bluuebunny/crossref_metadata_2025 huggingface dataset:
El ambiente virtual estrategia de aprendizaje y evaluación auténtica del cálculo diferencial en la modalidad escolarizada-presencial
Authors: Espinoza-López Inocencia
Published: March 2024

El presente trabajo describe la investigación realizada para demostrar que un ambiente virtual innovador a través de una plataforma educativa contribuye en el proceso de aprendizaje y evaluación auténtica, en la asignatura de cálculo diferencial del Centro de Bachillerato Tecnológico Industrial y de Servicios No. 83 de Actopan Hidalgo, aplicada en dos grupos con alumnos de cuarto semestre del turno vespertino, dicha investigación tiene un enfoque cualitativo basada en ella metodología de investigación-acción. El diseño consiste en la aplicación de una plataforma educativa Moodle, que complementa la Planeación Didáctica Centrada en el Aprendizaje que contribuye al logro de competencias genéricas y disciplinares por medio del uso de las TIC, con actividades que permiten el uso de la tecnología considerando los estilos de aprendizaje de los estudiantes.

Palabras clave:
Ambiente virtual, estrategia de aprendizaje y evaluación, cálculo diferencial.
 
ABSTRACT
The present work describes the research carried out to demonstrate that an innovative virtual environment through an educational platform contributes to the learning process and authentic evaluation, in the differential calculus subject of the Industrial and Services Technological Baccalaureate Center No. 83 of Actopan. Hidalgo, applied in two groups with fourth-semester students of the evening shift, said research has a qualitative approach based on it action-research methodology. The design consists of the application of a Moodle educational platform, which complements the Learning-Centered Didactic Planning that contributes to the achievement of generic and disciplinary competences through the use of ICT, with activities that allow the use of technology considering the styles of student learning.
Keywords:
Virtual environment, learning and evaluation strategy, differential calculus.
The ancient pattern in the Crimean cultural landscape
Authors: Khlevnoi Vladimir Aleksandrovich
Published: March 2024

The subject of the study is the ancient pattern in the cultural landscape of Crimea, expressed in architecture, sculpture, monumental and decorative arts. The object of the study is the Crimean artifacts of the ancient polis (architectural details, sculpture, vase painting) in comparison with similar objects of mainland Greece. The author pays special attention to the transformations of the ancient style in the Crimean diaspora, associated with the influence of autochthonous cultures: Taurian, Meotian, Cimmerian, Scythian-Sarmatian, and examples of the synthesis of the artistic stylistics of these cultures and the ancient style. The use of the ancient order system as the basis of all subsequent styles, including the Crimean modern, which is a reflection of the synthesis of cultures of the multiethnic cultural landscape of Crimea, is also traced. The continuous continuity of the ancient style up to the present is shown.  The article uses the method of historicism in retrospect of the ancient pattern in the cultural landscape of the Crimea, the comparative method in the comparative analysis of artifacts of the Crimea and mainland Greece, the method of stylistic analysis in classical architecture and decorative arts of the Crimea. The main conclusions of the study are: 1. The Crimean cultural landscape is diverse due to the historical polyethnicity of the region, associated with its geographical location and unique natural complex, which has become a place of numerous ethnic migrations throughout history. This is also connected with the appearance of ancient Greek culture in the Crimea, which left a significant mark on the peninsula. 2. The ancient order architectural system, as well as the use of classical anthropomorphic proportions in sculpture, wall painting, vase painting, became the basis of the classical approach in architecture and fine arts. The constructive expediency, conciseness and harmony inherent in ancient architecture became the reason for its global introduction into subsequent architectural and artistic styles, up to the present time. 3. The ancient pattern in the Crimean cultural landscape is unique in that it embodies the cultural synthesis of Greek classics and local autochthonous cultures.
Os Índios no Império do Brasil: a etnografia do IHGB entre as décadas de 1840 e 1860
Authors: Kodama Kaori
Published: March 2024

O principal objetivo da historiadora neste livro é analisar como se deu a criação da Seção de Etnografia e Arqueologia no Instituto Histórico e Geográfico do Brasil (IHGB). Formada pela elite letrada imperial oitocentista, esta Seção contava com homens comprometidos em originar um projeto político de desenho da nação brasileira que considerava o papel que caberia ao indígena nesse processo de gestação. A obra está fundamentada em uma sólida pesquisa documental. Ao se deparar com seu conteúdo, o leitor terá a oportunidade de percorrer a identidade nacional do século XIX em um de seus aspectos mais complexos – a questão indígena -, por uma via pouco explorada. Dividido em três partes, a primeira trata de um apanhado das diversas representações do índio brasileiro. Na segunda parte, a autora aponta os pressupostos implícitos na criação de um campo etnográfico no IHGB em diálogo com o problema da nação no Império do Brasil. Já na terceira e última parte, ela associa a criação do IHGB a certas práticas etnográficas levadas adiante em nome do próprio governo imperial.
Switching of RNA splicing regulators in immature neuroblasts: a key step in adult neurogenesis
Authors: Bernou Corentin , Mouthon Marc-André , Daynac Mathieu , Kortulewski Thierry , Demaille Benjamin , Barroca Vilma , Couillard-Despres Sébastien , Dechamps Nathalie , Ménard Véronique , Bellenger Léa , Antoniewski Christophe , Chicheportiche Alexandra , Boussin François D.
Published: March 2024

The lateral wall of the subventricular zone harbors neural stem cells (NSC, B cells) which generate proliferating transient-amplifying progenitors (TAP, C cells) that ultimately give rise to neuroblasts (NB, A cells). Molecular profiling at the single cell level struggles to distinguish these different cell types. Here, we combined transcriptome analyses of FACS-sorted cells and single-cell RNAseq to demonstrate the existence of an abundant, clonogenic and multipotent population of immature neuroblasts (iNB cells) at the transition between TAP and migrating NB (mNB). iNB are reversibly engaged in neuronal differentiation. Indeed, they keep molecular features of both undifferentiated progenitors, plasticity and unexpected regenerative properties. Strikingly, they undergo important progressive molecular switches, including changes in the expression of splicing regulators leading to their differentiation in mNB subdividing them into 2 subtypes, iNB1 and iNB2. Due to their plastic properties, iNB could represent a new target for regenerative therapy of brain damage.
Plasma extracellular vesicle synaptic proteins as biomarkers of clinical progression in patients with Parkinson’s disease
Authors: Hong Chien-Tai , Chung Chen-Chih , Yu Ruan-Ching , Chan Lung
Published: March 2024

Synaptic dysfunction plays a key role in Parkinson’s disease (PD), and plasma extracellular vesicle (EV) synaptic proteins are emerging as biomarkers for neurodegenerative diseases. Assessment of plasma EV synaptic proteins for their efficacy as biomarkers in PD and their relationship with disease progression was conducted. In total, 144 participants were enrolled, including 101 people with PD (PwP) and 43 healthy controls (HCs). The changes in plasma EV synaptic protein levels between baseline and 1-year follow-up did not differ significantly in both PwP and HCs. In PwP, the changes in plasma EV synaptic protein levels were significantly associated with the changes in Unified Parkinson’s Disease Rating Scale (UPDRS)-II and III scores. Moreover, PwP with elevated levels (first quartile) of any one plasma EV synaptic proteins (synaptosome-associated protein 25, growth-associated protein 43 or synaptotagmin-1) had significantly greater disease progression in UPDRS-II score and the postural instability and gait disturbance subscore in UPDRS-III than did the other PwP after adjustment for age, sex, and disease duration. The promising potential of plasma EV synaptic proteins as clinical biomarkers of disease progression in PD was suggested. However, a longer follow-up period is warranted to confirm their role as prognostic biomarkers.
TLR2 regulates hair follicle cycle and regeneration via BMP signaling
Authors: Xiong Luyang , Zhevlakova Irina , West Xiaoxia Z , Gao Detao , Murtazina Rakhilya , Horak Anthony , Brown J Mark , Molokotina Iuliia , Podrez Eugene A , Byzova Tatiana V
Published: March 2024

The etiology of hair loss remains enigmatic, and current remedies remain inadequate. Transcriptome analysis of aging hair follicles uncovered changes in immune pathways, including Toll-like receptors (TLRs). Our findings demonstrate that the maintenance of hair follicle homeostasis and the regeneration capacity after damage depend on TLR2 in hair follicle stem cells (HFSCs). In healthy hair follicles, TLR2 is expressed in a cycle-dependent manner and governs HFSCs activation by countering inhibitory BMP signaling. Hair follicles in aging and obesity exhibit a decrease in both TLR2 and its endogenous ligand carboxyethylpyrrole (CEP), a metabolite of polyunsaturated fatty acids. Administration of CEP stimulates hair regeneration through a TLR2-dependent mechanism. These results establish a novel connection between TLR2-mediated innate immunity and HFSC activation, which is pivotal to hair follicle health and the prevention of hair loss and provide new avenues for therapeutic intervention.
Machine Learning Based Modelling of Human and Insect Olfaction Screens Millions of compounds to Identify Pleasant Smelling Insect Repellents
Authors: Kowalewski Joel , Boyle Sean M. , Arvidson Ryan , Ejercito Jadrian , Ray Anandasankar
Published: March 2024

The rational discovery of behaviorally active odorants is impeded by a lack of understanding on how the olfactory system generates percept or valence for a volatile chemical. In previous studies we showed that chemical informatics could be used to model prediction of ligands for a large repertoire of odorant receptors in
Drosophila
(Boyle et al., 2013). However, it remained difficult to predict behavioral valence of volatiles since the activities of a large ensembles of odor receptors encode odor information, and little is known of the complex information processing circuitry. This is a systems-level challenge well-suited for Machine-learning approaches which we have used to model olfaction in two organisms with completely unrelated olfactory receptor proteins: humans (∼400 GPCRs) and insects (∼100 ion-channels). We use chemical structure-based Machine Learning models for prediction of valence in insects and for 146 human odor characters. Using these predictive models, we evaluate a vast chemical space of >10 million compounds
in silico.
Validations of human and insect behaviors yield very high success rates. The discovery of desirable fragrances for humans that are highly repulsive to insects offers a powerful integrated approach to discover new insect repellents.
Testosterone-Induced Metabolic Changes in Seminal Vesicle Epithelial cells Alter Plasma Components to Enhance Sperm Fertility
Authors: Yamanaka Takahiro , Xiao Zimo , Tsujita Natsumi , Awad Mahmoud , Umehara Takashi , Shimada Masayuki
Published: March 2024

Male factors account for almost half of the causes of infertility. In rodents and humans, most of the components of semen are supplied by the seminal vesicles, and they support male reproductive ability, but there are many unknown details. In this study, the metabolic changes in the seminal vesicle epithelial cells were focused on, and the mechanisms by which testosterone affects the seminal plasma composition were investigated. A factor that improves the linear motility of sperm was secreted from the seminal vesicles, which were synthesized in an androgen-dependent manner. Bioassays, gene expression, and flux analysis studies demonstrated that testosterone promotes glucose uptake in seminal vesicle epithelial cells via GLUT4, resulting in oleic acid synthesis. Oleic acid was shown to be taken up by sperm and to promote linear motility, thereby improving fertilization rates both
in vitro
and
in vivo
. ACLY was a critical factor in this metabolic change, which produces oleic acid and enhances their fertilization ability
in vivo
. In conclusion, the critical role of testosterone-induced metabolic changes in the seminal vesicles is to ensure the synthesis of oleic acid, which is important for sperm fertilization
in vivo
. These findings provide new perspectives for the development of potential biomarkers of male fertility and advances in the treatment of male infertility.
Testosterone-Induced Metabolic Changes in Seminal Vesicle Epithelial cells Alter Plasma Components to Enhance Sperm Fertility
Authors: Yamanaka Takahiro , Xiao Zimo , Tsujita Natsumi , Awad Mahmoud , Umehara Takashi , Shimada Masayuki
Published: March 2024

Male infertility depends on both sperm and seminal plasma and is induced by aging. In this study, male infertility was examined with seminal plasma and its synthesis mechanism. The factors ensuring
in vivo
fertilization potential was secreted from seminal vesicle where the factors were synthesized in an androgen-dependent manner. Androgen increased glucose uptake and glycolytic capacity in seminal vesicles, which caused activation of oleic acid synthesis rather than mitochondrial ATP synthesis. ACLY was identified as a key player in this metabolic mechanism for producing oleic acid that was incorporated into the sperm and enhanced fertilization potential
in vivo
. In conclusion, an important role of testosterone-induced metabolic pathways in the seminal vesicle was to ensure the synthesis of oleic acid, which is essential for sperm fertilization
in vivo
. These results provide new perspectives for the development of biochemical markers of semen to assess male fertility and for artificial insemination techniques.Testosterone induces ACLY expression in seminal vesicle, a key factor of forming seminal plasma to acquire
in vivo
fertilization ability of sperm.
Enhancing brain tumor diagnosis: an optimized CNN hyperparameter model for improved accuracy and reliability
Authors: Asiri Abdullah A. , Shaf Ahmad , Ali Tariq , Aamir Muhammad , Irfan Muhammad , Alqahtani Saeed
Published: March 2024

Hyperparameter tuning plays a pivotal role in the accuracy and reliability of convolutional neural network (CNN) models used in brain tumor diagnosis. These hyperparameters exert control over various aspects of the neural network, encompassing feature extraction, spatial resolution, non-linear mapping, convergence speed, and model complexity. We propose a meticulously refined CNN hyperparameter model designed to optimize critical parameters, including filter number and size, stride padding, pooling techniques, activation functions, learning rate, batch size, and the number of layers. Our approach leverages two publicly available brain tumor MRI datasets for research purposes. The first dataset comprises a total of 7,023 human brain images, categorized into four classes: glioma, meningioma, no tumor, and pituitary. The second dataset contains 253 images classified as “yes” and “no.” Our approach delivers exceptional results, demonstrating an average 94.25% precision, recall, and F1-score with 96% accuracy for dataset 1, while an average 87.5% precision, recall, and F1-score, with accuracy of 88% for dataset 2. To affirm the robustness of our findings, we perform a comprehensive comparison with existing techniques, revealing that our method consistently outperforms these approaches. By systematically fine-tuning these critical hyperparameters, our model not only enhances its performance but also bolsters its generalization capabilities. This optimized CNN model provides medical experts with a more precise and efficient tool for supporting their decision-making processes in brain tumor diagnosis.
AutoSCAN: automatic detection of DBSCAN parameters and efficient clustering of data in overlapping density regions
Authors: Bushra Adil Abdu , Kim Dongyeon , Kan Yejin , Yi Gangman
Published: March 2024

The density-based clustering method is considered a robust approach in unsupervised clustering technique due to its ability to identify outliers, form clusters of irregular shapes and automatically determine the number of clusters. These unique properties helped its pioneering algorithm, the Density-based Spatial Clustering on Applications with Noise (DBSCAN), become applicable in datasets where various number of clusters of different shapes and sizes could be detected without much interference from the user. However, the original algorithm exhibits limitations, especially towards its sensitivity on its user input parameters minPts and ɛ. Additionally, the algorithm assigned inconsistent cluster labels to data objects found in overlapping density regions of separate clusters, hence lowering its accuracy. To alleviate these specific problems and increase the clustering accuracy, we propose two methods that use the statistical data from a given dataset’s k-nearest neighbor density distribution in order to determine the optimal ɛ values. Our approach removes the burden on the users, and automatically detects the clusters of a given dataset. Furthermore, a method to identify the accurate border objects of separate clusters is proposed and implemented to solve the unpredictability of the original algorithm. Finally, in our experiments, we show that our efficient re-implementation of the original algorithm to automatically cluster datasets and improve the clustering quality of adjoining cluster members provides increase in clustering accuracy and faster running times when compared to earlier approaches.
RECOMENDACIONES PARA REDUCIR LA CONTAMINACIÓN DEL AIRE DEBIDO AL USO DE LEÑA EN VIVIENDAS
Authors: Simon François , Bustamante Waldo
Published: March 2024

Este documento presenta evidencia sobre la contaminación del aire causada por partículas de 2,5 μm (MP2,5) debido a la quema de leña en el sector residencial, excluyendo otras fuentes estacionarias y móviles, y su impacto en la salud pública y el entorno construido. Un estudio de caso en Temuco se presenta para ilustrar la problemática. Se analizan los marcos de políticas vigentes y se exploran oportunidades para la implementación de nuevas estrategias y políticas públicas capaces de reducir esta contaminación del aire.
PYMES Y VULNERABILIDAD LABORAL: LA FALSA PROMESA DEL «PAÍS DE EMPRENDEDORES»
Authors: Rehner Johannes , Señoret Andrés
Published: March 2024

Existe la idea generalizada de que los microemprendedores tienen un rol predominante en la creación de nuevos empleos, siendo más relevantes que las grandes empresas o el Estado. Sin embargo, estas ofrecen trabajos precarios, frente a lo cual las políticas de sustentabilidad del empleo (ODS 8) deberían reevaluar su relevancia.
Effects of pulsed and continuous wave 902 MHz mobile phone exposure on brain oscillatory activity during cognitive processing
Authors: Krause Christina M. , Pesonen Mirka , Haarala Björnberg Christian , Hämäläinen Heikki
Published: January 2007

The aim of the current double‐blind studies was to partially replicate the studies by Krause et al. [2000a, b, 2004] and to further investigate the possible effects of electromagnetic fields (EMF) emitted by mobile phones (MP) on the event‐related desynchronisation/synchronisation (ERD/ERS) EEG (electroencephalogram) responses during cognitive processing. Two groups, both consisting of 36 male participants, were recruited. One group performed an auditory memory task and the other performed a visual working memory task in six exposure conditions: SHAM (no EMF), CW (continuous wave EMF) and PM (pulse modulated EMF) during both left‐ and right‐side exposure, while the EEG was recorded. In line with our previous studies, we observed that the exposure to EMF had modest effects on brain oscillatory responses in the alpha frequency range (∼8–12 Hz) and had no effects on the behavioural measures. The effects on the EEG were, however, varying, unsystematic and inconsistent with previous reports. We conclude that the effects of EMF on brain oscillatory responses may be subtle, variable and difficult to replicate for unknown reasons. Bioelectromagnetics 28:296–308, 2007. © 2007 Wiley‐Liss, Inc.
Factors Affecting the Interlayer Arrangement of Transition Metal–Ethylenediaminetetraacetate Complexes Intercalated in Mg/Al Layered Double Hydroxides
Authors: Wu Guoqing , Wang Lianying , Yang Lan , Yang Junjiao
Published: January 2007

Transition metal (M)–ethylenediaminetetraacetate (edta) complexes {[M(edta)]2–} have been intercalated in layered double hydroxides (LDHs) by a hydrothermal method using MgAl–NO3 LDH as the precursor. The factors affecting the orientation of the incorporated [M(edta)]2– in the resulting well‐ordered materials were investigated. Whilst varying the metal cation in the intercalated complex has no major influence on the orientation of the [M(edta)]2– (M = Co, Ni, Cu, Zn) anion in the interlayer galleries, there is a marked dependence on layer charge density. The observed basal spacings of 1.402–1.461 nm for Mg2Al–M(edta) LDH and 1.254 nm for Mg3Al–Zn(edta) LDH can be ascribed to bilayer and monolayer arrangements, respectively, of the [M(edta)]2– anion. When the Mg/Al ratio is varied in the range 2.2–2.7 the two guest arrangements coexist. The evolution of the interlayer arrangement of [M(edta)]2– in LDHs with increasing temperature was studied by variable‐temperature in‐situ XRD measurements, variable‐temperature in‐situ FT‐IR, and combined thermogravimetric analysis and mass spectrometry (TGA‐MS). In the case of Mg2Al–M(edta) LDH, a metastable phase with a similar monolayer structure to that found in Mg3Al–M(edta) LDH was detected by XRD in the range 140–300 °C. Cooling of the calcined solid to room temperature in air leads to the recovery of the original bilayer structure. The reversible nature of the structural transformation indicates that a reorientation of the guest [M(edta)]2– complex in the interlayer galleries occurs on heating, rather than a grafting process. Heat treatment of Mg3Al–M(edta) LDH results only in a gradual contraction of the basal spacing associated with the loss of interlayer water without any reorientation of the guest [M(edta)]2– complex. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Tamoxifen‐induced modification of serum lipoprotein phospholipids in the cockerel
Authors: Breckenridge W. Carl , Lazier C. B.
Published: January 2007

The administration of tamoxifen (Tam), a nonsteroidal antiestrogen, or of a diphenyl‐methane derivative of Tam that does not bind to the estrogen receptor (DPPE) of cockerels results in a marked decrease in the concentration of serum lipoprotein constitutents with an apparent alteration in phospholipid composition. To establish the nature of changes in phospholipids, the molecular species of phosphatidylcholine (PC) and sphingomyelin (Sph) were isolated and characterized. Between 9 and 18 hr following the administration of Tam or DPPE, there was a marked decrease in the proportion of molecular species of serum PC containing C16 and C18 fatty acids, but there was an increase in the proportion of molecular species containing C20 and C22 polyunsaturated fatty acids. Fatty acid analyses revealed that this change was due to an increase in arachidonic and docosaxaenoic acids at the expense of oleic and linoleic acids. These proportional changes were due to an absolute decrease in serum of PC molecular species containing palmitic and stearic acids in association with oleic and linoleic acids with very little change in the absolute concentration of molecular species containing arachidonic and docosahexaenoic acids. By contrast, the composition of Sph, which contained palmitic acid as the major fatty acid, was not altered during treatment. It is concluded that the short‐term effect of Tam and DPPE on plasma phospholipids of the cockerel is due to a selective conservation of PC containing long chain polyunsaturated fatty acids.
Changes in muscle lipid composition and resistance adaptation to temperature in the freshwater crayfish,Austropotamobius pallipes
Authors: Cossins A. R.
Published: January 2007

The phospholipid and fatty acid composition of muscle lipid extracts from crayfish acclimated to 4 C and 25 C (18 hr‐light photoperiod) were analyzed. The phospholipid content and class distribution, and cholesterol content were unaffected by the acclimation treatment. Unsaturation of muscle phosphoglycerides was higher in cold acclimated crayfish. Serine/inositol phosphoglycerides from cold‐acclimated animals showed somewhat higher proportions of mono‐and polyunsaturated fatty acids, whereas choline and ethanolamine phosphoglycerides were less affected. This was correlated with a decreased resistance of cold‐acclimated crayfish to lethal high temperature. Acclimation at 4 C under an 8 hr‐light photoperiod caused an increased fatty acid unsaturation of the total phospholipid fraction compared to the 4 C, 18 hr‐light photoperiod acclimated animals. The resistance of 4 C acclimated crayfish to lethal high temperature, however, was unaffected by daylength treatment. The resistance of freshwater crayfish to lethal high temperature is not simply related to the degree of saturation of the muscle phospholipids. It is suggested that a breakdown in the integrity of a bulk‐lipid bilayer is not involved in the process of heat death; rather, that a membrane‐bound protein factor, whose thermal sensitivity is modified by changes in its phospholipid environment during temperature adaptation but not during photoperiod adaptation, is the primary site of heat injury.
Studies on metabolism of linoleic‐1‐14C acid in testes of hypophysectomized rats
Authors: Nakamura Masami , Privett O. S.
Published: January 2007

Studies are reported on the influence of hypophysectomy and pituitary gonadotrophins on the interconversion and incorporation of linoleic‐1‐14C acid into lipid classes of mature rat testis. Linoleic 1‐14C acid was injected into the testes of mature rats 3 weeks after hypophysectomy. Groups of animals were killed at 0.25, 0.50, 1, 3, 12, 24, 36 and 48 hr after injection of the radioactive linoleic acid, and the incorporation of radio‐activity into the fatty acids and lipid classes of the testicular lipids was determined. Similar experiments were carried out with hypophysectomized animals injected intramuscularly with luteinizing or follicle stimulating hormones, or both. The specific activitties of the triglyverides and phospholipids of the testicular lipid increased to a maximum ca. 1 hr after the injection of the radioactive linoleic acid, then decreased sharply. The general pattern of changes in the specific activities of these compounds indicated that the rate of fatty acid catabolism was greatly increased by hypophysectomy. In contrast, the specific activities of the cholesteryl esters and glyceryl ether diesters changed slowly after reaching a maximum at approximately the same time. This pattern, their accumulation in the lipid, and an increase in the constituent 22∶5 indicated that the turnover of these compounds was impaired by hypophysectomy. The conversion of linoleic acid to arachidonic acid was also impaired by hypophysectomy, as evidenced by an increase in the percentage and the high specific activity of 20∶3 compared to 20∶4. The administration of gonadotrophins partially prevented the effects of hypophysectomy, indicating that some of the enzymes in the testes involved in the metabolism of the lipids are hormone sensitive.
Water wave diffraction by a surface strip
Authors: GAYEN RUPANWITA , MANDAL B. N. , CHAKRABARTI A.
Published: January 2007

The two-dimensional problem of wave diffraction by a strip of arbitrary width is investigated here in the context of linearized theory of water waves by reducing it to a pair of Carleman-type singular integral equations. These integral equations have been solved earlier by an iterative process which is valid only for a sufficiently wide strip. A new method is described here by which solutions of these integral equations are determined by solving a set of four Fredholm integral equations of the second kind, and the process is valid for a strip of arbitrary width. Numerical solutions of these Fredholm integral equations are utilized to obtain fairly accurate numerical estimates for the reflection and transmission coefficients. Previous numerical results for a wide strip are recovered from the present analysis. Additional results for the reflection coefficient are presented graphically for moderate values of the strip width which exhibit a less oscillatory nature of the curve than the case of a wide strip.
Vortex scattering by step topography
Authors: HINDS A. K. , JOHNSON E. R. , MCDONALD N. R.
Published: January 2007

The scattering at a rectilinear step change in depth of a shallow-water vortex pair consisting of two patches of equal but opposite-signed vorticity is studied. Using the constants of motion, an explicit relationship is derived relating the angle of incidence to the refracted angle after crossing. A pair colliding with a step from deep water crosses the escarpment and subsequently propagates in shallow water refracted towards the normal to the escarpment. A pair colliding with a step from shallow water either crosses and propagates in deep water refracted away from the normal or, does not cross the step and is instead totally internally reflected by the escarpment. For large depth changes, numerical computations show that the coherence of the vortex pair is lost on encountering the escarpment.
Going to the Nation: the idea of Oklahoma in early blues recordings
Authors: SMITH CHRIS
Published: January 2007

This paper considers references to Oklahoma in blues recordings from 1924 to 1941, and the paradox that, although the reality of life for African-Americans in that state was little different from life in the Deep South, the recordings usually speak of migration to Oklahoma in optimistic terms. The notion that the Indian Nation (a.k.a. ‘the Territory’) had been a refuge for runaway slaves is rebutted, together with the conclusion that optimistic references in the blues preserve this idea as a collective memory. What is being recalled is rather the period between the Civil War and statehood (1907): the former slaves of Native Americans in Oklahoma became tribal members, gaining the civil and property rights accorded to tribes-people, and the black townships movement offered the prospect of autonomy and self-government on the frontier. Two songs which take a negative view of Oklahoma's Jim Crow reality are also considered.
Bessie Smith: ‘Down Hearted Blues’ and ‘Gulf Coast Blues’ revisited
Authors: SAGEE ALONA
Published: January 2007

A re-examination of Bessie Smith's first two released blues recordings – ‘Down Hearted Blues’ and ‘Gulf Coast Blues’ – demonstrates that her interpretative originality and expressive individuality were evident from the start of her recording career in 1923. The micro-components of Bessie's early vocal tendencies are revealed through full transcriptions of her vocal line on each of these recordings combined with detailed description and analysis of the pitch content, the main rhythmic and melodic characteristics, and the melodic-harmonic and text-music relationships. The method demonstrates that, although Bessie's phrases display some similarities with each other, they constantly vary in imaginative ways, matching her with true jazz improvisers.
The Verbal and the Visual in Science: A Heideggerian Perspective
Authors: Gross Alan G.
Published: January 2007

Argument

Heidegger's philosophy of science is notable for the prominence it gives to visuals and visualization. This is because for Heidegger, truth – including scientific truth – is the consequence of unconcealment, the lifting of a veil. But as scientific truth is a special kind, its visualization is also special: scientific truth reveals itself to us as, in Heidegger's words, “a calculable nexus of forces.” This nexus unconceals itself largely by means of instrumentation: it is this process of revelation that turns objects into objects of science. Despite its focus on visualization, however, Heidegger's philosophy of science cannot be applied directly to scientific visuals. His categories are not designed with visual exegesis in mind. For that purpose, semiotics, the science of meaning as defined by Charles Peirce, is a necessary intermediary between the abstract and the concrete, a taxonomy of icon, index, and symbol that can be employed as a set of hermeneutic probes that permit the exploration of scientific visuals as embodiments and carriers of scientific meaning. But not their sole embodiments and carriers. In achieving scientific semiosis, the verbal and visual must combine their particular strengths. This is also in accord with a Heideggerian view: science moves methodically from the visual to the propositional, though it never leaves the visual behind.
Implications for coral reef conservation of diver specialization
Authors: DEARDEN PHILIP , BENNETT MICHELLE , ROLLINS RICK
Published: January 2007

One activity with potential to provide a direct incentive for reef conservation is scuba diving. In the absence of effective management, diving can also have negative impacts. This study shows how an understanding of diver specialization can be used to help manage diving and increase its effectiveness as an incentive-driven conservation activity. Surveys were used to assess motivations, satisfactions and dive history of divers in Phuket (Thailand) and categorize divers by degree of specialization. Highly specialized divers were more likely to be on a live-aboard trip than less specialized divers and placed greater importance on the characteristics of the dive itself rather than the trip. Less specialized divers put more emphasis on non-dive characteristics. Satisfaction levels differed significantly among specialization groups in terms of overall satisfaction with the dive experience, satisfactions compared with motivations and satisfactions with specific trip characteristics. Overall there was a decline in satisfaction levels with increasing specialization. These finding are compared to a wildlife tourism model that links impacts with client characteristics and suggests a displacement of specialists by generalists and changes in the limits of acceptable change (LAC) over time. The dive data supported this progression leading to increased industry competition and reduced opportunities to sustain a broad-based dive industry that will act as an incentive-driven mechanism for reef conservation. Specific actions related to reef access and zoning according to a diver opportunity spectrum (DOS), establishing LAC and monitoring programmes, enforcing safety and environmental regulations are suggested to promote a more sustainable approach to dive management. Social science insights can be used to aid reef management strategies and increase the potential for diving to contribute towards reef conservation.
Poisson Representation of a Ewens Fragmentation Process
Authors: GNEDIN ALEXANDER , PITMAN JIM
Published: January 2007

A simple explicit construction is provided of a partition-valued fragmentation process whose distribution on partitions of [n] = 1,. . .,nat time θ ≥ 0 is governed by the Ewens sampling formula with parameter θ. These partition-valued processes are exchangeable and consistent, asnvaries. They can be derived by uniform sampling from a corresponding mass fragmentation process defined by cutting a unit interval at the points of a Poisson process with intensity θx−1dx on/mathbbR+, arranged to beintensifying as θ increases.
‘We have had nothing for so long that we don't know what to ask for’: New Deal for Communities and the Regeneration of Socially Excluded Terrain
Authors: Wallace Andrew
Published: January 2007

This paper explores New Labour's desire to refurbish the physical and social fabric of excluded neighbourhoods through its New Deal for Communities (NDC) programme. It begins by examining three key concepts that embody and underpin this policy intervention – community, agency and exclusion and proceeds by contrasting these conceptual dimensions with a set of discordant, intra-neighbourhood processes of conflict, contestation and division, identified by recently conducted fieldwork in an NDC area. I argue that such processes produce a complex social terrain that is inhabited by social agents with a diverse range of needs, values and experiences, before discussing how this challenges and de-stabilises NDC's aspiration to ‘promote’ community, change individual behaviour and tackle exclusion effectively. The paper concludes by questioning whether New Labour's desire to implement a ‘community’ project, shaped by theoretical precepts, constrains NDC's ability to deliver lasting change to excluded areas.
Nighttime ASTER thermal imagery as an elevation surrogate for filling SRTM DEM voids
Authors: Crippen Robert E. , Hook Simon J. , Fielding Eric J.
Published: January 2007

The Shuttle Radar Topographic Mission (SRTM) produced digital elevation models (DEMs) of most of Earth's land surface, but the radar observational geometry resulted in data voids in areas of high relief. Here we test the derivation of elevation from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) nighttime thermal data for the purpose of filling these voids. The method uses the general linear relationship between temperature and altitude as described by the environmental lapse rate. The results for the test area are generally superior to void filling by interpolation, particularly where voids cross ridges or canyons. Errors associated with the approach are identified along with potential improvements.
Xist and the order of silencing
Authors: Ng Karen , Pullirsch Dieter , Leeb Martin , Wutz Anton
Published: January 2007

X inactivation is the mechanism by which mammals adjust the genetic imbalance that arises from the different numbers of gene‐rich X‐chromosomes between the sexes. The dosage difference between XX females and XY males is functionally equalized by silencing one of the two X chromosomes in females. This dosage‐compensation mechanism seems to have arisen concurrently with early mammalian evolution and is based on the long functional Xist RNA, which is unique to placental mammals. It is likely that previously existing mechanisms for other cellular functions have been recruited and adapted for the evolution of X inactivation. Here, we critically review our understanding of dosage compensation in placental mammals and place these findings in the context of other cellular processes that intersect with mammalian dosage compensation.
A Multicompartment Vascular Model for Inferring Baseline and Functional Changes in Cerebral Oxygen Metabolism and Arterial Dilation
Authors: Huppert Theodore J , Allen Monica S , Benav Heval , Jones Phill B , Boas David A
Published: January 2007

Functional hemodynamic responses are the composite results of underlying variations in cerebral oxygen consumption and the dilation of arterial vessels after neuronal activity. The development of biophysically based models of the cerebral vasculature allows the separation of the neuro-metabolic and neuro-vascular influences on measurable hemodynamic signals such as functional magnetic resonance imaging or optical imaging. We describe a multicompartment model of the vascular and oxygen transport dynamics associated with stimulus-driven neuronal activation. Our model offers several unique features compared with previous formulations such as the ability to estimate baseline blood flow, volume, and oxygen consumption from functional data. In addition, we introduce a capillary compliance model, arterial and venous oxygen permeability, and model the dynamics of extravascular tissue oxygenation. We apply this model to multimodal optical spectroscopic and laser speckle imaging of the rat somato-sensory cortex during nine conditions of whisker stimulation. By fitting the model using a psuedo-Bayesian framework to incorporate multimodal observations, we estimate baseline blood flow to be 94 (±15) mL/100 g min and baseline oxygen consumption to be 6.7 (±1.3) mL O2/100 gmin. We calculate parametric, linear increases in arterial dilation ( R2 = 0.96) and CMRo2 ( R2 = 0.87) responses over the nine conditions. Other parameters estimated by the model include vascular transit time and volume reserve, oxygen content, saturation, diffusivity rate constants, and partial pressure of oxygen in the vascular compartments and in the extravascular tissue. Finally, we compare this model to earlier work and find that the multicompartment model more accurately describes the observed oxygenation changes when compared with a single compartment version.
Big roles for small GTPases in the control of directed cell movement
Authors: Charest Pascale G. , Firtel Richard A.
Published: January 2007

Small GTPases are involved in the control of diverse cellular behaviours, including cellular growth, differentiation and motility. In addition, recent studies have revealed new roles for small GTPases in the regulation of eukaryotic chemotaxis. Efficient chemotaxis results from co-ordinated chemoattractant gradient sensing, cell polarization and cellular motility, and accumulating data suggest that small GTPase signalling plays a central role in each of these processes as well as in signal relay. The present review summarizes these recent findings, which shed light on the molecular mechanisms by which small GTPases control directed cell migration.
Modeling of organic thin film transistors: Effect of contact resistances
Authors: Natali Dario , Fumagalli Luca , Sampietro Marco
Published: January 2007

Field effect transistors require an Ohmic source contact and an Ohmic drain contact for ideal operation. In many real situations, however, and specifically in organic devices, the injection of charge carriers from metals into semiconductors can be an inefficient process that is non-Ohmic. This has an adverse impact on the performance of thin film transistors and makes the analysis of electrical measurements a complex task because contact effects need to be disentangled from transistor properties. This paper deals with the effects of non-Ohmic contacts on the modeling of organic transistors and gives specific rules on how to extract the real transistor parameters (mobility, threshold voltage, and contact resistances) using only electrical measurements. The method consists of a differential analysis of the transfer characteristic curves (current versus gate voltage) and exploits the different functional dependences of current on gate voltage which is induced by the presence of contact resistances. This paper fully covers the situations from constant carrier mobility to power law gate-voltage-dependent mobility, from constant contact resistance to gate-voltage-dependent contact resistance, and in the linear and in the saturation regime of the operation of the transistor. It also gives important criteria for the validation of the extracted parameters to assess whether the conditions for the application of the method are fulfilled. Examples of application to organic transistors showing various behaviors are given and discussed.
Blue quantum electroabsorption modulators based on reversed quantum confined Stark effect with blueshift
Authors: Sari Emre , Nizamoglu Sedat , Ozel Tuncay , Demir Hilmi Volkan
Published: January 2007

The authors present the design, growth, fabrication, experimental characterization, and theoretical analysis of blue quantum electroabsorption modulators that incorporate ∼5nm thick In0.35Ga0.65N∕GaN quantum structures for operation between 420 and 430nm. Growing on polar c plane on sapphire, they obtain quantum structures with zigzag potential profile due to alternating polarization fields and demonstrate that their optical absorption blueshifts with applied electric field, unlike the redshift of conventional quantum confined Stark effect. In InGaN∕GaN quantum structures, they report the largest absorption change of 6000cm−1 for 6V bias swing around 424nm, holding promise for blue optical clock generation and injection directly into silicon chips.
Impact of epitaxial growth at the heterointerface of a-Si:H∕c-Si solar cells
Authors: Fujiwara Hiroyuki , Kondo Michio
Published: January 2007

The authors have demonstrated that interface structures of heterojunction solar cells consisting of hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si) have quite large impact on the solar cell performance. In particular, unintentional epitaxial growth was found to occur during an intended a-Si:H i-layer growth on c-Si in plasma-enhanced chemical vapor deposition (PECVD). By the formation of the epitaxial layer at the interface, the solar cell efficiency decreases significantly. Their result shows that the epitaxial layer is formed rather easily in PECVD, even without the presence of H2 gas, and may have affected many previous studies on a-Si:H∕c-Si solar cells seriously.
Large Outbreak of Infection and Colonization with Gram-Negative Pathogens Carrying the Metallo-β-Lactamase Gene blaIMP-4 at a 320-Bed Tertiary Hospital in Australia
Authors: Herbert Sophie , Halvorsen Dag S. , Leong Tim , Franklin Clare , Harrington Glenys , Spelman Denis
Published: January 2007

A large outbreak of infection and colonization with multiple genera of gram-negative bacilli carrying the metallo-β-lactamase gene blaIMP-4 occurred in a 36-bed intensive care unit at a tertiary hospital in Australia. The organisms emerged rapidly, caused severe infections, and contributed to mortality. Controlling the spread of these organisms remains a challenge for all staff involved.
Mating system of the meadow vole, Microtus pennsylvanicus
Authors: Boonstra Rudy , Xia Xuhua , Pavone Leo
Published: January 2007

Previous studies on parental and spacing behavior of Microtus pennsylvanicus suggest a promiscuous mating system, but attempts to find multiple paternity in single litters have been unsuccessful. In this paper we present evidence of multiple paternity in single litters conceived in the wild early in the breeding season. The proportion of litters sired by multiple males was estimated, by a conservative method, to be 33.1%.We argue that the presence of promiscuity, rather than polygyny, in M. pennsylvanicus is the result of two factors. First, overwintered breeding males are similar in age and size, resulting in small variation in competitive ability among males. This reduced variation in competitive ability reduces the possibility that some males defend several females and others defend none. Second, the habitat structure of the meadow vole makes it difficult for a male to detect other males nearby, and this reduces the possibility that one male excludes others from mating when a female comes into estrus.
Asymptotically optimal difference-based estimation of variance in nonparametric regression
Authors: HALL PETER , KAY J W , TITTERINGTON D M
Published: January 2007

We define and compute asymptotically optimal difference sequences for estimating error variance in homoscedastic nonparametric regression. Our optimal difference sequences do not depend on unknowns, such as the mean function, and provide substantial improvements over the suboptimal sequences commonly used in practice. For example, in the case of normal data the usual variance estimator based on symmetric second-order differences is only 64% efficient relative to the estimator based on optimal second-order differences. The efficiency of an optimal mth-order difference estimator relative to the error sample variance is 2m/(2m + 1). Again this is for normal data, and increases as the tails of the error distribution become heavier.