bluuebunny/crossref_metadata_2025 huggingface dataset:
10 Good Practices for News Organizations Using Twitter
Authors: Herrera Susana , Requejo José Luis
Published: September 2012

Today, participating in social media has become an obligation for all news organizations. Among these, Facebook and Twitter play central roles. Nevertheless, different reports show that, at least in Spain, several media outlets use these 2.0 tools with a 1.0 mentality. Thus, despite
the wide potential that Twitter provides for mainstream media, most broadcasters underuse the technology by only posting news headlines or using it for self-promotion while failing to adequately engage with their audiences or link to external content. In order to shed new light on the proper
use of Twitter, this paper presents a collection of some inspiring and valuable practices. To illustrate and enrich the analysis, screenshots are included.
To Buy or Not to Buy: Consumers’ Demand Response Patterns for Healthy versus Unhealthy Food
Authors: Talukdar Debabrata , Lindsey Charles
Published: September 2012

The authors integrate research on impulsivity from the psychology area with standard economic theories of consumer demand to make novel predictions about the effects of market price changes on consumers’ food consumption behavior. The results from multiple studies confirm that consumers exhibit undesirable asymmetric patterns of demand sensitivity to price changes for healthy and unhealthy food. For healthy food, demand sensitivity is greater for a price increase than for a price decrease. For unhealthy food, the opposite holds true. The research further shows that the undesirable patterns are attenuated or magnified for key policy-relevant factors that have been shown to decrease or increase impulsive purchase behavior, respectively. As the rising obesity trend brings American consumers’ food consumption behavior under increased scrutiny, the focal findings hold significant implications for both public policy makers and food marketers.
A tutorial on optics for ultrafast laser materials processing: basic microprocessing system to beam shaping and advanced focusing methods
Authors: Sugioka Koji , Cheng Ya
Published: September 2012

Ultrafast lasers have excellent characteristics for materials processing in terms of precision and quality. This tutorial paper introduces the basic concepts of ultrafast laser materials processing and the structure and key components of typical ultrafast laser microprocessing systems. The emphasis is on the pulse-shaping devices and systems for controlling and manipulating the spatial, temporal, and polarization properties of focused femtosecond laser pulses.
On the vertices of indecomposable summands of certain Lefschetz modules
Authors: Maginnis John , Onofrei Silvia
Published: September 2012

We study the reduced Lefschetz module of the complex of
Sodium Intake and Blood Pressure Among US Children and Adolescents
Authors: Yang Quanhe , Zhang Zefeng , Kuklina Elena V. , Fang Jing , Ayala Carma , Hong Yuling , Loustalot Fleetwood , Dai Shifan , Gunn Janelle P. , Tian Niu , Cogswell Mary E. , Merritt Robert
Published: September 2012

OBJECTIVE:

To assess the association between usual dietary sodium intake and blood pressure among US children and adolescents, overall and by weight status.

METHODS:

Children and adolescents aged 8 to 18 years (n = 6235) who participated in NHANES 2003–2008 comprised the sample. Subjects’ usual sodium intake was estimated by using multiple 24-hour dietary recalls. Linear or logistic regression was used to examine association between sodium intake and blood pressure or risk for pre-high blood pressure and high blood pressure (pre-HBP/HPB).

RESULTS:

Study subjects consumed an average of 3387 mg/day of sodium, and 37% were overweight/obese. Each 1000 mg per day sodium intake was associated with an increased SD score of 0.097 (95% confidence interval [CI] 0.006–0.188, ∼1.0 mm Hg) in systolic blood pressure (SBP) among all subjects and 0.141 (95% CI: –0.010 to 0.298, ∼1.5 mm Hg) increase among overweight/obese subjects. Mean adjusted SBP increased progressively with sodium intake quartile, from 106.2 mm Hg (95% CI: 105.1–107.3) to 108.8 mm Hg (95% CI: 107.5–110.1) overall (P = .010) and from 109.0 mm Hg (95% CI: 107.2–110.8) to 112.8 mm Hg (95% CI: 110.7–114.9; P = .037) among those overweight/obese. Adjusted odds ratios comparing risk for pre-HBP/HPB among subjects in the highest versus lowest sodium intake quartile were 2.0 (95% CI: 0.95–4.1, P = .062) overall and 3.5 (95% CI: 1.3–9.2, P = .013) among those overweight/obese. Sodium intake and weight status appeared to have synergistic effects on risk for pre-HBP/HPB (relative excess risk for interaction = 0.29 (95% CI: 0.01–0.90, P < .05).

CONCLUSIONS:

Sodium intake is positively associated with SBP and risk for pre-HBP/HPB among US children and adolescents, and this association may be stronger among those who are overweight/obese.
Hypertension Screening During Ambulatory Pediatric Visits in the United States, 2000–2009
Authors: Shapiro Daniel J. , Hersh Adam L. , Cabana Michael D. , Sutherland Scott M. , Patel Anisha I.
Published: September 2012

BACKGROUND AND OBJECTIVE:

Hypertension occurs in 2% to 5% of children in the United States, and its prevalence has increased during the obesity epidemic. There is no consensus among professional organizations about how frequently blood pressure should be measured in children >3 years old. The purpose of this study was to estimate the frequency of hypertension screening during ambulatory pediatric visits in the United States and to determine patient- and provider-level factors associated with screening during visits specifically for preventive care.

METHODS:

We analyzed data from a nationally representative sample of ambulatory visits by using the National Ambulatory Medical Care Survey and the National Hospital Ambulatory Medical Care Survey from 2000 through 2009. In the subset of visits involving patients aged 3 to 18 years, we estimated the frequency of screening during all visits, preventive visits, and preventive visits in which overweight/obesity was diagnosed. We used multivariable logistic regression to identify patient- and provider-level factors associated with screening.

RESULTS:

Hypertension screening occurred during 35% of ambulatory pediatric visits, 67% of preventive visits, and 84% of preventive visits in which overweight/obesity was diagnosed. Between 2000 and 2009, the frequency of screening increased in all visits and in preventive visits. Factors independently associated with screening included older age and overweight/obesity diagnosis.

CONCLUSIONS:

Providers do not measure blood pressure in two-thirds of pediatric visits and one-third of pediatric preventive visits. Providers may understand the importance of screening among overweight/obese children; however, efforts to encourage routine screening, particularly in young children, may be needed.
The allometry of fear: interspecific relationships between body size and response to predation risk
Authors: Preisser Evan L. , Orrock John L.
Published: September 2012

Body size is associated with fundamental biological processes such as metabolism, movement, and the rate of reproduction and evolution. Although allometric principles should also influence the range of potential behavioral responses for a given organism, evidence for such large‐scale and cross‐taxon relationships is lacking. If they exist, scaling‐related changes in behavior should be prominent in predator‐prey interactions: body size affects the likelihood of attack and the costs of predator avoidance. We take a interspecific perspective on a traditionally intraspecific topic by using a 142‐species data set containing organisms ranging over seven degrees of magnitude in body size to analyze the relationship between mean response to predation risk and both prey size and the predator : prey size ratio. We found a weak but significant relationship between two metrics of prey size (mean species‐level prey mass and mean species‐level predator : prey size ratio) and two of the five prey response variables: risk‐induced changes in prey habitat use and prey fecundity were significantly correlated with prey body size and the predator : prey ratio. Risk‐induced reductions in prey activity were positively correlated with prey mass. In contrast, there was no correlation between prey mass or the predator : prey size ratio and risk‐induced changes in either prey growth and survival. We also document considerable variation in response to predation risk among taxa, highlighting that many additional factors contribute to the effects of predation risk on prey behavior, growth, fecundity, and survival. The weak but significant large‐scale relationships we documented in our work suggest that allometric relationships may play a subtle role in structuring some of a prey organism's response to predation risk.
Estimating the Population Size of Men Who Have Sex with Men in the United States to Obtain HIV and Syphilis Rates§
Authors: Purcell David W , Johnson Christopher H , Lansky Amy , Prejean Joseph , Stein Renee , Denning Paul , Gau1 Zaneta , Weinstock Hillard , Su John , Crepaz Nicole
Published: September 2012

Background:

CDC has not previously calculated disease rates for men who have sex with men (MSM) because there is no single comprehensive source of data on population size. To inform prevention planning, CDC developed a national population size estimate for MSM to calculate disease metrics for HIV and syphilis.

Methods:

We conducted a systematic literature search and identified seven surveys that provided data on same-sex behavior in nationally representative samples. Data were pooled by three recall periods and combined using meta-analytic procedures. We applied the proportion of men reporting same-sex behavior in the past 5 years to U.S. census data to produce a population size estimate. We then calculated three disease metrics using CDC HIV and STD surveillance data and rate ratios comparing MSM to other men and to women.

Results:

Estimates of the proportion of men who engaged in same-sex behavior differed by recall period: past year = 2.9% (95%CI, 2.6–3.2); past five years = 3.9% (3.5–4.4); ever = 6.9% (5.1–8.6). Rates on all 3 disease metrics were much higher among MSM than among either other men or women (38 to 109 times as high).

Conclusions:

Estimating the population size for MSM allowed us to calculate rates for disease metrics and to develop rate ratios showing dramatically higher rates among MSM than among other men or women. These data greatly improve our understanding of the disproportionate impact of these diseases among MSM in the U.S. and help with prevention planning.
Piloting a System for Behavioral Surveillance Among Heterosexuals at Increased Risk of HIV in the United States
Authors: DiNenno Elizabeth A , Oster Alexandra M , Sionean Catlainn , Denning Paul , Lansky Amy
Published: September 2012

Objectives:

During the past decade, the number and proportion of reported HIV cases in the United States acquired through heterosexual contact has increased markedly. CDC employs the National HIV Behavioral Surveillance System (NHBS) to monitor risk behaviors and HIV prevalence in high-risk populations. To identify a target population for conducting NHBS among heterosexuals at increased risk for HIV (NHBS-HET), CDC designed, implemented and evaluated a pilot study.

Methods:

The pilot study was conducted in 25 US metropolitan statistical areas in 2006-7. We recruited men and women who reported sex with at least one opposite-sex partner during the past year for a behavioral survey and HIV test. We investigated the relationship between newly diagnosed HIV infection and individual risk behaviors, sexual network characteristics, and social-structural characteristics to arrive at a definition of a heterosexual at increased risk of HIV.

Results:

Of 14,750 participants in the analysis, 207 (1.4%) had newly diagnosed HIV infection. Using low socioeconomic status (SES) as a criterion for defining a heterosexual at increased risk for HIV resulted in optimal rates of HIV prevalence, specificity, sensitivity and practicality.

Conclusions:

Results from the NHBS pilot study underscore the key role of social factors as determinants of HIV infection risk among U.S. heterosexuals, and low SES was incorporated into the definition of a heterosexual at increased risk for HIV in NHBS-HET cycles. Future cycles of NHBS-HET will help tailor prevention programs for those populations most at risk of HIV in the US.
Transcriptional Regulation in the G1-S Cell Cycle Stage in Fungi: Insights through Computational Analysis
Authors: Martyanov Viktor , H. Gross Robert
Published: September 2012

The transcription factor complexes Mlu1-box binding factor (MBF) and Swi4/6 cell cycle box binding factor (SBF) regulate the cell cycle in Saccharomyces cerevisiae. They activate hundreds of genes and are responsible for nor-mal cell cycle progression from G1 to S phase. We investigated the conservation of MBF and SBF binding sites during fungal evolution. Orthologs of S. cerevisiae targets of these transcription factors were identified in 37 fungal species and their upstream regions were analyzed for putative transcription factor binding sites. Both groups displayed enrichment in specific putative regulatory DNA sequences in their upstream regions and showed different preferred upstream motif loca-tions, variable patterns of evolutionary conservation of the motifs and enrichment in unique biological functions for the regulated genes. The results indicate that despite high sequence similarity of upstream DNA motifs putatively associated with G1-S transcriptional regulation by MBF and SBF transcription factors, there are important upstream sequence feature differences that may help differentiate the two seemingly similar regulatory modes. The incorporation of upstream motif sequence comparison, positional distribution and evolutionary variability of the motif can complement functional infor-mation about roles of the respective gene products and help elucidate transcriptional regulatory pathways and functions.
A Multiple-Model Approach for Synchronous Generator Nonlinear System Identification
Authors: Ahmadi Seyed , Karrari Mehdi
Published: September 2012

A Multiple-Model Approach for Synchronous Generator Nonlinear System Identification

In this paper, a multiple model approach is proposed for the identification of synchronous generators. In the literature, the same structure often is used for all local models. Therefore, to obtain a precise model for the operating condition of the synchronous generator with severely nonlinear behavior, many local models are required. The proposed method determines the complexity of local models based on complexity of behavior of the synchronous generator at different operating conditions. There are two choices for increasing model precision at each iteration of the proposed method: (i) increasing the number of local models in one region, or (ii) increasing local model complexity in the same region. The proposed method has been tested on experimental data collected on a 3 kVA micro-machine. In the study, the field voltage is considered as the input and the active output power and the terminal voltage are considered as the outputs of the synchronous generator. The proposed method provides a more precise model with fewer parameters compared to some well known methods such as LOLIMOT and global polynomial models.
Instructional Advice and Information Providing and Receiving Behavior in Elementary Schools
Authors: Spillane James P. , Kim Chong Min , Frank Kenneth A.
Published: September 2012

Few studies identify those factors that might account for the development of social capital. Understanding those factors associated with the existence of a social tie among actors in schools is important because absent social ties, individuals do not have access to social resources. We investigate social tie formation in schools focusing on advice and information providing and receiving in the two core elementary school subjects. Using a multilevel p2 model, we examine the role of both formal organizational structure and individual characteristics in shaping advice and information providing and receiving about instruction. Our findings suggest that while the individual characteristics of race and gender are significantly associated with the formation of a tie, aspects of the formal school organization—grade-level assignment, having a formally designated leadership position, and teaching a single grade—are also significant and have larger estimated effects than individual characteristics. Formal organizational factors trump individual characteristics in the formation of a social tie, a necessary if insufficient condition for social capital development.
Acupuncture Points of the Horse’s Distal Thoracic Limb: A Neuroanatomic Approach to the Transposition of Traditional Points
Authors: Lancaster Lisa S. , Bowker Robert M.
Published: September 2012

Veterinary acupuncture charts were developed based on the concept of transpositional points whereby human acupuncture maps were adapted to animal anatomy. Transpositional acupuncture points have traditionally been placed in specific locations around the horse’s coronet and distal limb believed to be the closest approximation to the human distal limb points. Because the horse has a single digit and lacks several structures analogous to the human hand and foot, precisely transposing all of the human digital points is not anatomically possible. To date there is no published research on the effect of acupuncture treatment of the equine distal limb points. This paper presents a modified approach to equine distal limb point selection based on what is known from research on other species about the neuroanatomic method of acupuncture. A rationale is presented for modification of traditional equine ting points as well as additional points around the hoof and distal limb that do not appear in the standard textbooks of equine acupuncture. The anatomy and physiology of the equine foot likely to be affected by acupuncture are briefly reviewed. Modified neuroanatomic points are proposed that may be more accurate as transpositional points. As an example of clinical application, a neuroanatomic approach to acupuncture treatment of equine laminitis is presented.
Performance Analysis and Optimization of a Solar Powered Stirling Engine with Heat Transfer Considerations
Authors: Chen Chieh-Li , Ho Chia-En , Yau Her-Terng
Published: September 2012

This paper investigates the optimization of the performance of a solar powered Stirling engine based on finite-time thermodynamics. Heat transference in the heat exchangers between a concentrating solar collector and the Stirling engine is studied. The irreversibility of a Stirling engine is considered with the heat transfer following Newton's law. The power generated by a Stirling engine is used as an objective function for maximum power output design with the concentrating solar collector temperature and the engine thermal efficiency as the optimization parameters. The maximum output power of engine and its corresponding system parameters are determined using a genetic algorithm.
Natural Melanogenesis Inhibitors Acting Through the Down-Regulation of Tyrosinase Activity
Authors: Chang Te-Sheng
Published: September 2012

Melanogenesis is a biosynthetic pathway for the formation of the pigment melanin in human skin. A key enzyme, tyrosinase, catalyzes the first and only rate-limiting steps in melanogenesis, and the down-regulation of enzyme activity is the most reported method for the inhibition of melanogenesis. Because of the cosmetically important issue of hyperpigmentation, there is a big demand for melanogenesis inhibitors. This encourages researchers to seek potent melanogenesis inhibitors for cosmetic uses. This article reviews melanogenesis inhibitors that have been recently discovered from natural sources. The reaction mechanisms of the inhibitors on tyrosinase activity are also discussed.
Intranasal Rapamycin Rescues Mice from Staphylococcal Enterotoxin B-Induced Shock
Authors: Krakauer Teresa , Buckley Marilyn
Published: September 2012

Staphylococcal enterotoxin B (SEB) and related exotoxins produced by Staphylococcus aureus are potent activators of the immune system and cause toxic shock in humans. Currently there is no effective treatment except for the use of intravenous immunoglobulins administered shortly after SEB exposure. Intranasal SEB induces long-lasting lung injury which requires prolonged drug treatment. We investigated the effects of rapamycin, an immunosuppressive drug used to prevent graft rejection, by intranasal administration in a lethal mouse model of SEB-induced shock. The results show that intranasal rapamycin alone delivered as late as 17 h after SEB protected 100% of mice from lethal shock. Additionally, rapamycin diminished the weight loss and temperature fluctuations elicited by SEB. Intranasal rapamycin attenuated lung MCP-1, IL-2, IL-6, and IFNγ by 70%, 30%, 64%, and 68% respectively. Furthermore, short courses (three doses) of rapamycin were sufficient to block SEB-induced shock. Intranasal rapamycin represents a novel use of an immunosuppressant targeting directly to site of toxin exposure, reducing dosages needed and allowing a wider therapeutic window.
Synthesis of conformationally restricted glutamate and glutamine derivatives from carbonylation of orthopalladated phenylglycine derivatives
Authors: Urriolabeitia Esteban P , Laga Eduardo , Cativiela Carlos
Published: September 2012

A new method for the regioselective synthesis of 2-alkoxycarbonyl- and 2-(aminocarbonyl)phenylglycinate methyl esters has been developed. The reaction of the orthopalladated complex [Pd(μ-Cl)(C6H4(CH(CO2Me)NMe2)-2)]2 (1) with nucleophiles HNu under a CO atmosphere results in the selective incorporation of the C(O)Nu moiety to the phenyl ring and formation of the carbonyl species ortho-C6H4(C(O)Nu)(CH(CO2Me)NMe2) (2a–j) (Nu = OR, NHR, NR2). Compounds 2a–j are conformationally restricted analogues of glutamic acid and glutamine and are interesting due to their biological and pharmacological properties. The reaction of [Pd(μ-Cl)(C6H4(CH(CO2Me)NHTf)-2)]2 (3) with nucleophiles in a CO atmosphere results, however, in the formation of the cyclic isoindolinone or the open 2-carboxyphenylglycine methyl esters, with the reaction outcome being driven by the choice of the solvent.
Risk assessment of patulin intake from apple containing products by young children
Authors: Brandon E.F.A. , Baars A.J. , Biesebeek J.D. Te , Oomen A.G. , Bakker M.I. , De Heer C.
Published: September 2012

Patulin is a mycotoxin for which a provisional maximum tolerable daily intake (PMTDI) of 400 ng/kg bodyweight/ day has been set based on its most sensitive toxic effect, growth retardation. Apple containing products are the major source for patulin exposure, with major intake differences according to age and living region. Young children are most at risk of patulin intoxication, because they consume much higher amounts of apple products than adults. In this study, the patulin intake was calculated for Dutch children of 8 to 48 months and the risks of patulin intoxication were assessed. In addition, the bioaccessibility of patulin from apple containing products was investigated for a more refined risk assessment of patulin. The bioaccessibility of patulin was high, varying between 55 and 100%, and, consequently, no refinement of the risk assessment was possible. Based on the probabilistic intake calculations, children are exposed to levels below the PMTDI. Children aged 13-20 months with a high organic apple product intake have the highest patulin exposure, 342 ng/kg bodyweight/day at the upper confidence interval of the P95. No harmful effects are expected with the current patulin intake in young children. No concentration data are available for baby food (organic and conventional) and, therefore, concentrations were set at half the legal limit for intake calculations. Concentration data are needed for a more refined intake calculation for children younger than one year to estimate the actual risk in these children, because baby food comprises 23% of their diet.
Mycotoxin levels in maize produced in northern Italy in 2008 as influenced by growing location and FAO class of hybrid
Authors: Pietri A. , Battilani P. , Gualla A. , Bertuzzi T.
Published: September 2012

The occurrence of principal mycotoxins in maize produced in northern Italy in 2008 was surveyed. Some easily available information related to each sample, such as hybrid maturity class, maize growth location and mean daily meteorological data were considered in order to explain the observed wide variability in mycotoxin contamination. In addition, a previously developed simple predictive model for aflatoxin B1 contamination in maize was tested using the 2008 data. 197 samples were collected at harvest and meteorological data (mean daily temperature, daily rainfall) were collected from 40 weather stations located near the sampling regions during the period 1 June to 30 September 2008. The results indicated that aflatoxin contamination is of concern in a restricted geographic region (south-east Po Valley). In this region, about 75.0% of the maize samples showed aflatoxin levels higher than 0.5 μg/kg. After a slight modification, the predictive model could indicate a possible high contamination risk. Moreover, the study confirmed that maize harvested in northern Italy was contaminated with fumonisins; throughout the northern Italian plain contamination occurred at significant levels. On the other hand, contamination with trichothecenes and zearalenone was generally low. It has been observed that FAO class 300-400 maize hybrids can be more susceptible to aflatoxin contamination and less to Fusarium mycotoxins than later maturing hybrids.
Bipolar radiofrequency-induced thermotherapy of great saphenous vein: Our initial experience
Authors: Kasi Venkatesh , Kalyanpur Tejas M , Narsinghpura Kaustubh , Chakravarthy Deyananda , Mehta Pankaj , Cherian Mathew
Published: September 2012

The incidence of varicose veins in lower limbs is increasing in the Indian subcontinent. With the advent of radiofrequency ablation (RFA), an effective minimally invasive technique is now available to treat varicose veins. RFA can be performed with either unipolar or bipolar probes. We present a simple technique for bipolar radiofrequency-induced thermotherapy of the great saphenous vein. This can be a safe and effective alternative to surgical procedures.
Technical Note: Thoracic duct embolization for treatment of chylothorax: A novel guidance technique for puncture using combined MRI and fluoroscopy
Authors: Praveen Alampath , Sreekumar Karumathil Pullara , Nazar Puthukudiyil Kader , Moorthy Srikanth
Published: September 2012

Thoracic duct embolization (TDE) is an established radiological interventional procedure for thoracic duct injuries. Traditionally, it is done under fluoroscopic guidance after opacifying the thoracic duct with bipedal lymphangiography. We describe our experience in usinga heavily T2W sequence for guiding thoracic duct puncture and direct injection of glue through the puncture needle without cannulating the duct.
Are sesquiterpenes a good source of secondary organic cloud condensation nuclei (CCN)? Revisiting β-caryophyllene CCN
Authors: Tang X. , Cocker D. R. , Asa-Awuku A.
Published: September 2012

Abstract. Secondary organic aerosol (SOA) was formed in an environmental reaction chamber from the ozonolysis of β-caryophyllene (β-C) at low concentrations (5 ppb or 20 ppb). Experimental parameters were varied to characterize the effects of hydroxyl radicals, light and the presence of lower molecular weight terpene precursor (isoprene) for β-C SOA formation and cloud condensation nuclei (CCN) characteristics. Changes in β-C SOA chemicophysical properties (e.g., density, volatility, oxidation state) were explored with online techniques to improve our predictive understanding of β-C CCN activity. In the absence of OH scavenger, light intensity had negligible impacts on SOA oxidation state and CCN activity. In contrast, when OH reaction was effectively suppressed (> 11 ppm scavenger), SOA showed a much lower CCN activity and slightly less oxygenated state consistent with previously reported values. Though there is significant oxidized material present (O / C > 0.25), no linear correlation existed between the mass ratio ion fragment 44 in the bulk organic mass (f44) and O / C for the β-C-O3 system. No direct correlations were observed with other aerosol bulk ion fragment fraction (fx) and κ as well. A mixture of β-C and lower molecular weight terpenes (isoprene) consumed more ozone and formed SOA with distinct characteristics dependent on isoprene amounts. The addition of isoprene also improved the CCN predictive capabilities with bulk aerosol chemical information. The β-C SOA CCN activity reported here is much higher than previous studies (κ < 0.1) that use higher precursor concentration in smaller environmental chambers; similar results were only achieved with significant use of OH scavenger. Results show that aerosol formed from a mixture of low and high molecular weight terpene ozonolysis can be hygroscopic and can contribute to the global biogenic SOA CCN budget.
The accommodation coefficient of water molecules on ice-cirrus cloud studies at the AIDA simulation chamber
Authors: Skrotzki J. , Connolly P. , Schnaiter M. , Saathoff H. , Möhler O. , Wagner R. , Niemand M. , Ebert V. , Leisner T.
Published: September 2012

Abstract. Cirrus clouds and their impact on the Earth's radiative budget are subjects of current research. The processes governing the growth of cirrus ice particles are central to the radiative properties of cirrus clouds. At temperatures relevant to cirrus clouds, the growth of ice crystals smaller than a few microns in size is strongly influenced by the accommodation coefficient of water molecules on ice, αice, making this parameter relevant for cirrus cloud modeling. However, the experimentally determined magnitude of αice for cirrus temperatures is afflicted with uncertainties of almost three orders of magnitude and values for αice derived from cirrus cloud data lack significance so far. This has motivated dedicated experiments at the cloud chamber AIDA (Aerosol Interactions and Dynamics in the Atmosphere) to determine αice in the cirrus-relevant temperature interval between 190 K and 235 K under realistic cirrus ice particle growth conditions. The experimental data sets have been evaluated independently with two model approaches: the first relying on the newly developed model SIGMA (Simple Ice Growth Model for determining Alpha), the second one on an established model, ACPIM (Aerosol-Cloud-Precipitation Interaction Model). Within both approaches, a careful uncertainty analysis of the obtained αice values has been carried out for each AIDA experiment. The results show no significant dependence of αice on temperature between 190 K and 235 K. In addition, we find no evidence for a dependence of αice on ice particle size or on water vapor supersaturation for ice particles smaller than 20 μm and supersaturations of up to 70%. The temperature averaged and combined result from both models is αice=0.6−0.4+0.4 which implies that αice may only exert a minor impact on cirrus clouds and their characteristics when compared to the assumption of αice=1. Impact on prior calculations of cirrus cloud properties, e.g. in climate models, with αice typically chosen in the range 0.2–1 is thus expected to be negligible. In any case, we provide a well constrained αice which future cirrus model studies can rely on.
Black carbon concentration and deposition estimations in Finland by the regional aerosol-climate model REMO-HAM
Authors: Hienola A. I. , Pietikäinen J.-P. , Jacob D. , Pozdun R. , Petäjä T. , Hyvärinen A.-P. , Kerminen V.-M. , Kulmala M. , Laaksonen A.
Published: September 2012

Abstract. The prediction skill of the regional aerosol-climate model REMO-HAM was assessed against the black carbon (BC) concentration measurements from five locations in Finland, with focus on Hyytiälä station for the year 2005. We examined to what extent the model is able to reproduce the measurements using several statistical tools: median comparison, overlap coefficient OVL (the common area under two probability distributions curves) and Z-score (a measure of standard deviation, shape and spread of the distributions). The results of the statistics showed that the model is biased low, suggesting either an excessive loss of black carbon in the model, or missing emissions. A further examination of the precipitation data from both measurements and model showed that there is no correlation between REMO's excessive precipitation and BC underestimation. This suggests that the excessive wet removal is not the main cause for the low black carbon concentration output. In addition, a comparison of wind directions in relation with high black carbon concentrations shows that REMO-HAM is able to predict the BC source directions relatively well. Cumulative black carbon deposition fluxes over Finland were estimated, including the deposition on snow.
Primary production and respiration of hypersaline microbial mats as a response for high and low CO2 availability
Authors: Bento L. , Enrich-Prast A. , Nielsen L. P.
Published: September 2012

Abstract. Here we report a time series of experiments performed in a microcosm to test the response of hypersaline microbial mats to diverse atmospheric CO2 conditions. Different from most part of the literature, our study used a sample chamber were carbon dioxide concentration was controlled. Our aim was to test the effect of different atmospheric CO2 conditions in benthic gross and net primary production, and respiration. This study showed for the first time to our knowledge absolute carbon limitation in a microbial mat. Oxygen concentration profile varied from a flattened shape to almost linear when atmospheric CO2 at the chamber reached 0 ppm, with NPP reaching 0 nmol cm−3 s−1 throughout most part of the profile. In this conditions sediment community respiration represented 100% of GPP. Extreme close coupling between primary production and respiration in microbial mats can be even self-sustainable in environments with temporally no atmospheric CO2 available. When submitted to even high CO2 concentrations (550 ppm), our sample showed a characteristic shape that indicate limitation composed by a more rectilinear oxygen profile, and NPP peaks mainly restricted to deeper layers. Therefore, we suggest that phototrophic communities in aquatic shallow ecosystems can be carbon limited. This limitation could be common especially in ecosystems submitted to variable water depth conditions, like coastal lagoons and intertidal sediments.
Impact of open-ocean convection on particle fluxes and sediment dynamics in the deep margin of the Gulf of Lions
Authors: Stabholz M. , Durrieu de Madron X. , Canals M. , Khripounoff A. , Taupier-Letage I. , Testor P. , Heussner S. , Kerhervé P. , Delsaut N. , Houpert L. , Lastras G. , Denneliou B.
Published: September 2012

Abstract. The deep outer margin of the Gulf of Lions and the adjacent basin, in the Western Mediterranean Sea, are regularly impacted by open-ocean convection, a major hydrodynamic event responsible for the ventilation of the deep water in the Western Mediterranean Basin. However, the impact of open-ocean convection on the flux and transport of particulate matter remains poorly understood. The variability of water mass properties (i.e. temperature and salinity), currents, and particle fluxes was monitored between September 2007 and April 2009 at five instrumented mooring lines deployed between 2050 and 2350 m-depth in the deepest continental margin and adjacent basin. Four of the lines followed a NW–SE transect, while the fifth one was located on a sediment wave field to the west. The results of the main, central line SC2350 ("LION"), located at 42° 02.5′ N and 4° 41′ E, at 2350 m-depth, show that open-ocean convection reached mid-water depth (≈ 1000 m-depth) during winter 2007–2008, and reached the seabed (≈ 2350 m-depth) during winter 2008–2009. Horizontal currents were unusually strong with speeds up to 39 cm s−1 during winter 2008–2009. The measurements at all 5 different locations indicate that mid-depth and near-bottom currents and particle fluxes gave relatively consistent values of similar magnitude across the study area except during winter 2008–2009, when near-bottom fluxes abruptly increased by one to two orders of magnitude. Particulate organic carbon contents, which generally vary between 3 and 5%, were abnormally low (≤ 1%) during winter 2008–2009 and approached those observed in surface sediments (≈ 0.6%). Turbidity profiles made in the region demonstrated the existence of a bottom nepheloid layer, several hundred meters thick, and related to the resuspension of bottom sediments. These observations support the view that open-ocean deep convection events in the Gulf of Lions can cause significant remobilization of sediments in the deep outer margin and the basin, with a subsequent alteration of the seabed likely impacting the functioning of the deep-sea ecosystem.
Changes in Köppen-Geiger climate types under a future climate for Australia: hydrological implications
Authors: Crosbie R. S. , Pollock D. W. , Mpelasoka F. S. , Barron O. V. , Charles S. P. , Donn M. J.
Published: September 2012

Abstract. The Köppen-Geiger climate classification has been used for over a century to delineate climate types across the globe. As it was developed to mimic the distribution of vegetation, it may provide a useful surrogate for making projections of the future distribution of vegetation, and hence resultant hydrological implications, under climate change scenarios. This paper developed projections of the Köppen-Geiger climate types covering the Australian continent for a 2030 and 2050 climate relative to a 1990 historical baseline climate using 17 Global Climate Models (GCMs) and five global warming scenarios. At the highest level of classification for a +2.4 °C future climate (the upper limit projected for 2050) relative to the historical baseline, it was projected that the area of the continent covered by – tropical climate types would increase from 8.8% to 9.1%; – arid climate types would increase from 76.5% to 81.7%; – temperate climate types would decrease from 14.7% to 9.2%; – cold climate types would decrease from 0.016% to 0.001%. Previous climate change impact studies on water resources in Australia have assumed a static vegetation distribution. If the change in projected climate types is used as a surrogate for a change in vegetation, then the major transition in climate from temperate to arid in parts of Australia under a drier future climate could cause indirect effects on water resources. A transition from annual cropping to perennial grassland would have a compounding effect on the projected reduction in recharge. In contrast, a transition from forest to grassland would have a mitigating effect on the projected reduction in runoff.
Catchment features controlling nitrogen dynamics in running waters above the tree line (Central Italian Alps)
Authors: Balestrini R. , Arese C. , Freppaz M. , Buffagni A.
Published: September 2012

Abstract. The study of nitrogen cycling in mountain areas has a long tradition, both to better understand and describe ecosystem functioning and to quantify the long-distance effect of human activities on remote environments. Nonetheless, especially in Europe, very few studies paid attention on catchment features controlling nitrogen dynamics above the tree line, with focus on running waters. In this study, relationships between some water chemistry descriptors, including nitrogen species and dissolved organic carbon (DOC), and catchment characteristics were evaluated for a range of sites located above the tree line (1950–2650 m a.s.l.) at Val Masino, in the Central Italian Alps. Land cover categories as well as elevation and slope were assessed at each site. Water samples were collected during the 2007 and 2008 snow free periods, with a nearly monthly frequency. Differently to dissolved organic nitrogen, nitrate concentration in running waters showed a spatial pattern strictly connected to the fractional extension of tundra and talus in each basin. Exponential models significantly described the relationships between maximum NO3-N and the fraction of vegetated soil cover (negative relation) and talus (positive relation), explaining almost 90% of nitrate variation in running waters. Similarly to nitrate, but with an opposite behavior, DOC was positively correlated with vegetated soil cover and negatively correlated with talus. Therefore, land cover can be considered one of the most important factors affecting water quality in high elevation catchments, with a contrasting effect on N and C pools.
Assimilation of SLA along track observations in the Mediterranean with an oceanographic model forced by atmospheric pressure
Authors: Dobricic S. , Dufau C. , Oddo P. , Pinardi N. , Pujol I. , Rio M.-H.
Published: September 2012

Abstract. A large number of SLA observations at a high along track horizontal resolution are an important ingredient of the data assimilation in the Mediterranean Forecasting System (MFS). Recently, new higher-frequency SLA products have become available, and the atmospheric pressure forcing has been implemented in the numerical model used in the MFS data assimilation system. In a set of numerical experiments, we show that, in order to obtain the most accurate analyses, the ocean model should include the atmospheric pressure forcing and the observations should contain the atmospheric pressure signal. When the model is not forced by the atmospheric pressure, the high-frequency filtering of SLA observations, however, improves the quality of the SLA analyses. It is further shown by comparing the power density spectra of the model fields and observations that the model is able to extract the correct information from noisy observations even without their filtering during the pre-processing.
Obstacles and benefits of the implementation of a reduced-rank smoother with a high resolution model of the tropical Atlantic Ocean
Authors: Freychet N. , Cosme E. , Brasseur P. , Brankart J.-M. , Kpemlie E.
Published: September 2012

Abstract. Most of oceanographic operational centers use three-dimensional data assimilation schemes to produce reanalyses. We investigate here the benefits of a smoother, i.e. a four-dimensional formulation of statistical assimilation. A square-root sequential smoother is implemented with a tropical Atlantic Ocean circulation model. A simple twin experiment is performed to investigate its benefits, compared to its corresponding filter. Despite model's non-linearities and the various approximations used for its implementation, the smoother leads to a better estimation of the ocean state, both on statistical (i.e. mean error level) and dynamical points of view, as expected from linear theory. Smoothed states are more in phase with the dynamics of the reference state, an aspect that is nicely illustrated with the chaotic dynamics of the North Brazil Current rings. We also show that the smoother efficiency is strongly related to the filter configuration. One of the main obstacles to implement the smoother is then to accurately estimate the error covariances of the filter. Considering this, benefits of the smoother are also investigated with a configuration close to situations that can be managed by operational center systems, where covariances matrices are fixed (optimal interpolation). We define here a simplified smoother scheme, called half-fixed basis smoother, that could be implemented with current reanalysis schemes. Its main assumption is to neglect the propagation of the error covariances matrix, what leads to strongly reduce the cost of assimilation. Results illustrate the ability of this smoother to provide a solution more consistent with the dynamics, compared to the filter. The smoother is also able to produce analyses independently of the observation frequency, so the smoothed solution appears more continuous in time, especially in case of a low frenquency observation network.
Endothelial Nitric Oxide Synthase Glu298Asp Polymorphism as a Risk Factor for Prostate Cancer
Authors: Ziaei Seyed Amir Mohsen , Samzadeh Mohammad , Jamaldini Seyed Hamid , Afshari Mahdi , Haghdoost Ali Akbar , Hasanzad Mandana
Published: September 2012

Background

The endothelial form of nitric oxide synthases (eNOS) seems to have an important role in vascular development, maintenance of the vascular tone and tumor growth in human prostate cancer (PC). The purpose of this study was to investigate the association between grade and stage of disease, age of diagnosis, vascular or perineural invasion, pre-diagnostic plasma prostate-specific antigen (PSA) levels, prostate cancer risk and Glu298Asp polymorphism of the eNOS gene.

Methods

Ninety-five prostate cancer patients and 111 benign prostate hyperplasia subjects were included. The Glu298Asp polymorphism of the eNOS gene was determined by polymerase chain reaction and restriction fragment length polymorphism

Results

The odds ratio (OR) between the GT and GG polymorphism was 0.76, indicating that the presence of the GT polymorphism decreased the risk of prostate cancer of more than 20% compared to the GG polymorphism. This difference, however, was not statistically significant. The GT polymorphism had an inverse association with cancer grade compared to the reference group (OR=0.47, p value=0.2).

Conclusions

These results suggest that prostate cancer development is not associated with the Glu298Asp polymorphism of the endothelial nitric oxide synthase gene in our population. Further studies in larger samples are needed to confirm our results and characterize the molecular mechanisms by which eNOS is involved in the susceptibility to prostate cancer.
Electronically Controllable Explicit Current Output Sinusoidal Oscillator Employing Single VDTA
Authors: Prasad Dinesh , Bhaskar D. R.
Published: September 2012

A new current-mode sinusoidal oscillator employing a single voltage differencing transconductance amplifier (VDTA), two grounded capacitors, and one grounded resistor has been proposed. The proposed sinusoidal oscillator offers the following advantageous features: (i) use of grounded capacitors which are attractive from the view point of IC implementation as well as eliminating/accommodating parasitic capacitances, (ii) independent control of frequency of oscillation and condition of oscillation, (iii) ready availability of explicit current-mode output, (iv) low active and passive sensitivities, and (v) a very good frequency stability. The workability of the proposed configuration has been established by PSPICE simulations.
Finite Element Modeling of a Piezoelectric Composite Beam and Comparative Performance Study of Piezoelectric Materials for Voltage Generation
Authors: Nechibvute Action , Chawanda Albert , Luhanga Pearson
Published: September 2012

A comparative study of the traditional PZT ceramics and new single crystals is critical in selecting the best material and optimization of transducer design for applications such as conversion of ambient vibrations into useful electrical energy. However, due to material and fabrication costs and the need for rapid prototyping while optimizing transducer design, primary comparisons can be based on simulation. In this paper, the COMSOL Multiphysics finite element package was used to study the direct piezoelectric effect when an external load is applied at the free end of a piezoelectric composite beam. The primary output parameters such as electric potential and electric field were studied as a function of the input strain and stress. The modeling is presented for the relatively new single crystal lead magnesium niobate-lead titanate (PMN32) and three different lead zirconate titanate ceramics (PZT-5A, PZT-5H, and PZT-4). Material performance was assessed by using a common geometry and identical excitation conditions for the different piezoelectric materials. For each material, there are three analyses performed, namely, static, eigenfrequency, and transient/time-dependent analysis. Comparative results clearly suggest that the new crystal material PMN32 is capable of outperforming presently useing piezoelectric ceramics for voltage generation.