893 research outputs found
Scale Invariance and Nonlinear Patterns of Human Activity
We investigate if known extrinsic and intrinsic factors fully account for the
complex features observed in recordings of human activity as measured from
forearm motion in subjects undergoing their regular daily routine. We
demonstrate that the apparently random forearm motion possesses previously
unrecognized dynamic patterns characterized by fractal and nonlinear dynamics.
These patterns are unaffected by changes in the average activity level, and
persist when the same subjects undergo time-isolation laboratory experiments
designed to account for the circadian phase and to control the known extrinsic
factors. We attribute these patterns to a novel intrinsic multi-scale dynamic
regulation of human activity.Comment: 4 pages, three figure
Effects of privatization and agencification on citizens and citizenship: an international comparison
This study has been compiled as an internationally comparative contribution to the
parliamentary inquiry by the Dutch Senate into the effects of privatization and agencification
on the relationship between citizens and the (national) government. Knowledge on this topic
is scarce and scattered across different sources. Therefore, this paper consists of three
different sections. Each section deals with a different question and uses different sources. In
this overview we summarize the main findings of the three sections
Identification of Giardia lamblia DHHC Proteins and the Role of Protein S-palmitoylation in the Encystation Process
Protein S-palmitoylation, a hydrophobic post-translational modification, is performed by protein acyltransferases that have a common DHHC Cys-rich domain (DHHC proteins), and provides a regulatory switch for protein membrane association. In this work, we analyzed the presence of DHHC proteins in the protozoa parasite Giardia lamblia and the function of the reversible S-palmitoylation of proteins during parasite differentiation into cyst. Two specific events were observed: encysting cells displayed a larger amount of palmitoylated proteins, and parasites treated with palmitoylation inhibitors produced a reduced number of mature cysts. With bioinformatics tools, we found nine DHHC proteins, potential protein acyltransferases, in the Giardia proteome. These proteins displayed a conserved structure when compared to different organisms and are distributed in different monophyletic clades. Although all Giardia DHHC proteins were found to be present in trophozoites and encysting cells, these proteins showed a different intracellular localization in trophozoites and seemed to be differently involved in the encystation process when they were overexpressed. dhhc transgenic parasites showed a different pattern of cyst wall protein expression and yielded different amounts of mature cysts when they were induced to encyst. Our findings disclosed some important issues regarding the role of DHHC proteins and palmitoylation during Giardia encystation.Fil: Merino, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; ArgentinaFil: Zamponi, Nahuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; ArgentinaFil: Vranych, Cecilia Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; ArgentinaFil: Touz, Maria Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; ArgentinaFil: Ropolo, Andrea Silvana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; Argentin
Assisted evolution enables HIV-1 to overcome a high trim5α-imposed genetic barrier to rhesus macaque tropism
Diversification of antiretroviral factors during host evolution has erected formidable barriers to cross-species retrovirus transmission. This phenomenon likely protects humans from infection by many modern retroviruses, but it has also impaired the development of primate models of HIV-1 infection. Indeed, rhesus macaques are resistant to HIV-1, in part due to restriction imposed by the TRIM5α protein (rhTRIM5α). Initially, we attempted to derive rhTRIM5α-resistant HIV-1 strains using two strategies. First, HIV-1 was passaged in engineered human cells expressing rhTRIM5α. Second, a library of randomly mutagenized capsid protein (CA) sequences was screened for mutations that reduced rhTRIM5α sensitivity. Both approaches identified several individual mutations in CA that reduced rhTRIM5α sensitivity. However, neither approach yielded mutants that were fully resistant, perhaps because the locations of the mutations suggested that TRIM5α recognizes multiple determinants on the capsid surface. Moreover, even though additive effects of various CA mutations on HIV-1 resistance to rhTRIM5α were observed, combinations that gave full resistance were highly detrimental to fitness. Therefore, we employed an 'assisted evolution' approach in which individual CA mutations that reduced rhTRIM5α sensitivity without fitness penalties were randomly assorted in a library of viral clones containing synthetic CA sequences. Subsequent passage of the viral library in rhTRIM5α-expressing cells resulted in the selection of individual viral species that were fully fit and resistant to rhTRIM5α. These viruses encoded combinations of five mutations in CA that conferred complete or near complete resistance to the disruptive effects of rhTRIM5α on incoming viral cores, by abolishing recognition of the viral capsid. Importantly, HIV-1 variants encoding these CA substitutions and SIVmac239 Vif replicated efficiently in primary rhesus macaque lymphocytes. These findings demonstrate that rhTRIM5α is difficult to but not impossible to evade, and doing so should facilitate the development of primate models of HIV-1 infection
Ultra-strong Adhesion of Graphene Membranes
As mechanical structures enter the nanoscale regime, the influence of van der
Waals forces increases. Graphene is attractive for nanomechanical systems
because its Young's modulus and strength are both intrinsically high, but the
mechanical behavior of graphene is also strongly influenced by the van der
Waals force. For example, this force clamps graphene samples to substrates, and
also holds together the individual graphene sheets in multilayer samples. Here
we use a pressurized blister test to directly measure the adhesion energy of
graphene sheets with a silicon oxide substrate. We find an adhesion energy of
0.45 \pm 0.02 J/m2 for monolayer graphene and 0.31 \pm 0.03 J/m2 for samples
containing 2-5 graphene sheets. These values are larger than the adhesion
energies measured in typical micromechanical structures and are comparable to
solid/liquid adhesion energies. We attribute this to the extreme flexibility of
graphene, which allows it to conform to the topography of even the smoothest
substrates, thus making its interaction with the substrate more liquid-like
than solid-like.Comment: to appear in Nature Nanotechnolog
Benchmark Test Calculation of a Four-Nucleon Bound State
In the past, several efficient methods have been developed to solve the
Schroedinger equation for four-nucleon bound states accurately. These are the
Faddeev-Yakubovsky, the coupled-rearrangement-channel Gaussian-basis
variational, the stochastic variational, the hyperspherical variational, the
Green's function Monte Carlo, the no-core shell model and the effective
interaction hyperspherical harmonic methods. In this article we compare the
energy eigenvalue results and some wave function properties using the realistic
AV8' NN interaction. The results of all schemes agree very well showing the
high accuracy of our present ability to calculate the four-nucleon bound state.Comment: 17 pages, 1 figure
Caveolin-1 protects B6129 mice against Helicobacter pylori gastritis.
Caveolin-1 (Cav1) is a scaffold protein and pathogen receptor in the mucosa of the gastrointestinal tract. Chronic infection of gastric epithelial cells by Helicobacter pylori (H. pylori) is a major risk factor for human gastric cancer (GC) where Cav1 is frequently down-regulated. However, the function of Cav1 in H. pylori infection and pathogenesis of GC remained unknown. We show here that Cav1-deficient mice, infected for 11 months with the CagA-delivery deficient H. pylori strain SS1, developed more severe gastritis and tissue damage, including loss of parietal cells and foveolar hyperplasia, and displayed lower colonisation of the gastric mucosa than wild-type B6129 littermates. Cav1-null mice showed enhanced infiltration of macrophages and B-cells and secretion of chemokines (RANTES) but had reduced levels of CD25+ regulatory T-cells. Cav1-deficient human GC cells (AGS), infected with the CagA-delivery proficient H. pylori strain G27, were more sensitive to CagA-related cytoskeletal stress morphologies ("humming bird") compared to AGS cells stably transfected with Cav1 (AGS/Cav1). Infection of AGS/Cav1 cells triggered the recruitment of p120 RhoGTPase-activating protein/deleted in liver cancer-1 (p120RhoGAP/DLC1) to Cav1 and counteracted CagA-induced cytoskeletal rearrangements. In human GC cell lines (MKN45, N87) and mouse stomach tissue, H. pylori down-regulated endogenous expression of Cav1 independently of CagA. Mechanistically, H. pylori activated sterol-responsive element-binding protein-1 (SREBP1) to repress transcription of the human Cav1 gene from sterol-responsive elements (SREs) in the proximal Cav1 promoter. These data suggested a protective role of Cav1 against H. pylori-induced inflammation and tissue damage. We propose that H. pylori exploits down-regulation of Cav1 to subvert the host's immune response and to promote signalling of its virulence factors in host cells
Induced pseudoscalar coupling of the proton weak interaction
The induced pseudoscalar coupling is the least well known of the weak
coupling constants of the proton's charged--current interaction. Its size is
dictated by chiral symmetry arguments, and its measurement represents an
important test of quantum chromodynamics at low energies. During the past
decade a large body of new data relevant to the coupling has been
accumulated. This data includes measurements of radiative and non radiative
muon capture on targets ranging from hydrogen and few--nucleon systems to
complex nuclei. Herein the authors review the theoretical underpinnings of
, the experimental studies of , and the procedures and uncertainties
in extracting the coupling from data. Current puzzles are highlighted and
future opportunities are discussed.Comment: 58 pages, Latex, Revtex4, prepared for Reviews of Modern Physic
Integrating water exclusion theory into βcontacts to predict binding free energy changes and binding hot spots
10.1186/1471-2105-15-57BMC Bioinformatics151-BBMI
Condition and the state of coral reef management in Lembeh Island waters of Bitung City
Lembeh Island is a small island part of the minicipality of Bitung, It is an area that supportincluding the category of small island, but it is an area that support community life in the mainland who mainly living as fishermen. Those fishermen generally made coral reef ecosystems as a location for fishing. This research is aimed to provide information such as ecological conditions and states of coral reef, that can be used appropriately in planning and decision making for the development of Lembeh Island waters, especially in the management of coral reef ecosystems. Intern of coral cover Lembeh island can be categorized in good condition and the state of coral reef management can be seen from the utilization activity that still good but tend to degrade over time. The implication, shows that the management and development of today tend to cause less sustainableto coral ecosystems. Keywords : Lembeh Island, coral reef, manajement, sustainability A B S T R A K Pulau Lembeh merupakan pulau di Kota Bitung, termasuk kategori pulau kecil, tetapi merupakan kawasan yang menunjang kehidupan masyarakat di daratan utama, Masyarakat Pulau Lembeh yang berprofesi sebagai nelayan, umumnya menjadikan ekosistem terumbu karang sebagai lokasi penangkapan ikan karang. Penelitian ini dapat memberikan informasi berupa kondisi ekologi serta status pengelolaan ekosistem terumbu karang, sehingga dapat digunakan secara tepat dalam proses perencanaan dan pengambilan keputusan guna pengembangan perairan Pulau Lembeh, khususnya dalam pengelolaan ekosistem terumbu karang di masa mendatang. Kondisi terumbu karang Pulau Lembeh berdasarkan tutupan karang batu dapat dikategorikan baik, dan status pengelolaan terumbu karang dilihat dari kegiatan pemanfataan saat ini masih baik tapi cenderung menurunkan kualitas kawasan. Implikasinya, memperlihatkan bahwa pengelolaan dan pembangunan saat ini cenderung ditata ke arah kurang berkelanjutan. ________________________________________________________________ Keywords : pulau lembeh, terumbu karang, pengelolaan, keberlanjutan _____________________ 1 Alumni Program Studi Manajemen Sumberdaya Perairan FPIK Unsrat 2Staf Pengajar Fakultas Perikanan dan Ilmu Kelautan Universitas Sam Ratulangi 3;Staf Pengajar Fakultas Perikanan dan Ilmu Kelautan Universitas Sam Ratulang
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