bluuebunny/crossref_metadata_2025 huggingface dataset:
Orexin A modulates neuronal activity of the rodent suprachiasmatic nucleus in vitro
Authors: Klisch C. , Inyushkin A. , Mordel J. , Karnas D. , Pévet P. , Meissl H.
Published: June 2009

In mammals, as in rats and mice used in the present study, the major internal timekeeping mechanism is located in the suprachiasmatic nucleus (SCN). It is composed of a complex tissue of multiple, individual oscillator cells that drive numerous physiological and endocrine processes via an electrical and humoral output. Several afferent input systems can interact with the clock mechanism and lead to phase‐resetting actions. The recent discovery of orexin‐containing fibers in the SCN region and the presence of orexin receptors in the SCN prompted us to investigate the possible role of orexin in the SCN. Multielectrode array recordings from dispersed SCN neurons revealed that orexin A dose‐dependently enhanced the extracellularly recorded neuronal activity of many neurons (38%), whereas other neurons were inhibited (28%). The influence of orexin A on neuronal activity in the SCN was confirmed by whole‐cell patch‐clamp recordings from brain slices and dispersed cell cultures. Orexin A caused significant changes in the frequency but not mean amplitude or decay time constant of spontaneous inhibitory postsynaptic currents (sIPSCs). Low concentrations of orexin evoked an increase of sIPSCs, whereas the highest concentration predominantly caused a decrease of sIPSCs. The effects of orexin A on inhibitory postsynaptic currents were prevented by the orexin 1 receptor antagonist SB 334867 and also reduced in the presence of tetrodotoxin. Long‐term recordings of the discharge rate of SCN neurons revealed that orexin A is able to induce phase shifts in cultured SCN neurons as well as in organotypic brain slices.
Body mass index is not a prognostic marker for prostate‐specific antigen failure and survival in Dutch men treated with brachytherapy
Authors: Van Roermund Joep G.H. , Hinnen Karel A. , Battermann Jan J. , Witjes J. Alfred , Bosch J.L.H. Ruud , Kiemeney Lambertus A. , Van Vulpen Marco
Published: June 2009

Study Type – Prognosis (case series)

Level of Evidence 4

OBJECTIVE

To examine the relationship between body mass index (BMI) and biochemical recurrence (BCR), cancer‐specific (CSS) and overall survival (OS) in men treated with permanent prostate brachytherapy (PPB), as there is limited information on the affect of obesity on treatment outcomes for prostate cancer.

PATIENTS AND METHODS

In all, 1530 patients with clinically localized prostate cancer who underwent PPB were studied. Clinical and pathological data were retrospectively obtained from medical records. The BMI was classified as normal (<25 kg/m2), overweight (25–30 kg/m2) and obese (≥30 kg/m2). BCR was defined as a rise in PSA levels of ≥2 ng/mL after the nadir had been reached. The cause of death was determined for each deceased patient. Patients with metastatic prostate cancer who died of any cause were classified as prostate cancer deaths.

RESULTS

In all, 617 (40%) patients were classified as having a normal weight, 754 (49%) overweight and 159 (10%) were obese. The Kaplan–Meier 8‐year risk of BCR (95% confidence interval) was 33.3% (27.2–39.4), 29.2% (23.5–34.9) and 29.3% (12.4–46.2) for patients with a BMI of <25 kg/m2, 25–30 kg/m2 and ≥30 kg/m2, respectively. The 8‐year CSS was 88.2% (83.1–93.3), 88.6% (83.7–93.5) and 90.6% (79.9–101.4) and the 8‐year OS was 70.1% (63.6–76.6), 72.9% (66.6–79.2) and 81.8% (69.3–94.3) for these three groups, respectively. Multivariate proportional hazard regression analyses of BMI and established prognostic factors for BCR confirmed the absence of any prognostic value of BMI on BCR, CSS and OS.

CONCLUSIONS

BMI did not appear to have any prognostic value for BCR, CCS or OS in patients with clinically localized prostate cancer treated with PPB.
Investigating spontaneous attributions in mothers of individuals with intellectual disabilities and self‐injurious behaviour
Authors: Drysdale Emma E. , Jahoda Andrew , Campbell Elizabeth
Published: June 2009

Accessible summary

Mothers had many different explanations of why their children with intellectual disabilities hurt themselves and often weren’t hopeful that it would stop.

Some of the mothers felt they could sometimes help with their children’s behaviour and this helped with feelings of stress.

Professionals helping people with intellectual disabilities who hurt themselves need to listen more to what their families think and feel.

Mothers’ attributions of self injurious behaviour (SIB) in their children with intellectual disability have been largely ignored. However, attributions may predict maternal well‐being and engagement in treatment. Thirteen mothers of people who self‐injured were recruited. A qualitative design was employed, the data being subjected to thematic analysis according to Braun & Clarke’s (2006) guidelines. Weiner’s (1980) attributional model informed development of semi‐structured interviews, to explore the nature and content of their views about SIB. The mothers’ attributions were consistent with dimensions of locus of cause, stability and controllability. They held different, sometimes contradictory views about causes of SIB. Although pessimistic regarding long‐term improvement and often uncomfortable with interventions suggested by professionals, some felt able to exercise limited control over their offsprings’ SIB. Control was also linked to stress, and a sense of responsibility when there was inadequate support. Sensitive, effective professional support for individuals engaging in SIB requires collaboration with carers, and understanding carers’ views and feelings.
Functional anatomy of the gibbon forelimb: adaptations to a brachiating lifestyle
Authors: Michilsens Fana , Vereecke Evie E. , D'Août Kristiaan , Aerts Peter
Published: June 2009

It has been shown that gibbons are able to brachiate with very low mechanical costs. The conversion of muscle activity into smooth, purposeful movement of the limb depends on the morphometry of muscles and their mechanical action on the skeleton. Despite the gibbon's reputation for excellence in brachiation, little information is available regarding either its gross musculoskeletal anatomy or its more detailed muscle–tendon architecture. We provide quantitative anatomical data on the muscle–tendon architecture (muscle mass, physiological cross‐sectional area, fascicle length and tendon length) of the forelimb of four gibbon species, collected by detailed dissections of unfixed cadavers. Data are compared between different gibbon species and with similar published data of non‐brachiating primates such as macaques, chimpanzees and humans. No quantitative differences are found between the studied gibbon species. Both their forelimb anatomy and muscle dimensions are comparable when normalized to the same body mass. Gibbons have shoulder flexors, extensors, rotator muscles and elbow flexors with a high power or work‐generating capacity and their wrist flexors have a high force‐generating capacity. Compared with other primates, the elbow flexors of gibbons are particularly powerful, suggesting that these muscles are particularly important for a brachiating lifestyle. Based on this anatomical study, the shoulder flexors, extensors, rotator muscles, elbow flexors and wrist flexors are expected to contribute the most to brachiation.
Maternal age‐specific risk of non‐chromosomal anomalies
Authors: Loane M , Dolk H , Morris JK ,   a EUROCAT Working Group
Published: June 2009

Objectives  To determine the excess risk of non‐chromosomal congenital anomaly (NCA) among teenage mothers and older mothers.

Design and setting  Population‐based prevalence study using data from EUROCAT congenital anomaly registers in 23 regions of Europe in 15 countries, covering a total of 1.75 million births from 2000 to 2004.

Participants  A total of 38 958 cases of NCA that were live births, fetal deaths with gestational age ≥20 weeks or terminations of pregnancy following prenatal diagnosis of a congenital anomaly.

Main outcome measures  Prevalence of NCA according to maternal age, and relative risk (RR) of NCA and 84 standard NCA subgroups compared with mothers aged 25–29.

Results  The crude prevalence of all NCA was 26.5 per 1000 births in teenage mothers (<20 years), 23.8 for mothers 20–24 years, 22.5 for mothers 25–29 years, 21.5 for mothers 30–34 years, 21.4 for mothers 35–39 years and 22.6 for mothers 40–44 years. The RR adjusted for country for teenage mothers was 1.11 (95% CI 1.06–1.17); 0.99 (95% CI 0.96–1.02) for mothers 35–39; and 1.01 (95% CI 0.95–1.07) for mothers 40–44. The pattern of maternal age‐related risk varied significantly between countries: France, Ireland and Portugal had higher RR for teenage mothers, Germany and Poland had higher RR for older mothers. The maternal age‐specific RR varied for different NCAs. Teenage mothers were at a significantly greater risk (P < 0.01) of gastroschisis, maternal infection syndromes, tricuspid atresia, anencephalus, nervous system and digestive system anomalies while older mothers were at a significantly greater risk (P < 0.01) of fetal alcohol syndrome, encephalocele, oesophageal atresia and thanatophoric dwarfism.

Conclusions  Clinical and public health interventions are needed to reduce environmental risk factors for NCA, giving special attention to young mothers among whom some risk factors are more prevalent. Reassurance can be given to older mothers that their age in itself does not confer extra risk for NCA.
Range expansion by invasive marine algae: rates and patterns of spread at a regional scale
Authors: Lyons Devin A. , Scheibling Robert E.
Published: June 2009

Aim Introduced macroalgae are widespread in the world’s oceans and, despite increasing awareness and attempts to limit the phenomenon, the number of species introductions in coastal waters has increased exponentially over time. Little is known about the rates and mechanisms of spread, even among species that have received the most attention. We compare patterns of range expansion for nine species of invasive algae across eight geographic regions.

Location World‐wide.

Methods We compiled records of introduced algae from the scientific literature, herbaria, and by contacting experts to reconstruct chronologies for 22 algal invasions. These were used to map patterns of spread at a regional scale (thousands of km).

Results Range size tended to increase linearly with time, often after an initial lag. Range expansion occurred at rates of tens to hundreds of kilometres per year, often with large infrequent increases. Rates of range expansion differed significantly between species within the same region, and between regions for the same species.

Main conclusions Our results suggest that anthropogenic vectors likely play a key role in the spread of introduced macroalgae at a regional scale, although natural long‐distance dispersal also may be important for some species. The lack of consistency in the rates within individual species and regions suggests that multiple interacting factors (e.g. algal traits, characteristics of invaded communities, environmental conditions and anthropogenic activities) determine where propagules of introduced algae are delivered and whether they become established.
Legislative agenda‐setting in parliamentary democracies
Authors: BRÄUNINGER THOMAS , DEBUS MARC
Published: June 2009

Various strands of literature in comparative politics regard governments as the only noteworthy initiators and mainsprings of legislative policy making in parliamentary democracies. Opposition activity in policy making is more often associated with the intention to prevent, rather than to shape, policy. Does this perception reflect real‐life politics? To answer this question, this article discusses different arguments that link institutional and policy‐related characteristics to the incentives and constraints of different government and parliamentary actors to initiate or co‐sponsor legislative bills. More specifically, it relates policy‐, office‐ and vote‐related incentives, as well as institutional and resource constraints of legislative actors, to the likelihood that these actors will take the lead in legislative agenda‐setting. These arguments are confronted with original data on the universe of all legislative bills in four parliamentary systems over one and a half decades. The article concludes that opposition and, in particular, bipartisan agenda‐setting is indeed rare. Yet, in contrast to widely held maxims, it is neither absent nor spurious, but related to the allocation of power and the intensity of ideological conflict both within and between the (coalition) government and parliament.
Combination of 308‐nm Excimer Laser With Topical Pimecrolimus For the Treatment of Childhood Vitiligo
Authors: HUI‐LAN YANG , XIAO‐YAN HUANG , JIAN‐YONG FAN , ZONG‐RONG LIU
Published: June 2009

Abstract:  Forty‐nine patients enrolled in a single‐blinded, randomized, comparing 308‐nm excimer laser therapy together with topical 1% pimecrolimus cream twice daily (group A) with excimer laser therapy twice per week (group B). Of 48 patients evaluated after 30 weeks of treatment, 71% of patients from group A achieved Grade 3 or 4 repigmentation compared with 50% in group B. Significant difference was found between group A and B at the end of 30 weeks of treatment (p = 0.001).
Acquired Cutis Laxa in Childhood Sweet’s Syndrome
Authors: TIMMER‐DE MIK L. , BROEKHUIJSEN‐VAN HENTEN D.M. , OLDHOFF J.M. , DE GEER D.B. , SIGURDSSON V. , PASMANS S.G.M.A.
Published: June 2009

Abstract:  In Sweet’s syndrome, the essential features are the characteristic morphology of the lesions, their histologic appearance, the dramatic response to corticosteroids and the absence of scarring. We report an 8‐month‐old infant in whom Sweet’s syndrome was diagnosed and who developed acquired cutis laxa in the skin lesions.
Macrocephaly‐Capillary Malformation: A Report of Three Cases and Review of the Literature
Authors: Gonzalez Mercedes E. , Burk Cynthia J. , Barbouth Deborah S. , Connelly Elizabeth Alvarez
Published: June 2009

Abstract:  Macrocephaly‐Cutis Marmorata Telangiectatica Congenita (M‐CMTC) is a rare syndrome that was first delineated as distinct from Cutis Marmorata Telangiectatica Congenita (CMTC) in 1997. Since that time, there have been over 75 cases reported in the literature, though few are in the dermatology literature. The syndrome is characterized by macrocephaly, neonatal hypotonia, developmental delay, segmental overgrowth, syndactyly, asymmetry, connective tissue defects, and vascular stains. We report three new patients seen at the University of Miami Genodermatoses Clinic with features of M‐CMTC. We believe the skin findings in our patients and in the previously published cases of M‐CMTC are more consistent with capillary malformations rather than true CMTC. Therefore, we agree with recent publications that this condition be renamed Macrocephaly‐Capillary Malformation (M‐CM). The differential diagnoses for patients with M‐CMTC include Klippel Trenaunay Syndrome (KTS) and Proteus or Proteus‐like syndromes. Given the significant prognostic and likely genetic differences among these conditions it is important to distinguish M‐CMTC from these syndromes.
Hypertrophic Scarring is the Usual Outcome of Non‐Membranous Aplasia Cutis of the Scalp
Authors: CAMBIAGHI STEFANO , MAFFEIS LAURA , RESTANO LUCIA , GELMETTI CARLO
Published: June 2009

Abstract:  The outcome of aplasia cutis congenita of the scalp, nonmembranous type, in a series of 21 Caucasian patients is reported. In all the patients the congenital skin defect healed with irregular hypertrophic scar formation.
The Relationship BetweenSerotonin Receptor 1B Polymorphisms A‐161Tand Alcohol Dependence
Authors: Lee Sheng‐Yu , Lin Wei‐Wen , Huang San‐Yuan , Kuo Po‐Hsiu , Wang Chen‐Lin , Wu Pei‐Lin , Chen Shiou‐Lan , Wu Jo Yung‐Wei , Ko Huei‐Chen , Lu Ru‐Band
Published: June 2009

Background: Several studies have suggested that theserotonin receptor 1Bgene (5HT1B) may be important in the pathogenesis of alcohol dependence (alcoholism; ALC; AD). We examined whether5HT1BgeneA‐161Tpolymorphisms (rs130058) are a susceptibility factor for total AD and subgroups of AD. We further explored correlation of this5HT1Bgene variant between anxiety–depression alcoholism (ANX/DEP ALC) and antisocial alcoholism (antisocial ALC) subgroups because of the high comorbidity of anxiety–depression, antisocial personality disorder, and AD.

Methods: We recruited 522 Han Chinese in Taiwan for this study: 322 AD patients and 200 controls. The patient group was recruited primarily from medical teaching hospitals; patients with antisocial alcoholism were recruited from Taiwanese prisons. Individuals with AD were classified into 3 homogeneous clinical subgroups—pure alcoholism (pure ALC), ANX/DEP ALC, and antisocial ALC—using DSM‐IV diagnosis. The5HT1BgeneA‐161Tpolymorphism was determined using PCR–RFLP.

Results: No significant differences in genotypic and allelic frequencies were found between controls and the total AD group or between controls and the 3 AD subgroups. However, there were significant differences in the5HT1BgeneA‐161Tpolymorphism at both the genotype and allelic levels between the ANX/DEP ALC and antisocial ALC subgroups.

Conclusions: This study suggests that the5HT1BgeneA‐161Tpolymorphism alone is not a risk factor for increasing susceptibility to either AD or its subtypes. However,5HT1BgeneA‐161Tpolymorphisms might be one of the common genetic factors between the ANX/DEP ALC and antisocial ALC subgroups.
Transfusion safety on the African continent: an international quality control of virus testing in blood banks
Authors: Laperche Syria , Boukatou Geneviève , Kouegnigan Léonard , Nébié Yacouba , Boulahi Mohamed Ould , Tagny Claude Tayou , Yahaya Rakia , Tapko Jean‐Baptiste , Murphy Edward , Lefrère Jean Jacques
Published: June 2009

BACKGROUND: Following World Health Organization recommendations that a quality control (QC) system be implemented in African blood centers, a pilot study of the performance of human immunodeficiency virus antibody (anti‐HIV), hepatitis B surface antigen (HBsAg), and hepatitis C virus antibody (anti‐HCV) testing by several Sub‐Saharan African blood centers was initiated.

STUDY DESIGN AND METHODS: A reference laboratory sent a panel of 25 samples to six African blood center laboratories. The panel included eight negative samples; four anti‐HIV‐1–, one anti‐HIV‐2–, four anti‐HCV–, and five HBsAg‐positive samples; and three samples consisting of mixtures of two sera to mimic coinfections. Sensitivity, specificity, and overall quality (correct positive or negative status) scores were calculated.

RESULTS: From the 21 sets of results obtained (seven for each virus), eight were from rapid tests (two for HIV, three for HBV, and three for HCV) and 13 were from enzyme immunoassays (EIAs; all HIV EIAs were antigen/antibody combination assays). Overall assay sensitivity was 98% for HIV, 75% for HBV, and 88% for HCV; agreement between blood centers using the same assay was good. Sensitivity of rapid tests was notably poorer than EIAs, with overall sensitivity quality scores of 64.5% for rapid tests (20% for HBsAg rapid tests) compared to 100% for EIAs. The overall specificity quality scores were 98.3 and 94.5% for EIAs and rapid tests, respectively.

CONCLUSIONS: This pilot QC study organized for blood centers of Sub‐Saharan Africa showed the feasibility of the approach despite some logistic constraints. Although interlaboratory variability was small, the poor performance of rapid tests, especially for HBsAg, raises policy questions about their use as the only screening assay.
Master Sintering Curve Formulated from Constitutive Models
Authors: Park Seong Jin , Suri Pavan , Olevsky Eugene , German Randall M.
Published: June 2009

The classical master sintering curve (MSC) is derived from empirical sintering model and is applicable over a range of heating rates and temperatures. For simplicity, the MSC approach was modified by assuming one dominant densification mechanism to evaluate and predict densification response. However, the concept of MSC can be extended well beyond the original formulation or the subsequent simplifications. To this effect, generalized formulations are proposed based on several constitutive equations including both grain growth and densification. These formulations can be used very effectively to obtain material properties that in turn can be used in finite‐element method to improve the accuracy of the simulations.
Optimizing the mix of basic dental services for Southern Thai schoolchildren based on resource consumption, service needs and parental preference
Authors: Tianviwat Sukanya , Chongsuvivatwong Virasakdi , Birch Stephen
Published: June 2009

Abstract – 

Objectives:  To identify the optimal levels and mix of basic dental services (sealants and fillings for permanent teeth and extraction of primary teeth) under two different dental settings: hospital‐based and mobile dental clinics under specified resource constraints.

Methods:  A linear programming model is used based on explicit identification of system objectives and resource constraints. The objective was to maximize benefits as measured by parental willingness to pay (WTP) for basic dental services provided to schoolchildren subject to constraints on total resources, service need and parental preferences among different dental care settings.

Results:  Optimization was identified to require 270, 180, 552, 828, 228 and 532 cases of hospital sealant, mobile sealant, hospital filling, mobile filling, hospital extraction and mobile extraction, respectively. The corresponding current service levels were 48, 281, 191, 170, 479, and 677 respectively. The optimal service configuration produced a total WTP of 485 860 baht which exceeded the WTP for the current service configuration by more than 75.4%.

Conclusions:  Mobile clinic fillings were the highest priority among basic dental services. The current service configurations fail to reflect the setting preferences and provide greater emphasis to extractions than the optimal configuration with less emphasis given to preventive and restorative services.
Do different ethnic groups need different sun protection?
Authors: Antoniou Christina , Lademann Juergen , Schanzer Sabine , Richter Heike , Sterry Wolfram , Zastrow Leonhard , Koch Stefan
Published: June 2009

Background: In the present study, the transmission of sunlight trough the human skin barrier into the living tissue was investigated in the spectral region between 280 and 700 nm.

Methods: The experiments were performed with a fiber‐based spectrometer on sliced skin obtained from volunteers with different skin types. One fiber was positioned directly on the skin surface and the second one underneath the skin samples. The distribution of the sunlight under the epidermis was determined.

Results: Significant differences were found in the absorption properties of the different skin types, which were mainly determined by the variations in melanin concentration and distribution. It was found that sunscreens for specific ethnic groups need different combinations of UV filters, if a balanced relation between ultraviolet B (UVB) and ultraviolet A (UVA) protection is to be obtained. On the other hand, it could be demonstrated that the human skin is also well protected against visible and near‐infrared light by melanin.

Conclusions: The higher the skin type category, the better the protection in the visible part of the spectrum of the sun. This stimulates the hot discussion at the present time, as to whether sunscreens should also contain protection compounds in the visible and near‐infrared parts of the spectrum.
ORIGINAL ARTICLE: The Role of IL‐6, IL‐10, TNF‐α and its Receptors TNFR1 and TNFR2 in the Local Regulatory System of Normal and Impaired Human Spermatogenesis
Authors: Białas Małgorzata , Fiszer Dorota , Rozwadowska Natalia , Kosicki Włodzimierz , Jedrzejczak Piotr , Kurpisz Maciej
Published: June 2009

Problem  To investigate the expression of genes coding for selected cytokines with antagonistic functions (IL‐6, IL‐10, TNF‐α) as well as TNF‐α receptors (TNFR1 and TNFR2) in correct spermatogenesis (normal proliferation), maturation arrest (proliferation inhibited) and testicular tumors (overgrowth).

Method of study  Transcription levels of genes coding for IL‐6, IL‐10, TNF‐α, TNFR1 and TNFR2 were quantitatively examined using a real‐time RT‐PCR.

Results  Significantly higher amounts of IL‐6 mRNA were observed in testicular tumor samples than in normal spermatogenesis or in some syndromes with maturation arrest (MA at spermatid level or SCOS), while IL‐10 gene levels were fairly stable. In homogenates with maturation arrest, the expression of TNFR1 gene was markedly higher than in testicular tumors, while the opposite phenomenon was found in respect to TNFR2 gene.

Conclusion  The results obtained indicate that changes in activities of intra‐testicular cytokines may promote different distinct pathologies such as testicular cancer or infertility.
On the common mass scale of the Milky Way satellites
Authors: Li Yang-Shyang , Helmi Amina , De Lucia Gabriella , Stoehr Felix
Published: June 2009

We use a hybrid approach that combines high-resolution simulations of the formation of a Milky Way-like halo with a semi-analytic model of galaxy formation to study the mass content of dwarf galaxies in the concordance Λ cold dark matter cosmology. We find that the mass within 600 pc of dark matter haloes hosting luminous satellites has a median value of ∼3.2 × 107 M⊙ with very little object-to-object scatter. In contrast, the present-day total luminosities of the model satellites span nearly five orders of magnitude. These findings are in very good agreement with the results recently reported in the literature for the dwarf spheroidal galaxies of the Milky Way. In our model, dwarf irregular galaxies like the Small Magellanic Cloud, are predicted to have similar or slightly larger dark matter mass within 600 pc.
Molecular Changes in White Matter Adjacent to an Active Demyelinating Lesion in Early Multiple Sclerosis
Authors: Zeis Thomas , Probst Alfonse , Steck Andreas Johann , Stadelmann Christine , Brück Wolfgang , Schaeren‐Wiemers Nicole
Published: June 2009

A stereotactic biopsy of a 17‐year‐old woman revealed an active inflammatory demyelinating lesion compatible with pattern III multiple sclerosis (MS) according to Lucchinetti et al. The biopsy included a white matter region distant from the active inflammatory demyelinating lesion with abnormal MRI signal, lacking histopathological signs of demyelination and/or oligodendrocyte apoptosis. Expression analysis of this area revealed a strong up‐regulation of neuronal nitric oxide synthase (nNOS). Furthermore, detection of nitrotyrosine provided evidence for reactive nitrogen species (RNS)‐mediated damage to oligodendrocytes. Concomitantly, genes involved in neuroprotection against oxidative stress such as heme oxygenase 1 were up‐regulated. Even though a single case report, this study shows earliest molecular changes in white matter surrounding an actively demyelinating lesion during the first manifestation of MS, pointing toward a more widespread pathological process. Therapeutic targeting of the identified mechanisms of tissue injury might be crucial to prevent further lesion formation or secondary tissue damage.
Fluid Evolution and Metallogenic Dynamics during Tectonic Regime Transition: Example from the Jiapigou Gold Belt in Northeast China
Authors: Deng Jun , Yang Liqiang , Gao Bangfei , Sun Zhongshi , Guo Chunying , Wang Qingfei , Wang Jianping
Published: June 2009

The Jiapigou gold belt, one of the most important gold‐producing districts in China, is located in the northern margin of the North China Craton (NCC). The tectonic evolution of the gold belt is closely related to the Siberian Plate (SP) in the north, Yangtze Craton (YC) in the south and Pacific Plate in the east. In order to investigate the nature of the tectono‐fluid‐metallogenic system, the authors investigated the relationships among the tectonic regimes, fluid evolution and metallogenesis. This paper examined the corresponding spatial–temporal relationship between the ore‐controlling tectonic regime and hydrothermal fluid evolution in the Jiapigou gold belt. There are two types of gold mineralization: disseminated ores that are distributed within the NW‐trending main ductile shear zone and gold‐bearing quartz veins and minor disseminated ores that are distant to the ductile shear zone. The fluid inclusions in quartz contain a large amount of CO2. Metamorphic fluids of middle to high temperatures and pressures and meteoric waters of low temperatures and pressures mixed together during mineralization. A proposed ore‐forming model is as follows: in the pre‐ore phase, the collision of SP and NCC resulted in the NS‐trending compression of the ore belt. This formed the NE‐trending and NW‐trending shear faults and EW‐trending folds. During the ore‐forming phase, the collision of YC and NCC resulted in dextral shearing of the NW‐trending Jiapigou fault and the NE‐trending Green faults. High‐pressure fluids caused by the compression flowed into the dilatant zone. This may have caused both phase separation of CO2‐bearing fluids and the mixing of meteoric waters, metamorphic waters and magmatic source fluids and finally resulted in the disequilibrium of the ore fluids and precipitation of ore minerals.
Geology and Lead‐Isotope Study of the Baiyinnuoer Zn‐Pb‐Ag Deposit, South Segment of the Da Hinggan Mountains, Northeastern China
Authors: Zeng Qingdong , Liu Jianming , Zhang Zuolun , Jia Changshun , Yu Changming , Ye Jie , Liu Hongtao
Published: June 2009

The Baiyinnuoer deposit (32.74 Mt ore with grades of 5.44% Zn, 2.02% Pb and 31.36 g t−1 Ag), the largest Zn‐Pb‐Ag deposit in northern China, is hosted by crystalline limestone and slate of the Early Permian Huanggangliang Formation. Detailed cross‐section mapping indicates stratigraphic and fold structural controls on the mineralization. The Zn‐Pb‐Ag mineralization is hosted predominantly by skarn, which occurs as bedding‐parallel lens that pinch out at the margins of the main economic zone. Three skarn stages are identified at the deposit: (i) garnet‐clinopyroxene; (ii) sulfides; and (iii) carbonate‐epidote. Lead isotopic compositions were determined for galena and sphalerite of the ores, whole rock samples of the Yanshanian granite and granodiorite, Permian marble and tuff, and Jurassic volcanic and subvolcanic rocks in and around the Baiyinnuoer area in order to discuss the sources of ore‐forming materials and the relationship between the ore formation and these whole rocks. Galena and sphalerite of the Baiyinnuoer ore have uniform isotopic ratios (206Pb/204Pb, 18.267–18.369; 207Pb/204Pb, 15.506–15.624; 208Pb/204Pb, 38.078–38.394) consistent with the granite and granodiorite (206Pb/204Pb, 18.252–18.346; 207Pb/204Pb, 15.504–15.560; 208Pb/204Pb, 38.141–38.320), whereas the ratios for Jurassic volcanic and subvolcanic rocks are variable and radiogenic (206Pb/204Pb, 18.468–18.614; 207Pb/204Pb, 15.521–15.557; 208Pb/204Pb, 38.304–38.375). These results indicate that the mineralization was not related to the Jurassic volcanism, but to the Yanshanian magmatism. The Permian strata may have a slight contribution to the mineralization. All features show that the Baiyinnuoer deposit is related to the Yanshanian granitic magmatism, and can be classified as a zinc‐lead‐silver skarn deposit.
Ore‐Forming Fluid Characteristics of the Dayingezhuang Gold Deposit, Jiaodong Gold Province, China
Authors: Yang Liqiang , Deng Jun , Guo Chunying , Zhang Jing , Jiang Shaoqing , Gao Bangfei , Gong Qingjie , Wang Qingfei
Published: June 2009

The Dayingezhuang gold deposit is located in the central part of the Zhaoping Fault Zone, which is one of the most important gold‐hosting faults in the Jiaodong gold province of China. Dayingezhuang is a typical large‐scale shear zone‐hosted disseminated gold deposit with superimposed silver mineralization. Fluid inclusion (FI) petrography and microthermometry, and analysis of oxygen and hydrogen isotopes for fluid inclusions were conducted to determine the characteristics of the ore‐forming fluids and the processes of silver mineralization. Microthermometry data of FI indicated that ore‐forming fluids are characterized by low salinity and low density. Homogenization pressures of FI are estimated at 20 × 105–220 × 105 Pa. The change in ore‐forming fluids from K2SO4type to NaCl type indicates the superposition of two hydrothermal mineralizing events. Ore‐forming fluids were dominated by magmatic components in the early mineralization period, and affected by meteoric waters in the late period. Gold may have been transported as Au‐S or Au‐Cl complexes, whereas silver was transported as Ag‐Cl complexes. Early fluid boiling and later fluid mixing are thought to be two of the main factors causing the deposition and superimposing of gold and silver to form the large deposit.
Metabolic engineering of cobalamin (vitamin B12) production in Bacillus megaterium
Authors: Biedendieck Rebekka , Malten Marco , Barg Heiko , Bunk Boyke , Martens Jan‐Henning , Deery Evelyne , Leech Helen , Warren Martin J. , Jahn Dieter
Published: June 2009

Cobalamin (vitamin B12) production in Bacillus megaterium has served as a model system for the systematic evaluation of single and multiple directed molecular and genetic optimization strategies. Plasmid and genome‐based overexpression of genes involved in vitamin B12 biosynthesis, including cbiX, sirA, modified hemA, the operons hemAXCDBL and cbiXJCDETLFGAcysGAcbiYbtuR, and the regulatory gene fnr, significantly increased cobalamin production. To reduce flux along the heme branch of the tetrapyrrole pathway, an antisense RNA strategy involving silencing of the hemZ gene encoding coproporphyrinogen III oxidase was successfully employed. Feedback inhibition of the initial enzyme of the tetrapyrrole biosynthesis, HemA, by heme was overcome by stabilized enzyme overproduction. Similarly, the removal of the B12 riboswitch upstream of the cbiXJCDETLFGAcysGAcbiYbtuR operon and the recombinant production of three different vitamin B12 binding proteins (glutamate mutase GlmS, ribonucleotide triphosphate reductase RtpR and methionine synthase MetH) partly abolished B12‐dependent feedback inhibition. All these strategies increased cobalamin production in B. megaterium. Finally, combinations of these strategies enhanced the overall intracellular vitamin B12 concentrations but also reduced the volumetric cellular amounts by placing the organism under metabolic stress.
Interaction of enteroaggregative Escherichia coli with salad leaves
Authors: Berger Cedric N. , Shaw Robert K. , Ruiz‐Perez Fernando , Nataro James P. , Henderson Ian R. , Pallen Mark J. , Frankel Gad
Published: June 2009

Enteroaggregative Escherichia coli (EAEC) are important human pathogens. However, their environmental reservoir is unknown. As fresh salad leaves are increasingly recognized as an important environmental vector for human pathogens, we investigated leaf attachment capability of EAEC strains. We found that binding of clinical EAEC isolates to leaves from Eruca vesicaria (commonly known as rocket or arugula) can be divided into high, moderate and low adherent phenotypes. Using the prototype EAEC strain 042 to investigate the underlining mechanisms involved in leaf attachment, we found small attached bacterial aggregates over the entire leaf surface and dense bacterial attachment to the guard cell of the stomata. An aaf 042 mutant lost the ability to bind the epidermis while retaining stomatal adherence. In contrast, a fliC 042 mutant retained the ability to bind the epidermis but lost stomatal tropism. These results show that multiple adherence factors are involved in the interaction of EAEC with leaves, that EAEC uses similar colonization factors to bind mucosal and leaf surfaces and that fresh produce might be an important reservoir of EAEC strains.
Analysis of Milling Stability by the Chebyshev Collocation Method: Algorithm and Optimal Stable Immersion Levels
Authors: Butcher Eric A. , Bobrenkov Oleg A. , Bueler Ed , Nindujarla Praveen
Published: June 2009

In this paper the dynamic stability of the milling process is investigated through a single degree-of-freedom model by determining the regions where chatter (unstable) vibrations occur in the two-parameter space of spindle speed and depth of cut. Dynamic systems such as milling are modeled by delay-differential equations with time-periodic coefficients. A new approximation technique for studying the stability properties of such systems is presented. The approach is based on the properties of Chebyshev polynomials and a collocation expansion of the solution. The collocation points are the extreme points of a Chebyshev polynomial of high degree. Specific cutting force profiles and stability charts are presented for the up- and down-milling cases of one or two cutting teeth and various immersion levels with linear and nonlinear regenerative cutting forces. The unstable regions due to both secondary Hopf and flip (period-doubling) bifurcations are found, and an in-depth investigation of the optimal stable immersion levels for down-milling in the vicinity of where the average cutting force changes sign is presented.
Parameter Analysis and Normalization for the Dynamics and Design of Multibody Systems
Authors: Kövecses József , Ebrahimi Saeed
Published: June 2009

In this paper, we introduce a novel concept for parametric studies in multibody dynamics. This includes a technique to perform a natural normalization of the dynamics in terms of inertial parameters. This normalization technique rises out from the underlying physical structure of the system and the trajectory investigated. This structure is mathematically expressed in the form of eigenvalue problems. It leads to the introduction of the concept of dimensionless inertial parameters. This, in turn, makes it possible to introduce an analysis approach for studying design and control problems where parameter estimation and sensitivity are of importance.
Discrete ice lens theory for frost heave beneath pipelines
Authors: Nixon J. F. (Derick)
Published: June 2009

The discrete ice lens theory of frost heave in one-dimensional soil columns was developed to provide a better physical basis for engineering predictions of frost heave in soils. The theory has now been extended to the two-dimensional heat- and mass-flow situation beneath a buried chilled pipeline. Although the frozen and unfrozen soil regions beneath a buried cold pipeline are two dimensional, and the temperature and water-flow fields are potentially complex, considerable simplifications can be made by invoking the so-called quasi-static approach for estimating temperature fields around the buried pipeline. It is proposed that the curved, quasi-static temperature profiles available from published relationships are appropriate for frost-heave predictions in the two-dimensional region beneath a pipeline. Using these curved temperature profiles in the same program and solution procedure developed previously for one-dimensional soil columns allows frost-heave predictions for a buried pipeline to be carried out with a minimum of computational effort. Therefore, the lengthy and tedious numerical procedures that have been a feature of previous attempts to model heat and mass flow and the resulting frost heave in two dimensions can be avoided. The procedure has been used to predict the frost depth and heave beneath two well-documented pipeline test sections at Calgary, Alta., and Caen, France, with very good agreement between prediction and observation. Some predictions for a practical field situation indicate the initial ground temperature plays an important role in frost heave, frost penetration, and the time at which the final ice lens forms in the freezing soil. Key words : frost heave, discrete ice lens, pipeline, segregation potential, hydraulic conductivity of frozen soil.
Remarks on the design of clay liners used in lagoons as hydraulic barriers
Authors: Leroueil S. , Bihan J. P. Le , Bouchard R.
Published: June 2009

Considering that (i) the hydraulic conductivity of compacted clays is smaller on the wet side of optimum; (ii) the plastic limit is the water content below which the soil develops fissures under small stresses; (iii) the plastic limit and the optimum standard Proctor water content are similar for many natural soils; and (iv) the strength of compacted clays, thus the limit of trafficability, is a function of (w – wopt)/Ip, relevant conditions for the design of clay liners and the evaluation of their hydraulic conductivity are proposed. Key words : compacted clay, liner, hydraulic conductivity, strength, design.
The strength and dilatancy of sand
Authors: Vaid Y. P. , Sasitharan S.
Published: June 2009

The effects of stress path and loading direction in the triaxial test on strength and dilatancy of sand are investigated. It is shown that the unique relationship observed between peak friction angle and dilation rate at peak in conventional triaxial tests is followed regardless of stress path, confining stress at failure, relative density, and the mode of loading (compression or extension). Key words : sand, peak friction angle, dilatancy, stress path, triaxial test.
PIGGYBACKING THRESHOLD PROCESSES WITH A FINITE STATE MARKOV CHAIN
Authors: BOUCHER THOMAS R. , CLINE DAREN B. H.
Published: June 2009

The state-space representations of certain nonlinear autoregressive time series are general state Markov chains. The transitions of a general state Markov chain among regions in its state-space can be modeled with the transitions among states of a finite state Markov chain. Stability of the time series is then informed by the stationary distributions of the finite state Markov chain. This approach generalizes some previous results.
ESTIMATING MATERIAL PROPERTY AND FAILURE OF A LIVING CELL: NUMERICAL STUDY
Authors: CHIZARI MAHMOUD , WANG BIN
Published: June 2009

This paper presents finite element modelling of the deformation of a detached living cell subjected to microinjection and through the simulation, an investigation of the material properties of the cell components. The model is verified using images of the deformed cell as well as the measured penetration forces in the tests reported in the open literature. It is hoped that the modelling in this context will help to quantitatively evaluate the mechanical properties of the cells, and in particular, the failure strain of the cell cortex when penetration occurs.
LATERAL AND TORSIONAL VIBRATIONS OF A TWO-DISK ROTOR-STATOR SYSTEM WITH AXIAL CONTACT/RUBS
Authors: ZHANG KUNPENG , DING QIAN
Published: June 2009

The dynamics of a rotor system with axial contact/rub events between the disks and stator are investigated by numerical simulations. The formula for determining the contact/rub points, axial contact forces and dry friction forces are deduced. To account for their influence, the axial contact forces are substituted by equivalent forces acting at the disk centers, based on the equivalent moment rule. One-parametric model is used to estimate the contact-induced dry friction forces. The coupled equations of lateral and torsional motions of rotor and the lateral motion of disk are then established. Numerical simulations are carried out to reveal the lateral and torsional vibrations for both two-disk contact/rubs with different axial clearances, and one disk contact/rubs. Bifurcation diagrams, orbits, phase portraits, amplitude-frequency spectra and Poincaré maps are adopted to demonstrate the dynamical behaviors of the system. The results show that though both the lateral and torsional vibrations can reflect the influences of contact/rubs on rotor dynamics, the spectrum analyses of the torsional vibrations are more suitable to determine straight the extent of their effect.
POSTBUCKLING OF NANO RODS/TUBES BASED ON NONLOCAL BEAM THEORY
Authors: WANG C. M. , XIANG Y. , KITIPORNCHAI S.
Published: June 2009

This paper is concerned with the postbuckling problem of cantilevered nano rods/tubes under an end concentrated load. Eringen's nonlocal beam theory is used to account for the small length scale effect. The governing equation is derived from statical and geometrical considerations and Eringen's nonlocal constitutive relation. The nonlinear differential equation is solved using the shooting method for the postbuckling load and the buckled shape. By comparing with the classical postbuckling solutions, the sensitivity of the small length scale effect on the buckling load and buckled shape may be observed. It is found that the small length scale effect decreases the postbuckling load and increases the deflection of the rod.
THE COMPLEX VARIABLE ELEMENT-FREE GALERKIN (CVEFG) METHOD FOR TWO-DIMENSIONAL ELASTICITY PROBLEMS
Authors: PENG MIAOJUAN , LIU PEI , CHENG YUMIN
Published: June 2009

Based on element-free Galerkin (EFG) method and the complex variable moving least-squares (CVMLS) approximation, the complex variable element-free Galerkin (CVEFG) method for two-dimensional elasticity problems is presented in this paper. With the CVMLS approximation, the trial function of a two-dimensional problem is formed with a one-dimensional basis function. The number of unknown coefficients in the trial function of the CVMLS approximation is less than in the trial function of moving least-squares (MLS) approximation, and we can thus select fewer nodes in the meshless method that is formed from the CVMLS approximation than are required in the meshless method of the MLS approximation with no loss of precision. The formulae of the CVEFG method for two-dimensional elasticity problems is obtained. Compared with the conventional meshless method, the CVEFG method has a greater precision and computational efficiency. For the purposes of demonstration, some selected numerical examples are solved using the CVEFG method.
DUCTILE FRACTURE CHARACTERIZATION OF ALUMINUM ALLOY 2024-T351 USING DAMAGE PLASTICITY THEORY
Authors: XUE LIANG , WIERZBICKI TOMASZ
Published: June 2009

This paper presents the calibration procedure for aluminum alloy 2024-T351 using a recently developed damage plasticity theory. The damage plasticity theory consists of a full three dimensional damage evolution law where the pressure sensitivity and the Lode angle dependence are included in a fracture envelope and the equivalent plastic strain is used as a time-like variable to determine the damage rate. Because of the coupled nature of the plastic strain and the damage, material parameters are calibrated from a parallel study of numerical simulations and experimental measurements. A set of 10 tests that cover a wide range stress states for both the hydrostatic pressure and the Lode angle are conducted in order to capture the fracture envelope in the interested stress range. The experimental setups include un-notched and notched round bars with three different notch radii, a doubly grooved flat plate and compressed cylinders of three different heights at two friction conditions. The detailed numerical and experimental procedure of calibration is demonstrated by using four of these tests. The accuracy of the calibrated material parameters is further assessed by the remainder of tests. Notch sensitivity in tensile round bars and the friction conditions in upsetting tests are discussed in detail. Good agreement in the tested load conditions is achieved for both the fracture patterns and the load-displacement curves.