463 research outputs found
Functional Bosonization of Non-Relativistic Fermions in Dimensions
We analyze the universality of the bosonization rules in non-relativistic
fermionic systems in . We show that, in the case of linear fermionic
dispersion relations, a general fermionic theory can be mapped into a gauge
theory in such a way that the fermionic density maps into a magnetic flux and
the fermionic current maps into a transverse electric field. These are
universal rules in the sense that they remain valid whatever the interaction
considered. We also show that these rules are universal in the case of
non-linear dispersion relations provided we consider only density-density
interactions. We apply the functional bosonization formalism to a
non-relativistic and non-local massive Thirring-like model and evaluate the
spectrum of collective excitations in several limits. In the large mass limit,
we are able to exactly calculate this spectrum for arbitrary density-density
and current-current interactions. We also analyze the massless case and show
that it has no collective excitations for any density-density potential in the
Gaussian approximation. Moreover, the presence of current interactions may
induce a gapless mode with a linear dispersion relation.Comment: 26 Pages, LaTeX, Final version to appear in International Journal of
Modern Physics
Descriptions of two new Pseudophacopteron species (Hemiptera: Psylloidea: Phacopteronidae) inducing galls on Aspidosperma (Apocynaceae) in Brazil
Two new species of the large pantropical jumping plant-louse genus Pseudophacopteron Enderlein, 1921 (Hemiptera: Psylloidea: Phacopteronidae) are described from dry woodland habitats in the Midwest, Southeast and South of Brazil. Pseudophacopteron aspidospermi sp. nov. is associated with Aspidosperma australe, P. longicaudatum sp. nov. has been found on Aspidosperma macrocarpon and A. tomentosum (Apocynaceae). Both species induce intralaminar lenticular galls on the leaves of their host trees which have been the subject of several structural, histochemical and ecological publications. Adult males and females, fifth instar immatures and galls are illustrated including diagnostic morphological details, and compared with other Neotropical and Old World species of Pseudophacopteron and Phacopteronidae. The distribution of Pseudophacopteron in the Neotropical Region is briefl y discussed
ChemT, an open-source software for building template-based chemical libraries
In computational chemistry vast quantities of compounds are generated, and there is a need for cheminformatic tools to efficiently build chemical compound libraries. Several software tools for drawing and editing compounds structures are available, but they lack options for automatic generation of chemical libraries. We have implemented ChemT, an easy-to-use open-source software tool that automates the process of preparing custom-made template-based chemical libraries. ChemT automatically generates three-dimensional chemical libraries by inputting a chemical template and the functional groups of interest. The graphical user interface of ChemT is self-explanatory, and a complete tutorial is provided. Several file formats are accepted by ChemT, and it is possible to filter the generated compounds according to different physicochemical properties. The compounds can be subject to force field minimization, and the resulting three-dimensional structures recorded on commonly used file formats. ChemT may be a valuable tool for investigators interested in using in silico virtual screening tools, like QSAR modelling or molecular docking, in order to prioritize compounds for further chemical synthesis. To demonstrate the usefulness of ChemT, we describe an example based on a thieno[3,2-b]pyridine template.Fundação para a CiĂȘncia e a Tecnologia (FCT)COMPETE/QREN/E
Fluorescence studies on new potential antitumoral benzothienopyran-1-ones in solution and in lipid membranes
This work was funded by Foundation for Science and Technology (FCT, Portugal) and FEDER through CFUM and CQ-UM, research project PTDC/QUI/81238/2006 and PhD grants of M.S.D. Carvalho SFRH/BD/47052/2008 and of R.C. Calhelha SFRH/BD/29274/2006
A 3D Perfusable Platform for In Vitro Culture of Patient Derived Xenografts
Many advanced cancer models, such as patient-derived xenografts (PDXs), offer significant benefits in their preservation of the native tumor\u27s heterogeneity and susceptibility to treatments, but face significant barriers to use in their reliance on a rodent host for propagation and screening. PDXs remain difficult to implement in vitro, particularly in configurations that enable both detailed cellular analysis and high-throughput screening (HTS). Complex multilineage co-cultures with stromal fibroblasts, endothelium, and other cellular and structural components of the tumor microenvironment (TME) further complicate ex vivo implementation. Herein, the culture of multiple prostate cancer (PCa)-derived PDX models as 3D clusters within engineered biomimetic hydrogel matrices, in a HTS-compatible multiwell microfluidic format, alongside bone marrow-derived stromal cells and a perfused endothelial channel. Polymeric hydrogel matrices are customized for each cell type, enabling cell survival in vitro and facile imaging across all conditions. PCa PDXs demonstrate unique morphologies and reliance on TME partners, retention of known phenotype, and expected sensitivity or resistance to standard PCa therapeutics. This novel integration of technologies provides a fully human model, and expands the information to be gathered from each specimen, while avoiding the time and labor involved with animal-based testing
VIBRATION TRANSMISSIBILITY OF THE COFFEE FRUIT-PEDUNCLE SYSTEM: A FORCED VIBRATION STUDY OF HIGH FREQUENCY AIMING MECHANICAL HARVESTING
ABSTRACT Semi-mechanized and mechanized harvesting use machines that promote the transference of vibrational energy and impact to achieve the detachment of coffee fruits. The aim of this study was to evaluate the vibration transmissibility in coffee fruit-peduncle systems, using high-speed cameras, submitted to high frequency harmonic excitation in different combinations between frequency and amplitude of vibration, identifying working ranges suitable to perform selective harvesting. Vibration transmissibility was determined for the coffee fruit-peduncle systems, for the maturation stages unripe and ripe that were subjected to a sinusoidal harmonic displacement, in which the input parameters were frequency (35, 45 and 55 Hz) and peak-to-peak amplitude (3.5, 5.0 and 6.5 mm). An experiment was used to study the effect of frequency and amplitude on vibration transmissibility in a completely randomized design in a factorial scheme 3 x 3 x 2, with three replications. The frequency of 35 Hz, associated with the amplitudes 3.5-6.5 mm, was the one that most influenced the results of vibration transmissibility. For the frequency of 55 Hz and amplitude of 6.5 mm, in the ripe maturation stage, the vibration transmissibility was higher than 1.0, which could be a suitable combination for selective coffee harvesting
Fluorescence studies on new potential antitumoral benzothienopyran-1-ones in solution and in liposomes
Fluorescence properties of four new potential
antitumoral compounds, 3-arylbenzothieno[2,3-c]pyran-1-ones, were studied in solution and in lipid membranes of dipalmitoyl phosphatidylcholine (DPPC), egg yolk phosphatidylcholine (Egg-PC) and dioctadecyldimethylammonium bromide (DODAB). The 3-(4-methoxyphenyl)benzothieno[2,3-c]pyran-1-one (1c) exhibits the higher fluorescence quantum yields in all solvents studied. All compounds present a solvent sensitive emission, with significant red shifts in polar solvents for the methoxylated compounds. The results point to an ICT character of the excited state, more pronounced for compound 1c. Fluorescence (steady-state) anisotropy measurements of the compounds incorporated in liposomes of DPPC, DODAB and Egg-PC indicate that all compounds have two different locations, one due to a deep penetration in the lipid membrane and another corresponding to a more hydrated environment. In general, the methoxylated compounds prefer hydrated environments inside the liposomes. The 3-(4-
fluorophenyl)benzothieno[2,3-c]pyran-1-one (1a) clearly prefers a hydrated environment, with some molecules located at the outer part of the liposome interface. On the contrary, the preferential location of 3-(2-fluorophenyl)benzothieno[2,3-c]pyran-1-one (1b) is in the region of lipid hydrophobic tails. Compounds with a planar geometry (1a and 1c) have higher mobility in the lipid membranes when phase transition occurs.Portugal and FEDER (Fundo Europeu de Desenvolvimento Regional), for financial support through Centro de FĂsica (CFUM) and Centro de QuĂmica (CQ-UM) of University of Minho and through the Project PTDC/QUI/81238/2006. M.S.D. Carvalho and R.C. Calhelha acknowledge FCT for their PhD grants SFRH/BD/47052/2008 and SFRH/BD/29274/2006, respectively.Fundação para a CiĂȘncia e a Tecnologia (FCT
Variations of training load, monotony, and strain and dose-response relationships with maximal aerobic speed, maximal oxygen uptake, and isokinetic strength in professional soccer players
This study aimed to identify variations in weekly training load, training monotony, and training strain across a 10-week period (during both, pre- and in-season phases); and to analyze the dose-response relationships between training markers and maximal aerobic speed (MAS), maximal oxygen uptake, and isokinetic strength. Twenty-seven professional soccer players (24.9±3.5 years old) were monitored across the 10-week period using global positioning system units. Players were also tested for maximal aerobic speed, maximal oxygen uptake, and isokinetic strength before and after 10 weeks of training. Large positive correlations were found between sum of training load and extension peak torque in the right lower limb (r = 0.57, 90%CI[0.15;0.82]) and the ratio agonist/antagonist in the right lower limb (r = 0.51, [0.06;0.78]). It was observed that loading measures fluctuated across the period of the study and that the load was meaningfully associated with changes in the fitness status of players. However, those magnitudes of correlations were small-to-large, suggesting that variations in fitness level cannot be exclusively explained by the accumulated load and loading profile
Recent acquisition of Helicobacter pylori by Baka Pygmies
Both anatomically modern humans and the gastric pathogen Helicobacter pylori originated in Africa, and both species have been associated for at least 100,000 years. Seven geographically distinct H. pylori populations exist, three of which are indigenous to Africa: hpAfrica1, hpAfrica2, and hpNEAfrica. The oldest and most divergent population, hpAfrica2, evolved within San hunter-gatherers, who represent one of the deepest branches of the human population tree. Anticipating the presence of ancient H. pylori lineages within all hunter-gatherer populations, we investigated the prevalence and population structure of H. pylori within Baka Pygmies in Cameroon. Gastric biopsies were obtained by esophagogastroduodenoscopy from 77 Baka from two geographically separated populations, and from 101 non-Baka individuals from neighboring agriculturalist populations, and subsequently cultured for H. pylori. Unexpectedly, Baka Pygmies showed a significantly lower H. pylori infection rate (20.8%) than non-Baka (80.2%). We generated multilocus haplotypes for each H. pylori isolate by DNA sequencing, but were not able to identify Baka-specific lineages, and most isolates in our sample were assigned to hpNEAfrica or hpAfrica1. The population hpNEAfrica, a marker for the expansion of the Nilo-Saharan language family, was divided into East African and Central West African subpopulations. Similarly, a new hpAfrica1 subpopulation, identified mainly among Cameroonians, supports eastern and western expansions of Bantu languages. An age-structured transmission model shows that the low H. pylori prevalence among Baka Pygmies is achievable within the timeframe of a few hundred years and suggests that demographic factors such as small population size and unusually low life expectancy can lead to the eradication of H. pylori from individual human populations. The Baka were thus either H. pylori-free or lost their ancient lineages during past demographic fluctuations. Using coalescent simulations and phylogenetic inference, we show that Baka almost certainly acquired their extant H. pylori through secondary contact with their agriculturalist neighbors
Current situation of endemic mycosis in the Americas and the Caribbean: Proceedings of the first international meeting on endemic mycoses of the Americas (IMEMA)
Background: The Americas are home to biologically and clinically diverse endemic fungi, including Blastomyces, Coccidioides, Emergomyces, Histoplasma, Paracoccidioides and Sporothrix. In endemic areas with high risk of infection, these fungal pathogens represent an important public health problem. Objectives: This report aims to summarise the main findings of the regional analysis carried out on the status of the endemic mycoses of the Americas, done at the first International Meeting on Endemic Mycoses of the Americas (IMEMA). Methods: A regional analysis for the Americas was done, the 27 territories were grouped into nine regions. A SWOT analysis was done. Results: All territories reported availability of microscopy. Seventy percent of territories reported antibody testing, 67% of territories reported availability of Histoplasma antigen testing. None of the territories reported the use of (1â3)-ÎČ-d-glucan. Fifty two percent of territories reported the availability of PCR testing in reference centres (mostly for histoplasmosis). Most of the territories reported access to medications such as trimethoprim-sulfamethoxazole, itraconazole, voriconazole and amphotericin B (AMB) deoxycholate. Many countries had limited access to liposomal formulation of AMB and newer azoles, such as posaconazole and isavuconazole. Surveillance of these fungal diseases was minimal. Conclusions: A consensus emerged among meeting participants, this group concluded that endemic mycoses are neglected diseases, and due to their severity and lack of resources, the improvement of diagnosis, treatment and surveillance is needed.Fil: Caceres, Diego H.. Universidad Colegio Mayor de Nuestra Señora del Rosario; Colombia. Centers for Disease Control and Prevention; Estados UnidosFil: Echeverri Tirado, Laura C.. Universidad de Antioquia; ColombiaFil: Bonifaz, Alexandro. Hospital General de Mexico; MĂ©xicoFil: Adenis, Antoine. Inserm; FranciaFil: Gomez, Beatriz L.. Universidad Colegio Mayor de Nuestra Señora del Rosario; ColombiaFil: Bnada Flores, Claudia Lizett. Universidad Peruana Cayetano Heredia; PerĂșFil: Canteros, Cristina Elena. Instituto Nacional de Enfermedades Infecciosas; ArgentinaFil: Santos, Daniel Wagner. Universidade Federal do Maranhao; BrasilFil: Arathoon, Eduardo. AsociaciĂłn de Salud Integral; GuatemalaFil: Ramirez Soto, Elia. Centro Nacional de Enfermedades Tropicales; BoliviaFil: Queiroz-Telles, Flavio. Universidade Federal do ParanĂĄ; BrasilFil: Schwartz, Ilan S.. University of Alberta; CanadĂĄFil: Zurita, Jeannete. Pontificia Universidad CatĂłlica del Ecuador; EcuadorFil: Serra Damasceno, Lisandra. Universidade Estadual do CearĂĄ; BrasilFil: Garcia, Nataly. Sociedad Venezolana de MicrobiologĂa; VenezuelaFil: Fernandez, Norma B.. Universidad de Buenos Aires. Facultad de Medicina. Hospital de ClĂnicas General San MartĂn; ArgentinaFil: Chincha, Omayra. Universidad Peruana Cayetano Heredia; PerĂșFil: Araujo, Patricia. Ministerio de Salud PĂșblica y Bienestar Social; ParaguayFil: Rabagliati, Ricardo. No especifĂca;Fil: Chiller, Tom. Centers for Disease Control and Prevention; Estados UnidosFil: Giusiano, Gustavo Emilio. Universidad Nacional del Nordeste. Instituto de Medicina Regional; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Nordeste; Argentin
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