bluuebunny/crossref_metadata_2025 huggingface dataset:
Lifetimes of tidally limited star clusters with different radii
Authors: Gieles M. , Baumgardt H.
Published: July 2008

We study the escape rate of stars, , from clusters with different radii on circular orbits in a tidal field using analytical predictions and direct N-body simulations. We find that depends on the ratio , where rh is the half-mass radius and rJ the radius of the zero-velocity surface around the cluster. For , the ‘tidal regime’, there is almost no dependence of on . To first order this is because the fraction of escapers per half-mass relaxation time, trh, scales approximately as , which cancels out the r3/2h term in trh. For , the ‘isolated regime’, scales as . The dissolution time-scale, tdis, falls in three regimes. Clusters that start with their initial , in the tidal regime dissolve completely in this regime and their tdis is, therefore, insensitive to the initial rh. Our model predicts that has to be 10−20–10−10 for clusters to dissolve completely in the isolated regime. This means that realistic clusters that start with always expand to the tidal regime before final dissolution. Their tdis has a shallower dependence on than what would be expected when tdis is a constant times trh. For realistic values of , the lifetime varies by less than a factor of 1.5 due to changes in . This implies that the ‘survival’ or ‘vital’ diagram for globular clusters should allow for more small clusters to survive. We note that with our result it is impossible to explain the universal peaked mass function of globular cluster systems by dynamical evolution from a power-law initial mass function, since the peak will be at lower masses in the outer parts of galaxies. Our results finally show that in the tidal regime tdis scales as N0.65/ω, with ω the angular frequency of the cluster in the host galaxy.
Liquidity, the Value of the Firm, and Corporate Finance
Authors: Amihud Yakov , Mendelson Haim
Published: July 2008

The theory of corporate finance has been based on the idea that a company's market value is determined mainly by just two variables: the company's expected after‐tax operating cash flows or earnings, and the risk associated with producing them. The authors argue that there is another important factor affecting a company's value: the liquidity of its own securities, debt as well as equity. The paper supports this argument by reviewing the large and growing body of evidence showing that differences—and changes—in liquidity can have major effects on the pricing of corporate stocks and bonds or, equivalently, on investors' required returns for holding them.

The authors also suggest that the liquidity of a company's securities can be managed by corporate policies and actions. For those companies whose value is likely to be increased by having more liquid securities—which is by no means true of all companies (mature firms that don't need outside capital may well benefit from having more concentrated ownership and hence less liquidity)—management should consider actions such as reducing leverage and substituting dividends for stock repurchases as well as measures designed to increase the effectiveness of their disclosure and investor relations program and the size of their investor base.
Real Asset Valuation: A Back‐to‐basics Approach
Authors: Laughton David , Guerrero Raul , Lessard Donald
Published: July 2008

Different valuation methods can lead to different corporate investment decisions, and the conventional “static, single discount rate” DCF approach in particular is biased against many of the kinds of decisions that corporate managers tend to view as “strategic.” Reducing the bias from valuations involves two main tasks: treating risk in a way that is consistent with observed market pricing, and accounting for the ability of companies to make decisions “dynamically” over time. The authors propose two separate tools, market‐based valuation and complete decision tree analysis, for accomplishing these two improvements in valuation.

The authors also suggest working with the full distribution of future cash flows, one possible realization at a time, rather than working with the aggregate measure of expected cash flow. From a technical perspective, it is necessary to work with the full distribution to value real options properly. Valuing the cash flows one realization at a time also leads to a much better understanding of the interaction between economy‐level, systematic risks and local asset‐level, technical risks. Just as important, the proposed approaches support an effective division of labor between local asset managers, who are better positioned to model technical considerations and other asset specifics, and the central finance staff, who can ensure the consistent treatment of economy‐wide risk and to create the rules of engagement for evaluating opportunities.

After presenting an overview of both the valuation and the organizational issues, the authors present a case involving a corporate investment in carbon capture and storage that illustrates both the application of the proposed methods and the various sources of bias in the typical DCF analysis.
Expected Inflation and the Constant‐Growth Valuation Model*
Authors: Bradley Michael , Jarrell Gregg A.
Published: July 2008

In the presence of inflation, the standard Constant‐Growth valuation model found throughout the finance literature is not valid in cases where a company either (1) makes no net new investments or (2) invests only in zero Net Present Value projects. If expected inflation is positive, the generally accepted and widely used expression for the value of the firm under either of these two conditions seriously understates the true value of the firm, even with modest levels of inflation.

The authors also show that the Weighted Average Cost of Capital (WACC), as developed by Modigliani and Miller (M&M), will be misleading if inflation is positive. They provide an adjustment factor that corrects this deficiency of the M&M model. Finally, the authors show that the WACC formula developed by Miles and Ezzell is correct when the parameters are stated in nominal terms, and therefore no adjustment is necessary.
The Era of Cross‐Border M&A: How Current Market Dynamics are Changing the M&A Landscape
Authors: Zenner Marc , Matthews Matt , Marks Jeff , Mago Nishant
Published: July 2008

Rising equity volatility, surging energy prices, a weakening dollar, and widening credit spreads are influencing both tactical financing decisions and long‐term financial strategy. Amid this turbulence is a quickly changing global M&A landscape that portends long‐term opportunities to deliver value to shareholders.

In this environment, the authors offer the following suggestions for U.S. multinationals: (1) continue looking overseas for well‐positioned targets, especially in emerging markets, even in the context of a weak U.S. dollar; (2) consider using their financial flexibility for opportunistic deals today now that asset values are contracting; and (3) critically evaluate non‐core assets at home or abroad that might be valuable to cross‐border acquirers.

For multinationals in Europe and developing economies, the time may be right to consider transformational cross‐border “megadeals.” Emerging‐market companies have the opportunity to buy low and sell high by using high‐valued equity as an acquisition currency, particularly to gain access to developed markets. Companies in need of new capital should consider the financial and strategic benefits of selling minority stakes to a sovereign wealth fund or other foreign partner.
The Equity Market Risk Premium and the Valuation of Overseas Investments
Authors: Soenen Luc , Johnson Robert
Published: July 2008

There is little agreement among academics or practitioners about how to measure the size of the equity market risk premium, particularly when it relates to investments in emerging markets. Using monthly equity returns for 22 developed and 24 emerging markets covering the period 1976–2006, the authors find that developed capital markets have experienced significant increases in their degree of integration with the U.S. and world market indexes, while emerging markets remain at least partly segmented from those of the U.S. and the world.

For countries that are reasonably well integrated into global capital markets, the authors suggest using the U.S.—based equity market risk premium. But when valuing investments in emerging markets, they recommend use of the Capital Asset Pricing Model adjusted for political risk and a measure of co‐movement between the foreign and U.S. stock markets. The authors also remind readers that the equity market risk premium is supposed to be a forward‐looking measure, and that the common practice of inferring the future from the past can be misleading, particularly in the case of rapidly developing emerging markets.
Stock Option Expensing: The Role of Corporate Governance
Authors: Deshmukh Sanjay , Howe Keith M. , Luft Carl
Published: July 2008

Analysis of the corporate stock option expensing decision (before the practice became mandatory in 2006) continues to be of interest because it provides insight into the underlying factors affecting not only expense recognition, but the overall corporate decision‐making process. Using a sample of 207 companies that volunteered to expense options and more than 1,000 non‐expensing firms, the authors found that companies that provide more disclosure and appeared to have a stronger alignment of managerial and shareholder interests were also more likely to expense stock options—a finding that the authors view as indirect evidence that voluntary expensing was more likely to occur in companies that practiced effective corporate governance. And consistent with the prediction of efficient market theorists, the study also found no significant market reaction to announcements of these decisions to expense options.

The study also found that companies that were the heaviest users of options—notably, smaller, high—growth, and less‐profitable firms—were least likely to expense them. And while this finding adds to the weight of evidence suggesting that companies often make accounting decisions designed to boost reported earnings, the authors also recognize that the possibility that the decision by other companies not to expense may have been a strategy designed primarily to preserve access to capital markets.
Real Options Valuation: A Case Study of an E‐commerce Company
Authors: Sáenz‐Diez Rocío , Gimeno Ricardo , De Abajo Carlos
Published: July 2008

This paper presents a real options valuation model with original solutions to some issues that arise frequently when trying to apply these models to real‐life situations. The authors build on existing models by introducing an innovative and intuitive risk neutral adjustment that allows us to work with all the simulated paths. The problem of incorporating real options into each path is solved with a “nearest neighbors” technique, and uncertainty is simulated using a beta distribution that adapts better to company‐specific information.

The model is then applied to a real life e‐commerce company to produce the following insights: the expanded present value is higher than the traditional present value; the presence of several real options make them interact so that their values are nonadditive; and part of the expanded present value is explained by the presence of “Jensen's inequality” that stems from the “convexity” between the value of each year's cash flow and the uncertain variables.
Detection Thresholds for 2‐Isopropyl‐3‐Methoxypyrazine in Concord and Niagara Grape Juice
Authors: Pickering G.J. , Karthik A. , Inglis D. , Sears M. , Ker K.
Published: July 2008

ABSTRACT:  2‐Isopropyl‐3‐methoxypyrazine (IPMP) is the compound responsible for the off‐flavor known as ladybug taint, which occurs when Harmonia axyridis beetles become incorporated with the grapes during juice processing. It is also an important grape‐derived component of juice flavor in some varieties. The main objective of this study was to determine the orthonasal (ON) and retronasal (RN) detection thresholds for IPMP in juice. The ASTM E679 ascending forced choice method of limits was used to determine detection thresholds for 26 individuals in Concord and Niagara juices. Group best estimate thresholds (BETs) averaged 0.93 ng/L and were 50% and 21% higher in Concord than in Niagara juices for ON and RN evaluation, respectively. Group BETs for IPMP (ng/L) for Concord were ON: 1.11; RN: 1.02 and for Niagara were ON: 0.74; RN: 0.84. Variation in individual detection thresholds was observed, although familiarity with ladybug taint was not associated with individual threshold values. We conclude that humans are very sensitive to IPMP in juice, and that detection thresholds are more strongly influenced by grape variety than evaluation mode. These results may assist juice producers in establishing tolerance levels for IPMP in juice affected by ladybug taint or derived from grapes of suboptimal ripeness.
Tracking Stock or Spin‐Off? Determinants of Choice
Authors: Danielova Anna N.
Published: July 2008

I examine the roles of valuable internal capital markets, cross‐subsidization, and insider ownership as determinants of choice between tracking stock and spin‐offs in corporate equity restructuring. I show that conglomerates are more likely to choose tracking stock if they want to obtain some of the benefits offered by a spin‐off, without loosing the potential for valuable internal capital markets. My results suggest that the market rewards firms with valuable internal capital markets that opt for tracking stocks, and penalizes the possibility of consolidated tax treatments. The market also reacts more favorably to unanticipated tracking‐stock announcements.
Ownership Structure and IPO Valuation—Evidence from Taiwan
Authors: Yeh Yin‐Hua , Shu Pei‐Gi , Guo Re‐Jin
Published: July 2008

We investigate the effect of ownership structure on initial public offering (IPO) valuation in the Taiwanese market, in which many large shareholders exert control through pyramidal structures and cross‐shareholdings with voting rights that are in excess of cash flow rights. Our analysis indicates that outside shareholders incorporate the effect of potential expropriation by entrenched large shareholders in valuing an IPO, since a deviating voting‐cash structure is negatively associated with the valuation metric at both the offer and initial secondary market prices relative to the corresponding intrinsic value. We also show that a deviating voting‐cash structure correlates negatively with IPO underpricing.
Native wildlife on rangelands to minimize methane and produce lower‐emission meat: kangaroos versus livestock
Authors: Wilson George R. , Edwards Melanie J.
Published: July 2008

Ruminant livestock produce the greenhouse gas methane and so contribute to global warming and biodiversity reduction. Methane from the foregut of cattle and sheep constitutes 11% of Australia's total greenhouse gas emissions (GHG). Kangaroos, on the other hand, are nonruminant forestomach fermenters that produce negligible amounts of methane. We quantified the GHG savings Australia could make if livestock were reduced on the rangelands where kangaroo harvesting occurs and kangaroo numbers increased to 175 million to produce same amount of meat. Removing 7 million cattle and 36 million sheep by 2020 would lower Australia's GHG emissions by 16 megatonnes, or 3% of Australia's annual emissions. However, the change will require large cultural and social adjustments and reinvestment. Trials are underway based on international experiences of managing free‐ranging species. They are enabling collaboration between farmers, and if they also show benefits to sustainability, rural productivity, and conservation of biodiversity, they could be expanded to incorporate change on the scale of this article. Farmers have few options to reduce the contribution that livestock make to GHG production. Using kangaroos to produce low‐emission meat is an option for the Australian rangelands which would avoid permit fees under Australia's Emissions Trading Scheme, and could even have global application.
Slip Flow Heat Transfer in Annular Microchannels With Constant Heat Flux
Authors: Duan Zhipeng , Muzychka Y. S.
Published: July 2008

Microscale fluid dynamics has received intensive interest due to the emergence of microelectromechanical systems technology. When the mean free path of the gas is comparable to the channel’s characteristic dimension, the continuum assumption is no longer valid and velocity slip and temperature jump may occur at the duct walls. Slip flow heat transfer in annular microchannels has been examined. The effects of velocity slip and temperature jump on the hydrodynamically and thermally fully developed heat transfer characteristics for laminar flow have been studied analytically. The analysis is carried out for both uniform wall heat flux on one wall, adiabatic on the other wall, and uniform wall heat flux on both walls. The results indicate that the slip flow Nusselt numbers are lower than those for continuum flow and decrease with an increase in Knudsen number for most practical engineering applications. The effects of Knudsen number, radius ratio, and heat flux ratio on heat transfer characteristics are discussed, respectively.
In Vitro and In Vivo Studies of the Trypanocidal Activity of a Diarylthiophene Diamidine against
Trypanosoma cruzi
Authors: da Silva Cristiane França , Batista Marcos Meuser , Batista Denise da Gama Jaen , de Souza Elen Mello , da Silva Patrícia Bernardino , de Oliveira Gabriel Melo , Meuser Andrea Souza , Shareef Abdur-Rafay , Boykin David W. , Soeiro Maria de Nazaré C.
Published: July 2008

Aromatic diamidines are DNA minor groove-binding ligands that display excellent antimicrobial activity against fungi, bacteria, and protozoa. Due to the currently unsatisfactory chemotherapy for Chagas’ disease and in view of our previous reports regarding the effect of diamidines and analogues against both in vitro and in vivo
Trypanosoma cruzi
infection, this study evaluated the effects of a diarylthiophene diamidine (DB1362) against both amastigotes and bloodstream trypomastigotes of
T. cruzi
, the etiological agent of Chagas’ disease. The data show the potent in vitro activity of DB1362 against both parasite forms that are relevant for mammalian infection at doses which do not exhibit cytotoxicity. Ultrastructural analysis and flow cytometry studies show striking alterations in the nuclei and mitochondria of the bloodstream parasites. In vivo studies were performed at two different drug concentrations (25 and 50 mg/kg/day) using a 2-day or a 10-day regimen. The best results were obtained when acutely infected mice were treated with two doses at the lower concentration, resulting in 100% survival, compared to the infected and untreated mice. Although it did not display higher efficacy than benznidazole, DB1362 reduced both cardiac parasitism and inflammation, and in addition, it protected against the cardiac alterations (determined by measurements) common in
T. cruzi
infection. These results support further investigation of diamidines and related compounds as potential agents against Chagas’ disease.
Tipranavir-Ritonavir Genotypic Resistance Score in Protease Inhibitor-Experienced Patients
Authors: Marcelin Anne-Genevieve , Masquelier Bernard , Descamps Diane , Izopet Jacques , Charpentier Charlotte , Alloui Chakib , Bouvier-Alias Magali , Signori-Schmuck Anne , Montes Brigitte , Chaix Marie-Laure , Amiel Corinne , Santos Georges Dos , Ruffault Annick , Barin Francis , Peytavin Gilles , Lavignon Marc , Flandre Philippe , Calvez Vincent
Published: July 2008

To identify mutations associated with the virological response (VR) to a tipranavir-ritonavir (TPV/r)-based regimen, 143 patients previously treated with protease inhibitor (PI) were studied. VR was defined by a decrease of at least 1 log10in, or undetectable, human immunodeficiency virus (HIV) RNA at month 3. The effect of each mutation in the protease, considering all variants at a residue as a single variable, on the VR to TPV/r was investigated. Mutations at six residues were associated with a lower VR (E35D/G/K/N, M36I/L/V, Q58E, Q61D/E/G/H/N/R, H69I/K/N/Q/R/Y, and L89I/M/R/T/V), and one mutation was associated with a higher VR (F53L/W/Y). The genotypic score M36I/L/V − F53L/W/Y + Q58E + H69I/K/N/Q/R/Y + L89I/M/R/T/V was selected as providing a strong association with VR. For the seven patients with a genotypic score of −1 (viruses with only mutation at codon 53), the percentage of responders was 100% and the percentages were 79%, 56%, 33%, 21%, and 0% for those with scores of 0, 1, 2, 3, and 4, respectively. The percentage of patients showing a response to TPV/r was lower for patients infected with non-clade B viruses (n= 16, all non-B subtypes considered together) than for those infected with clade B viruses (n= 127) (25% and 59%, respectively;P= 0.015). Most mutations associated with VR to TPV/r had not previously been associated with PI resistance. This is consistent with phenotypic analysis showing that TPV has a unique resistance profile. Mutations at five positions (35, 36, 61, 69, and 89) were observed significantly more frequently in patients infected with a non-B subtype than in those infected with the B subtype, probably explaining the lower VR observed in these patients.
Heterocyclic Compounds That Inhibit Rev-RRE Function and Human Immunodeficiency Virus Type 1 Replication
Authors: Shuck-Lee Deidra , Chen Fei Fei , Willard Ryan , Raman Sharmila , Ptak Roger , Hammarskjold Marie-Louise , Rekosh David
Published: July 2008

A cell-based screening assay was performed to identify compounds that inhibited the postintegration stage of the human immunodeficiency virus (HIV) life cycle. This assay utilized a cell line that contains the HIVgagandpolgenes expressed in a Rev-dependent fashion. The cell line produces about 10 to 15 ng of p24 per milliliter of medium over a 24-h period in the form of viruslike particles. Any compound that inhibits a postintegration step in the HIV life cycle scores in this assay by decreasing particle production. Forty thousand compounds were screened, and 192 compounds were selected from the original screen because they showed more than 50% inhibition at a 10 μM concentration. The cumulative evidence presented in this study strongly suggests that 2 of the 192 compounds work as inhibitors of HIV Rev function. This was determined by a variety of cell-based assays, although the compounds do not interfere with Rev-RRE (Rev response element) binding in vitro. Both compounds inhibit replication of the lab isolate NL4-3 as well as an HIV primary isolate from Brazil (93BR021) and thus are promising leads as therapeutic candidates that target HIV replication through inhibition of Rev function.
In Vivo Pharmacodynamic Target Investigation for Micafungin against
Candida albicans
and
C. glabrata
in a Neutropenic Murine Candidiasis Model
Authors: Andes D. R. , Diekema D. J. , Pfaller M. A. , Marchillo K. , Bohrmueller J.
Published: July 2008

Previous studies using in vivo candidiasis models have demonstrated that the concentration-associated pharmacodynamic indices, the maximum concentration of a drug in serum/MIC and 24-h area under the curve (AUC)/MIC, are associated with echinocandin treatment efficacy. The current investigations used a neutropenic murine model of disseminated
Candida albicans
and
C. glabrata
infection to identify the 24-h AUC/MIC index target associated with a stasis and killing endpoint for the echinocandin, micafungin. The kinetics after intraperitoneal micafungin dosing were determined in neutropenic infected mice. Peak levels and AUC values were linear over the 16-fold dose range studied. The serum drug elimination half-life ranged from 7.5 to 16 h. Treatment studies were conducted with 4
C. albicans
and 10
C. glabrata
isolates with micafungin MICs varying from 0.008 to 0.25 μg/ml to determine whether similar 24-h AUC/MIC ratios were associated with efficacy. The free drug AUC/MICs associated with stasis and killing (1-log) endpoints were near 10 and 20, respectively. The micafungin exposures associated with efficacy were similar for the two
Candida
species. Furthermore, the free drug micafungin exposures required to produce stasis and killing endpoints were similar to those recently reported for another echinocandin, anidulafungin, against the identical
Candida
isolates in this model.
In Vitro and In Vivo Treatments of
Echinococcus
Protoscoleces and Metacestodes with Artemisinin and Artemisinin Derivatives
Authors: Spicher Martin , Roethlisberger Carole , Lany Catharina , Stadelmann Britta , Keiser Jennifer , Ortega-Mora Luis M. , Gottstein Bruno , Hemphill Andrew
Published: July 2008

In vitro treatment of
Echinococcus multilocularis
and
Echinococcus granulosus
larval stages with the antimalarials dihydroartemisinin and artesunate (10 to 40 μM) exhibited promising results, while 6 weeks of in vivo treatment of mice infected with
E. multilocularis
metacestodes (200 mg/kg of body weight/day) had no effect. However, combination treatments of both drugs with albendazole led to a substantial but statistically not significant reduction in parasite weight compared to results with albendazole alone.
Immunomodulatory Effects of Voriconazole on Monocytes Challenged withAspergillus fumigatus: Differential Role of Toll-Like Receptors
Authors: Simitsopoulou Maria , Roilides Emmanuel , Paliogianni Fotini , Likartsis Christodoulos , Ioannidis John , Kanellou Kalliopi , Walsh Thomas J.
Published: July 2008

Voriconazole (VRC) has activity againstAspergillus fumigatus, the most frequent cause of invasive aspergillosis in immunocompromised patients. The combination of VRC andA. fumigatushyphae induced a more pronounced profile of expression of genes encoding inflammatory molecules in human monocytes thanAspergillusalone did. Herein, we provide further evidence of the potential mechanism underlying this immunomodulatory effect of VRC on human monocytes in response toA. fumigatushyphae. A significant additive antifungal effect was shown when VRC was combined with monocytes againstA. fumigatushyphae. BothA. fumigatushyphae and VRC induced pronounced profiles of mRNA and protein expression of Toll-like receptor 2 (TLR2) as well as tumor necrosis factor alpha (TNF-α) in THP-1 monocytic cells compared to untreated cells. The VRC-induced increase was greater than that induced by hyphae. The combination of VRC and hyphae increased mRNA and protein expression of TLR2 and TNF-α to even higher levels than did either VRC or hyphae alone. In contrast, TLR4 expression, both at the mRNA and protein levels, was not increased by either VRC or hyphae or their combination. In addition, significantly more NF-κB was translocated to the nuclei of THP-1 cells treated with VRC than untreated cells. While VRC induced more NF-κB than hyphae did, treatment with the combination of the two factors induced the greatest NF-κB expression. The pronounced profile of TLR2 signaling, TNF-α expression, and NF-κB activation in the presence of VRC suggests an immunomodulatory effect leading to a more efficient response toA. fumigatus.
Delay of Active Antimicrobial Therapy and Mortality among Patients with Bacteremia: Impact of Severe Neutropenia
Authors: Lin Michael Y. , Weinstein Robert A. , Hota Bala
Published: July 2008

Increasing bacterial antimicrobial resistance has prompted physicians to choose broad-spectrum antimicrobials in order to reduce the likelihood of inactive empirical therapy. However, for bacteremic patients already receiving supportive care, it is unclear whether delay of active antimicrobial therapy significantly impacts patient outcomes. We performed a retrospective cohort study of patients with monomicrobial bloodstream infections at a large urban hospital in the United States from 2001 to 2006. We assessed the impact of delay of active antimicrobial therapy on mortality by using multivariable logistic regression modeling with and without propensity score methodology. We evaluated 1,523 episodes of monomicrobial bacterial bloodstream infections at our institution. Nine hundred eighty-three bacteremic episodes (64.5%) were treated with an active antimicrobial agent within 24 h of the index blood culture; the remaining 540 episodes (35.5%) were considered to have delay of active antimicrobial therapy. In adjusted analysis, among patients in the non-intensive-care-unit setting with an absolute neutrophil count (ANC) of <100 cells/μl, delay was associated with increased mortality (odds ratio [OR], 18.0; 95% confidence interval [CI], 2.84 to 114.5;
P
< 0.01); among intensive-care-unit patients with an ANC of <100 cells/μl, the effect of delay on mortality was nearly significant (OR, 5.56; 95% CI, 0.85 to 36.3;
P
= 0.07). However, for patients who were nonneutropenic (ANC, >500 cells/μl) or had ANCs of 100 to 500 cells/μl, delay was not associated with increased mortality. While the delay of active antimicrobial therapy was not significantly associated with higher mortality for most patients in this cohort, patients with severe neutropenia appeared to be vulnerable.
Analysis ofPRA1and Its Relationship toCandida albicans- Macrophage Interactions
Authors: Marcil A. , Gadoury C. , Ash J. , Zhang J. , Nantel A. , Whiteway M.
Published: July 2008

Phagocytosis ofCandida albicansby either primary bone marrow-derived mouse macrophages or RAW 264.7 cells upregulated transcription ofPRA1, which encodes a cell wall/membrane-associated antigen previously described as a fibrinogen binding protein. However, apra1null mutant was still able to bind fibrinogen, showing that Pra1p is not uniquely required for fibrinogen binding. As well, Pra1 tagged with green fluorescent protein did not colocalize with AlexaFluor 546-labeled human fibrinogen, and whilePRA1expression was inhibited whenCandidawas grown in fetal bovine serum-containing medium,Candidabinding to fibrinogen was activated by these conditions. Therefore, it appears that Pra1p can play at most a minor role in fibrinogen binding toC. albicans. PRA1gene expression is induced in vitro by alkaline pH, and therefore its activation in phagosomes suggested that phagosome maturation was suppressed by the presence ofCandidacells. LysoTracker red-labeled organelles failed to fuse with phagosomes containing liveCandida, while phagosomes containing deadCandidaunderwent a normal phagosome-to-phagolysosome maturation. Immunofluorescence staining with the early/recycling endosomal marker transferrin receptor (CD71) suggested that liveCandidamay escape macrophage destruction through the inhibition of phagolysosomal maturation.
Validity of physical activity monitors in adults participating in free-living activities
Authors: Berntsen S , Hageberg R , Aandstad A , Mowinckel P , Anderssen S A , Carlsen K-H , Andersen L B
Published: July 2008

Background

For a given subject, time in moderate to very vigorous intensity physical activity (MVPA) varies substantially among physical activity monitors.

Objective

In the present study, the primary objective, whether time in MVPA recorded with SenseWear Pro2Armband (Armband; BodyMedia, Pittsburgh, Pennsylvania, USA), ActiGraph (7164, LLC, Fort Walton Beach, Florida, USA), ikcal (Teltronic AG, Biberist, Switzerland) and ActiReg (PreMed AS, Oslo, Norway) is different compared with indirect calorimetry, was determined. The secondary objective, whether these activity monitors estimate energy expenditure differently compared with indirect calorimetry, was also determined.

Material and methods

The activity monitors and a portable oxygen analyser were worn by 14 men and 6 women for 120 min doing a variety of activities of different intensities. Resting metabolic rate was measured with indirect calorimetry. The cutoff points defining moderate, vigorous and very vigorous intensity were three, six and nine times resting metabolic rate.

Results

Time in MVPA was overestimated by 2.9% and 2.5% by Armband and ActiGraph, respectively, and was underestimated by 11.6% and 98.7% by ikcal and ActiReg, respectively. ActiReg (p = 0.004) and ActiGraph (p = 0.007) underestimated energy expenditure in MVPA, and all monitors underestimated total energy expenditure (by 5% to 21%).

Conclusions

Recorded time in MVPA and energy expenditure varies substantially among physical activity monitors. Thus, when comparing physical activity level among studies, it is essential to know the type of physical activity monitor being used.
Initiating and maintaining resistance training in older adults: a social cognitive theory-based approach
Authors: Winett R A , Williams D M , Davy B M
Published: July 2008

Numerous research studies performed in “lab-gyms” with supervised training have demonstrated that simple, brief (20–30 min) resistance training protocols performed 2–3/week following the American College of Sports Medicine’s guidelines positively affect risk factors associated with heart disease, cancers, diabetes, sarcopenia and other disabilities. For more than a decade, resistance training has been recommended for adults, particularly older adults, as a prime preventive intervention, and increasing the prevalence of resistance training is an objective ofHealthy People 2010. However, the prevalence rate for resistance training is only estimated at 10–15% for older adults, despite the leisure time of older adults and access to facilities in developed countries. The reasons that the prevalence rate remains low include public health policy not emphasising resistance training, misinformation, and the lack of theoretically driven approaches demonstrating effective transfer and maintenance of training to minimally supervised settings once initial, generally successful, supervised training is completed. Social cognitive theory (SCT) has been applied to physical activity and aerobic training with some success, but there are aspects of resistance training that are unique including its intensity, progression, precision, and time and place specificity. Social cognitive theory, particularly with a focus on self-regulation and response expectancy and affect within an ecological context, can be directly applied to these unique aspects of resistance training for long-term maintenance.
Elevation of systemic matrix metalloproteinases 2 and 7 and tissue inhibitor of metalloproteinase 2 in patients with a history of Achilles tendon rupture: pilot study
Authors: Pasternak B , Schepull T , Eliasson P , Aspenberg P
Published: July 2008

Objectives

In this study, serum levels of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) between patients with a history of Achilles tendon rupture and blood donor controls were compared, and their relation to mechanical properties of the tendons during healing were studied.

Methods

More than 3 years after injury, serum levels of MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9 and MMP-13, TIMP-1 and TIMP-2 in eight patients who had Achilles tendon rupture were measured. Twelve blood donors served as controls. During the early phase of healing, the tendon modulus of elasticity was calculated from radiostereometric data and tendon cross-sectional area.

Results

Patients with a history of Achilles tendon rupture had increased levels of MMP-2 (median difference 10%, p=0.01), MMP-7 (median difference 15%, p=0.02) and TIMP-2 (median difference 36%, p=0.02), compared with controls. Levels of MMP-7, measured 3 years after injury, correlated inversely to tendon modulus of elasticity (rs=20.83, p=0.02) and positively to tendon elongation (rs=0.74, p=0.05) during the early phase of healing. There was a trend towards positive correlation between MMP-7 and cross-sectional area during the early phase of healing (rs=0.67, p=0.08).

Conclusions

Patients with a history of Achilles tendon rupture appear to have elevated levels of MMP-2, MMP-7 and TIMP-2 in serum. In these pilot data, the view that the MMP–TIMP system is involved in tendinopathy is supported and that disturbances in proteolytic control might be generalised are suggested.
General practitioners’ perceptions and practices of physical activity counselling: changes over the past 10 years
Authors: Buffart L M , van der Ploeg H P , Smith B J , Kurko J , King L , Bauman A E
Published: July 2008

Objective:

In this work, trends in general practitioners’ (GP) knowledge, confidence and practices in promoting physical activity to patients over a 10-year period (1997–2007) were studied.

Design:

Repeated cross-sectional population survey

Setting:

General practice in New South Wales (Australia)

Participants:

646 (40%), 747 (53%) and 511 (64%) GPs that were registered in a selection of urban and rural divisions in New South Wales participated in 2007, 2000 and 1997, respectively.

Main outcome measures:

Self-report questionnaire on the GP’s knowledge, confidence, role perception, attendance of continuous professional development and counselling practice with regard to promoting physical activity in their patients were the main outcome measures.

Results:

The majority of GPs felt confident in giving physical activity advice and saw it as their role to do so. The proportion of GPs with high confidence and role perception increased between 1997 and 2000 (p<0.001) but remained unchanged thereafter. In 1997, GPs were 0.54 times less likely (95% CI 0.42 to 0.69, p<0.001) to discuss physical activity with more than 10 patients per week than GPs in 2007. However, the percentage of new patients that were asked about their physical activity did not change over the last decade.

Conclusions:

Most increases in the proportion of GPs reporting high knowledge, role perception and confidence in giving physical activity advice to patients occurred between 1997 and 2000 and remained unchanged thereafter. In 2007, GPs appeared to give more physical activity advice, but Australian general practice is not yet living up to its potential with regard to physical activity promotion.
Changes in plasma arginine vasopressin concentrations in cyclists participating in a 109-km cycle race
Authors: Hew-Butler T , Dugas J P , Noakes T D , Verbalis J G
Published: July 2008

Objective

To evaluate the osmotic and non-osmotic regulation of arginine vasopressin (AVP) during endurance cycling.

Design

Observational study.

Setting

109 km cycle race.

Participants

33 Cyclists.

Interventions

None.

Main outcome measurements

Plasma sodium concentration ([Na+]), plasma volume (PV) and plasma arginine vasopressin (AVP) concentration ([AVP]p).

Results

A fourfold increase in [AVP]poccurred despite a 2-mmol l−1decrease in plasma [Na+] combined with only modest (5%) PV contraction. A significant inverse correlation was noted between [AVP]pΔ and urine osmolality Δ (r = −0.41, p<0.05), whereas non-significant inverse correlations were noted between [AVP]pand both plasma [Na+] Δ and % PV Δ. Four cyclists finished the race with asymptomatic hyponatraemia. The only significant difference between the entire cohort with this subset of athletes was postrace plasma [Na+] (137.7 vs 133.5 mmol l−1, p<0.001) and plasma [Na+] Δ (−1.9 vs −5.1 mmol l−1, p<0.05). The mean prerace [AVP]pof these four cyclists was just below the minimum detectable limit (0.3 pg ml−1) and increased marginally (0.4 pg ml−1) despite the decline in plasma [Na+].

Conclusions

The osmotic regulation of [AVP]pduring competitive cycling was overshadowed by non-osmotic AVP secretion. The modest decrease in PV was not the primary non-osmotic stimulus to AVP. Partial suppression of AVP occurred in four (12%) cyclists who developed hyponatraemia during 5 h of riding. Therefore, these results confirm that non-osmotic AVP secretion and exercise-associated hyponatraemia does, in fact, occur in cyclists participating in a 109 km cycle race. However, the stimuli to AVP is likely different between cycling and running.
A VANISHING VISCOSITY APPROACH TO FRACTURE GROWTH IN A COHESIVE ZONE MODEL WITH PRESCRIBED CRACK PATH
Authors: CAGNETTI FILIPPO
Published: July 2008

The existence of crack evolutions based on critical points of the energy functional is proved, in the case of a cohesive zone model with prescribed crack path. It turns out that evolutions of this type satisfy a maximum stress criterion for the crack initiation. With an explicit example, it is shown that evolutions based on the absolute minimization of the energy functional do not enjoy this property.
SYNTHESIS OF ANATASE TiO2 PARTICLES AND THEIR SIZE-RELATED STRUCTURAL, OPTICAL AND RAMAN SPECTROSCOPY STUDIES
Authors: KHANG NGUYEN CAO , VAN MINH NGUYEN
Published: July 2008

We have prepared TiO 2 anatase in powder form, studied their structure, Raman spectroscopic and optical properties in relation with the particle size. The average diameter of the particles was found by XRD pattern and SEM to be in the range of 1 μm-10 nm, depending on the synthesis condition. The effects of annealing temperature on the morphology, structural phase and particle size distribution of the particles were studied by scanning electron microscopy, X-ray diffraction, Raman spectroscopy and optical absorption techniques. The distinct changes of the measured results with respect to variations in particle size and synthesis parameter signify the promising application of the optical and Raman spectroscopy for comprehensive physical characterization of nanoparticles.
CALCULATED THRESHOLD OF SUPRATRANSMISSION PHENOMENA IN WAVEGUIDE ARRAYS WITH SATURABLE NONLINEARITY
Authors: SUSANTO H. , KARJANTO N.
Published: July 2008

In this work, we consider a semi-infinite discrete nonlinear Schrödinger equation with saturable nonlinearity driven at one edge by a driving force. The equation models the dynamics of coupled photorefractive waveguide arrays. It has been reported that when the frequency of the driving force is in the forbidden band, energy can be trasmitted along the lattices provided that the driving amplitude is above a critical value. This nonlinear tunneling is called supratransmission. Here, we explain the source of supratransmission using geometric illustrations. Approximations to the critical amplitude for supratransmission are presented as well.
EFFECTS OF TIME DELAY ON TWO NEURONS INTERACTION MORRIS–LECAR MODEL
Authors: MA S. Q. , LU Q. S. , WANG Q. Y. , FENG Z. S.
Published: July 2008

The effects of time delay on two neurons interaction Morris–Lecar model are investigated. It is assumed the two neurons are coupled via gap junction thus time delay arises naturally since information signals take time transmitting from pre-synaptic to post-synaptic of the neurite. It is found that time delay leads the both neurons to quiescent states at the lower reversal potential value of Ca + channel. However, the bifurcation diagram of inter-spike interval (ISI) uncovers the complex firing behavior as time delay is above a certain critical value. Finally, the complete synchronization and lag synchronization of two neurons are reported under an efficient time delay and reversal potential value of Ca + channel.
BIFURCATION ANALYSIS FOR A PREDATOR-PREY SYSTEM WITH PREY DISPERSAL AND TIME DELAY
Authors: GAN QINTAO , XU RUI , YANG PINGHUA
Published: July 2008

In this paper, a predator-prey model with prey dispersal and time delay is investigated. By analyzing the corresponding characteristic equation of a positive equilibrium, the local stability of the positive equilibrium and the existence of Hopf bifurcation are discussed. By using the normal form theory and center manifold reduction, explicit formulae are derived to determine the stability, direction and other properties of bifurcating periodic solutions. Numerical simulations are given to illustrate the theoretical predictions.
DYNAMICS OF A NONAUTONOMOUS SYSTEM WITH IMPULSIVE OUTPUT
Authors: TAN YUANSHUN , TAO FENGMEI , CHEN LANSUN
Published: July 2008

In this paper, an impulsive exploitation of single species modelled by a general nonautonomous equation is considered. The persistence of the population can be obtained under sufficiently weak conditions and also be distinguished from conditions that cause extinction. These attributes resemble corresponding features of the related autonomous population growth model and improve the results of [6–8].
AN SIQS INFECTION MODEL WITH NONLINEAR AND ISOLATION
Authors: XIUXIANG YANG , CHUNRONG XUE
Published: July 2008

By means of asymptotically stable theory and infection model theory of ordinary differential equation, we do research on SIQS model with nonlinear and isolation. Firstly, we obtain the existence of threshold value R0of disease-free equilibration point and local disease equilibration point. Secondly, we prove disease-free equilibration point is locally asymptotically stable when R0< 1, and local disease equilibration point is locally asymptotically stable when R0> 1. Furthermore, we have disease-free equilibration point and local disease equilibration point are globally asymptotically stable with the help of Liapunov function. Lastly, we explain at the point of biology.
ESTIMATES OF SOLUTIONS OF IMPULSIVE PARABOLIC EQUATIONS AND APPLICATION
Authors: SONG GUOHUA
Published: July 2008

This paper is concerned with the estimates of solutions for an impulsive parabolic equations under general boundary condition. We prove that the solutions of impulsive parabolic equations can be controlled and estimated by the solutions of dominating impulsive ordinary differential equations. We also apply the above results to a model problem arising from population biology.
Auxin Receptors and Plant Development: A New Signaling Paradigm
Authors: Mockaitis Keithanne , Estelle Mark
Published: July 2008

The plant hormone auxin, in particular indole-3-acetic acid (IAA), is a key regulator of virtually every aspect of plant growth and development. Auxin regulates transcription by rapidly modulating levels of Aux/IAA proteins throughout development. Recent studies demonstrate that auxin perception occurs through a novel mechanism. Auxin binds to TIR1, the F-box subunit of the ubiquitin ligase complex SCFTIR1, and stabilizes the interaction between TIR1 and Aux/IAA substrates. This interaction results in Aux/IAA ubiquitination and subsequent degradation. Regulation of the Aux/IAA protein family by TIR1 and TIR1-like auxin receptors (AFBs) links auxin action to transcriptional regulation and provides a model by which the vast array of auxin influences on development may be understood. Moreover, auxin receptor function is the first example of small-molecule regulation of an SCF ubiquitin ligase and may have important implications for studies of regulated protein degradation in other species, including animals.
Short-term flexibility of myocardial triglycerides and diastolic function in patients with type 2 diabetes mellitus
Authors: Hammer Sebastiaan , van der Meer Rutger W. , Lamb Hildo J. , de Boer Hans H. , Bax Jeroen J. , de Roos Albert , Romijn Johannes A. , Smit Johannes W. A.
Published: July 2008

Short-term caloric restriction increases plasma levels of nonesterified fatty acids (NEFAs) and is associated with increased myocardial triglyceride (TG) content and decreased myocardial function in healthy subjects. Whether this flexibility of myocardial TG stores and myocardial function is also present in patients with type 2 diabetes mellitus (T2DM) is yet unknown. Myocardial TG content and left ventricular (LV) ratio between the early (E) and atrial (A) diastolic filling phase (E/A) were determined using magnetic resonance (MR) spectroscopy and MR imaging, respectively, before and after a 3-day very low-calorie diet (VLCD) in 11 patients with T2DM. In addition, we studied patients after a 3-day VLCD combined with the antilipolytic drug acipimox. The VLCD induced myocardial TG accumulation [from 0.66 ± 0.09% (mean ± SE, baseline) to 0.98 ± 0.16%, P = 0.028] and a decrease in E/A ratio [from 1.00 ± 0.05 (baseline) to 0.90 ± 0.06, P = 0.002]. This was associated with increased plasma NEFA levels (from 0.57 ± 0.08 mmol/l at baseline to 0.92 ± 0.12, P = 0.019). After the VLCD with acipimox, myocardial TG content, diastolic function, and plasma NEFA levels were similar to baseline values. In conclusion, in patients with T2DM, a VLCD increases myocardial TG content and is associated with a decrease in LV diastolic function. These effects were not observed when a VLCD was combined with acipimox, illustrating the physiological flexibility of myocardial TG stores and myocardial function in patients with T2DM.