bluuebunny/crossref_metadata_2025 huggingface dataset:
Chromatin Modulation at the FLO11 Promoter of Saccharomyces cerevisiae by HDAC and Swi/Snf Complexes
Authors: Barrales Ramón R , Korber Philipp , Jimenez Juan , Ibeas José I
Published: April 2012

Cell adhesion and biofilm formation are critical processes in the pathogenicity of fungi and are mediated through a family of adhesin proteins conserved throughout yeasts and fungi. In Saccharomyces cerevisiae, Flo11 is the main adhesin involved in cell adhesion and biofilm formation, making the study of its function and regulation in this nonpathogenic budding yeast highly relevant. The S. cerevisiae FLO11 gene is driven by a TATA-box-containing promoter that is regulated through one of the longest regulatory upstream regions (3 kb) in yeast. We reported recently that two chromatin cofactor complexes, the Rpd3L deacetylase and the Swi/Snf chromatin-remodeling complexes, contribute significantly to the regulation of FLO11. Here, we analyze directly how these complexes impact on FLO11 promoter chromatin structure and dissect further the interplay between histone deacetylases, chromatin remodeling, and the transcriptional repressor Sfl1. We show that the regulation of chromatin structure represents an important layer of control in the highly complex regulation of the FLO11 promoter.
Remarkably Simple Sequence Requirement of the M-Factor Pheromone ofSchizosaccharomyces pombe
Authors: Seike Taisuke , Yamagishi Yoshikazu , Iio Hideo , Nakamura Taro , Shimoda Chikashi
Published: April 2012

The mating reaction is triggered by specific pheromones in a wide variety of organisms. Small peptides are used as mating pheromones in yeasts and fungi. In the fission yeast Schizosaccharomyces pombe, M-factor is a C terminally farnesylated nonapeptide secreted from M-cells, and its counterpart, P-factor, is a simple peptide composed of 23 amino acids. The primary structure requirements for the biological activity of pheromone peptides remain to be elucidated. Here, we conducted comprehensive substitution of each of the amino acids in M-factor peptide and inspected the mating ability of these missense mutants. Thirty-five sterile mutants were found among an array of 152 mutants with single amino acid substitutions. Mapping of the mutation sites clearly indicated that the sterile mutants were associated exclusively with four amino acid residues (VPYM) in the carboxyl-terminal half. In contrast, the substitution of four amino-terminal residues (YTPK) with any amino acid had no or only a slightly deleterious effect on mating. Furthermore, deletion of the three N-terminal residues caused no sterility, although truncation of a fourth residue had a marked effect. We conclude that a farnesylated hexapeptide (KVPYMCFar–OCH3) is the minimal M-factor that retains pheromone activity. At least 15 nonfunctional peptides were found to be secreted, suggesting that these mutant M-factor peptides are no longer recognized by the cognate receptor.
Disentangling the Roles of History and Local Selection in Shaping Clinal Variation of Allele Frequencies and Gene Expression in Norway Spruce (Picea abies)
Authors: Chen Jun , Källman Thomas , Ma Xiaofei , Gyllenstrand Niclas , Zaina Giusi , Morgante Michele , Bousquet Jean , Eckert Andrew , Wegrzyn Jill , Neale David , Lagercrantz Ulf , Lascoux Martin
Published: April 2012

Understanding the genetic basis of local adaptation is challenging due to the subtle balance among conflicting evolutionary forces that are involved in its establishment and maintenance. One system with which to tease apart these difficulties is clines in adaptive characters. Here we analyzed genetic and phenotypic variation in bud set, a highly heritable and adaptive trait, among 18 populations of Norway spruce (Picea abies), arrayed along a latitudinal gradient ranging from 47°N to 68°N. We confirmed that variation in bud set is strongly clinal, using a subset of five populations. Genotypes for 137 single-nucleotide polymorphisms (SNPs) chosen from 18 candidate genes putatively affecting bud set and 308 control SNPs chosen from 264 random genes were analyzed for patterns of genetic structure and correlation to environment. Population genetic structure was low (FST = 0.05), but latitudinal patterns were apparent among Scandinavian populations. Hence, part of the observed clinal variation should be attributable to population demography. Conditional on patterns of genetic structure, there was enrichment of SNPs within candidate genes for correlations with latitude. Twenty-nine SNPs were also outliers with respect to FST. The enrichment for clinal variation at SNPs within candidate genes (i.e., SNPs in PaGI, PaPhyP, PaPhyN, PaPRR7, and PaFTL2) indicated that local selection in the 18 populations, and/or selection in the ancestral populations from which they were recently derived, shaped the observed cline. Validation of these genes using expression studies also revealed that PaFTL2 expression is significantly associated with latitude, thereby confirming the central role played by this gene in the control of phenology in plants.
Establishment of New Mutations in Changing Environments
Authors: Peischl Stephan , Kirkpatrick Mark
Published: April 2012

Understanding adaptation in changing environments is an important topic in evolutionary genetics, especially in the light of climatic and environmental change. In this work, we study one of the most fundamental aspects of the genetics of adaptation in changing environments: the establishment of new beneficial mutations. We use the framework of time-dependent branching processes to derive simple approximations for the establishment probability of new mutations assuming that temporal changes in the offspring distribution are small. This approach allows us to generalize Haldane’s classic result for the fixation probability in a constant environment to arbitrary patterns of temporal change in selection coefficients. Under weak selection, the only aspect of temporal variation that enters the probability of establishment is a weighted average of selection coefficients. These weights quantify how much earlier generations contribute to determining the establishment probability compared to later generations. We apply our results to several biologically interesting cases such as selection coefficients that change in consistent, periodic, and random ways and to changing population sizes. Comparison with exact results shows that the approximation is very accurate.
A Regulatory Module Controlling Pharyngeal Development and Function in Caenorhabditis elegans
Authors: Fay David S , Polley Stanley R G , Kuang Jujiao , Kuzmanov Aleksandra , Hazel James W , Mani Kumaran , Veo Bethany L , Yochem John
Published: April 2012

In Caenorhabditis elegans, the differentiation and morphogenesis of the foregut are controlled by several transcriptional regulators and cell signaling events, and by PHA-1, an essential cytoplasmic protein of unknown function. Previously we have shown that LIN-35 and UBC-18–ARI-1 contribute to the regulation of pha-1 and pharyngeal development through the Zn-finger protein SUP-35/ZTF-21. Here we characterize SUP-37/ZTF-12 as an additional component of the PHA-1 network regulating pharyngeal development. SUP-37 is encoded by four distinct splice isoforms, which contain up to seven C2H2 Zn-finger domains, and is localized to the nucleus, suggesting a role in transcription. Similar to sup-35, sup-37 loss-of-function mutations can suppress both LOF mutations in pha-1 as well as synthetic-lethal double mutants, including lin-35; ubc-18, which are defective in pharyngeal development. Genetic, molecular, and expression data further indicate that SUP-37 and SUP-35 may act at a common step to control pharyngeal morphogenesis, in part through the transcriptional regulation of pha-1. Moreover, we find that SUP-35 and SUP-37 effect pharyngeal development through a mechanism that can genetically bypass the requirement for pha-1 activity. Unlike SUP-35, SUP-37 expression is not regulated by either the LIN-35 or UBC-18–ARI-1 pathways. In addition, SUP-37 carries out two essential functions that are distinct from its role in regulating pharyngeal development with SUP-35. SUP-37 is required within a subset of pharyngeal muscle cells to facilitate coordinated rhythmic pumping and in the somatic gonad to promote ovulation. These latter observations suggest that SUP-37 may be required for the orchestrated contraction of muscle cells within several tissues.
Temporal Variation in Selection Accelerates Mutational Decay by Muller’s Ratchet
Authors: Wardlaw Alison M , Agrawal Aneil F
Published: April 2012

Asexual species accumulate deleterious mutations through an irreversible process known as Muller’s ratchet. Attempts to quantify the rate of the ratchet have ignored the role of temporal environmental heterogeneity even though it is common in nature and has the potential to affect overall ratchet rate. Here we examine Muller’s ratchet in the context of conditional neutrality (i.e., mutations that are deleterious in some environmental conditions but neutral in others) as well as more subtle changes in the strength (but not sign) of selection. We find that temporal variation increases the rate of the ratchet (mutation accumulation) and the rate of fitness decline over that of populations experiencing constant selection of equivalent average strength. Temporal autocorrelation magnifies the effects of temporal heterogeneity and can allow the ratchet to operate at large population sizes in which it would be halted under constant selection. Classic studies of Muller’s ratchet show that the rate of fitness decline is maximized when selection is of a low but intermediate strength. This relationship changes quantitatively with all forms of temporal heterogeneity studied and changes qualitatively when there is temporal autocorrelation in selection. In particular, the rate of fitness decline can increase indefinitely with the strength of selection with some forms of temporal heterogeneity. Our finding that temporal autocorrelation in selection dramatically increases ratchet rate and rate of fitness decline may help to explain the paucity of asexual taxa.
Multiple Barriers to Nonhomologous DNA End Joining During Meiosis inDrosophila
Authors: Joyce Eric F , Paul Anshu , Chen Katherine E , Tanneti Nikhila , McKim Kim S
Published: April 2012

Repair of meiotic double-strand breaks (DSBs) uses the homolog and recombination to yield crossovers while alternative pathways such as nonhomologous end joining (NHEJ) are suppressed. Our results indicate that NHEJ is blocked at two steps of DSB repair during meiotic prophase: first by the activity of the MCM-like protein MEI-218, which is required for crossover formation, and, second, by Rad51-related proteins SPN-B (XRCC3) and SPN-D (RAD51C), which physically interact and promote homologous recombination (HR). We further show that the MCM-like proteins also promote the activity of the DSB repair checkpoint pathway, indicating an early requirement for these proteins in DSB processing. We propose that when a meiotic DSB is formed in the absence of both MEI-218 and SPN-B or SPN-D, a DSB substrate is generated that can enter the NHEJ repair pathway. Indeed, due to its high error rate, multiple barriers may have evolved to prevent NHEJ activity during meiosis.
The correlation between smoking, environmental tobacco smoke and preterm birth
Authors: Fogarasi-Grenczer Andrea , Balázs Péter
Published: May 2012

The rate of preterm births is very high in Hungary; it was 8.9% of the total livebirths in 2010. Preterm birth (<37 weeks) has a considerable health impact, because it is responsible for 85% of infant mortality and morbidity as well as for numerous chronic diseses in the long-term. Many maternal and fetal diseases can be identified in the background, but in a number of cases, preterm labor begins unexpectedly, without any prodrome. Presumably, the socioeconomic background and the presence of harmful lifestyle factors are related to preterm birth in these cases. Tobacco smoking is the most frequent harmful health behavior. At national level, the rate of smoking during pregnancy was 14.4% in the last 13 years, but in some counties, this proportion mounted to 25%. In these counties, the prevalence of preterm births also exceeds the national average. This summary highlights the factors related to disadvantaged socio-economic status that can be responsible for the higher number of preterm birth cases. Orv. Hetil., 2012, 153, 690–694.
Periodontal Disease, Hypertension, and Blood Pressure Among Older Adults in Puerto Rico
Authors: Rivas‐Tumanyan Sona , Campos Maribel , Zevallos Juan C. , Joshipura Kaumudi J.
Published: May 2012

Background: Current scientific evidence addressing the relationship between periodontitis and hypertension is limited to studies producing inconsistent results.

Methods: All participants of an ongoing representative cohort of Puerto Rican elderly who were ≥70 years old and residing in the San Juan metropolitan area were invited to this cross‐sectional study. Periodontal probing depth (PD) and attachment loss (AL) were summarized using the Centers for Disease Control and Prevention and the American Academy of Periodontology definition for severe periodontitis (≥2 teeth with AL ≥6 mm and ≥1 tooth with PD ≥5 mm). Three repeated blood pressure (BP) measurements taken were averaged using a standardized auscultatory method. Information on hypertension history, use of antihypertensive medications, and potential confounders (age, sex, smoking, heavy and binge drinking, diabetes, use of preventive dental services, flossing, body mass index, consumption of fruits, vegetables, whole wheat bread, and high‐fiber cereal) was collected during in‐person interviews. High BP was defined as average systolic BP ≥140 mm Hg or diastolic ≥90 mm Hg. Multivariate logistic regression models were used to study the relationship between severe periodontitis, hypertension history, and high BP.

Results: The study population comprised 182 adults. In multivariate analysis, there was no association between severe periodontitis and hypertension history (odds ratio [OR] = 0.99; 95% confidence interval [CI]: 0.40 to 2.48). Severe periodontitis was associated with high BP, with OR of 2.93 (95% CI: 1.25 to 6.84), after adjusting for age, sex, smoking, and binge drinking. This association was stronger when restricted to those with hypertension or taking antihypertensive medications: OR = 4.20 (95% CI: 1.28 to 13.80).

Conclusion: The results of this study suggest that periodontitis may contribute to poor BP control among older adults.
Severe Loss of Clinical Attachment Level: An Independent Association With Low Hip Bone Mineral Density in Postmenopausal Females
Authors: Gondim Valéria , Aun Juliana , Fukuda Cassia Tiemi , Takayama Liliam , Latorre Maria do Rosário , Pannuti Cláudio Mendes , Rodrigues Pereira Rosa Maria , Romito Giuseppe Alexandre
Published: May 2012

Background: Bone loss is a feature of both periodontitis and osteoporosis, and several studies have analyzed whether the periodontal destruction could have been influenced by systemic bone loss. The aim of this study is to assess the association between clinical attachment level (CAL) and bone mineral density (BMD) at the lumbar spine and hip, lifestyle, smoking, sociodemographic factors, and dental clinical variables in postmenopausal women.

Methods: One hundred forty‐eight women were interviewed using a structured written questionnaire and clinically examined. The periodontal examination, which was performed by calibrated investigators, included CAL, probing depth, gingival recession, bleeding on probing (BOP), visible plaque, supragingival calculus, and mean tooth loss. The sample was stratified into two groups: moderate and severe CAL. The moderate group had all sites with CAL ≤5 mm. The severe group had ≥1 site with CAL >5 mm. BMD, measured using dual‐energy x‐ray absorptiometry, was assessed at the lumbar spine, femoral neck, and total femur (grams per square centimeters).

Results: Severe CAL was identified in 86 women (58.1%). The multiple linear regression analysis using CAL (dependent variable), adjusted by menopause, education, and family income, demonstrated an inverse relationship of severe CAL with the BMD of the femoral neck (P = 0.015), as well as a positive association of severe CAL with tooth loss (P = 0.000), BOP (P = 0.004), and heavy smokers (P = 0.001).

Conclusions: Our study demonstrated that severe CAL was associated with low BMD of the femoral neck and deleterious clinical dental parameters and smoking. Our findings suggest that, in addition to appropriate oral care, individuals with severe CAL may also require additional attention to their systemic bone health.
Tar Characterization for Optimum Reservoir Management Strategy
Authors: Al-Harthi Muhammad , Al-Ali Mohammed , Gunarto Ronny
Published: May 2012

Tar mats are extra-heavy bitumen that occur between aquifers and overlaying oil columns. They seal either partially or completely an oil reservoir from its aquifer and reduces aquifer support. Tar characterization includes evaluation of the tar distribution and its sealing degree. It is an important prerequisite to optimize the water injection well's requirement and placement to maximize sweep and recovery.

This paper discusses a case study and demonstrates an integrated methodology by using static and dynamic data to determine the tar distribution and its sealing degree. The study includes both early life data before the subject field was put in production, as put on production, and post-production data to refine the characterization. Additionally, the use of formation pressure while drilling and Pyrolytic Oil-Productivity Index (POPI) analysis to optimize the injector's placement will also be highlighted. Moreover, saturation and production logging tool analysis were incorporated to determine if there is aquifer influx across the tar mat. The degree of the aquifer influx is also evaluated using material balance and reservoir simulation.
Detecting and Managing Inter-Reservoir Communication between Two Stacked Reservoirs
Authors: SayedAkram Nawaf I. , Tubayyeb Abdulaziz S. , Ansah Joseph , Shamrani Sultan S.
Published: May 2012

The challenge of how to effectively manage a field with multiple reservoirs that are in hydraulic communication comes up routinely when the field is under waterflood. Conventional management of such fields can result in many undesired outcomes such as a premature water production caused by cross-channeling from different reservoirs, inefficient pressure support to some of the individual reservoirs, or large volumes of bypassed oil. The main challenge that leads to such outcomes is the ability to identify the medium and magnitude of the inter-reservoir communication within the field. This paper addresses a field practice to pinpoint the communication between two reservoirs while the field is on production, along with its capability to further improve the effective reservoir management.

The field consists of two large carbonate reservoirs separated by thick non-reservoir formation. Historical data proved the inter-reservoir communication in the field. I-Field technology was a primary component in the development of this field. This technology has become a tool for an effective day-to-day reservoir management. This enables pro-active management rather than the traditional, re-active, management with respect to field life due to its added advantage of early detection of anomalies and subsequently enhances characterization. In this field, i-field facilitated a field-wide interference test that was conducted prior to field production start-up to help with field characterization including inter-reservoir communication between the two reservoirs.

Field cases describing the integration of static and dynamic data that led to better understanding of the field are presented. Results of this study will play a major role in building a robust dynamic model that can capture the fluids exchange between the two reservoirs. Such model will become an important tool for managing both reservoirs in order to maximize ultimate recovery from the field.
CEACAM1 is a Privileged Cell Surface Antigen to Design Novel ScFv Mediated-Immunotherapies of Melanoma, Lung Cancer and Other Types
of Tumors
Authors: Cianfriglia Maurizio , Fiori Valentina , Dominici Sabrina , Zamboni Silvia , Flego Michela , Luisa Dupuis Maria , Ascione Alessandro , Gellini Mara , Mallano Alessandra , Magnani Mauro
Published: May 2012

Carcinoembryonic antigen–related cell adhesion molecule 1 (CEACAM1) is a cell surface glycoprotein
involved in intercellular binding, belonging to the immunoglobulin superfamily. It is involved in cell-cell recognition and
modulates cellular processes that range from vascular angiogenesis to the regulation of insulin homeostasis and T-cell
proliferation. Aberrant expression of CEACAM1 is often associated with progression and metastatic potential in
melanoma, lung carcinoma and other types of tumor. Tumor-specific antigens such as CEACAM1 are ideal targets for
cancer immunotherapy because they are over-expressed by the cancer cell and not on non-malignant tissues, minimizing
the risk of autoimmune destruction. Many of the limitations of therapeutic use of rodent monoclonal antibodies (mAbs)
can now be overcome by exploiting the use of recombinant antibody fragments and the advances in antibody engineering
methods to improve tumor retention, reduce immunogenicity and modulate pharmacokinetics. In addition, a novel
effective model of immunotherapeutic treatments of tumors includes antibody drug conjugates (ADCs) that combine
specific mAbs and antibody fragments with cytotoxic drugs, proteins, enzymes, radionuclides and nanoparticles. This
review aims to describe how these antibody engineering approaches can meet the challenges for generating new and
effective antibody constructs for diagnosis and therapy of CEACAM1 expressing malignancies.
Anthropological Foundation of Dialogue
Authors: Juhant Janez
Published: May 2012

Anthropological Foundation of Dialogue

The dialogue of the society in the post-communist countries seems to be a problem. Both the post-communist countries and in the countries with a long democratic tradition are developing the postmodern individualistic mentality. On the orther hand, the world is becoming a unity, throug economic and productive processes. A man tries to solve his own problems, yet he is not prepared to share his own life and participate in the community. This is the one of the greatest problems of the so-called postmodern society. Present world is full of conflicts, not only in level of Islamic and the Christian world, but we, people of dialogue can solve them.
The Search for the Identity of the Church of Christ
Authors: Paločko Štefan
Published: May 2012

The Search for the Identity of the Church of Christ

If we consider Christ to be the only Savior, then it is also necessary to find his Church, his mystical body, where the salvation of man is realized. After two thousand years of existence of Christendom, we can observe more than 25.000 different Christian communities that claim to be the Church founded by Christ, or to be the part of it. This paper brings a method of finding the Church founded by Jesus Christ for our salvation among many churches and Christian confessions that exist today.
The Relationship Between 1 Hour Glycemia, During Oral Glucose Tolerance Test and Cardiometabolic Risk
Authors: Albai Oana , Timar Romulus
Published: May 2012

The Relationship Between 1 Hour Glycemia, During Oral Glucose Tolerance Test and Cardiometabolic Risk

Background Diabetes mellitus is a very common disease, worldwide there are currently over 366 million diabetics. It seems that people with normal glucose tolerance and blood glucose at 1 hour during OGTT ≥200mg% represent an intermediate phenotype of abnormal glucose metabolism, another disturbance of carbohydrate metabolism that is associated with increased cardiometabolic risk. Objectives Starting from these premises, we decided to analyze the subjects with glucose at 1 hour during OGTT ≥200mg%, but with normal values for fasting glucose and 2 hours glucose. In this subgroup of subjects some parameters of CMR were analyzed. We also performed a comparison of this subgroup of subjects with both normal glucose tolerance and 1-hour glucose <200mg%, and with those with abnormal glucose tolerance. Results According to currently used recommendations to diagnose diabetes mellitus, from the 778 people included in this study, 167 (21.5%) had disturbances of carbohydrate metabolism, being classified as patoglycemic and 611 persons (78.5%) had normal values of fasting glucose and 2 hours glucose during OGTT, being considered normoglycemic. From the 611 people who were classified as normal glucose tolerance, based on the currently used criteria for diagnosis of diabetes mellitus, a total of 44 persons (7.2%) had, however, the value of 1-hour glucose during OGTT ≥200mg%, which represents 5.6% of the entire group studied. Conclusions Patients with normal glucose tolerance and glucose ≥200mg% at 1 hour during OGTT represent a new subgroup of impaired glucose tolerance, which requires strict lifestyle advice and possibly pharmacological measures to prevent or delay progression to abnormal glucose tolerance.
Predictors of Changes in Physical Properties of Skin in Patients with Diabetes Mellitus
Authors: Crăciun Anca-Elena , Moldovan Mirela , Rusu Adriana , Niţă Cristina , Crăciun C. , Tătaru A.
Published: May 2012

Predictors of Changes in Physical Properties of Skin in Patients with Diabetes Mellitus

Introduction: The skin, the largest human organ, is often affected by diabetes mellitus (DM). We know that DM affects the hydration of stratum corneum (SC), the sebum content of the skin and to some extent, the barrier function of the epidermis and elasticity, but we do not know the factors leading to these changes. Objectives: The objectives of this study were to determine the factors associated with changes in physical properties of the skin (skin hydration degree, sebumetry, transepidermal water loss and skin elasticity) in patients with diabetes. Materials and methods: The physical properties of the skin were assessed using the Multi Probe Adapter Systems MPA ® (Courage-Khazaka, Germany) in 57 patients with diabetes and 46 non-diabetic. Results: Statistical analysis of the entire group of 103 subjects showed a significant association between female gender and decreased SC hydration (p<0.05 in all cases), decreased values of transepidermal water loss (TEWL) (β=-0.282, p=0.006) and decreased elasticity of the skin in forearm (β=-0.216, p=0.043). Also, the presence of DM was negatively associated with levels of SC hydration measured on the forearm (β=-0.281, p=0.005). Furthermore, in patients with diabetes, the presence of diabetic neuropathy (DNP) was negatively associated with the hydration of SC measured at all levels (forearm: β=-0.465, p<0.001; leg: β=-0.590, p<0.001; tight: β=-0.198, p<0.001). The observed relationship was independent of age and sex of the participants (p<0.05 after adjustment for age and sex). Regarding skin elasticity, increasing age was associated with lower levels of skin elasticity both in entire group and in patients with DM, at all sites of measurements (p<0.05 in all cases). Additionally, in patients with diabetes, elasticity of the skin measured at forearm and tight was negativelly associated with type of DM (forearm: β=-0.335, p=0.023; tight: β=-0.522, p<0.001). In our study, nor diabetes neither DNP were not associated with TEWL values. Conclusions: The presence of DNP seems to be the main predictor of decreased SC hydration in all measuring points and skin elasticity is significantly associated with age. There are some gender-related modification in physical properties of the skin. Surprisingly, type 2 DM was associated with reduced elasticity in the thigh, and this association was independent of age and sex.
Do Black Children Benefit More From Small Classes? Multivariate Instrumental Variable Estimators With Ignorable Missing Data
Authors: Shin Yongyun
Published: April 2012

Does reduced class size cause higher academic achievement for both Black and other students in reading, mathematics, listening, and word recognition skills? Do Black students benefit more than other students from reduced class size? Does the magnitude of the minority advantages vary significantly across schools? This article addresses the causal questions via analysis of experimental data from Tennessee’s Student/Teacher Achievement Ratio study where students and teachers are randomly assigned to small or regular class type. Causal inference is based on a three-level multivariate simultaneous equation model (SM) where the class type as an instrumental variable (IV) and class size as an endogenous regressor interact with a Black student indicator. The randomized IV causes class size to vary which, by hypothesis, influences academic achievement overall and moderates a disparity in academic achievement between Black and other students. Within each subpopulation characterized by the ethnicity, the effect of reduced class size on academic achievement is the average causal effect. The difference in the average causal effects between the race ethnic groups yields the causal disparity in academic achievement. The SM efficiently handles ignorable missing data with a general missing pattern and is estimated by maximum likelihood. This approach extends Rubin’s causal model to a three-level SM with cross-level causal interaction effects, requiring intact schools and no interference between classrooms as a modified Stable Unit Treatment Value Assumption. The results show that, for Black students, reduced class size causes higher academic achievement in the four domains each year from kindergarten to third grade, while for other students, it improves the four outcomes except for first-grade listening in kindergarten and first grade only. Evidence shows that Black students benefit more than others from reduced class size in first-, second-, and third-grade academic achievement. This article does not find evidence that the causal minority disparities are heterogeneous across schools in any given year.
Analyzing Regression-Discontinuity Designs With Multiple Assignment Variables
Authors: Wong Vivian C. , Steiner Peter M. , Cook Thomas D.
Published: April 2012

In a traditional regression-discontinuity design (RDD), units are assigned to treatment on the basis of a cutoff score and a continuous assignment variable. The treatment effect is measured at a single cutoff location along the assignment variable. This article introduces the multivariate regression-discontinuity design (MRDD), where multiple assignment variables and cutoffs may be used for treatment assignment. For an MRDD with two assignment variables, we show that the frontier average treatment effect can be decomposed into a weighted average of two univariate RDD effects. The article discusses four methods for estimating MRDD treatment effects and compares their relative performance in a Monte Carlo simulation study under different scenarios.
Oceanic mechanical forcing of a marine-terminating Greenland glacier
Authors: Walter Jacob I. , Box Jason E. , Tulaczyk Slawek , Brodsky Emily E. , Howat Ian M. , Ahn Yushin , Brown Abel
Published: May 2012

Dynamics of marine-terminating major outlet glaciers are of high interest because of their potential for drawing down large areas of the Greenland ice sheet. We quantify short-term changes in ice flow speed and calving at a major West Greenland glacier and examine their relationship to the presence of the sea-ice melange and tidal stage. A field campaign at the terminus of Store Gletscher (70.40˚N, 50.55˚W) spanning the spring and summer of 2008 included four broadband seismometers, three time-lapse cameras, a tide gauge, an automatic weather station and an on-ice continuous GPS station. Sub-daily fluctuations in speed coincide with two modes of oceanic forcing: (1) the removal of the ice melange from the terminus front and (2) tidal fluctuations contributing to speed increases following ice melange removal. Tidal fluctuations in ice flow speed were observed 16km from the terminus and possibly extend further. Seismic records suggest that periods of intensive calving activity coincide with ice-flow acceleration following breakup of the melange in spring. A synchronous increase in speed at the front and clearing of the melange suggests that the melange directly resists ice flow. We estimate a buttressing stress (~30–60 kPa) due to the presence of the ice melange that is greater than expected from the range of observed tides, though an order of magnitude less than the driving stress.
Evaluating Land Use Effects on Groundwater Quality in Lagos-Nigeria Using Water Quality Index
Authors: Balogun I. I. , Akoteyon I. S. , Adeaga O.
Published: May 2012

The study relates groundwater quality to land use types in Lagos State. Fourteen samples were collected from hand dug wells and boreholes, seven each from rural and urban land uses in the study area. Ten parameters (pH, electrical conductivity, total dissolved solids, total hardness, calcium, magnesium, chloride, nitrate and sulfate) were determined using standard methods. The resulting water quality indices revealed that 58.09% of the samples were rated very poor while 21.73%, 9.08% and 11.1% were rated poor, good and excellent, respectively in rural land use. The analysis of samples drawn from urban land use revealed that 76.55% of the water was unfit for drinking while 14.4%, 6.42% and 2.63% were found to be very poor, good and excellent, respectively. pH, total dissolved solids, chloride, total hardness and nitrate were beyond the permissible limits for urban land use while, pH, total hardness and nitrate were above permissible limits for rural land use. These parameters were found to be responsible for the poor water quality rating in the study areas. The paper recommends a comprehensive effective sewerage system for safe disposal of sewage, efficient waste water handling and control of urban runoff to prevent groundwater quality deterioration in the study areas.Keywords: Evaluation; Groundwater; Quality; Land use; Water quality index; Lagos-Nigeria.© 2012 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi: http://dx.doi.org/10.3329/jsr.v4i2.7142 J. Sci. Res. 4 (2), 397-409 (2012)
Effects of Reynolds and Prandtl Number on Mixed Convection in an Octagonal Channel with a Heat-Generating Hollow Cylinder
Authors: Parvin S. , Nasrin R.
Published: May 2012

A numerical study has been executed to analyze the effects of Reynolds and Prandtl number on mixed convective flow and heat transfer characteristics inside an octagonal vertical channel in presence of a heat-generating hollow circular cylinder placed at the centre. All the walls of the octagon are considered to be adiabatic. Galerkin weighted residual finite element method is used to solve the governing equations of mass, momentum and energy. Results are presented in terms of streamlines, isotherms, the average Nusselt number and the maximum fluid temperature for different combinations of controlling parameters namely, Reynolds number, Prandtl number and Richardson number. The results indicate that the flow and thermal fields as well as the heat transfer rate and the maximum fluid temperature in the octagonal channel depend significantly on the mentioned parameters.Keywords: Heat-generation; Hollow cylinder; Octagonal channel; Mixed convection; Finite element method.© 2012 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi: http://dx.doi.org/10.3329/jsr.v4i2.8142   J. Sci. Res. 4 (2), 337-348 (2012)
On Left Centralizers of Semiprime Γ-Rings
Authors: Dey K. K. , Paul A. C.
Published: May 2012

Let M be a semiprime G-ring satisfying an assumption   xaybz = xbyaz for all x, y, z?M, a, b?G. In this paper, we prove that a mapping T: M ? M is a centralizer if and only if it is a centralizing left centralizer. We also show that if T and S are left centralizers of M such that T(x)a x + x a S(x)?Z(M) (the center of M) for all x?M, a?G, then both T and S are centralizers. Keywords: Semiprime G-ring; Left (right) centralizer; Centralizer; Commuting mapping; Centralizing mapping: Extended centroid.© 2012 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi: http://dx.doi.org/10.3329/jsr.v4i2.8691    J. Sci. Res. 4 (2), 349-356 (2012)
Applicability of Vaisburd and Evdokimov Model to Ionic Targets
Authors: Sabrin F. , Uddin M. A. , Haque A. K. F.
Published: May 2012

The Vaisburd and Evdokimov proposed an empirical model to calculate the electron impact single ionization cross-sections of atoms and molecules. The model has been applied to some atoms and molecules. To examine the efficiency of the model, the present work applies the model to calculate cross-sections for  Ne-isonuclear series Ne+, Ne2+, Ne3+, Ne4+, Ne5+, Ne6+, Ne7+, Ne8+, Ne9+ . The separate sets of values of the parameters of the model are determined by comparison with the available experimental data using a non-linear least-squares fitting computer code. Keywords: Electron impact ionization; Empirical model; Ionic targets. © 2012 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. doi: http://dx.doi.org/10.3329/jsr.v4i2.8704 J. Sci. Res. 4 (2), 307-313 (2012)
Effect of Ca-substitution on the Magnetic and Dielectric Properties of Mn-Zn Ferrites
Authors: Rahman M. M. , Halder P. K. , Ahmed F. , Hossain T. , Rahaman M.
Published: May 2012

Spinel Mn-Zn ferrites with composition MnxZn0.4Ca0.6-2xFe2+xO4, where x = 0.10, 0.15, 0.20, 0.25 and 0.30 have been prepared by conventional ceramic technique sintered at    1300 °C for 4 hours. The influence of Ca-substitution on various properties of Mn-Zn ferrites have been studied in this work. Investigations were carried out by the measurements of Curie temperature, permeability, loss tangent, Q-factor, dielectric constant and AC resistivity of the samples. Curie temperature (Tc), the real part of initial permeability (µ´), loss tangent (tan ?), and AC resistivity have been found to be decreased while the Q-factor increases with the increase in Ca-content. The frequency characteristics of the dielectric constant and AC resistivity have been found to be decreased as the frequency increases. Maxwell-Wagner interfacial type of dielectric polarization was observed with the addition of Ca-content over the entire range of frequency considered. Keywords: Spinel ferrites; Sintering temperature; Initial permeability; Dielectric constant.© 2012 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi: http://dx.doi.org/10.3329/jsr.v4i2.9752 J. Sci. Res. 4 (2), 297-306 (2012)
An Introduction to the Methodology of Earthquake Resistant Structures of Uniform Response
Authors: Grigorian Mark , Grigorian Carl E.
Published: May 2012

Structures of Uniform Response are special earthquake resistant frames in which members of similar groups such as beams, columns and braces of similar nature share the same demand-capacity ratios regardless of their location within the group. The fundamental idea behind this presentation is that seismic structural response is largely a function of design and construction, rather than analysis. Both strength and stiffness are induced rather than investigated. Failure mechanisms and stability conditions are enforced rather than tested. Structures of Uniform Response are expected to sustain relatively large inelastic displacements during major earthquakes. A simple technique has been proposed to control and address the gradual softening of such structures due to local/partial instabilities and formation of plastic hinges. In structures of uniform response, the magnitude and shape of distribution of lateral forces affects the distribution of story stiffness in proportion with story moments, therefore affecting the dynamic behavior of the system as a whole. Simple closed form formulae describing the nonlinear behavior of moment frames of uniform response have been proposed. While the scope of this contribution is limited to moment frames, the proposed method can successfully be extended to all types of recognized earthquake resisting systems.
Post-Transcriptional Control of Type I Interferon Induction by Porcine Reproductive and Respiratory Syndrome Virus in Its Natural Host Cells
Authors: Wang Xiuqing , Christopher-Hennings Jane
Published: May 2012

Porcine reproductive and respiratory syndrome virus (PRRSV) is not only a poor inducer of type I interferon but also inhibits the efficient induction of type I interferon by porcine transmissible gastroenteritis virus (TGEV) and synthetic dsRNA molecules, Poly I:C. However, the mechanistic basis by which PRRSV interferes with the induction of type I interferon in its natural host cells remains less well defined. The purposes of this review are to summarize the key findings in supporting the post-transcriptional control of type I interferon in its natural host cells and to propose the possible role of translational control in the regulation of type I interferon induction by PRRSV.
Development and characterization of microsatellite markers for Berberis thunbergii (Berberidaceae)
Authors: Allen Jenica M. , Obae Samuel G. , Brand Mark H. , Silander John A. , Jones Kenneth L. , Nunziata Schyler O. , Lance Stacey L.
Published: April 2012

• Premise of the study: Microsatellite markers were isolated and characterized in Berberis thunbergii, an invasive and ornamental shrub in the eastern United States, to assess genetic diversity among populations and potentially identify horticultural cultivars.

• Methods and Results: A total of 12 loci were identified for the species. Eight of the loci were polymorphic and were screened in 24 individuals from two native (Tochigi and Ibaraki prefectures, Japan) and one invasive (Connecticut, USA) population and 21 horticultural cultivars. The number of alleles per locus ranged from three to seven, and observed heterozygosity ranged from 0.048 to 0.636.

• Conclusions: These new markers will provide tools for examining genetic relatedness of B. thunbergii plants in the native and invasive range, including phylogeographic studies and assessment of rapid evolution in the invasive range. These markers may also provide tools for examining hybridization with other related species in the invasive range.
Unique expression of a sporophytic character on the gametophytes of notholaenid ferns (Pteridaceae)
Authors: Johnson Anne K. , Rothfels Carl J. , Windham Michael D. , Pryer Kathleen M.
Published: April 2012

• Premise of the study: Not all ferns grow in moist, shaded habitats; some lineages thrive in exposed, seasonally dry environments. Notholaenids are a clade of xeric‐adapted ferns commonly characterized by the presence of a waxy exudate, called farina, on the undersides of their leaves. Although some other lineages of cheilanthoid ferns also have farinose sporophytes, previous studies suggested that notholaenids are unique in also producing farina on their gametophytes. For this reason, consistent farina expression across life cycle phases has been proposed as a potential synapomorphy for the genus Notholaena. Recent phylogenetic studies have shown two species with nonfarinose sporophytes to be nested within Notholaena, with a third nonfarinose species well supported as sister to all other notholaenids. This finding raises the question: are the gametophytes of these three species farinose like those of their close relatives, or are they glabrous, consistent with their sporophytes?

• Methods: We sowed spores of a diversity of cheilanthoid ferns onto culture media to observe and document whether their gametophytes produced farina. To place these species within a phylogenetic context, we extracted genomic DNA, then amplified and sequenced three plastid loci. The aligned data were analyzed using maximum likelihood to generate a phylogenetic tree.

• Key results: Here we show that notholaenids lacking sporophytic farina also lack farina in the gametophytic phase, and notholaenids with sporophytic farina always display gametophytic farina (with a single exception). Outgroup taxa never displayed gametophytic farina, regardless of whether they displayed farina on their sporophytes.

• Conclusions: Notholaenids are unique among ferns in consistently expressing farina across both phases of the life cycle.
Structural, electronic and photovoltaic characterization of multiwalled carbon nanotubes grown directly on stainless steel
Authors: Camilli Luca , Scarselli Manuela , Gobbo Silvano Del , Castrucci Paola , Gautron Eric , De Crescenzi Maurizio
Published: May 2012

We have taken advantage of the native surface roughness and the iron content of AISI-316 stainless steel to grow multiwalled carbon nanotubes (MWCNTs) by chemical vapour deposition without the addition of an external catalyst. The structural and electronic properties of the synthesized carbon nanostructures have been investigated by a range of electron microscopy and spectroscopy techniques. The results show the good quality and the high graphitization degree of the synthesized MWCNTs. Through energy-loss spectroscopy we found that the electronic properties of these nanostructures are markedly different from those of highly oriented pyrolytic graphite (HOPG). Notably, a broadening of the π-plasmon peak in the case of MWCNTs is evident. In addition, a photocurrent was measured when MWCNTs were airbrushed onto a silicon substrate. External quantum efficiency (EQE) and photocurrent values were reported both in planar and in top-down geometry of the device. Marked differences in the line shapes and intensities were found for the two configurations, suggesting that two different mechanisms of photocurrent generation and charge collection are in operation. From this comparison, we are able to conclude that the silicon substrate plays an important role in the production of electron–hole pairs.
Recherche comparative internationale à la base de trois méthodes de LSP
Authors: Verjans Martine
Published: April 2012

Linguaplan Limburg, recherche comparative internationale, a d’abord dressé l’inventaire des problèmes d’ordre linguistique de 1 000 PME-PMI. Cette première partie quantitative fut suivie par une phase axée sur une analyse qualitative à double objectif : l’établissement de profils langagiers détaillés de certains métiers-professions résultant du susdit inventaire d’une part, la constitution et l’analyse de corpus écrits et oraux d’autre part. Cette exploration qualitative a constitué la base de la troisième phase, celle de la conception et de l’élaboration de modules langagiers d’apprentissage ciblés et multimédias, de la taille la plus opérationnelle possible, et se prêtant à l’auto-apprentissage.