Exploring Web keyword analysis as an alternative to link analysis: a multi-industry case

The study explored the feasibility of using Web keyword analysis as an alternative to link analysis and tested the feasibility in a multi-industry environment. The keyword is the organization??s name, in this case the company name. American companies from five industries were included in the study. The study found that the Web visibility of a company as measured by the number of Webpages on which the company name appears correlates with the company??s business measures (revenue, profits, and assets). The correlation coefficients are similar to that between the inlink counts and the business measures. This suggests that the keyword count (searched by the company name) could replace inlink count as an alternative indicator of some commonly used business measures. The co-word (the co-occurrence of the names of two companies on Webpages) count was used as a measure of the relatedness of the two companies. Multidimensional scaling (MDS) analysis was applied to the co-word matrices and generated MDS maps that showed relationships among companies in a multi-industry context. Keyword data were collected from three different types of Websites (general Websites, blog sites, and Web news sites) and results were compared. The study found blog sites to be the better source to collect data for this type of study. The comparison of MDS maps generated from co-link data and the blog co-word data showed that the co-word analysis is as effective as co-link analysis in mapping business relationships. The value of the study is not limited to the business sector as the co-word method could be applied to analysing relationships among other types of organizations.     

Cell morphology and focal adhesion location alters internal cell stress

Extracellular mechanical cues have been shown to have a profound effect on osteogenic cell behaviour. However, it is not known precisely how these cues alter intracellular mechanics to initiate changes in cell behaviour. In this study, a combination of in vitro culture of MC3T3-E1 cells and finite-element modelling was used to investigate the effects of passive differences in substrate stiffness on intracellular mechanics. Cells on collagen-based substrates were classified based on the presence of cell processes and the dimensions of various cellular features were quantified. Focal adhesion (FA) density was quantified from immunohistochemical staining, while cell and substrate stiffnesses were measured using a live-cell atomic force microscope. Computational models of cell morphologies were developed using an applied contraction of the cell body to simulate active cell contraction. The results showed that FA density is directly related to cell morphology, while the effect of substrate stiffness on internal cell tension was modulated by both cell morphology and FA density, as investigated by varying the number of adhesion sites present in each morphological model. We propose that the cells desire to achieve a homeostatic stress state may play a role in osteogenic cell differentiation in response to extracellular mechanical cues.     

Acute β-Hydroxy-β-Methyl Butyrate Suppresses Regulators of Mitochondrial Biogenesis and Lipid Oxidation While Increasing Lipid Content in Myotubes

Leucine modulates synthetic and degradative pathways in muscle, possibly providing metabolic benefits for both athletes and diseased populations. Leucine has become popular among athletes for improving performance and body composition, however little is known about the metabolic effects of the commonly consumed leucine‐derived metabolite β‐hydroxy‐β‐methyl butyrate (HMB). Our work measured the effects of HMB on metabolic protein expression, mitochondrial content and metabolism, as well as lipid content in skeletal muscle cells. Specifically, cultured C2C12 myotubes were treated with either a control or HMB ranging from 6.25 to 25 μM for 24 h and mRNA and/or protein expression, oxygen consumption, glucose uptake, and lipid content were measured. Contrary to leucine's stimulatory effect on metabolism, HMB‐treated cells exhibited significantly reduced regulators of lipid oxidation including peroxisome proliferator‐activated receptor alpha (PPARα) and PPARβ/δ, as well as downstream target carnitine palmitoyl transferase, without alterations in glucose or palmitate oxidation. Furthermore, HMB significantly inhibited activation of the master regulator of energetics, AMP‐activated protein kinase. As a result, HMB‐treated cells also displayed reduced total mitochondrial content compared with true control or cells equivocally treated with leucine. Additionally, HMB treatment amplified markers of lipid biosynthesis (PPARγ and fatty acid synthase) as well as consistently promoted elevated total lipid content versus control cells. Collectively, our results demonstrate that HMB did not improve mitochondrial metabolism or content, and may promote elevated cellular lipid content possibly through heightened PPARγ expression. These observations suggest that HMB may be most beneficial for populations interested in stimulating anabolic cellular processes.     

Find the firn line! The suitability of ERS-1 and ERS-2 SAR data for the analysis of glacier facies on Icelandic icecaps

Icelandic Icecaps are sensitive indicators of climatic fluctuations. Glacier facies boundaries can be identified using remote sensing techniques; SAR data represents the first real opportunity to monitor glacier facies, without cloud attenuation at regular or inter-annual intervals. This study assesses the overall suitability of the data for the monitoring of glacier facies and in particular the firn line altitude (FLA) on Icelandic Icecaps. The results show that the firn line can be identified and located to within +/- 20-40m (vertically). These results were validated using aerial photograph and ground data. RAIDS (Rapid Information Dissemination System) processed data were found to compare favourably with other satellite data for this type of application.     

Noise Reduction Methods for Weighing Lysimeters

Mechanical vibration of the grass and crop weighing lysimeters, located at the University of California West Side Field Research and Extension Station at Five Points, Calif. generated noise in lysimeter mass measurements and reduced the quality of evapotranspiration (ET) data. The estimated power spectral density (PSD) for grass lysimeter mass data acquired at 1.3?ms intervals contained a large peak at 11?Hz. Crop lysimeter data produced similar peaks at frequencies greater than 1?Hz. An effective method for eliminating this noise source is arithmetic averaging of the data, which should be acquired sufficiently rapidly to avoid aliasing. The PSD also increased with decreasing frequency in the range 1.0–0.1?Hz. This noise was addressed by Savitsky–Golay (SG) filtering using 7-, 11-, and 15-point filters. Each filter was applied to the same data set consisting of 2,560 measurements taken during a 1-min interval every 10?min over a 26.3-h period. Noise reduction factors, defined as the ratio of standard deviation of filtered lysimeter mass to standard deviation of unfiltered mean values of lysimeter mass for subsequences of the same data, were 0.90, 0.88, and 0.86 for the 7-, 11-, and 15-point filters, respectively. For the daytime data only, the factors were 0.88, 0.85, and 0.83. The SG filters were more effective during daytime when most of the lysimeter ET occurs. These methods are simple enough to be programmed into commercially available dataloggers for real time filtering. Hourly averages of the standard deviations of lysimeter mass measurements bear a distinct nonlinear relationship to hourly mean wind speed confirming earlier suppositions that wind loading causes noise in counterbalanced weighing lysimeters.     

Differential binding of tropane-based photoaffinity ligands on the dopamine transporter

Benztropine and its analogs are tropane ring-containing dopamine uptake inhibitors that produce behavioral effects markedly different from cocaine and other dopamine transporter blockers. We investigated the benztropine binding site on dopamine transporters by covalently attaching a benztropine-based photoaffinity ligand, [125I]N-[n-butyl-4-(4"'-azido-3"'-iodophenyl)]-4', 4"-difluoro-3alpha-(diphenylmethoxy)tropane ([125I]GA II 34), to the protein, followed by proteolytic and immunological peptide mapping. The maps were compared with those obtained for dopamine transporters photoaffinity labeled with a GBR 12935 analog, [125I]1-[2-(diphenylmethoxy)ethyl]-4-[2-(4-azido-3-iodophenyl)ethy l]p iperazine ([125I]DEEP), and a cocaine analog, [125I]3beta-(p-chlorophenyl)tropane-2beta-carboxylic acid, 4'-azido-3'-iodophenylethyl ester ([125I]RTI 82), which have been shown previously to interact with different regions of the primary sequence of the protein. [125I]GA II 34 became incorporated in a membrane-bound, 14 kDa fragment predicted to contain transmembrane domains 1 and 2. This is the same region of the protein that binds [125I]DEEP, whereas the binding site for [125I]RTI 82 occurs closer to the C terminal in a domain containing transmembrane helices 4-7. Thus, although benztropine and cocaine both contain tropane rings, their binding sites are distinct, suggesting that dopamine transport inhibition may occur by different mechanisms. These results support previously derived structure-activity relationships suggesting that benztropine and cocaine analogs bind to different domains on the dopamine transporter. These differing molecular interactions may lead to the distinctive behavioral profiles of these compounds in animal models of drug abuse and indicate promise for the development of benztropine-based molecules for cocaine substitution therapies.     

Mechanisms of induction of apoptotic DNA fragmentation

PURPOSE: Despite its common use as an indicator of apoptosis, little is known about the mechanisms controlling apoptotic DNA fragmentation in irradiated cells. This review discusses the pathways of chromatin fragmentation, and the role of both nucleases and chromatin structure in this process. DEFINITIONS: DNA fragmentation linked to apoptosis is a combination of cleavage events excising both large DNA fragments within the range 0.4-1.0 Mbp and 50 kbp followed by random cuts within internucleosomal regions (i.e. DNA laddering). The first two cleavage steps can be detected in virtually all apoptotic cells, but DNA laddering is not ubiquitously observed. Endonucleases that mediate this cleavage of chromatin may be classified by substrate specificity, mode of DNA cleavage and their cofactor requirements. CONCLUSIONS: Three major pathways of DNA fragmentation are proposed and discussed: (1) upregulation of endonucleases, (2) their intranuclear/intracellular redistribution and (3) primary changes of chromatin structure.     

Hall and drift mobilities in molecular beam epitaxial grown GaAs

A series of nominally undoped and Si-doped GaAs samples have been grown by molecular beam epitaxy (MBE) with Hall concentrations ranging from 10¹⁵ to 10¹⁹ cm⁻³ and mobilities measured at 77 and 300K by Hall-van der Pauw methods. Drift mobilities were calculated using the variational principle method and Hall scattering factors obtained from a relaxation-time approximation to permit cross-correlation of experimental data with drift or Hall mobilities and actual or Hall electron concentrations. At 77K, both high purity and heavily doped samples are well represented by either drift or Hall values since piezoelectric acoustic phonon scattering and strongly screened ionized impurity scattering hold the Hall factor close to unity in the respective regimes. Between n≊10¹⁵ and 10¹⁷ cm⁻³, where lightly screened ionized impority scattering predominates, Hall mobility overestimates drift mobility by up to 50 percent and Hall concentration similarly underestimates n. At 300K, polar optical phonons limit mobility and a Hall factor up to 1.4 is found in the lowest doped material, falling close to unity above about 10¹⁶ cm⁻³. Our calculation also agrees remarkably well with the Hall mobility of the highest purity MBE grown sample reported to date.     

Medical causes of seizures

Seizures are commonly encountered in patients who do not have epilepsy. Factors that may provoke such seizures include organ failure, electrolyte imbalance, medication and medication withdrawal, and hypersensitive encephalopathy. There is usually one underlying cause, which may be reversible in some patients. A full assessment should be done to rule out primary neurological disease. Treatment of seizures in medically ill patients is aimed at correction of the underlying cause with appropriate short-term anticonvulsant medication. Phenytoin is ineffective in the management of seizures secondary to alcohol withdrawal, and in those due to theophylline or isoniazid toxicity. Control of blood pressure is important in patients with renal failure and seizures. Non-convulsive status epilepticus should be considered in any patient with confusion or coma of unclear cause, and electroencephalography should be done at the earliest opportunity. Most ill patients with secondary seizures do not have epilepsy, and this should be explained to patients and their families. Only those patients with recurrent seizures and uncorrectable predisposing factors need long-term treatment with anticonvulsant medication.