2,354 research outputs found
A Study in Wing Veination: Family Aphididae
The purpose of this paper is to give the results of a study of the wing venation in the family Aphididae with a view of replacing the arbitrary nomenclature as applied to this family by the general nomenclature of wing venation
Detection of functional PTEN lipid phosphatase protein and enzyme activity in squamous cell carcinomas of the head andeck, despite loss of heterozygosity at this locus
The human tumour suppressor gene PTEN located at 10q23 is mutated in a variety of tumour types particularly metastatic cases and in the germline of some individuals with Cowdens cancer predisposition syndrome. We have assessed the status of PTEN and associated pathways in cell lines derived from 19 squamous cell carcinomas of the head and neck. Loss of heterozygosity is evident at, or close to the PTEN gene in 5 cases, however there were no mutations in the remaining alleles. Furthermore by Western analysis PTEN protein levels are normal in all of these SCC-HN tumours and cell lines. To assess the possibility that PTEN may be inactivated by another mechanism, we characterized lipid phosphatase levels and from a specific PIP3 biochemical assay it is clear that PTEN is functionally active in all 19 human SCCs. Our data strongly suggest the possibility that a tumour suppressor gene associated with development of SCC-HN, other than PTEN, is located in this chromosomal region. This gene does not appear to be MXI-1, which has been implicated in some other human tumour types. PTEN is an important negative regulator of PI3Kinase, of which subunit alpha is frequently amplified in SCC-HN. To examine the possibility that PI3K is upregulated by amplification in this tumour set we assessed the phosphorylation status of Akt, a downstream target of PI3K. In all cases there is no detectable increase in Akt phosphorylation. Therefore there is no detectable defect in the PI3K pathway in SCC-HN suggesting that the reason for 3q26.3 over-representation may be due to genes other than PI3K110Ξ±. Β© 2001 Cancer Research Campaign http://www.bjcancer.co
Enhanced radiative strength in the quasi-continuum of 117Sn
Radiative strength functions of 117Sn has been measured below the neutron
separation energy using the (3He,3He'gamma) reactions. An increase in the slope
of the strength functions around E_gamma= 4.5 MeV indicates the onset of a
resonance-like structure, giving a significant enhancement of the radiative
strength function compared to standard models in the energy region 4.5 <=
E_gamma <= 8.0 MeV. For the first time, the functional form of this
resonance-like structure has been measured in an odd tin nucleus below neutron
threshold in the quasi-continuum region.Comment: 4 pages, 3 figure
Evolution of level density step structures from 56,57-Fe to 96,97-Mo
Level densities have been extracted from primary gamma spectra for 56,57-Fe
and 96,97-Mo nuclei using (3-He,alpha gamma) and (3-He,3-He') reactions on
57-Fe and 97-Mo targets. The level density curves reveal step structures above
the pairing gap due to the breaking of nucleon Cooper pairs. The location of
the step structures in energy and their shapes arise from the interplay between
single-particle energies and seniority-conserving and seniority-non-conserving
interactions.Comment: 9 pages, including 5 figure
Characterization of ply mixing rules for non-symmetric forms of fully orthotropic laminates
Stacking sequence listings are presented for fully orthotropic angle-ply
laminates, with up to 21 plies, together with rules for mixing these
sequences to form laminates containing any number of plies. The mixing
rules are demonstrated through an abridged set of sequences, which are
characterized in terms of angle- and cross-ply sub-sequence symmetries. The
abridged set of sequences is derived from a new definitive list that
supersedes previously published listings. Stacking sequences are presented
together with dimensionless parameters from which the bending stiffness
terms are readily calculated and an assessment of the bending stiffness
efficiency made for angle- and cross-ply sub-sequences. Expressions
relating the dimensionless parameters to the well-known lamination
parameters are also given, together with graphical representations of
feasible domains for all sub-sequence symmetries contained in the definitive
list. Feasible domains for extensionally isotropic and fully isotropic
laminates are also presented as important sub-sets of fully orthotropic
laminates. Finally, examples are given for tapered laminates with fully
orthotropic properties, derived from compatible sequences in the definite
list
An urban sprawl index based on multivariate and Bayesian factor analysis with application at the municipality level in Valencia
[EN] Urban sprawl is now a common and threatening phenomenon in Europe, severely affecting
environmental and economic sustainability. An analytical characterization and measurement of
urban sprawl are required to gain a better understanding of the phenomenon and to propose the
possible solutions. Traditional factor analysis techniques, especially Principal Component Analysis
and Factor Analysis, have been commonly used. In this paper, we additionally test Independent
Component Analysis with the aim to obtain a multidimensional characterization of the sprawl
phenomenon. We also use Bayesian Factor Analysis to obtain a single (unidimensional) measuring
index of sprawl, which also allows us to obtain the uncertainty of the inferred index, in contrast to
traditional approaches. All these techniques have been applied to study the phenomenon of urban
sprawl at the municipality level in Valencia, Spain using a wide set of variables related to the
characteristics and patterns of urban land use.Gielen, E.; Riutort-Mayol, G.; Palencia JimΓ©nez, JS.; Cantarino-MartΓ, I. (2017). An urban sprawl index based on multivariate and Bayesian factor analysis with application at the municipality level in Valencia. Environment and Planning B Planning and Design. 1-27. doi:10.1177/2399808317690148S12
Lamivudine-Induced Liver Injury
BACKGROUND: Lamivudine is a nucleoside analogue antiretroviral drug, known for its low toxicity at clinically prescribed dose. However, the toxicity or mechanism of toxicity and target tissue effects during prolonged administration of higher doses were hardly given sufficient laboratory attention.
AIM: The present work was designed to investigate the biochemical and histopathological changes in the liver of rat administered with prolonged doses of lamivudine.
MATERIAL AND METHODS: Lamivudine in multiple doses of five ranging from 4 mg/kg to 2500 mg/kg were administered, in vitro, by injection into the air-sac of 10βday old fertile embryonated eggs of Gallus domesticus. Also, female rats of the Wistar strain received oral doses, up to 500 mg/kg singly or repeatedly for 15 or 45 days, respectively. Spectrophotometric techniques were employed to monitor activities of the aminotransferases (ALT and AST), Ξ³βglutamyltransferase (GGT) and total protein concentration in serum while activities of glutathione Sβtransferase (GST), GGT and superoxide dismutase (SOD) as well as concentrations of malondialdehyde (MDA) and protein were determined in liver. Histopathological studies were carried out on liver. Data were analysed using ANOVA and were considered significant when p < 0.05.
RESULTS: The LD50 for the drug calculated from the incubation experiment was 427 mg/kg. Total serum protein concentration significantly reduced while enzymes activities significantly increased at 500 mg/kg only among the repeat-dosed rats. Hepatic GGT, GST and SOD activities as well as MDA concentration were significantly elevated at 20 mg/kg. Histopathological studies showed multifocal lymphoid cell population in the liver sinusoid of the chicken and hydropic degeneration of hepatocytes were recorded among rats repeatedly exposed to the drug respectively at doses β₯ 100 mg/kg
Formalization of hydrocarbon conversion scheme of catalytic cracking for mathematical model development
The issue of improving the energy and resource efficiency of advanced petroleum processing can be solved by the development of adequate mathematical model based on physical and chemical regularities of process reactions with a high predictive potential in the advanced petroleum refining. In this work, the development of formalized hydrocarbon conversion scheme of catalytic cracking was performed using thermodynamic parameters of reaction defined by the Density Functional Theory. The list of reaction was compiled according to the results of feedstock structural-group composition definition, which was done by the n-d-m-method, the Hazelvuda method, qualitative composition of feedstock defined by gas chromatography-mass spectrometry and individual composition of catalytic cracking gasoline fraction. Formalized hydrocarbon conversion scheme of catalytic cracking will become the basis for the development of the catalytic cracking kinetic model
Midlatitude Oceanic Cloud and Precipitation Properties as Sampled by the ARM Eastern North Atlantic Observatory
An edited version of this paper was published by AGU. Copyright 2019 American Geophysical Union.Marine low clouds are critical to the climate system because of their extensive coverage and associated controls on boundary layer dynamics and radiative energy balance. The primary foci for this study are marine low cloud observations over a heavily instrumented site on the Azores archipelago in the Eastern North Atlantic and their associated raindrop size distribution (DSD) properties, relative low cloud contributions to the precipitation, and additional sampling (instrument, environmental) considerations. The contribution from low clouds (e.g., cloud top < 4 km) to the overall precipitation over midlatitude oceans is poorly understood, in part because of the lack of coupled, highβquality measurements of precipitation and low cloud properties. Cloud regime and precipitation breakdowns performed for a multiyear (2014β2017) record emphasize diurnal precipitation and raindrop size distribution characteristics for both low and deeper clouds, as well as differences between the two disdrometer types used. Results demonstrate that marine low clouds over this Eastern North Atlantic location account for a significant (45%) contribution to the total rainfall and exhibit a diurnal cycle in cloud (thickness, top, and base) and precipitation characteristics similar to satellite records. Additional controls on observed surface rainfall characteristics of low clouds allowed by the extended groundβbased facility data sets are also explored. From those analyses, it is suggested that the synoptic state exerts a significant control on low cloud and surface precipitation properties
Stacking sequences for extensionally isotropic, fully isotropic and quasi-homogeneous orthotropic laminates
Stacking sequence listings are presented for fully uncoupled Extensionally
Isotropic (EILs), Fully Isotropic (FILs) and Quasi-Homogeneous Orthotropic
(QHOLs) angle-ply Laminates, with up to 21 plies. All are sub-sets of a
definitive list of Fully Orthotropic Laminates (FOLs), containing generally
non-symmetric stacking sequences that are characterized in terms of angle-
and cross-ply sub-sequence symmetries. Dimensionless parameters are given
for each stacking sequence, from which the ABD matrix is readily derived.
Expressions relating these dimensionless parameters to the well-known
lamination parameters are also given, together with graphical
representations of the feasible domains for Pi/3 and Pi/4 EILs and angle-ply
QHOLs containing two and three ply orientations. The feasible domain for
Pi/3 FILs is represented graphically by a single point, whereas the domain
for angle-ply QHOLs containing four ply orientations is represented by a
single stacking sequence
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