinal hernia and/or cryptorchidism (16.1%), and seizures (15%). Medical features in adulthood included hypogonadism (100%), DVT (18.2%), intention tremor (71%) and type II diabetes (18.2%). Brain MRI (n = 35) showed white matter abnormalities in 45.7% of patients and enlarged ventricles in 22.8%. Neurodevelopmental and psychological difficulties were a significant component of the behavioral phenotype, with developmental delays and learning disabilities universal but variable in severity. Twenty‐six percent had full‐scale IQs in the range of intellectual disability (MR), and adaptive functioning was significantly impacted with 68% with adaptive composite scores <70. Rates of neurodevelopmental disorders, including ADHD (72.2%), autism spectrum disorders (28.3%), mood disorders (46.8%), and tic disorders (18.9%), were elevated with 55.9% on psychopharmacologic medication overall. Recommendations for evaluation and treatment are summarized. © 2008 Wiley‐Liss, Inc.
Synthesis and characterization of thermally stable polymers (polybenzimidazoles)
Authors: Özaytekin İlkay , Karataş İbrahim
Published: May 2008

In this study, an alternative synthesis of polybenzimidazoles was performed with aromatic hydroxamoyl chloride. In contrast to the literature, polybenzimidazoles were obtained through the reaction of hydroxamoyl chlorides with 3,3′‐diaminobenzidine or 1,2,4,5‐tetraaminobenzene. The characterization of the polymers was performed with Fourier transform infrared, 1H‐NMR, elemental analysis, LC mass spectrometry, and differential thermogravimetry/thermogravimetric analysis. Finally, the adhesion, corrosion resistance, and conducting properties of the synthesized polymers were examined. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Gene cloning and expression analysis of ubiquitin derived from Musca domestica
Authors: Ren Qian , Zhang Wei , Zhao Xiao‐Fan , Wang Jin‐Xing
Published: May 2008

Ubiquitin (Ub) is a highly conserved 8‐kDa protein that was first identified as a tag for protein degradation. Recently, its role in nonproteolytic cellular processes such as DNA repair and endocytosis has also been reported. An ubiquitin‐fusion gene was cloned from Musca domestica. The complete length of this ubiquitin‐fusion gene is 531 bp, of which 471 bp is an open reading frame (ORF) encoding a 156‐amino acid peptide, and 60 bp is a 3′‐untranslated region with the polyadenylation sequence AATAAA and a poly(A) tail. The ubiquitin‐fusion protein includes an ubiquitin monomer of 76 amino acids with a 6‐amino acid motif (LRLRGG) and 3 conserved lysine functional sites, which participate in the formation of the ubiquitin–protease complex. The ubiquitin‐fusion protein also contains an 80‐amino acid carboxyl extension protein, namely, ribosomal protein S27 with a classical zinc finger motif C‐X4‐C‐X14‐C‐X2‐C. Because of its carboxyl extension protein S27, the M. domestica ubiquitin‐fusion protein was named MubS27. It has a predicted molecular weight of 18 kDa and a theoretical isoelectric point of 9.82. No signal peptides were predicted for the protein. Northern blot analysis revealed that MubS27 transcript level is higher at the embryo stage than that at any other developmental stages. When houseflies develop into 5‐day pupae, the Ub mRNA level is relatively low. After infection with gram‐negative and gram‐positive bacteria, MubS27 transcript level was upregulated. MubS27 transcript level was also regulated by heat or cold stress. Arch. Insect Biochem. Physiol. 68:89–99, 2008. © 2008 Wiley‐Liss, Inc.