bluuebunny/crossref_metadata_2025 huggingface dataset:
Facilitadores y obstaculizadores de la retención escolar de estudiantes migrantes en Chile: experiencias de cuatro escuelas de Valparaíso
Authors: Mendoza Lira Michelle , Muñoz Jorquera Solange , Ballesta Acevedo Emilio , Covarrubias Apablaza Carmen Gloria
Published: January 2024

El aumento de la población migrante en las escuelas chilenas ha significado grandes desafíos para el sistema educativo. Si bien hay avances en cuanto a las políticas que favorecen su inserción, estos estudiantes presentan mayor tasa de deserción en comparación con los nativos. El objetivo del estudio fue comprender cuáles son los facilitadores y obstaculizadores socioeducativos para el término de la escolaridad obligatoria de alumnos(as) migrantes, desde la perspectiva de los(las) agentes educativos(as). A partir de una metodología cualitativa, se realizaron un total de 47 entrevistas a directivos, profesionales de apoyo y docentes de 4 escuelas de la Región de Valparaíso (Chile). Los resultados dan cuenta de que existen factores a nivel individual, sociofamiliar y propios de las comunidades educativas que influyen en la retención de los y las estudiantes migrantes de las escuelas chilenas estudiadas. Se concluye que esta población, a pesar de contar con varios factores protectores, resultan más vulnerables y propensos a abandonar la escuela, por lo cual se vuelven indispensables el diseño e implementación de nuevas y mejores políticas educativas ajustadas a sus necesidades.
Spectral analysis techniques in measuring neutron-induced gamma production cross-section
Authors: Xiao Shi-Liang , Wang Zhao-Hui , Wu Hong-Yi , Chen Xiong-Jun , Sun Qi , Tan Bo-Yu , Wang Hao , Qi Fu-Gang ,   School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, China,   Key Laboratory of Nuclear Data, China Institute of Atomic Energy, Beijing 102413, China
Published: January 2024

In neutron reaction cross-section measurements, the prompt gamma ray method is a method of obtaining cross-section data by measuring the characteristic gamma rays emitted by a nuclear reaction, thereby avoiding the interference generated by competing reaction channels. However, the prompt gamma ray method is an on-line experiment with abundant background sources, high background counts of the obtained experimental spectra, and numerous interferences such as weak peaks, overlapping peaks, Compton scattering peaks, and neutron effect peaks of Ge in HPGe, which cause the difficulty in analysing the on-line experimental spectra and the high uncertainty in the results. In this work, we study and summarise the spectrum analysis techniques of the prompt gamma ray method that can be used for measuring the neutron cross-section, and comprehensively consider the physical processes of the formation of different characteristic peaks of the prompt gamma ray method, so as to reduce the uncertainty of calculating the net area of the effect peaks in the process of on-line experimental spectrum processing. The Compton edge, weak peaks, overlapping peaks, and the neutron response peaks of the HPGe detector on-line experiment are discussed and analysed, and the net area of the effect peaks is accurately extracted by combining several reasonable functions to fit the total energy peak, the background, and the interferences. For the net area of weak peaks, this method can reduce the peak area selection caused fluctuation from 30% to less than 1%, and the difference between the fitted value of the net area and the theoretical value is comparable to the statistical uncertainty; for the overlapping peaks’ decomposition, the difference between the results obtained by this method and the theoretical value is significantly lower than 1%. The reliability of the spectral analysis method is simultaneously verified by efficiency curve analysis and goodness-of-fit calculation.
Cavus Foot in Soccer Players: Increased Prevalence in Experienced Players and Risk Factor for Injury
Authors: Ménard Anne-Laure , Begon Mickael , Barrette Justin , Nault Marie-Lyne
Published: January 2024

Background: Foot type, especially cavus foot, is associated with foot and ankle soccer injuries, such as ankle sprains, ankle instability, and foot and ankle lateral injuries. The aim of this study was to identify risk factors for foot and ankle injuries among soccer players.

Methods: Male and female soccer players, from beginners to semiprofessionals, aged between 10 and 40 years were enrolled in this cross-sectional study. Players filled in questionnaires about their training and injury history. Clinical measurements included foot length, Foot Posture Index-6, and arch height flexibility. Each variable was dichotomized: age (<18 years versus ≥18 years), level of play (AA and below versus AAA and above), foot type (cavus or not), and injury. Injury occurrence was analyzed using χ2 tests between each group of variables, and significance was set at P < .05.

Results: A total of 277 players, including 81 females, volunteered; 147 were younger than 18 years and 180 were AA level or below. Cavus foot prevalence was 30%. In the cavus foot group, 51.8% of players had reached at least an AAA level compared with 27.8% in the normal-arched group (P < .001 [χ2]). Injuries were associated with a cavus foot type (P < .01 [χ2]) and with sex, age, or highest level played (P < .001 [χ2]).

Conclusions: This study identified a high prevalence of cavus foot among soccer players of all ages, with an increased prevalence among higher-level players. The injury risk factors were female sex, older age, playing at a higher level, and cavus feet.
Failed Bilateral Total Silastic First Metatarsophalangeal Joint Implant Reconstructed with Osteochondral Allograft Implantation
Authors: Poynter Thomas S. , Ford Timothy
Published: January 2024

First metatarsophalangeal joint (MPJ) arthritis is a very common form of arthritis seen in the foot. Some signs and symptoms include pain, swelling, decreased passive and active range of motion, difficulty with shoe gear, and so forth. Surgically, options for alleviating symptomatic hallux limitus and arthritis fall into two broad categories: joint sparing and joint sacrificing. In this case study, we present a patient with a bilateral failed total silastic implant of the first MPJ and our proposed revision using an osteochondral bone allograft to fill the deficit left behind from silastic implant removal. The ability for immediate weightbearing and to perform this procedure bilaterally is an advantage to this surgical treatment option compared with other described revision techniques. Postoperatively, the patient has adequate range of motion and no pain when ambulatory. We believe this osteochondral allograft implant may be a viable option for revision first MPJ arthroplasty in select patient populations.
Genetic basis of Arabidopsis thaliana responses to infection by naïve and adapted isolates of turnip mosaic virus
Authors: Butković Anamarija , Ellis Thomas James , González Rubén , Jaegle Benjamin , Nordborg Magnus , Elena Santiago F.
Published: January 2024

Plant viruses account for enormous agricultural losses worldwide, and the most effective way to combat them is to identify genetic material conferring plant resistance to these pathogens. Aiming to identify genetic associations with responses to infection, we screened a large panel of
Arabidopsis thaliana
natural inbred lines for four disease-related traits caused by infection by
A. thaliana
-naïve and -adapted isolates of the natural pathogen turnip mosaic virus (TuMV). We detected a strong, replicable association in a 1.5 Mb region on chromosome 2 with a 10-fold increase in relative risk of systemic necrosis. The region contains several plausible causal genes as well as abundant structural variation, including an insertion of a
Copia
transposon into a Toll/interleukin receptor (TIR-NBS-LRR) coding for a gene involved in defense, that could be either a driver or a consequence of the disease-resistance locus. When inoculated with TuMV, loss-of-function mutant plants of this gene exhibited different symptoms than wild-type plants. The direction and severity of symptom differences depended on the adaptation history of the virus. This increase in symptoms severity was specific for infections with the adapted isolate. Necrosis-associated alleles are found worldwide, and their distribution is consistent with a trade-off between resistance during viral outbreaks and a cost of resistance otherwise, leading to negative frequency-dependent selection.
Experience shapes chandelier cell function and structure in the visual cortex
Authors: Seignette Koen , Jamann Nora , Papale Paolo , Terra Huub , Porneso Ralph O , de Kraker Leander , van der Togt Chris , van der Aa Maaike , Neering Paul , Ruimschotel Emma , Roelfsema Pieter R , Montijn Jorrit S , Self Matthew W , Kole Maarten HP , Levelt Christiaan N
Published: January 2024

Detailed characterization of interneuron types in primary visual cortex (V1) has greatly contributed to understanding visual perception, yet the role of chandelier cells (ChCs) in visual processing remains poorly characterized. Using viral tracing we found that V1 ChCs predominantly receive monosynaptic input from local layer 5 pyramidal cells and higher-order cortical regions. Two-photon calcium imaging and convolutional neural network modeling revealed that ChCs are visually responsive but weakly selective for stimulus content. In mice running in a virtual tunnel, ChCs respond strongly to events known to elicit arousal, including locomotion and visuomotor mismatch. Repeated exposure of the mice to the virtual tunnel was accompanied by reduced visual responses of ChCs and structural plasticity of ChC boutons and axon initial segment length. Finally, ChCs only weakly inhibited pyramidal cells. These findings suggest that ChCs provide an arousal-related signal to layer 2/3 pyramidal cells that may modulate their activity and/or gate plasticity of their axon initial segments during behaviorally relevant events.
dact1/2 modifies noncanonical Wnt signaling and calpain 8 expression to regulate convergent extension and craniofacial development
Authors: Carroll Shannon H. , Schafer Sogand , Kawasaki Kenta , Tsimbal Casey , Julé Amélie M. , Hallett Shawn A. , Li Edward , Liao Eric C.
Published: January 2024

Wnt signaling plays a crucial role in the early embryonic patterning and development, to regulate convergent extension during gastrulation and the establishment of the dorsal axis. Further, Wnt signaling is a crucial regulator of craniofacial morphogenesis. The adapter proteins Dact1 and Dact2 modulate the Wnt signaling pathway through binding to Disheveled, however, the distinct relative functions of Dact1 and Dact2 during embryogenesis remain unclear. We found that
dact1
and
dact2
genes have dynamic spatiotemporal expression domains that are reciprocal to one another and to
wnt11f2l
, that suggest distinct functions during zebrafish embryogenesis. We found that both
dact1
and
dact2
contribute to axis extension, with compound mutants exhibiting a similar convergent extension defect and craniofacial phenotype to the
wnt11f2
mutant. Utilizing single-cell RNAseq and
gpc4
mutant that disrupts noncanonical Wnt signaling, we identified
dact1/2
specific roles during early development. Comparative whole transcriptome analysis between wildtype,
gpc4
and
dact1/2
mutants revealed a novel role for
dact1/2
in regulating the mRNA expression of the classical calpain
capn8
. Over-expression of
capn8
phenocopies
dact1/2
craniofacial dysmorphology. These results identify a previously unappreciated role of
capn8
and calcium-dependent proteolysis during embryogenesis. Taken together, our findings highlight the distinct and overlapping roles of
dact1
and
dact2
in embryonic craniofacial development, providing new insights into the multifaceted regulation of Wnt signaling.
Cell-autonomous targeting of arabinogalactan by host immune factors inhibits mycobacterial growth
Authors: Qin Lianhua , Xu Junfang , Chen Jianxia , Wang Sen , Zheng Ruijuan , Cui Zhenling , Liu Zhonghua , Wu Xiangyang , Wang Jie , Huang Xiaochen , Wang Zhaohui , Wang Mingqiao , Pan Rong , Kaufmann Stefan H.E. , Meng Xun , Zhang Lu , Sha Wei , Liu Haipeng
Published: January 2024

Deeper understanding of the crosstalk between host cells and
Mycobacterium tuberculosis
(Mtb) provides crucial guidelines for the rational design of novel intervention strategies against tuberculosis (TB). Mycobacteria possess a unique complex cell wall with arabinogalactan (AG) as critical component. AG has been identified as a virulence factor of Mtb which is recognized by host galectin-9. Here we demonstrate that galectin-9 directly inhibited mycobacterial growth through AG-binding property of carbohydrate-recognition domain 2. Furthermore, IgG antibodies with AG specificity were detected in serum of TB patients. Based on the interaction between galectin-9 and AG, we developed monoclonal antibody (mAb) screening assay and identified AG-specific mAbs which profoundly inhibit Mtb growth. Mechanistically, proteomic profiling and morphological characterizations revealed that AG-specific mAbs regulate AG biosynthesis, thereby inducing cell wall swelling. Thus, direct AG-binding by galectin-9 or antibodies contributes to protection against TB. Our findings pave the way for the rational design of novel immunotherapeutic strategies for TB control.
Sistema OLGA (Operative Link on Gastritis Assessment) como marcador para cáncer gástrico y displasia en una población colombiana de alto riesgo: estudio multicéntrico
Authors: Carlosama Yeison Harvey , Acosta Claudia Patricia , Sierra Carlos Hernán , Rosero Carol Yovanna , Bolaños Harold Jofre
Published: January 2024

Introducción. En Asia y Europa, el sistema OLGA ha sido útil como marcador de riesgo de cáncer gástrico. Sin embargo, su utilidad en poblaciones de alto riesgo en Colombia aún se desconoce.Objetivo. Establecer si los estadios OLGA se asocian con un mayor riesgo de cáncer y displasia en una población de alto riesgo en Colombia y determinar la capacidad diagnóstica de la escala para evaluar dicho riesgo. Materiales y métodos. Se realizó un estudio multicéntrico con pacientes con cáncer gástrico y displasia (casos), y pacientes con atrofia y metaplasia intestinal (controles), provenientes de tres centros de una zona de alto riesgo de cáncer gástrico en Colombia. Se incluyeron 506 pacientes cuyo estudio endoscópico e histopatológico fue realizado mediante el sistema de Sydney y la estadificación de OLGA propuesta por Rugge. El efecto de cada variable de interés sobre la enfermedad (cáncer gástrico y displasia) se evaluó mediante modelos bivariados y multivariados. Un valor de p menor de 0,05 se consideró estadísticamente significativo.Resultados. Los estadios elevados del sistema OLGA (III-IV) se asociaron con un mayor riesgo de displasia y cáncer gástrico (OR ajustado = 8,71; IC95 % = 5,09-14,9; p=0,001) con una sensibilidad del 54,9 %, especificidad del 89,3 % y una razón de probabilidad positiva de 5,17.Conclusiones. El estadio OLGA es un marcador de riesgo de cáncer gástrico y displasia en la población de estudio. Se recomienda su implementación como estrategia para optimizar el diagnóstico oportuno y el seguimiento de pacientes con mayor riesgo.
Classification and selection of the main features for the identification of toxicity inAgaricusandLepiotawith machine learning algorithms
Authors: Ortiz-Letechipia Jacqueline S. , Galvan-Tejada Carlos E. , Galván-Tejada Jorge I. , Soto-Murillo Manuel A. , Acosta-Cruz Erika , Gamboa-Rosales Hamurabi , Celaya Padilla José María , Luna-García Huizilopoztli
Published: January 2024

The occurrence of fungi is cosmopolitan, and while some mushroom species are beneficial to human health, others can be toxic and cause illness problems. This study aimed to analyze the organoleptic, ecological, and morphological characteristics of a group of fungal specimens and identify the most significant features to develop models for fungal toxicity classification using genetic algorithms and LASSO regression. The results of the study indicated that odor, spore print color, and habitat were the most significant characteristics identified by the genetic algorithm GALGO. Meanwhile, odor, gill size, stalk shape, and twelve other features were the relevant characteristics identified by LASSO regression. The importance score of the odor variable was 99.99%, gill size obtained 73.7%, stalk shape scored 39.9%, and the remaining variables did not score higher than 18%. Logistic regression, k-nearest neighbor (KNN), and XG-Boost classification algorithms were used to develop models using the features selected by both GALGO and LASSO. The models were evaluated using sensitivity, specificity, and accuracy metrics. The models with the highest AUC values were XGBoost, with a maximum value of 0.99 using the features selected by LASSO, followed by KNN with a maximum value of 0.99. The GALGO selection resulted in a maximum AUC of 0.98 in KNN and XGBoost. The models developed in this study have the potential to aid in the accurate identification of toxic fungi, which can prevent health problems caused by their consumption.
Comparing the Clinical Spectrum of Paediatric In-patients in pre-COVID-19, during COVID19 and post-COVID-19 Pandemic Periods in a Tertiary Level Teaching Centre
Authors: Anand Veena , Vinitha AO , Joseph Susy , Sankar VH , Yadev IP
Published: January 2024

Introduction: Public awareness of the COVID-19 pandemic has resulted in a reduction in healthcare utilisation for other diseases. Understanding how the COVID-19 pandemic affects hospital admissions and the disease patterns is crucial for proper triaging and planning of health resources in future pandemics. Aim: To compare the clinical spectrum of paediatric inpatients in the post-COVID-19, pre-COVID-19 and during COVID-19 pandemic periods in a tertiary level teaching centre. Materials and Methods: This ambispective study was conducted at the Paediatrics Department of SAT, Govt. Medical College, Thiruvananthapuram, Kerala, India. The analysis included all cases hospitalised from April 2019 to March 2022, with the data divided into three time periods. The discharge diagnoses of all cases admitted during the study period were coded according to the ICD-10 criteria and included in the analysis. Differences in admissions, disease patterns, and ICU admissions during the three time periods (pre-COVID-19, postCOVID-19, and during COVID-19) were compared using oneway ANOVA and Tukey's post-hoc test. Results: In the present study, ward admissions (p-value <0.001), respiratory infections (p-value 0.031), asthma (p-value 0.009), and chronic systemic diseases (p-value 0.018) decreased in the post-COVID-19 period compared to the pre-COVID-19 period, whereas ICU admissions (p-value 0.010) and Diabetic Ketoacidosis (DKA) (p-value 0.002) increased. When comparing COVID-19 and post-COVID-19 periods, there was an increase in ward admissions (p-value 0.01), respiratory infections (p-value 0.018), and diarrhoea (p-value 0.029), but a decrease in the proportion of ICU admissions (p-value 0.01). There was no significant difference in mortality among the three time periods. Conclusion: There was a significant difference in the clinical spectrum of paediatric inpatients. The significant decrease in admissions of chronic systemic diseases, which require regular follow-up for management changes, raises concerns about the potential impact on patient care.
Influence of Explants Type, Nodal Positions and Two Cytokinins on Cassava (Manihot esculenta, Crantz) In vitro Organogenesis
Authors: Cacai Gilles Habib Todjro , Houngue Jerôme Anani , Houedjissin Serge S. , Pativoh Fleur Gbèmandé , Ahanhanzo Corneille
Published: January 2024

Cassava In vitro regeneration is essentially influenced by exogen factors as well as explants nature.  This work aimed to evaluate explants type and positions influence, phytohormone on cassava plantlets regeneration in modified MS media. The apex and nodes of the position 3, 5, and 7 were initiated on Murashige and Skoog (MS) based media supplemented with Gamborg B5 vitamins and growth regulators such as naphthalene acetic acid (NAA), 6-benzylaminopurine (BAP) and zeatin (ZEAT) in different concentrations. The results indicated a significant difference (p=0.0001) among explants sprouted regarding the nodes position and the cultivar genotype during the time of culture. The highest rate of regenerated plantlets was found with nodes of position 5 (95.33%) followed respectively by nodes of the position 7 (93.33%), nodes of the position 3 (89.33%), and the apex (76%). Regarding the growth regulators, NAA (0.5 mg/l) + BAP (0.5 mg/l) combination was favorable for height growth (26.2cm), and leaves development (7.84 cm) in most of cultivars, whereas NAA (0.5 mg/l) + ZEAT (0.5 mg/l) combination was more favorable to rhizogenesis in overall cultivars. Among the cultivars, the best performance in stem height (26.2 cm), in leaf length (7.84 cm), and roots number (4.64) were observed with INA 1er cultivar. The cultivars RB89509, BEN 86052, and DOKU were less grown on MS supplemented with 0.5 mg/l of BAP or ZEAT. These findings could contribute of using nodes of the positions 5, 7 as potential explants and Zeatin for cassava plantlets rhizogenesis.
Assessment of Soil Fertility Status in Selected Fields under Maize Production in Kongwa District, Dodoma Region, Tanzania
Authors: Nhunda Daniel M. , Semoka Johnson M. , Hamisi Tindwa
Published: January 2024

This study was conducted in the Kongwa District to assess the fertility status of soils of the selected fields under maize production to understand fertility variability among soils and recommend appropriate fertilizer rates. The study involved randomly selected 24 maize fields. Composite soil samples were collected in these fields at 0–20 cm deep and characterized for soil fertility status. Results indicated that 48% of the soils were sandy clay loam and 26% were sandy loam. The remaining fields had clay or loamy sand textural classes. The soil pH ranged from extremely acidic (3.52) to moderately alkaline (7.7), organic carbon ranged from very low to medium (0.19-1.60%) and total N were very low to low (0.01-0.15%). Also, results indicated that 42% of soils had P deficiency and 16.7% had inadequate S levels. In addition, 45.8% of the soils had inadequate exchangeable K and exchangeable Mg levels ranged from very low to high (0.29-4.06 cmol(+) kg-1). Exchangeable Ca was low to very high (1.06 to 10.04 cmol(+) kg-1) with favourable base saturation for crop production. The CEC ranged from very low (2.62 cmol(+) kg-1) to medium (18.9 cmol(+) kg-1). Extractable micronutrients such as Cu, Fe, and Mn were adequate but Zn was inadequate in 58% of the soils. Categorizing nutrient status in soils of the study area showed that fertility is poor regarding N, P, K, Zn, Mg, and Ca. Hence, the studied soils need external nutrient inputs and proper management to optimize crop production.
Growth Performance of Nutri-Cereals in India
Authors: Gangadharan S.  , Pillai Abhinav , Aravind S. , Premsai Mavalluru , Vinupriya R.
Published: January 2024

The Nutrient rich millet crops can be cultivated in adverse soil and climate conditions. As a behest from India United Nations with the aim of creating awareness, to increase production and consumption of millets declared 2023 as the International Year of Millets. Hence the study focussed on estimating the growth performance of Nutri cereals (Millets) in India. The growth performance was estimated using the Compound Annual Growth Rate (CAGR). The secondary data on millets area, production and productivity from 1992 to 2021 were collected from various publications like Indiastat and APEDA. This study revealed that the area and production is declining for the past three periods as a result of the green revolution. There was a significant increase in productivity in the last two periods due to the introduction of high yielding, pest and disease resistant varieties. This study will help in understanding the growth trend of millet during the periods and be able to suggest ways in increasing area, production and productivity of millet cultivation in India.
The Effect of Soaking K-300 Concrete Using Seawater on Concrete Quality
Authors: Musrifah  , Oktaviani Viva , Tukimun
Published: January 2024

Concrete is a mixture of cement, fine aggregate, coarse aggregate, and water with or without additional ingredients to form a solid mass, its use is very common in building structures, but the final quality of the strength of the concrete depends on many factors, including the implementation of its manufacture. and immersion. The research aimed to determine changes in the quality of k-300 concrete and the maximum strength of concrete immersed in salt water. The research was carried out in the Laboratory of the Faculty of Engineering, University of 17 August 1945 Samarinda for 2 months. The stages of research activities are starting, literature study, preparation of materials and tools, testing concrete building materials in the laboratory, designing concrete mixes, making test objects/samples, evaluation, testing concrete compressive strength, conclusions, and reporting. Tests carried out in the laboratory include: (1) checking wear/abrasion of coarse aggregate using the Los Angeles method; (2) examination of coarse aggregate and fine aggregate sieve analysis; (3) examination of specific gravity and SSD absorption of coarse aggregate and fine aggregate; (4) checking water content; (5) checking mud and clay levels; (6) checking the bulk density of coarse aggregate, fine aggregate and mixed aggregate; (7) inspection of concrete slump experiments; (8) soaking concrete using seawater and freshwater; and (9) checking concrete compression strength. The research results show that: (1) The compressive strength of K-300 concrete soaked in seawater, namely 304,915 f'c, is lower than that soaked in fresh water, namely 308,580 f'c; and (2) differences in concrete compressive strength occur at old concrete ages (21 days and 28 days) but at young concrete ages (3, 7 and 14 days) there are no differences in compressive strength.
Holocene Palaeosalinity in a Maya Wetland, Belize, Inferred from the Microfaunal Assemblage
Authors: Alcala-Herrera Javier A. , Jacob John S. , Castillo Maria Luisa Machain , Neck Raymond W.
Published: October 2002

A 5.4-m sequence of peat and marl overlying a basal clay in a northern Belize wetland was studied to assess salinity changes over the past 7000 yr. The distribution of ostracods, gastropods, and foraminifers revealed initially freshwater conditions in a terrestrial wetland, changing to at least mesohaline conditions by about 5600 yr B.P. The mesohaline conditions corresponded to the formation of an open-water lagoon (and precipitation of a lacustrine marl) that was contemporaneous with rapidly rising sea level in the area. A mangrove peat filled the lagoon by 4800 yr B.P. probably as a result of increasingly shallow waters as sea level rise slowed and marl precipitation continued. A new lagoon began to form sometime after 3400 yr B.P. Freshwater ostracods and gastropods found in the marl of this lagoon suggest that it formed under near-limnetic conditions. Freshwater input likely resulted from massive deforestation by the Maya that began by 4400 yr B.P. Subsidence of the mangrove peat likely permitted the formation of a lagoon. A peat has filled the lagoon since at least 500 yr B.P.
Two Creeks Interstade Dated through Dendrochronology and AMS
Authors: Kaiser Klaus Felix
Published: October 2002

Dendrochronological analysis of fossil wood from Two Creeks, Wisconsin, reveals that the Two Creekan Intetstade lasted at least 252 yr. The sites crossdated by tree rings cover an area of about 970 km2. AMS determinations from the beginning and end of the chronology open a14C time window for the episode from 12,050 to 11,750 yr B.P. The interval is contemporaneous with the Older Dryas in northern Europe. The development of a forest covering at least 970 km2on the western shore of Lake Michigan indicates a water level about as low as in modern times. Glacier retreat must have opened drainage channels either through the Straits of Mackinac or via the Indian River Plateau into the eastern lakes. The beginning of the tree-ring chronology coincides with the peak of meltwater pulse 1A at 12,000 yr B.P. Increased amounts of meltwater seem to have disturbed the heat exchange between the waters and the atmosphere in the North Atlantic off the Gulf of St. Lawrence or affected the δ18O-ratio of the evaporation, causing the climatic or isotopic reversal of the Older Dryas in Greenland and northern Europe.
Late Quaternary Floodplain History of the Brazos River in East-Central Texas
Authors: Waters Michael R. , Nordt Lee C.
Published: October 2002

The floodplain along a 75-km segment of the Brazos River, traversing the Gulf Coastal Plain of Texas, has a complex late Quaternary history. From 18,000 to 8500 yr B.P., the Brazos River was a competent meandering stream that migrated from one side of the floodplain to the other, creating a thick layer of coarse-grained lateral accretion deposits. After 8500 yr B.P., the hydrologic regime of the Brazos River changed. The river became an underfit meandering stream that repeatedly became confined within narrow and unstable meander belts that would occasionally avulse. Avulsion occurred four times; first at 8100 yr B.P., then at 2500 yr B.P., again around 500 yr B.P., and finally around 300 yr B.P. The depositional regime on the floodplain also changed after 8500 yr B.P., with floodplain construction dominated by vertical accretion. Most vertical accretion occurred from 8100 to 4200 yr B.P. and from 2500 to 1250 yr B.P. Two major and three minor periods of soil formation are documented in the floodplain sequence. The two most developed soils formed from 4200 to 2500 yr B.P. and from around 1250 to 500 yr B.P. These changes on the floodplain appear to be the result not of a single factor, but of the complex interplay among changes in climate, sediment yield, and intrinsic floodplain variables over time.
Eolian Quartz Flux to Lake Biwa, Central Japan, over the Past 145,000 Years
Authors: Xiao Jule , Inouchi Yoshio , Kumai Hisao , Yoshikawa Shusaku , Kondo Yoichi , Liu Tungsheng , An Zhisheng
Published: October 2002

Eolian quartz flux (EQF, g cm−2(103 yr)−1) to Lake Biwa, central Japan, provides direct information on variations of the East Asian winter monsoon. Lake Biwa sediments spanning the past ca. 145,000 yr are characterized by two main periods when EQF values were significantly greater than 5.50 g cm−2(103 yr)−1, and two main intervals during which EQF values were lower. Two periods with EQF values >5.50 g cm−2(103 yr)−1occurred from ca. 145,000 to 125,000 and 73,000 to 13,000 yr B.P., while times of lower EQF values occurred from ca. 125,000 to 73,000 yr B.P. and around ca. 5500 yr B.P. Between ca. 125,000 and 73,000 yr B.P., three minimum EQF values and two intervening peaks of slightly higher EQF values are recorded. EQF increased markedly from ca. 73,000 to 13,000 yr B.P., whereas between ca. 53,000 and 20,000 yr B.P. the values recorded were relatively lower than those recorded during either the preceding or the subsequent episodes. The data imply that the East Asian winter monsoon strengthened during the periods when EQF values were high, and weakened during the intervals with low EQF values. The EQF record of Lake Biwa can be correlated with the grain-size record of the quartz fraction in Chinese loess and with the SPECMAP marine δ18O record. However, the EQF record apparently lags ca. 5000 yr behind the loess and δ18O records during stage 6/5 and 2/1 transitions and ca. 10,000 yr during stage 5/4 transition. These apparent lags could be due to problems with the chronology; alternatively, they may imply that the eolian quartz flux depended more on the extent of dust source regions than on wind intensity during these transitions.
Intra‐industry effects of bank layoff announcements
Authors: Madura Jeff , Akhigbe Aigbe , Bartunek Kenneth S.
Published: October 2002

Bank layoffs have increased in recent years as a means of reducing operating expenses. To the extent that bank layoffs signal information about other banks, intra‐industry effects should occur. Our objective is to determine whether intra‐industry effects exist, and to explain the variation in intra‐industry effects following bank layoff announcements. Our analysis shows positive and significant intra‐industry effects, which are interpreted as negative information for the announcing bank, as competitors may be able to gain market share. The intra‐industry effects are more favorable when the banks announcing layoffs are in the same region as rival banks, and when banking industry earnings are relatively high.
Thermal inactivation of reduced ferredoxin (flavodoxin):NADP+ oxidoreductase from Escherichia coli
Authors: Jarrett Joseph T , Wan Jason T
Published: October 2002

Ferredoxin (flavodoxin):NADP+ oxidoreductase (FNR) is an essential enzyme that supplies electrons from NADPH to support flavodoxin‐dependent enzyme radical generation and enzyme activation. FNR is a monomeric enzyme that contains a non‐covalently bound FAD cofactor. We report that reduced FNR from Escherichia coli is subject to inactivation due to unfolding of the protein and dissociation of the FADH2 cofactor at 37°C. The inactivation rate is temperature‐dependent in a manner that parallels the thermal unfolding of the protein and is slowed by binding of ferredoxin or flavodoxin. Understanding factors that minimize inactivation is critical for utilizing FNR as an accessory protein for S‐adenosyl‐L‐methionine‐dependent radical enzymes and manipulating FNR as an electron source for biotechnology applications.
Swelling of mitochondria in cultured rat hippocampal astrocytes is induced by high cytosolic Ca2+ load, but not by mitochondrial depolarization
Authors: Kahlert Stefan , Reiser Georg
Published: October 2002

The influence of cytosolic Ca2+ load and of mitochondrial membrane potential change on mitochondrial morphology was investigated in cultured rat hippocampal astrocytes. The uncoupler FCCP, applied together with oligomycin, depolarized mitochondria rapidly but did not change their morphology. Depolarization was associated with a moderate cytosolic [Ca2+]i rise of up to 0.3 μM. Only high cytosolic Ca2+ load (above a threshold of 50 μM), which was evoked by application of the ionophore 4‐Br‐A23187 in Ca2+‐containing medium, caused drastic change of mitochondrial morphology. The shape change from the typical rod‐like to a spherical shape, indicating mitochondrial swelling, was associated with depolarization. Cyclosporin A sensitivity suggests involvement of permeability transition. Thus, a dramatic cytosolic [Ca2+]i rise is required to induce mitochondrial swelling and depolarization. A large but still moderate [Ca2+]i rise evoked by physiological stimulation, however, has no comparable effect.
Transfection of a phosphatidyl‐4‐phosphate 5‐kinase gene into rat atrial myocytes removes inhibition of GIRK current by endothelin and α‐adrenergic agonists
Authors: Bender Kirsten , Wellner-Kienitz Marie-Cécile , Pott Lutz
Published: October 2002

GIRK (G protein‐activated inward‐rectifying K+ channel) channels, important regulators of membrane excitability in the heart and in the central nervous, are activated by interaction with βγ subunits from heterotrimeric G proteins upon receptor stimulation. For activation interaction of the channel with phosphatidylinositol 4,5‐bisphosphate (PtIns(4,5)P2) is conditional. Previous studies have provided evidence that in myocytes PtIns(4,5)P2 levels relevant to GIRK channel regulation are under regulatory control of receptors activating phospholipase C. In the present study a phosphatidyl‐4‐phosphate 5‐kinase was expressed in atrial myocytes by transient transfection. This did not affect basal properties of GIRK current activated by acetylcholine via M2 receptors but completely abolished inhibition of guanosine triphosphate‐γ‐S activated current by endothelin‐1 or α‐adrenergic agonists. We conclude that though PtIns(4,5)P2 is conditional for channel gating, its normal level in the membrane is not limiting basal function of GIRK channels. Moreover, our data provide further evidence for a regulation of GIRK channels by α1A receptors and endothelin‐A receptors, endogenously expressed in atrial myocytes, via depletion of PtIns(4,5)P2.
The effect of work stoppages on the value of firms in Canada
Authors: Hanrahan Robert , Kushner Joseph , Martinello Felice , Masse Isidore
Published: October 2002

Event date methodology is used to estimate the impact of work stoppages on the expected profitability of Canadian firms listed on the Toronto Stock Exchange. Stoppages during collective bargaining decrease returns by 4.5%, whereas illegal stoppages during the term of a collective agreement have little effect on expected returns. The longer the stoppage, the greater the negative impact on the firm. The impact of stoppages also varies across legislative jurisdictions.
China's International Relations Think Tanks: Evolving Structure and Process
Authors: Shambaugh David
Published: October 2002

Over the past two decades China's international relations (IR) think tanks have come to play increasingly important roles in China's foreign policy making and intelligence analysis, as well as serving as an increasingly important liaison to officials and specialists in foreign countries. During this period China's IR think tanks have expanded in quantity as well as improving the quality of personnel and analytical product. Publications by, and discussions with, these think tanks often offer important indications of broader policy debates and competition among institutes and their staff. This article surveys the current organization and state of research in China's IR think tanks, offers historical perspectives on the evolution of this community, and provides current information of relevance to those who interact with these institutions and read their publications.
Chinese Civilian Foreign Policy Research Institutes: Evolving Roles and Increasing
Influence
Authors: Glaser Bonnie S. , Saunders Phillip C.
Published: October 2002

A more pragmatic Chinese foreign policy and a more bureaucratic policy-making process have increased the opportunities for China's civilian research institutes to affect foreign policy. Beijing's growing involvement in the international community has created increased demand for research and analysis to aid Chinese leaders in making informed decisions. A more pluralistic and competitive policy environment has given analysts at think tanks more influence, but has also created new competition from analysts and authors working outside the traditional research institute system. This article examines the evolving role of Chinese civilian foreign policy research institutes, their relationships to policy makers, and the pathways through which they provide input into Chinese foreign policy formulation. It provides an overview of the key civilian research institutes, identifies important trends affecting them, and examines the roles and functions they play. The article concludes with an assessment of sources of policy influence within the Chinese foreign policy process.
Functional anatomy of the midgut gland of Gammarus locusta (Crustacea: Amphipoda)
Authors: Correia A.D. , Pereira A.L. , Costa M.H. , Carrapiço F.
Published: October 2002

A description of the midgut gland of Gammarus locusta with the aim of using this organ as a complementary tool in ecotoxicological studies was made. The hepatopancreas is composed of two pairs of blind-ending tubular structures. The thickness and length of these tubules were ∼50 μm and 5 mm, respectively, in adult males (10–12 mm length). The distal part of each tubule is characterized by non-vacuolated E-cells typically exhibiting a relatively high nuclear to cytoplasmatic ratio. The epithelium of the remaining tubules is characterized by abundant columnar R- and F-cells, both ∼40 μm long. Large vacuolated B-cells (∼60 μm length) were very common along the midgut gland but seemed to increase in number in the proximal region of each tubule. An SEM examination revealed a delicate network of muscle fibres that limits the organ.
Are Rhodophyceae a dietary component for deep-sea holothurians?
Authors: Bühring S.I. , Koppelmann R. , Christiansen B. , Weikert H.
Published: October 2002

Eicosatetraenoic acid (20:4(n-6)), a polyunsaturated fatty acid (PUFA), was found in deep-sea holothurians at a depth of nearly 5000 m in the temperate north-east Atlantic. It has been suggested that deep-sea animals may be able to synthesize this compound de novo. Since this fatty acid is typical of Rhodophyceae, which has previously been found incorporated in gelatinous material captured in the deep sea, an alternative origin of this fatty acid in the deep-sea holothurians is proposed.
A new species of Hydroides (Polychaeta: Serpulidae) from western Mexico
Authors: Bastida-Zavala J. Rolando , de León-González J. Angel
Published: October 2002

A new species of Hydroides (Polychaeta: Serpulidae), is described. Thirty specimens of Hydroides tenhovei sp. nov. were found on a flat PVC structure on soft-bottoms near Punta San Juanico and five additional specimens from Cabo San Lázaro, Baja California Sur, Mexico. The new species is characterized by the presence of a verticil with three large dorsal hammer-shaped spines, partially fused; basal internal spinules are absent in these spines; other spines curve outwards, with sharp tips and a basal internal spinule.
Weak amenability of certain classes of Banach algebras without
bounded approximate identities
Authors: GHAHRAMANI F. , LAU A. T. M.
Published: October 2002

In a recent paper [3] Dales and Pandey have shown that the class Sp of Segal
algebras is weakly amenable. In this paper, for various classes of Segal algebras, we
characterize derivations and multipliers from a Segal algebra into itself and into its
dual module. In particular, we prove that every Segal algebra on a locally compact
abelian group is weakly amenable and an abstract Segal subalgebra of a commutative weakly amenable Banach algebra is weakly amenable. We also introduce the
Lebesgue–Fourier algebra of a locally compact group G and study its Arens regularity when G is discrete or compact.
Malagasy scincid lizards: descriptions of nine new species, with notes on the morphology, reproduction and taxonomy of some previously described species (Reptilia, Squamata: Scincidae)
Authors: Andreone Franco , Greer Allen E.
Published: October 2002

The taxonomy and/or natural history of 33 species of scincid lizards from Madagascar are reviewed. Most of the material, consisting of 187 specimens now housed in the Museo Regionale di Scienze Naturali, Turin, Italy, has been collected recently, but some dates to the 19th century. Nine new species are described in three genera: Amphiglossus mandady, A. nanus, A. spilostichus, A. stylu, A. tanysoma, Paracontias manify, P. hafa, P. tsararano and Pseudoacontiasmenamainty, increasing the known skink fauna of Madagascar (62 species) by 14.5%. All the new species come from the closed forests of north‐eastern Madagascar. Additionally, Amphiglossus praeornatus is resurrected from the synonymy of A. frontoparietalis, and Androngo alluaudi, A. crenni and A. elongatus are transferred to the genus Amphiglossus. There is also a key to the species of Paracontias and a new interspecifically variable character for Mabuya. Information on morphological variation, basic reproductive biology, habits and habitats is provided, as available, for all species. Perhaps most interestingly, Amphiglossus nanus n. sp. represents the eighth skink lineage in which an oviduct has been lost and Amphiglossus melanopleura decreases the number of longitudinal scale rows at mid‐body and the number of subdigital lamellae with altitude.
Rovibrational structure of the Ar–CO complex based on a novel three-dimensional ab initio potential
Authors: Bondo Pedersen Thomas , López Cacheiro Javier , Fernández Berta , Koch Henrik
Published: October 2002

The first three-dimensional ab initio intermolecular potential energy surface of the Ar–CO van der Waals complex is calculated using the coupled cluster singles and doubles including connected triples model and the augmented correlation-consistent polarized valence quadruple zeta (aug-cc-pVQZ) basis set extended with a (3s3p2d1f1g) set of midbond functions. The three-dimensional surface is averaged over the three lowest vibrational states of CO. Rovibrational energies are calculated up to 50 cm−1 above the ground state, thus enabling comprehensive comparison between theory and available experimental data as well as providing detailed guidance for future spectroscopic investigations of higher-lying states. The experimental transitions are reproduced with a root-mean-square error of 0.13 cm−1, excluding states observed around 25 cm−1 above the ground state. The latter states are at variance with the experimentally deduced ordering.
The Torsatron TJ-K, an experiment for the investigation of turbulence in a toroidal low-temperature plasma
Authors: Krause N. , Lechte C. , Stöber J. , Stroth U. , Ascasibar E. , Alonso J. , Niedner S.
Published: October 2002

The Torsatron TJ-K is a toroidal device operated with a magnetically confined low-temperature plasma to study turbulence and wave propagation. The magnetic configuration is the same as for a fusion plasma device. However, the plasma parameters are such that probes can be used in the entire plasma cross section to measure the detailed spatiotemporal structure of the turbulence. At the same time, the dimensionless parameters governing turbulence are in the same range as those of the fusion plasma edge. The objective of the experiment is to obtain data, which allow a close comparison with drift-wave turbulence simulations. Furthermore, the propagation of the helicon heating wave in a toroidal geometry as well as excited gap Alfvén modes will be studied. The article presents the experimental setup and the diagnostics. It is demonstrated that the TJ-K plasma has parameters and profiles relevant to achieve the objectives of the project. First results of turbulence and wave studies are presented.
Computer simulations of the dynamics of doubly occupied N2 clathrate hydrates
Authors: van Klaveren E. P. , Michels J. P. J. , Schouten J. A. , Klug D. D. , Tse J. S.
Published: October 2002

We have studied the dynamical properties of doubly and singly occupied structure II N2 clathrate hydrates by performing a series of classical molecular dynamics calculations. The intermolecular vibrational density of states of the guest molecules show the most explicit changes when going from single to double occupancies. Instead of the narrow peak for single occupancy (at 20 cm−1), a broad range of frequencies occurs between 0 and 200 cm−1 with four modes, which have been assigned to the possible vibrations in the cage. This spectrum provides a unique fingerprint of double occupancy. For the host lattice, the libron band and the optic phonon branch show lower frequencies as compared to single fillings. In contrast, the acoustic phonon branch shifts to lower frequencies for a single filling of the large cases. We find that there is a large vibrational guest–host coupling for both single and double occupancies, although the frequency range is broader in the latter case. There is a significant translational diffusion of the N2 molecules in the doubly occupied cages. Occasionally both molecules simultaneously migrate from one local energy minimum to another. An orientational order of the N2 molecules occurs only within the small cages. However, the relative orientation of the two molecules in the doubly occupied cages is preserved in time.
Flux pinning and critical currents at low-angle grain boundaries in high-temperature superconductors
Authors: Agassi D. , Christen D. K. , Pennycook S. J.
Published: October 2002

Calculations of the pinning potential at low-angle grain boundaries in high-temperature superconductors are presented which fully incorporate the periodic nature of the low-angle boundary. A nonlocal kernel provides a smooth transition from an Abrikosov vortex far from the boundary to a Josephson vortex near the dislocations. We examine the angular dependence of critical current in the two idealized limits of pure strain and pure band bending. Recent data appear limited by band bending with significant potential for improvement through doping.