bluuebunny/crossref_metadata_2025 huggingface dataset:
In Situ Determination of the Nanoscale Chemistry and Behavior of Solid-Liquid Systems
Authors: Eswaramoorthy Santhana K. , Howe James M. , Muralidharan Govindarajan
Published: November 2007

Many fundamental questions in crystal-growth behavior remain unanswered because of the difficulties encountered in simultaneously observing phases and determining elemental concentrations and redistributions while crystals nucleate and grow at the nanoscale. We show that these obstacles can be overcome by performing energy-dispersive x-ray spectroscopy on partially molten Al-Si-Cu-Mg alloy particles during in situ heating in a transmission electron microscope. Using this technique, we were able to (i) determine that the aluminum and silicon concentrations change in a complementary and symmetric manner about the solid-liquid interface as a function of temperature; (ii) directly measure the solid- and liquid-phase compositions at equilibrium and in highly undercooled conditions for quantitative comparison with thermodynamic calculations of the liquidus and solidus phase boundaries; and (iii) provide direct evidence for homogeneous nucleation of the aluminum-rich solid.
Flow of Mantle Fluids Through the Ductile Lower Crust: Helium Isotope Trends
Authors: Kennedy B. Mack , van Soest Matthijs C.
Published: November 2007

Heat and mass are injected into the shallow crust when mantle fluids are able to flow through the ductile lower crust. Minimum
3
He/
4
He ratios in surface fluids from the northern Basin and Range Province, western North America, increase systematically from low crustal values in the east to high mantle values in the west, a regional trend that correlates with the rates of active crustal deformation. The highest ratios occur where the extension and shear strain rates are greatest. The correspondence of helium isotope ratios and active transtensional deformation indicates a deformation-enhanced permeability and that mantle fluids can penetrate the ductile lithosphere, even in regions where there is no substantial magmatism. Superimposed on the regional trend are local, high
3
He/
4
He anomalies indicating hidden magmatic activity and/or deep fluid production with locally enhanced permeability, identifying zones with high resource potential, particularly for geothermal energy development.
Solvent Tuning of Electrochemical Potentials in the Active Sites of HiPIP Versus Ferredoxin
Authors: Dey Abhishek , Jenney Francis E. , Adams Michael W. W. , Babini Elena , Takahashi Yasuhiro , Fukuyama Keiichi , Hodgson Keith O. , Hedman Britt , Solomon Edward I.
Published: November 2007

A persistent puzzle in the field of biological electron transfer is the conserved iron-sulfur cluster motif in both high potential iron-sulfur protein (HiPIP) and ferredoxin (Fd) active sites. Despite this structural similarity, HiPIPs react oxidatively at physiological potentials, whereas Fds are reduced. Sulfur K-edge x-ray absorption spectroscopy uncovers the substantial influence of hydration on this variation in reactivity. Fe-S covalency is much lower in natively hydrated Fd active sites than in HiPIPs but increases upon water removal; similarly, HiPIP covalency decreases when unfolding exposes an otherwise hydrophobically shielded active site to water. Studies on model compounds and accompanying density functional theory calculations support a correlation of Fe-S covalency with ease of oxidation and therefore suggest that hydration accounts for most of the difference between Fd and HiPIP reduction potentials.
Expression and Function of Junctional Adhesion Molecule-C in Myelinated Peripheral Nerves
Authors: Scheiermann Christoph , Meda Paolo , Aurrand-Lions Michel , Madani Rime , Yiangou Yiangos , Coffey Peter , Salt Thomas E. , Ducrest-Gay Dominique , Caille Dorothée , Howell Owain , Reynolds Richard , Lobrinus Alexander , Adams Ralf H. , Yu Alan S. L. , Anand Praveen , Imhof Beat A. , Nourshargh Sussan
Published: November 2007

JAM-C is an adhesion molecule that is expressed on cells within the vascular compartment and epithelial cells and, to date, has been largely studied in the context of inflammatory events. Using immunolabeling procedures in conjunction with confocal and electron microscopy, we show here that JAM-C is also expressed in peripheral nerves and that this expression is localized to Schwann cells at junctions between adjoining myelin end loops. Sciatic nerves from JAM-C–deficient [having the JAM-C gene knocked out (KO)] mice exhibited loss of integrity of the myelin sheath and defective nerve conduction as indicated by morphological and electrophysiological studies, respectively. In addition, behavioral tests showed motor abnormalities in the KO animals. JAM-C was also expressed in human sural nerves with an expression profile similar to that seen in mice. These results demonstrate that JAM-C is a component of the autotypic junctional attachments of Schwann cells and plays an important role in maintaining the integrity and function of myelinated peripheral nerves.
Learning from Words
Authors: Lakoff Robin
Published: November 2007

The Stuff of Thought
. Language as a Window into Human Nature.
By Steven Pinker
. Viking, New York, 2007. 511 pp. $29.95, C$37.50. ISBN 9780670063277.

The author addresses the question of how the mind works by considering the way in which we use words.
Dancing Continents
Authors: Burke Kevin
Published: November 2007

Supercontinent
. Ten Billion Years in the Life of Our Planet.
By Ted Nield
. Harvard University Press, Cambridge, MA, 2007. 304 pp. $29.95. ISBN 9780674026599. Granta Books, London, 2007. £18.99. ISBN 9781862079434.

Writing for a broad, popular audience, the author offers an account of the assembly and destruction of supercontinents as well as the development of our understanding of such tectonics.
Evaluation of an Indirect Immunofluorescence Assay for Detection of Immunoglobulin M (IgM) and IgG Antibodies against Yellow Fever Virus
Authors: Niedrig Matthias , Kürsteiner Oliver , Herzog Christian , Sonnenberg Karen
Published: November 2007

The first commercial indirect immunofluorescence assay (IFA) using Euroimmun Biochip technology was evaluated for the serodiagnosis of immunoglobulin G (IgG) and IgM antibodies against yellow fever virus (YFV) and was compared with the plaque reduction neutralization test (PRNT), which is currently the gold standard test for YFV. An overall correlation between the tests of 98.7% was established based on the analysis of 150 sera from individuals after vaccination with the 17D yellow fever vaccine. The sensitivity and specificity, calculated using the 150 sera from vaccinees and 150 sera from healthy blood donors, were 95% and 95%, respectively, for the IgG IFA and 94% and 97% for the IgM IFA. Antibody titers found in the PRNT correlated poorly with the IgM and IgG titers detected by IFA. The analysis of preexisting heterologous flaviviral immunity revealed the presence of antibodies reactive with YFV, tick-borne encephalitis virus, West Nile virus, Japanese encephalitis virus, and dengue virus serotypes 1 to 4 in 20 out of the 150 vaccinees. The indirect IFA showed that nine of these individuals with previous flaviviral exposure who received 17D vaccine failed to produce detectable IgM antibodies. Despite this preexisting immunity, all vaccinees developed protective immunity as detected by PRNT and anti-YFV IgG antibodies as detected by IFA. The high specificity and sensitivity of the IFA make it a useful tool for rapid diagnosis of yellow fever during outbreaks, for epidemiological studies, and for serosurveillance after vaccination.
Cellular Entry of Lymphocytic Choriomeningitis Virus
Authors: Rojek Jillian M. , Perez Mar , Kunz Stefan
Published: November 2007

In contrast to most enveloped viruses that enter the host cell via clathrin-dependent endocytosis, the Old World arenavirus lymphocytic choriomeningitis virus (LCMV) enters cells via noncoated vesicles that deliver the virus to endosomes, where pH-dependent membrane fusion occurs. Here, we investigated the initial steps of LCMV infection. We found that the attachment of LCMV to its cellular receptor α-dystroglycan occurs rapidly and is not dependent on membrane cholesterol. However, subsequent virus internalization is sensitive to cholesterol depletion, indicating the involvement of a cholesterol-dependent pathway. We provide evidence that LCMV entry involves an endocytotic pathway that is independent of clathrin and caveolin and that does not require the GTPase dynamin. In addition, neither the structural integrity nor the dynamics of the actin cytoskeleton are required for infection. These findings indicate that the prototypic Old World arenavirus LCMV uses a mechanism of entry that is different from clathrin-mediated endocytosis, which is used by the New World arenavirus Junin virus, and pathways used by other enveloped viruses.
Increased Levels of Galactose-Deficient Anti-Gal Immunoglobulin G in the Sera of Hepatitis C Virus-Infected Individuals with Fibrosis and Cirrhosis
Authors: Mehta Anand S. , Long Ronald E. , Comunale Mary Ann , Wang Mengjun , Rodemich Lucy , Krakover Jonathan , Philip Ramila , Marrero Jorge A. , Dwek Raymond A. , Block Timothy M.
Published: November 2007

Hepatitis B and C viruses are major causative agents of liver fibrosis, cirrhosis, and liver cancer. Using comparative glycoproteomics, we identified a glycoprotein that is altered both in amount and in glycosylation as a function of liver fibrosis and cirrhosis. Specifically, this altered glycoprotein is an immunoglobulin G (IgG) molecule reactive to the heterophilic alpha-Gal epitope [Galα-1-3Galβ1-(3)4GlcNAc-R]. While similar changes in glycosylation have been observed in several autoimmune diseases, the specific immunoglobulins and their antigen recognition profiles were not determined. Thus, we provide the first report identifying the specific antigenic recognition profile of an immunoglobulin molecule containing altered glycosylation as a function of liver disease. This change in glycosylation allowed increased reactivity with several fucose binding lectins and permitted the development of a plate-based assay to measure this change. Increased lectin reactivity was observed in 100% of the more than 200 individuals with stage III or greater fibrosis and appeared to be correlated with the degree of fibrosis. The reason for the alteration in the glycosylation of anti-Gal IgG is currently unclear but may be related to the natural history of the disease and may be useful in the noninvasive detection of fibrosis and cirrhosis.
Macrophage-Derived Simian Immunodeficiency Virus Exhibits Enhanced Infectivity by Comparison with T-Cell-Derived Virus
Authors: Gaskill Peter J. , Zandonatti Michelle , Gilmartin Tim , Head Steven R. , Fox Howard S.
Published: November 2007

Human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) infect and productively replicate in macrophages and T lymphocytes. Here, we show that SIV virions derived from macrophages have higher levels of infectivity than those derived from T cells. The lower infectivity of T-cell-derived viruses is influenced by the quantity or type of mannose residues on the virion. Our results demonstrate that the cellular origin of a virus is a major factor in viral infectivity. Cell-type-specific factors in viral infectivity, and organ-specific or disease stage-specific differences in cellular derivation of virions, can be critical in the pathogenesis of HIV and AIDS.
Murine Endogenous Retrovirus MuERV-L Is the Progenitor of the “Orphan” Epsilon Viruslike Particles of the Early Mouse Embryo
Authors: Ribet David , Louvet-Vallée Sophie , Harper Francis , de Parseval Nathalie , Dewannieux Marie , Heidmann Odile , Pierron Gérard , Maro Bernard , Heidmann Thierry
Published: November 2007

Viruslike particles which displayed a peculiar wheellike appearance that distinguished them from A-, B- or C-type particles had previously been described in the early mouse embryo. The maximum expression of these so-called epsilon particles was observed in two-cell-stage embryos, followed by their rapid decline at later stages of development and no particles detected at the zygote one-cell stage. Here, we show that these particles are in fact produced by a newly discovered murine endogenous retrovirus (ERV) belonging to the widespread family of mammalian ERV-L elements and named MuERV-L. Using antibodies that we raised against the Gag protein of these elements, Western blot analysis and in toto immunofluorescence studies of the embryos at various stages disclosed the same developmental expression profile as that observed for epsilon particles. Using expression vectors for cloned, full-length, entirely coding MuERV-L copies and cell transfection, direct identification of the epsilon particles was finally achieved by high-resolution electron microscopy.
Lifetime medical expenditure and life expectancy lost attributable to smoking through major smoking related diseases in Taiwan
Authors: Chung Chih-Wen , Wang Jung-Der , Yu Cheng-Fen , Yang Ming-Chin
Published: November 2007

Objective:

To estimate the lifetime financial burden on Taiwan’s national health insurance (NHI) system, life expectancy and years of life expectancy lost (YLEL) attributable to smoking from major smoking related diseases.

Methods:

10 major smoking related diseases (seven cancers, stroke, acute myocardial infarction and chronic obstructive pulmonary disease) were selected for this study. A survival analysis was conducted on linked cohorts from the National Death Registry database and the National Cancer Registry (NCR) and patients at the National Taiwan University Hospital (NTUH). Estimation of the smoking attributable fraction (SAF) for the study diseases was undertaken by combining the relative risks of smokers against non-smokers and the prevalence of smoking in Taiwan. The YLEL attributable to smoking was calculated for the study diseases by combining the survival analysis results, the SAF and the annual incidences of each disease. The lifetime medical expenditure for the study diseases was estimated by integrating the survival curve and the mean annual medical costs calculated from NHI reimbursement records.

Results:

There were 241 280 incidents of the 10 study diseases in 2001, of which about 53 648 cases (22.2%) were attributable to smoking, with a total YLEL of 191 313 at an average of about 3.6 YLEL per case. For each case, the average survival time was about 10.2 years. Under two different annual discount rates, the total lifetime financial burden on the NHI was estimated at between $291 million (£147 million; €216 million) (3% discount) and $336 million (1% discount) for all diseases attributable to smoking in 2001, accounting for about 24.6% of the total estimated lifetime medical expenditure for all incidents of the 10 study diseases.

Conclusions:

Smoking places tremendous financial and health burdens upon both society and individuals. A much more stringent tobacco control strategy is needed to curb the damage from smoking.
Mortality attributable to passive smoking in Spain, 2002
Authors: López M J , Pérez-Ríos M , Schiaffino A , Nebot M , Montes A , Ariza C , García M , Juárez O , Moncada A , Fernández E
Published: November 2007

Objective:

Exposure to environmental tobacco smoke (ETS) is associated with a variety of health effects, including lung cancer and ischaemic heart disease. The objective of this study was to estimate the number of deaths caused by exposure to ETS among non-smokers in Spain during the year 2002

Methods:

Prevalence of ETS exposure among never smokers was gathered from three region based health interview surveys. The relative risks of lung cancer and ichaemic heart diseases were selected from three meta-analyses. Population attributable risk (PAR) was computed using a range of prevalences (minimum-maximum). The number of deaths attributable to ETS was calculated by applying PARs to mortality not attributable to active smoking in 2002. The analyses were stratified by sex, age and source of exposure (home, workplace and both combined). In addition, a sensitivity analysis was performed for different scenarios.

Results:

Among men, deaths attributable to ETS ranged from 408 to 1703. From 247 to 1434 of these deaths would be caused by the exposure only at home, 136–196 by exposure only in the workplace and 25–73 by exposure at both home and the workplace. Among women, the number of attributable deaths ranged from 820 to 1534. Between 807 and 1477 of these deaths would be caused by exposure only at home, 9–32 by exposure only in the workplace and 4–25 by exposure both at home and in the workplace.

Conclusion:

Exposure to ETS at home and at work in Spain could be responsible for 1228–3237 of deaths from lung cancer and ischaemic heart disease. These data confirm that passive smoking is an important public health problem in Spain that needs urgent attention.
A systematic review of interventions for smokers who contact quitlines
Authors: Stead Lindsay F , Perera Rafael , Lancaster Tim
Published: November 2007

Objective:

To evaluate the effect of different types of adjunctive support to stop smoking for individuals contacting telephone “quitlines,” including call-back counselling, different counselling techniques and provision of self help materials.

Data sources:

This review includes quitline studies identified as part of Cochrane reviews of telephone counselling and self help materials for smoking cessation. We updated the searches for this review.

Study selection:

We included studies that were randomised or quasi-randomised controlled trials of any quitline or related service with follow-up of at least six months.

Data extraction:

Data were extracted by one author and checked by a second. The cessation outcome was numbers quit at longest follow-up taking the strictest definition of abstinence available, and assuming participants lost to follow-up continued to smoke.

Data synthesis:

We identified 14 relevant studies. Eight studies (18 500 participants) comparing multiple call-backs to a single contact increased quitting in the intervention group (Mantel-Haenszel fixed effect odds ratio 1.41, 95% confidence interval 1.27 to 1.57). Two unpublished studies without sufficient data to include in the meta-analysis also reported positive effects. Three call-back trials compared two schedules of multiple calls. Two found a significant dose-response effect and one did not detect a difference. We did not find consistent differences in comparisons between counselling approaches (two trials) or between different types of self help materials supplied following quitline contact (three trials).

Conclusions:

Multiple call-back counselling improves long term cessation for smokers who contact quitline services. Offering more calls may improve success rates. We failed to detect an effect of the type of counselling or the type of self help materials supplied as adjuncts to quitline counselling.
Offering free NRT through a tobacco quitline: impact on utilisation and quit rates
Authors: Tinkelman David , Wilson Steven M , Willett Jeff , Sweeney Christine T
Published: November 2007

Objective:

To assess the impact on quitline utilisation and cessation outcomes of adding free nicotine patches to the existing programme offerings.

Methods:

Tobacco use status data from the Ohio tobacco quitline were collected from a subset of quitline callers 6 months after the initial intake call. To evaluate the impact of the nicotine replacement therapy (NRT) initiative, quit rates for two groups were compared: those who entered and exited the quitline programme before the availability of free NRT (n = 4657) and those who entered and exited the quitline programme after the availability of free NRT (n = 5715).

Results:

Call volume increased from 2351 intakes calls per month or 78 calls per day before the availability of free NRT to 3606 intake calls per month or 188 intakes per day following the availability of free NRT (p<0.0001). 7-day point prevalence abstinence at 6 months among all quitline callers increased from 10.3% (95% confidence interval (CI) 9.7 to 10.9) before the availability of NRT to 14.9% (95% CI 14.3 to 15.5) after the availability of NRT.

Conclusion:

Offering free NRT through a state quitline is an effective means of increasing quitline utilisation and improving quit rates.
Increasing reach of quitline services in a US state with comprehensive tobacco treatment
Authors: Swartz Woods Susan , Haskins Amy E
Published: November 2007

Objective:

The population reach of tobacco quitlines is an important measure of treatment seeking and penetration of services. Maine offers an opportunity to examine temporal changes in quitline reach and referral sources in the context of a comprehensive tobacco treatment programme. The impact of a $1.00 cigarette tax increase is also examined.

Methods:

This is a descriptive analysis of Maine Tobacco Helpline call volume September 2001 to December 2006. Annual reach was estimated using a cross sectional state surveillance survey. Weekly call volume was examined during 2005, a year of marked changes in tobacco taxes and quitline resources. Referral patterns were analysed yearly.

Results:

Maine’s Tobacco Helpline observed more than a threefold increase in population reach during a four year interval, from 1.9% to over 6% per year. Calls increased substantially in 2005, concurrent with added hours of operation and a rise in the cigarette tax. Over time, callers increasingly reported hearing about the quitline from health professionals, from 10% in 2001 to 38% in 2006.

Conclusions:

Tobacco treatment programmes offering free nicotine therapy and professional medical education can drive quitline utilisation over time. Call volume can also be affected by quitline operational and policy changes that promote the reduction of tobacco use.
Minimal dataset for quitlines: a best practice
Authors: Campbell H Sharon , Ossip-Klein Deborah , Bailey Linda , Saul Jessie
Published: November 2007

Objectives:

This paper discusses the development of a minimal dataset (MDS) for tobacco cessation quitlines across North America. The goal was to create a standardised instrument and protocol that would allow for comparisons and pooling of data across quitlines for evaluation and research purposes. Principles of utilisation focused evaluation were followed to achieve consensus across diverse stakeholder groups in two countries.

Methods:

The North American Quitline Consortium (NAQC) assembled a working group with representatives from quitline service providers, funders, evaluators and researchers from Canada and the United States. An extensive, iterative consultation process over two years led to consensus on the evaluation domains, indicators and specific items. Descriptive information on quitline service models, data collection protocols and methodological issues were addressed.

Results:

The resulting minimal dataset (MDS) includes 15 items collected from eligible callers at intake and eight items collected from smokers participating in evaluation. Recommendations for selecting evaluation participants, length of follow-up and repeat callers were developed. Full MDS questions and technical documents are available on the NAQC website.

Conclusion:

Adoption and implementation of the MDS occurred in the majority of North American quitlines by the end of 2006. Key success factors included a focus on utility and feasibility, a commitment to meeting multiple and varied needs, sensitivity to situational factors and investment in working interactively with stakeholders. The creation and implementation of a MDS across two countries is an important “first” in tobacco control which will help speed the creation of practice based evidence and facilitate practice based research.
Aboriginal users of Canadian quitlines: an exploratory analysis
Authors: Hayward Lynda M , Campbell H Sharon , Sutherland-Brown Carol
Published: November 2007

Objectives:

To conduct an exploratory, comparative study of the utilisation and effectiveness of tobacco cessation quitlines among aboriginal and non-aboriginal Canadian smokers.

Setting:

Population based quitlines that provide free cessation information, advice and counselling to Canadian smokers.

Subjects:

First time quitline callers, age 18 years of age and over, who called the quitline between August 2001 and December 2005 and who completed the evaluation and provided data on their ethnic status (n = 7082).

Main measures:

Demographic characteristics and tobacco behaviours of participants at intake and follow-up; reasons for calling; actions taken toward quitting, and 6-month follow-up quit rates.

Results:

7% of evaluation participants in the time period reported aboriginal origins. Aboriginal participants were younger than non-aboriginals but had similar smoking status and level of addiction at intake. Concern about future health and current health problems were the most common reasons aboriginal participants called. Six months after intake aboriginals and non-aboriginals had taken similar actions with 57% making a 24-hour quit attempt. Quit rates were higher for aboriginals than non-aboriginals, particularly for men. The 6-month prolonged abstinence rate for aboriginal men was 16.7% compared with 7.2% for aboriginal women and 9.4% and 8.3% for non-aboriginal men and women, respectively.

Conclusions:

This exploratory analysis showed that even without targeted promotion, aboriginal smokers do call Canadian quitlines, primarily for health related reasons. We also showed that the quitlines are effective at helping them to quit. As a population focused intervention, quitlines can reach a large proportion of smokers in a cost efficient manner. In aboriginal communities where smoking rates exceed 50% and multiple health risks and chronic diseases already exist, eliminating non-ceremonial tobacco use must be a priority. Our results, although exploratory, suggest quitlines can be an effective addition to aboriginal tobacco cessation strategies.
The costs of smoking in Vietnam: the case of inpatient care
Authors: Ross Hana , Trung Dang Vu , Phu Vu Xuan
Published: November 2007

Objective:

To estimate the social costs of smoking related to inpatient care in Vietnam using 2005 data.

Design:

The cost of illness as a result of hospitalisation for three major smoking-related diseases combined with the prevalence-based approach to obtain the costs of smoking in Vietnam for inpatient care.

Main outcome measure:

Smoking-attributable costs of inpatient care for lung cancer, chronic obstructive pulmonary disease (COPD), and ischaemic heart disease.

Results:

The total cost of inpatient health care caused by smoking in Vietnam reached at least 1 161 829 million Vietnamese dollars ($VN) (or $US77.5 million) in 2005. This represents about 0.22% of Vietnam gross domestic product (GDP) and 4.3% of total healthcare expenditure. The majority of these expenses are related to COPD treatment ($VN1 033 541 million or $US68.9 million per year) followed by lung cancer ($VN78 143 million, or $US5.2 million per year) and ischaemic disease ($VN50 145 million, or $US3.3 million per year). The government directly finances about 51% of these costs. The rest is financed either by households (34%) or by the insurance sector (15%).

Conclusions:

The social costs of smoking in Vietnam as the percentage of GDP is lower compared to estimates from high-income countries. The true costs would be substantially higher if all smoking-related diseases, outpatient care and mortality-related costs are included. More research is needed to augment the estimates presented in this paper.
Exposure to domestic violence associated with adult smoking in India: a population based study
Authors: Ackerson Leland K , Kawachi Ichiro , Barbeau Elizabeth M , Subramanian S V
Published: November 2007

Objective:

To investigate the relation between domestic violence and tobacco use among adults in India.

Design:

Multilevel cross sectional analyses of a nationally representative population based sample from the 1998–9 Indian national family health survey.

Participants:

278 977 individuals aged 15 or older; and 89 092 ever married women aged 15–49.

Main outcome:

Dichotomous variables for smoking and chewing tobacco.

Results:

Women who reported being abused more than one year ago and those who reported being abused in the past year were more likely to smoke and chew tobacco than women who have never experienced domestic violence. Compared to individuals who lived in homes where no abuse was reported, those who lived in homes where a woman reported experiencing domestic violence were more likely to smoke and chew tobacco.

Conclusion:

Domestic violence is associated with higher odds of smoking and chewing tobacco in India. Efforts to control tobacco use need to consider the larger psychosocial circumstances within which individuals who practise such harmful health behaviours reside.
MBE GROWTH AND STUDY OF Cr2+:ZnSe LAYERS FOR MID-IR LASERS
Authors: KAZAKOV I. P. , MIROV S. B. , FEDOROV V. V. , GALLIAN A. , KERNAL J. , ALLMAN J. , ZABEZHAYLOV A. O. , DIANOV E. M.
Published: November 2007

MBE growth and photoluminescence study of thin films and bulk Cr 2+: ZnSe are reported. We show that MBE provides optically active chromium in ZnSe and is viable for fabrication of optically and electrically pumped laser structures.
SPACE-CHARGE SPECTROSCOPY OF ELECTRONIC STATES IN Ge/Si QUANTUM DOTS WITH TYPE-II BAND ALIGNMENT
Authors: YAKIMOV A. I. , DVURECHENSKII A. V. , NIKIFOROV A. I. , BLOSHKIN A. A.
Published: November 2007

Space-charge spectroscopy was employed to study electronic structure in a stack of four layers of Ge quantum dots coherently embedded in an n-type Si (001) matrix. Evidence for an electron confinement in the vicinity of Ge dots was found. From the frequency-dependent measurements the electron binding energy was determined to be ~50 meV, which is consistent with the results of numerical analysis. The data are explained by a modification of the conduction band alignment induced by inhomogeneous tensile strain in Si around the buried Ge dots.
RESONANT RAYLEIGH SCATTERING OF LIGHT BY SEMICONDUCTOR MICROCAVITY
Authors: LEBEDEV M. V. , DEMENEV A. A. , KULAKOVSKII V. D.
Published: November 2007

Experimental study of Resonant Rayleigh Scattering (RRS) of light by a semiconductor microcavity was carried out on a double cavity sample. The shifts of RRS lines spectral positions with sample rotation demonstrate clearly polariton dispersion. The shape of the lines depends strongly on the position of the excitation spot on the structure surface and temperature. The treatment of experimental data in terms of the Fano quantum mechanical interference between a discreet state and continuum gives a direct method to study polariton scattering probabilities.
SPATIAL STRUCTURE OF AN INDIVIDUAL DEEP ACCEPTOR IN A CUBIC CRYSTAL
Authors: MONAKHOV A. M. , ROMANOV K. S. , PANAIOTTI I. E. , AVERKIEV N. S.
Published: November 2007

The wave-function of a hole localized on a deep acceptor is considered. The cubic symmetry of the crystal has been taken into account. The obtained pictures qualitatively agree with the STM image of Mn in GaAs .
POLARIZED PHOTOLUMINESCENCE OF EXCITONS IN n-, p- AND UNDOPED InAs/GaAs QUANTUM DOTS
Authors: FÜRST J. , PASCHER H. , SHALYGIN V. A. , VOROBJEV L. E. , FIRSOV D. A. , TONKIKH A. A. , POLYAKOV N. K. , SAMSONENKO YU. B. , CIRLIN G. E. , USTINOV V. M.
Published: November 2007

Polarized photoluminescence from InAs / GaAs self-assembled quantum dots has been investigated under continuous wave excitation by circularly polarized light. Depolarization of the photoluminescence in a magnetic field perpendicular to the wavevector of the exciting light (Hanle effect) was studied. For n-doped, undoped and p-doped quantum dots the observed Hanle curves exhibit qualitatively different shapes: single-, bi-, and tri-Lorentzian, respectively. In the two latter cases the complicated shape of the Hanle curve is attributed to the different processes of radiative recombination which take place simultaneously. Recombination of uncharged excitons and recombination of positively charged exciton complexes are considered. Corresponding spin lifetimes are determined.
GROUND AND EXCITED STATE PHOTOLUMINESCENCE MAPPING ON InAs/InGaAs QUANTUM DOT STRUCTURES
Authors: TORCHYNSKA T. V. , LOZADA E. VELÁZQUEZ , DYBIEC M. , OSTAPENKO S. , ELISEEV P. G. , STINTZ A. , MALLOY K. J. , SIERRA R. PENA
Published: November 2007

This paper presents the photoluminescence study at 12 K and scanning photoluminescence spectroscopy investigation of the ground and excited states at 80 and 300 K on InAs QDs inserted in In 0.15 Ga 0.85 As / GaAs QW structures and created at different QD growth temperatures. It is shown that investigated structures are characterized by the long range variation of an average QD size in QD ensemble across the wafer. This long range QD size inhomogeneity was used for investigation of the multi-excited state energy trend versus ground state energy (or QD sizes).
ASYMMETRIC DOUBLE QUANTUM WELLS AS EXCITON SPIN SEPARATOR
Authors: ZAITSEV S. V. , BRICHKIN A. S. , DOROZHKIN P. S. , KULAKOVSKII V. D. , WELSCH M. K. , BACHER G.
Published: November 2007

Exciton recombination in asymmetric CdMgTe / CdTe / CdMgTe / CdTe / CdMnTe double quantum wells (ADQW) with different barrier widths is studied in magnetic field up to 10 T. As grown structures were subjected to temperature annealing to introduce Mn and Mg atoms from the barriers into the CdTe quantum wells (QW). At low fields exciton transition in QW with magnetic impurity ( Mn ) is higher in energy than that in QW with nonmagnetic impurity ( Mg ), and interwell exciton relaxation is fast independently on the spin state. In contrast, at high fields, when the energy order reverses, an unexpectedly low relaxation rate of σ- polarized excitons from nonmagnetic QW to the ground σ+ polarized state in magnetic QW has been observed. Effect strongly correlates with hh–lh splitting value Δhh – lh and discussed in terms of valence band mixing. Such a slowing down of relaxation allows separation of oppositely polarized excitons in different QWs.
Chronobiological characterization of women with primary vasospastic syndrome: body heat loss capacity in relation to sleep initiation and phase of entrainment
Authors: Vollenweider Stephanie , Wirz-Justice Anna , Flammer Josef , Orgül Selim , Kräuchi Kurt
Published: November 2007

Women with primary vasospastic syndrome (VS), but otherwise healthy, exhibit a functional disorder of vascular regulation (main symptom: cold extremities) and often suffer from difficulties initiating sleep (DIS). Diverse studies have shown a close association between distal vasodilatation before lights off and a rapid onset of sleep. Therefore, we hypothesized that DIS in women with VS could be due to a reduced heat loss capacity in the evening, i.e., subjects are physiologically not ready for sleep. The aim of the study was to elucidate whether women having both VS and DIS (WVD) or not (controls) show different circadian characteristics (e.g., phase delay of the circadian thermoregulatory system with respect to the sleep-wake cycle). Healthy young women ( n = 9 WVD and n = 9 control) completed a 40-h constant routine protocol (adjusted to habitual bedtime) before and after an 8-h sleep episode. Skin temperatures [off-line calculated as distal-proximal skin temperature gradient (DPG)] and core body temperature (CBT; rectal) were continuously recorded. Half-hourly saliva samples were collected for melatonin assay and subjective sleepiness was assessed on the Karolinska Sleepiness Scale (KSS). Compared with control, WVD showed no differences in habitual bed times, but a 1-h circadian phase delay of dim light-melatonin onset (hours after lights on: WVD 14.6 ± 0.3 h; control 13.5 ± 0.2 h; P = 0.01). Similar phase shifts were observed in CBT, DPG, and KSS ratings. In conclusion, WVD exhibit a phase delay of the endogenous circadian system with respect to their habitual sleep-wake cycle, which could be a cause of DIS.
Patterns of electrical propagation in the intact pregnant guinea pig uterus
Authors: Lammers Wim J. E. P. , Mirghani H. , Stephen B. , Dhanasekaran S. , Wahab A. , Al Sultan M. A. H. , Abazer F.
Published: November 2007

Previous studies have reported on propagation of individual spikes in isolated segments of the pregnant uterus, but there is no information on patterns of spike propagation in the intact organ. There is also no information on propagation of myometrial burst. The aim of this study was to record, at high resolution, patterns of propagation of electrical activities in the pregnant uterus. Sixteen timed-pregnant guinea pigs were euthanized at term, and their uteruses isolated. Fetuses were removed and replaced by an equal amount of Tyrode. A 240-electrode array was positioned at various locations along the organ, all signals were recorded simultaneously, and the electrical propagations were reconstructed. In the intact pregnant uterus at term, spikes propagated with high velocity in longitudinal (6.8 ± 2.4 cm/s) and slower velocity in circular direction (2.8 ± 1.0 cm/s; P < 0.01). Direction of propagation and frequency of activity were highly variable but showed similar patterns at the ovary or cervical end and along the anterior, posterior, and antimesometrial borders. Along mesometrium, spike propagation was sparse and fractionated. Migration of burst (0.6 ± 0.4 cm/s) was significantly much slower than that of individual spikes ( P < 0.001). Initial burst activity was located at variable locations along the ovarial end of the antimesometrial border, while the latest excitation occurred at the cervical end (1.2 ± 0.9 min). In conclusion, high resolution electrical mapping of the intact pregnant uterus reveals fundamental properties in spatial and temporal patterns of spike and burst propagation that determine the contraction of the organ.
The small GTPase Rac-1 is a regulator of mesangial cell morphology and thrombospondin-1 expression
Authors: Giehl Klaudia , Graness Angela , Goppelt-Struebe Margarete
Published: November 2007

Thrombospondin-1 (TSP-1), which is synthesized by mesangial cells, is known for its anti-angiogenic activity and its ability to activate latent TGF-β. TSP-1 is upregulated in renal diseases associated with tissue remodeling. Therefore, we hypothesized that the expression of TSP-1 might be modulated by changes in cell morphology involving proteins of the Rho family. Spreading of mesangial cells after detachment and reseeding was characterized by the formation of lamellipodia and focal adhesions, pointing toward a Rac-1-mediated rearrangement of actin structures. Clustering of focal adhesion proteins was also observed in a model system of nocodazole-induced disruption of microtubules. These morphological alterations were impeded by pharmacological inhibition of Src family kinases, of the small GTPase Rac-1, or by downregulation of Rac-1 by siRNA. Upon cell spreading, TSP-1 was upregulated in the absence and much more prominently in the presence of serum, but also after nocodazole treatment. TSP-1 upregulation was controlled by activation of Src family kinases, ERK 1/2 and Rac-1, whereas activation of RhoA-ROCK signaling was not linked to TSP-1 induction. We thus provide evidence that TSP-1 expression is induced by common signaling pathways, which are activated by morphological alterations of renal mesangial cells or by soluble factors as contained in serum, and these pathways include Src family kinases, ERK 1/2 and Rac-1. Our data suggest that tissue remodeling activates gene expression of pathophysiologically relevant proteins such as TSP-1.
Differential effects of acute hypoxia and high altitude on cerebral blood flow velocity and dynamic cerebral autoregulation: alterations with hyperoxia
Authors: Ainslie Philip N. , Ogoh Shigehiko , Burgess Katie , Celi Leo , McGrattan Ken , Peebles Karen , Murrell Carissa , Subedi Prajan , Burgess Keith R.
Published: November 2007

We hypothesized that 1) acute severe hypoxia, but not hyperoxia, at sea level would impair dynamic cerebral autoregulation (CA); 2) impairment in CA at high altitude (HA) would be partly restored with hyperoxia; and 3) hyperoxia at HA and would have more influence on blood pressure (BP) and less influence on middle cerebral artery blood flow velocity (MCAv). In healthy volunteers, BP and MCAv were measured continuously during normoxia and in acute hypoxia (inspired O2 fraction = 0.12 and 0.10, respectively; n = 10) or hyperoxia (inspired O2 fraction, 1.0; n = 12). Dynamic CA was assessed using transfer-function gain, phase, and coherence between mean BP and MCAv. Arterial blood gases were also obtained. In matched volunteers, the same variables were measured during air breathing and hyperoxia at low altitude (LA; 1,400 m) and after 1–2 days after arrival at HA (∼5,400 m, n = 10). In acute hypoxia and hyperoxia, BP was unchanged whereas it was decreased during hyperoxia at HA (−11 ± 4%; P < 0.05 vs. LA). MCAv was unchanged during acute hypoxia and at HA; however, acute hyperoxia caused MCAv to fall to a greater extent than at HA (−12 ± 3 vs. −5 ± 4%, respectively; P < 0.05). Whereas CA was unchanged in hyperoxia, gain in the low-frequency range was reduced during acute hypoxia, indicating improvement in CA. In contrast, HA was associated with elevations in transfer-function gain in the very low- and low-frequency range, indicating CA impairment; hyperoxia lowered these elevations by ∼50% ( P < 0.05). Findings indicate that hyperoxia at HA can partially improve CA and lower BP, with little effect on MCAv.
Fine Detail of Neurovascular Coupling Revealed by Spatiotemporal Analysis of the Hemodynamic Response to Single Whisker Stimulation in Rat Barrel Cortex
Authors: Berwick J. , Johnston D. , Jones M. , Martindale J. , Martin C. , Kennerley A. J. , Redgrave P. , Mayhew J.E.W.
Published: November 2007

The spatial resolution of hemodynamic-based neuroimaging techniques, including functional magnetic resonance imaging, is limited by the degree to which neurons regulate their blood supply on a fine scale. Here we investigated the spatial detail of neurovascular events with a combination of high spatiotemporal resolution two-dimensional spectroscopic optical imaging, multichannel electrode recordings and cytochrome oxidase histology in the rodent whisker barrel field. After mechanical stimulation of a single whisker, we found two spatially distinct cortical hemodynamic responses: a transient response in the “upstream” branches of surface arteries and a later highly localized increase in blood volume centered on the activated cortical column. Although the spatial representation of this localized response exceeded that of a single “barrel,” the spread of hemodynamic activity accurately reflected the neural response in neighboring columns rather than being due to a passive “overspill.” These data confirm hemodynamics are capable of providing accurate “single-condition” maps of neural activity.
Multiple Modes of Amplification of Synaptic Inhibition to Motoneurons by Persistent Inward Currents
Authors: Bui Tuan V. , Grande Giovanbattista , Rose P. Ken
Published: November 2007

The ability of inhibitory synaptic inputs to dampen the excitability of motoneurons is augmented when persistent inward currents (PICs) are activated. This amplification could be due to an increase in the driving potential of inhibitory synapses or the deactivation of the channels underlying PICs. Our goal was to determine which mechanism leads to the amplification of inhibitory inputs by PICs. To reach this goal, we measured inhibitory postsynaptic currents (IPSCs) in decerebrate cats during somatic voltage-clamp steps. These IPSCs were generated by tonic activation of Renshaw cells. The IPSCs exhibited a rapid rise and a slower decay to a plateau level. Activation of PICs always led to an increase in the peak of the IPSC, but the amount of decay after the peak of the IPSC was inversely related to the size of the IPSC. These results were replicated in simulations based on compartmental models of motoneurons incorporating distributions of Renshaw cell synapses based on anatomical observations, and L-type calcium channels distributed as 100-μm-long hot spots centered 100 to 400 μm away from the soma. For smaller IPSCs, amplification by PICs was due to an increase in the driving force of the inhibitory synaptic current. For larger IPSCs, amplification was caused by deactivation of the channels underlying PICs leading to a lesser decay of the IPSCs. As a result of this change in the time course of the IPSC, deactivation of the channels underlying PICs leads to a greater amplification of the total inhibitory synaptic current.
Nineteenth Annual Pezcoller Symposium: Hypothesis-Driven Clinical Investigation in Cancer
Authors: Kaelin William G. , Sawyers Charles L. , Mihich Enrico
Published: November 2007

This symposium was held in Trento, Italy, from June 14 to 16, 2007, and was cochaired by William G. Kaelin, Enrico Mihich, and Charles L. Sawyers. A session was deveted to the proof of concept derived from successes in target-oriented therapeutics. Molecular targets must be identified in each patients because they are equally present in all patients with the same tumor type. A session was devoted to the identification of markers of drug effectiveness. Two sessions were focused on opportunities for developing new specific molecular target-oriented therapies. [Cancer Res 2007;67(23):11102–5]
Populations of Tightly Coupled Neurons: The RGC/LGN System
Authors: Sirovich Lawrence
Published: November 2007

A mathematical model, of general character for the dynamic description of coupled neural oscillators is presented. The population approach that is employed applies equally to coupled cells as to populations of such coupled cells. The formulation includes stochasticity and preserves details of precisely firing neurons. Based on the generally accepted view of cortical wiring, this formulation is applied to the retinal ganglion cell (RGC)/lateral geniculate nucleus (LGN) relay cell system, of the early mammalian visual system. The smallness of quantal voltage jumps at the retinal level permits a Fokker-Planck approximation for the RGC contribution; however, the LGN description requires the use of finite jumps, which for fast synaptic dynamics appears as finite jumps in the membrane potential.

Analyses of equilibrium spiking behavior for both the deterministic and stochastic cases are presented. Green's function methods form the basis for the asymptotic and exact results that are presented. This determines the spiking ratio (i.e., the number of RGC arrivals per LGN spike), which is the reciprocal of the transfer ratio, under wide circumstances. Criteria for spiking regimes, in terms of the relatively few parameters of the model, are presented.

Under reasonable hypotheses, it is shown that the transfer ratio is ≤1/2, in the absence of input from other areas. Thus, the model suggests that the LGN/RGC system may be a relatively unsophisticated spike editor. In the absence of other input, the system is designed to fire an LGN spike only when two or more RGC spikes appear in a relatively short time. Transfer ratios that briefly exceed 1/2 (but are less than 1) have been recorded in the laboratory. Inclusion of brain stem input has been shown to provide a signal that elevates the transfer ratio (Ozaki & Kaplan, 2006). A model that includes this contribution is also presented.
Gamma Oscillations and Stimulus Selection
Authors: Börgers Christoph , Kopell Nancy J.
Published: November 2007

More coherent excitatory stimuli are known to have a competitive advantage over less coherent ones. We show here that this advantage is amplified greatly when the target includes inhibitory interneurons acting via GABAA-receptor-mediated synapses and the coherent input oscillates at gamma frequency. We hypothesize that therein lies, at least in part, the functional significance of the experimentally observed link between attentional biasing of stimulus competition and gamma frequency rhythmicity.