bluuebunny/crossref_metadata_2025 huggingface dataset:
Chlortetracycline fluorescence patterns andin vitrofertilisation of frozen-thawed boar spermatozoa incubated under various bicarbonate concentrations
Authors: Abeydeera Lalantha R. , Funahashi Hiroaki , Kim Nam-Hyung , Day Billy N.
Published: September 2008

Porcine oocyte-cumulus complexes were cultured in bovine serum albumin(BSA)-free North Carolina State University (NCSU)23 medium containing porcine follicular fluid (10%), cysteine (0.1 mg/ml)and hormonal supplements (eCG and hCG: 10IU/ml each) for 22h. They were then cultured in the same medium but without hormonal supplements for an additional 22h. After culture, cumulus cells were removed and oocytes were co-incubated with frozen-thawed ejaculated boar spermatozoa in tissue culture medium (TCM)199 containing caffeine (5mM), fetal calf serum (FCS; 10%) and varying concentrations (26–56 mM)of NaHCO3for 9h(experiment 1). In experiment 2, chlortetracycline (CTC) was used to assess the functional state of spermatozoa incubated under different NaHCO3concentrations. Experiment 3 examined the effect of FCS (1% and 10%)and NaHCO3(26 and 46 mM) on fertilisation parameters. Compared with 26 mM, penetration rate was significantly higher (p<0.05)at 36–56mM NaHCO3. Polyspermy showed a similar pattern although no difference was observed between 26 and 36 mM. At 46mM NaHCO3, the mean number of spermatozoa (MNS) penetrated per oocyte increased significantly (p< 0.05). A significantly higher proportion of spermatozoa were capacitated and acrosome reacted at 46 and 56mM NaHCO3, respectively. The fertilisation medium containing 46mM NaHCO3and 1% FCS showed a higher penetration rate (84%)with a relatively low incidence of polyspermy (39%). The results indicate that NaHCO3stimulates capacitation and/or the acrosome reaction of boar spermatozoa in a dose-dependent manner and thus affects fertilisation parameters.
Caffeine overrides the S-phase cell cycle block in sea urchin embryos
Authors: Patel Rajnikant , Wright Elizabeth M. , Whitaker Michael
Published: September 2008

During the early mitotic cell cycles of the sea urchin embryo, the cell oscillates between S-phase and M-phase. In the presence of aphidicolin, a DNA synthesis inhibitor, a checkpoint control blocks the activation of the p34cdc2protein kinase, by keeping it in the inactive, tyrosine phosphorylated form, and the embryos do not enter mitosis. Caffeine has been shown to bypass the G2/M-phase checkpoint in mammalian cells and in cyclingXenopusextracts and to induce mitosis despite the presence of damaged or unreplicated DNA. In this study we show that caffeine also induces mitosis and cell division in sea urchin embryos, in the presence of unreplicated DNA, by stimulating the tyrosine dephosphorylation of p34cdc2and switching on its protein kinase activity. We also show that the caffeine-induced activation of the p34cdc2protein kinase is not mediated by either of the two second messengers, calcium and cAMP, or by inhibition of the p34cdc2tyrosine kinase. Thus, none of the mechanisms proposed for caffeine's action can explain how it overrides the S-phase checkpoint in the early cell cycles of the sea urchin embryo.
Primordial germ cells and oocytes ofBranchiostoma virginiae(Cephalochordata, Acrania) are flagellated epithelial cells: relationship between epithelial and primary egg polarity
Authors: Frick Jennifer E. , Ruppert Edward E.
Published: September 2008

Primordial germ cells (PGCs) are described from the gonad ofc. 2 cm juvenileBranchiostoma virginiae; early oocytes (c. 10 μm) and enlarging, previtellogenic oocytes (c. 35 μm) are described from the ovary ofc. 5 cm adults. The germinal epithelium of the juvenile gonad and adult ovary is composed of both germinal and somatic cells. In the juvenile, somatic cells retain contact with the basal lamina of the germinal epithelium though their perikarya may be displaced towards the lumen; the germinal epithelium is, therefore, a simple but pseudostratified epithelium. In the adult ovary, somatic cells may lose contact with the basal lamina and the epithelium appears to become stratified. PGCs and oocytes are identified as germ cells by the presence of nuage. PGCs and oocytes are polarised epithelial cells. They rest on a basal lamina, extend apically towards a lumen, form adhering junctions with neighbouring cells, and exhibit apical-basal polarity. PGCs and early oocytes have an apical flagellum with an associated basal body, accessory centriole, and one or more striated rootlet fibres. The flagellum is surrounded by a collar of microvilli. Once oocytes begin to enlarge and bulge basally into the connective tissue layer, the flagellum is lost, but the basal bodies and ciliary rootlets are present at the apex of 35 μm oocytes. Similarities of the oogenic pattern in cephalochordates and echinoderms indicate that the establishment of egg polarity in deuterostomes is influenced by the polarity of the germinal epithelium.
Transcription and DNA replication of sperm nuclei introduced into blastomeres of 2-cell mouse embryos
Authors: Plusa Berenika , Ciemerych Maria A. , Borsuk Ewa , Tarkowski Andrzej K.
Published: September 2008

The aim of this study was to investigate the behaviour of sperm nuclei in the cytoplasm of the 2-cell mouse embryo. To this end, we produced hybrids between anucleate fertilised oocyte fragments and blastomeres of the 2-cell embryos. When sperm nuclei at the stage of decondensation or recondensation were introduced into blastomeres the development of male pronuclei was usually retarded and they never reached the size of the blastomere nuclei. These abortive male pronuclei were unable to initiate transcription but they were capable of synthesising DNA. The majority of sperm nuclei introduced into blastomeres as early male pronuclei developed normally and reached the size of the blastomere nuclei. They synthesised DNA simultaneously with blastomere nuclei and were transcriptionally active. In addition they participated in the cleavage division of hybrid cells. This shows that the very early male pronucleus when transmitted from the oocyte cytoplasm to the blastomere cytoplasm can respond positively to the new cytoplasmic factors, i.e. it undertakes both DNA replication and transcription according to the time schedule characteristic of the second cell cycle.
Chromatin dynamics inTriturus cristatusoogenesis: an epigenetic approach
Authors: Burlibaşa Liliana , Zărnescu Otilia , Cucu Natalia , Gavrilă Lucian
Published: September 2008

Oogenesis is a critical event in the formation of female gametes, whose role in development is to transfer genomic information to the next generation. During this process, the gene expression pattern changes dramatically concomitant with genome remodelling, while genomic information is stably maintained. The aim of the present study was to investigate the chromatin architecture in newt oocytes. Using fluorescence microscopy, as well as transmission electron microscopy (TEM), immunohistochemical method and RE-ChIP assay, some peculiar aspects of chromatin and chromosome organization and evolution in crested newt oogenesis were investigated. We focussed our investigations on detection of certain epigenetic modifications (H4 hyperacetylation, H2A ubiquitinylation and cytosine methylation) at the rRNA gene (18S–5.8S–28S) promoter region. Our findings suggest that there is an involvement of some epigenetic modifications as well as of linker histone variants in chromatin architecture dynamics during crested newt oogenesis.
The current strategy of repair of tetralogy of Fallot in children and adults
Authors: He Guo-Wei , Liu Xiao-Cheng , Kong Xiang-Rong , Liu Li-Xin , Yan Ying-Qun , Chen Bao-Jun , Li Zong-Xiao , Jing Wen-Bin , Wang Zheng-Qing , Wang Kai , Zhang Wei , Chen Tie-Nan , Wang Ping-Shan , Lu Wan-li , Zhang Jian-Liang , Guo Zhi-Peng , Xue Lan-Gang , Zhu Yu-Xiang , Wang Xiu-Li , Xi Lei
Published: September 2008

Objectives

The strategies of repair of tetralogy of Fallot change with the age of patients. In children older than 4 years and adults, the optimal strategy may be to use different method of reconstruction of the right ventricular outflow tract from those followed in younger children, so as to avoid, or reduce, the pulmonary insufficiency that is increasingly known to compromise right ventricular function.

Methods

From April, 2001, through May, 2008, we undertook complete repair in 312 patients, 180 male and 132 female, with a mean age of 11.3 years ±0.4 years, and a range from 4 to 48 years, with typical clinical and morphological features of tetralogy of Fallot, including 42 patients with the ventriculo-arterial connection of double outlet right ventricle. The operation was performed under moderate hypothermia using blood cardioplegia. The ventricular septal defect was closed with a Dacron patch. When it was considered necessary to resect the musculature within the right ventricular outflow tract, or perform pulmonary valvotomy, we sought to preserve the function of the pulmonary valve by protecting as far as possible the native leaflets, or creating a folded monocusp of autologous pericardium.

Results

The repair was achieved completely through right atrium in 192, through the right ventricular outflow tract in 83, and through the right atrium, the outflow tract, and the pulmonary trunk in 36 patients. A transjunctional patch was inserted in 169 patients, non-valved in all but 9. There were no differences regarding the periods of aortic cross-clamping or cardiopulmonary bypass. Of the patients, 5 died (1.6%), with no influence noted for the transjunctional patch. Of those having a non-valved patch inserted, three-tenths had pulmonary regurgitation of various degree, while those having a valved patch had minimal pulmonary insufficiency and good right ventricular function postoperatively, this being maintained after follow-up of 8 to 24-months.

Conclusions

Based on our experience, we suggest that the current strategy of repair of tetralogy of Fallot in older children and adults should be based on minimizing the insertion of transjunctional patches, this being indicated only in those with very small ventriculo-pulmonary junctions. If such a patch is necessary, then steps should be taken to preserve the function of the pulmonary valve.
Mindfulness Approaches in Cognitive Behavior Therapy
Authors: Singh Nirbhay N. , Lancioni Giulio E. , Wahler Robert G. , Winton Alan S. W. , Singh Judy
Published: September 2008

Mindfulness is the latest addition to the armamentarium of cognitive behavioral therapists. Mindfulness methods from the wisdom traditions, as well as from current psychological theories, are beginning to be used as cognitive behavioral strategies for alleviating psychological distress and for personal transformation. The use of mindfulness as a clinical tool is in its infancy, with attendant growing pains in theory, research and practice. We briefly discuss the historical context of the use of mindfulness, recent developments in theory, research and practice, and future developments. We conclude that mindfulness shows a lot of promise as a clinical treatment modality, but there are inherent pitfalls in the developing approaches.
Arterielle Hypertonie – Arzneimittel-Dosierung am Anfang und Ende einer Therapie
Authors: Middeke Martin
Published: September 2008

Einschleichen, Aufsättigen, Absetzen und Ausschleichen haben im Rahmen der antihypertensiven Medikation einen sehr unterschiedlichen Stellenwert. Unter klinisch-praktischen Gesichtspunkten hat bei der Anwendung der modernen Antihypertensiva (ACE-Hemmer, AT1-Blocker, Betablocker, Diuretika und Kalziumantagonisten) der Aspekt der einschleichenden Therapie bzw. Titration neben der Verwendung langwirksamer Substanzen, den höchsten Stellenwert. Eine Aufsättigung bis zur maximalen Dosis wird heute als nicht mehr zeitgemäß betrachtet: Die Dosis-Wirkungskurve verflacht in höherer Dosierung, die Nebenwirkungsrate steigt dagegen überproportional an. Bevorzugt wird daher niedriger dosiert zu kombinieren, bevorzugt in fixer Kombination. Das Absetzen kann bei den meisten Patienten mit modernen Substanzen problemlos erfolgen. Ein Ausschleichen ist dabei allenfalls bei Patienten mit KHK unter Betablockade in Abhängigkeit von der klinischen Situation zu berücksichtigen. Ein kontrollierter Auslassversuch unter ärztlicher Führung, ist heute mittels telemetrischer Blutdrucküberwachung sicher zu steuern. Für Reservesubstanzen wie Prazosin und Doxazosin, Clonidin, Moxonidin und Methyldopa sowie Vasodilatatoren (Dihydralazin, Minoxidil) gelten prinzipiell die gleichen Aspekte. Im Einzelfall sind jedoch pharmakologische Besonderheiten zu berücksichtigen, z.B. ein Rebound-Phänomen nach Absetzung von Clonidin.
KHK und Dyslipidämie – Arzneimittel-Dosierung am Anfang und Ende einer Therapie
Authors: Blessing Erwin
Published: September 2008

In der Behandlung von Patienten mit koronarer Herzerkankung kommen in der Sekundärprävention Thrombozytenaggegationshemmer, β-Blocker, ACE-Hemmer bzw. Angiotensinrezeptorantagonisten sowie Statine zum Einsatz. Eine einschleichende Therapie ist bei den erwähnten Substanzen nicht zwingend erforderlich. Bei nicht vorbehandelten Patienten mit akutem Koronarsyndrom oder im Falle einer Stentimplantation sollte zum schnelleren Wirkungseintritt eine Aufsättigung mit Acetylsalicylsäure bzw. Clopidogrel erfolgen. Zur besseren Verträglichkeit sollte die Therapie mit einem Nikotinsäurepräparat eingeschlichen werden und die Dosierung stufenweise erhöht werden. Bei Patienten mit KHK sollte eine β-Blockertherapie wenn möglich nicht abrupt beendet werden. Bei Beendigung der Therapie sollte eine engmaschige Blutdruckkontrolle und gegebenenfalls Anpassung der antihypertensiven Begleitmedikation erfolgen. Ein abruptes Absetzen einer vorbestehenden Statintherapie sollte in der Akutphase nach kardiovaskulären Ereignissen vermieden werden.
Antikoagulation und Thrombozytenaggregationshemmung – Arzneimittel-Dosierung am Anfang und Ende einer Therapie
Authors: Ivandic Boris T. , Zankl Alexandra , Katus Hugo A.
Published: September 2008

Antithrombotika, also Antikoagulanzien und Thrombozytenaggregationshemmer, sind wichtige therapeutische Werkzeuge der modernen kardiovaskulären Medizin. Sie werden bei einer ständig wachsenden Patientenzahl angewendet und stellen insbesondere beim Ansetzen, Absetzen oder Unterbrechen (wenn invasive Eingriffe nötig sind) eine Herausforderung an das Patientenmanagement dar. In naher Zukunft stehen neue irreversibel oder reversibel gerinnungshemmende Substanzen mit direkten und indirekten Wirkmechanismen zur Verfügung. Ihre Auswahl und Anwendung erfordern pharmakodynamische und -kinetische Kenntnisse. Auch die Pharmakogenomik wird zunehmend wichtiger für die optimale Therapie. Diese Übersicht vermittelt klinisch relevante Prinzipien und diskutiert sie vor dem Hintergrund der individuellen Thrombembolie- und Blutungsrisikoabschätzung.
Asthma und COPD – Arzneimittel-Dosierung am Anfang und Ende einer Therapie
Authors: Grunze Martin , Petermann
Published: September 2008

Für die bei Asthma und COPD eingesetzten Arzneimittel sind bei zwei Stoffgruppen Maßnahmen im Sinne von Ein- oder Ausschleichen erforderlich: Einschleichen der Allergendosis bei Desensibilisierungsbehandlungen und Ausschleichen nach einer länger dauernden, höher dosierten systemischen Glukokortikoid-Therapie. Kurzfristige Exazerbationsbehandlungen mit systemischen Glukokortikoiden bedürfen nach derzeitigem Wissensstand keiner ausschleichenden Dosierung.
Ein- und Ausschleichen von Antiepileptika
Authors: Gueler Nevzat , Krämer Günter
Published: September 2008

Indikationsstellung und Management einer adäquaten medikamentösen antiepileptischen Behandlungsstrategie erfordern eine differenziert ausgerichtete, situationsabhängige, individuelle, epileptologisch-diagnostische Evaluierung. Unter Berücksichtigung der vorliegenden wissenschaftlichen Datenlage werden die Einsatzmöglichkeiten und Besonderheiten der wichtigsten antikonvulsiven Medikamente hinsichtlich eines raschen Aufsättigens oder langsamen Einschleichens bei Therapiebeginn beziehungsweise hinsichtlich eines abrupten Absetzens oder langsamen Ausschleichens bei Therapiebeendigung in unterschiedlichen klinischen Situationen dargestellt.
Spatial patterns of ecosystem carbon residence time and NPP‐driven carbon uptake in the conterminous United States
Authors: Zhou Tao , Luo Yiqi
Published: September 2008

Ecosystem carbon (C) uptake is determined largely by C residence times and increases in net primary production (NPP). Therefore, evaluation of C uptake at a regional scale requires knowledge on spatial patterns of both residence times and NPP increases. In this study, we first applied an inverse modeling method to estimate spatial patterns of C residence times in the conterminous United States. Then we combined the spatial patterns of estimated residence times with a NPP change trend to assess the spatial patterns of regional C uptake in the United States. The inverse analysis was done by using the genetic algorithm and was based on 12 observed data sets of C pools and fluxes. Residence times were estimated by minimizing the total deviation between modeled and observed values. Our results showed that the estimated C residence times were highly heterogeneous over the conterminous United States, with most of the regions having values between 15 and 65 years; and the averaged C residence time was 46 years. The estimated C uptake for the whole conterminous United States was 0.15 P g C a−1. Large portions of the taken C were stored in soil for grassland and cropland (47–70%) but in plant pools for forests and woodlands (73–82%). The proportion of C uptake in soil was found to be determined primarily by C residence times and be independent of the magnitude of NPP increase. Therefore, accurate estimation of spatial patterns of C residence times is crucial for the evaluation of terrestrial ecosystem C uptake.
Effects of 2000–2050 changes in climate and emissions on global tropospheric ozone and the policy‐relevant background surface ozone in the United States
Authors: Wu Shiliang , Mickley Loretta J. , Jacob Daniel J. , Rind David , Streets David G.
Published: September 2008

We use a global chemical transport model (GEOS‐Chem) driven by a general circulation model (NASA Goddard Institute for Space Studies GCM) to investigate the effects of 2000–2050 global change in climate and emissions (the Intergovernmental Panel on Climate Change A1B scenario) on the global tropospheric ozone budget and on the policy‐relevant background (PRB) ozone in the United States. The PRB ozone, defined as the ozone that would be present in U.S. surface air in the absence of North American anthropogenic emissions, has important implications for setting national air quality standards. We examine separately and then together the effects of changes in climate and anthropogenic emissions of ozone precursors. We find that the 2000–2050 change in global anthropogenic emissions of ozone precursors increases the global tropospheric ozone burden by 17%. The 2000–2050 climate change increases the tropospheric ozone burden by 1.6%, due mostly to lightning in the upper troposphere, and also increases global tropospheric OH by 12%. In the lower troposphere, by contrast, climate change generally decreases the background ozone. The 2000–2050 increase in global anthropogenic emissions of ozone precursors increases PRB ozone by 2–6 ppb in summer; the maximum effect is found in April (3–7 ppb). The summertime PRB ozone decreases by up to 2 ppb with 2000–2050 climate change, except over the Great Plains, where it increases slightly as a result of increasing soil NOx emission. Climate change cancels out the effect of rising global anthropogenic emissions on the summertime PRB ozone in the eastern United States, but there is still a 2–5 ppb increase in the west.
Validation of the Coupled Thermosphere Ionosphere Plasmasphere Electrodynamics model: CTIPE‐Mass Spectrometer Incoherent Scatter temperature comparison
Authors: Codrescu M. V. , Fuller‐Rowell T. J. , Munteanu Vlad , Minter C. F. , Millward G. H.
Published: September 2008

New requirements for specification and forecast of the space environment and the availability of unprecedented amounts of real‐time data are now driving the development of data assimilation schemes for the thermosphere and ionosphere. Such schemes require accurate knowledge of any biases affecting the models. Finding the biases is not trivial and requires significant effort. Here we present a first step in the validation of a coupled thermosphere ionosphere general circulation model in preparation for its inclusion in a data assimilation scheme. We present a comparison between the Mass Spectrometer Incoherent Scatter (MSIS) radar empirical model neutral temperatures and the Coupled Thermosphere Ionosphere Plasmasphere Electrodynamics (CTIPE) neutral temperature predictions for three solar cycle conditions (F10.7 = 70, 125, and 200), three geomagnetic activity conditions (Kp = 1, 3, and 7), and three seasons (equinox, summer, and winter). The CTIPE model was run for each case with constant inputs until a diurnally reproducible (“steady state”) global temperature pattern was obtained. MSIS predictions were generated for “perpetually constant” equivalent conditions. The temperature comparisons are performed on a 300 km altitude shell. We present global temperature averages, area‐weighted root mean square differences, and zonally averaged temperature comparisons. CTIPE temperatures at 300 km altitude are lower than MSIS if Joule heating calculations do not include small‐scale E field variability. This is the first global assessment of a general circulation model for the thermosphere over such a wide range of geomagnetic and solar conditions.
Inverse groundwater modeling for hydraulic conductivity estimation using Bayesian model averaging and variance window
Authors: Tsai Frank T.‐C. , Li Xiaobao
Published: September 2008

This study proposes a Bayesian model averaging (BMA) method to address parameter estimation uncertainty arising from nonuniqueness in parameterization methods. BMA is able to incorporate multiple parameterization methods for prediction through the law of total probability and to obtain an ensemble average of hydraulic conductivity estimates. Two major issues in applying BMA to hydraulic conductivity estimation are discussed. The first problem is using Occam's window in usual BMA applications to measure approximated posterior model probabilities. Occam's window only accepts models in a very narrow range, tending to single out the best method and discard other good methods. We propose a variance window to replace Occam's window to cope with this problem. The second problem is the Kashyap information criterion (KIC) in the approximated posterior model probabilities, which tends to prefer highly uncertain parameterization methods by considering the Fisher information matrix. With sufficient amounts of observation data, the Bayesian information criterion (BIC) is a good approximation and is able to avoid controversial results from using KIC. This study adopts multiple generalized parameterization (GP) methods such as the BMA models to estimate spatially correlated hydraulic conductivity. Numerical examples illustrate the issues of using KIC and Occam's window and show the advantages of using BIC and the variance window in BMA application. Finally, we apply BMA to the hydraulic conductivity estimation of the “1500‐foot” sand in East Baton Rouge Parish, Louisiana.
Simulated response of water quality in public supply wells to land use change
Authors: McMahon P. B. , Burow K. R. , Kauffman L. J. , Eberts S. M. , Böhlke J. K. , Gurdak J. J.
Published: September 2008

Understanding how changes in land use affect water quality of public supply wells (PSW) is important because of the strong influence of land use on water quality, the rapid pace at which changes in land use are occurring in some parts of the world, and the large contribution of groundwater to the global water supply. In this study, groundwater flow models incorporating particle tracking and reaction were used to analyze the response of water quality in PSW to land use change in four communities: Modesto, California (Central Valley aquifer); York, Nebraska (High Plains aquifer); Woodbury, Connecticut (Glacial aquifer); and Tampa, Florida (Floridan aquifer). The water quality response to measured and hypothetical land use change was dependent on age distributions of water captured by the wells and on the temporal and spatial variability of land use in the area contributing recharge to the wells. Age distributions of water captured by the PSW spanned about 20 years at Woodbury and >1,000 years at Modesto and York, and the amount of water <50 years old captured by the PSW ranged from 30% at York to 100% at Woodbury. Short‐circuit pathways in some PSW contributing areas, such as long irrigation well screens that crossed multiple geologic layers (York) and karst conduits (Tampa), affected age distributions by allowing relatively rapid movement of young water to those well screens. The spatial component of land use change was important because the complex distribution of particle travel times within the contributing areas strongly influenced contaminant arrival times and degradation reaction progress. Results from this study show that timescales for change in the quality of water from PSW could be on the order of years to centuries for land use changes that occur over days to decades, which could have implications for source water protection strategies that rely on land use change to achieve water quality objectives.
North‐south asymmetry of warm water volume transport related with El Niño variability
Authors: Ishida Akio , Kashino Yuji , Hosoda Shigeki , Ando Kentaro
Published: September 2008

A better understanding of variability in the volume of warm water in the equatorial Pacific pycnocline (warm water volume, or WWV) is critical to understanding El Niño‐Southern Oscillation (ENSO) variability. We have investigated the meridional WWV transport in the Northern (NH) and Southern Hemispheres (SH) using a high‐resolution general circulation model. The transport in the western boundary region compensates the interior transport in the SH, where Sverdrup balance holds approximately. In contrast, such compensation does not hold in the NH, because the boundary transport lags interior transport by about 7 months. Hence, the WWV exchange in the NH has more impact on the recharge‐discharge of the equatorial WWV. The north‐south asymmetry of the WWV transport, which is interpreted based on the linear Rossby theory, is related with the southward migration of westerly wind and the negative wind curl over the northwestern off‐equatorial region after the mature stage of ENSO.
Time reversal location of glacial earthquakes
Authors: Larmat Carène , Tromp Jeroen , Liu Qinya , Montagner Jean‐Paul
Published: September 2008

In 2003, Ekström et al. reported the detection and location of a new class of earthquakes occurring in the polar regions of the Earth. The proposed source mechanism involves large and sudden sliding motions of glaciers, which gave the name “glacial earthquakes” to these events. In this study we localize some of these earthquakes with a time reversal mirror (TRM) algorithm, which, contrary to ordinary back projection methods, does not involve testing each possible source location. In TRM localization, an earthquake is located on the basis of only one 3‐D spectral element simulation of seismic wave propagation by using the full complexity of recorded data as simultaneous time‐reversed sources. We show that on the basis of this approach, even glacial earthquakes with a faint signal can be correctly localized and that the pattern of the time‐reversed wavefield is coherent with the motion of glaciers down their valley.
Comparison of marine stratocumulus cloud top heights in the southeastern Pacific retrieved from satellites with coincident ship‐based observations
Authors: Garay Michael J. , de Szoeke Simon P. , Moroney Catherine M.
Published: September 2008

In order to better understand the general problem of satellite cloud top height retrievals for low clouds, observations made by NOAA research vessels in the stratocumulus region in the southeastern Pacific during cruises in 2001 and 2003 to 2006 were matched with near‐coincident retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Multiangle Imaging SpectroRadiometer (MISR) instruments on the Terra satellite, along with a limited set of ISCCP 30‐km (DX) retrievals. The ISCCP cloud top heights, determined from the cloud top pressures, were found to be biased high by between 1400 and 2000 m within the limited comparison data set. Like the International Satellite Cloud Climatology Project (ISCCP) results, the MODIS retrievals were biased high by more than 2000 m, while the MISR retrievals had errors on the order of 230 to 420 m, with the wind corrected heights having almost no bias. The extremely large bias in the ISCCP and MODIS retrievals was traced to their reliance on low‐resolution observations or models of the atmospheric temperature structure. Cloud top height retrievals based on satellite cloud top temperatures and a constant atmospheric lapse rate agreed substantially better with the ship‐based measurements.
Structural insights into microneme protein assembly reveal a new mode of EGF domain recognition
Authors: Sawmynaden Kovilen , Saouros Savvas , Friedrich Nikolas , Marchant Jan , Simpson Peter , Bleijlevens Boris , Blackman Michael J , Soldati‐Favre Dominique , Matthews Stephen
Published: September 2008

The obligate intracellular parasite Toxoplasma gondii, a member of the phylum Apicomplexa that includes Plasmodium spp., is one of the most widespread parasites and the causative agent of toxoplasmosis. Adhesive complexes composed of microneme proteins (MICs) are secreted onto the parasite surface from intracellular stores and fulfil crucial roles in host‐cell recognition, attachment and penetration. Here, we report the high‐resolution solution structure of a complex between two crucial MICs, TgMIC6 and TgMIC1. Furthermore, we identify two analogous interaction sites within separate epidermal growth factor‐like (EGF) domains of TgMIC6—EGF2 and EGF3—and confirm that both interactions are functional for the recognition of host cell receptor in the parasite, using immunofluorescence and invasion assays. The nature of this new mode of recognition of the EGF domain and its abundance in apicomplexan surface proteins suggest a more generalized means of constructing functional assemblies by using EGF domains with highly specific receptor‐binding properties.
Persisting Depletion of Brain Glucose following Cortical Spreading Depression, despite Apparent Hyperaemia: Evidence for Risk of an Adverse Effect of Leão's Spreading Depression
Authors: Hashemi Parastoo , Bhatia Robin , Nakamura Hajime , Dreier Jens P , Graf Rudolf , Strong Anthony J , Boutelle Martyn G
Published: September 2008

Rapid sampling microdialysis (rsMD) directed towards the cerebral cortex has allowed identification of a combined time-series signature for glucose and lactate that characterizes peri-infarct depolarization in experimental focal ischaemia, but no comparable data exist for ‘classical’ cortical spreading depression (CSD) associated with hyperaemia in the normally perfused brain. Here, we examined the rsMD responses of dialysate glucose and lactate to five hyperaemic spreading depressions induced with intracortical microinjections, typically of 1 mol/L KCl, in open-skull preparations in five cats under chloralose anaesthesia. Depolarization was verified with microelectrodes, and laser speckle flowmetry was used to examine propagation of the events and perfusion responses near the MD probe. Ten minutes after depolarization, dialysate glucose fell and lactate rose by 28% and 58% respectively. There was no recovery of dialysate glucose 30 mins after depolarization. Mean baseline indicative cerebral blood flow was 25.5 ± 4.1 mL/100 g/min and mean maximum hyperaemic increase was by 29.6 ± 6 mL/100 g/min; hyperaemia remained present 30 mins after CSD. As CSD events are repetitive, frequent, and often clustered temporally in human acute brain injury, these results indicate a high risk of depletion of extracellular glucose in association with depolarization events of a pattern previously thought to be largely benign.
A bizarre Jurassic maniraptoran from China with elongate ribbon-like feathers
Authors: Zhang Fucheng , Zhou Zhonghe , Xu Xing , Wang Xiaolin , Sullivan Corwin
Published: September 2008

Recent coelurosaurian discoveries have greatly enriched our knowledge of the dinosaur-bird transition, but all reported taxa close to this transition are from relatively well-known coelurosaurian groups^1-3^. Here we report a new basal avialan, Epidexipteryx hui gen. et sp. nov., from the Middle-Late Jurassic of Inner Mongolia, China. This new species is characterized by an unexpected combination of characters seen in several different theropod groups, particularly the Oviraptorosauria. Phylogenetic analysis shows it to be the sister taxon to Epidendrosaurus^4,5^, forming a new clade at the base of Avialae^6^. Epidexipteryx also possesses two pairs of elongate ribbon-like tail feathers (ETFs), and its limbs lack contour feathers for flight. This finding shows that a member of the avialan lineage experimented with integumentary ornamentation as early as the Middle-Late Jurassic, and provides further evidence relating to this important aspect of the transition from non-avian theropods to birds.
Steroidal anti inflammatory drug betamethasone significantly alters level of striatal dopamine in a rat model of Parkinson’s disease
Authors: Shafiee Ardestani Mehdi , Mehrab Hasan , Geravand Amin , Mohajer Nasir , Saffari Mostafa
Published: September 2008

Many scientific efforts have been well done to investigate the effects of anti inflammatory agents on the degenerative brain diseases such as Parkinson’s (PD) or Alzheimer’s disease and their affiliated sings. Previously we showed the effectiveness of steroids on rigidity of PD and in the study for further mechanistic investigation of that observation the microdialysis technique was employed to determine the striatal dopamine changes in parkinsonian rats after administration of betamethasone (0.12, 0.24 mg/kg) respectively. Our findings showed us the significant increase in the striatal dopaminergic neurotransmission (P<0.05) after administration of betamethasone comparing to the controls. These observations suggest a new mechanism for betamethasone on striatum dopaminergic neurotransmission leading us to gather further evidence about effectiveness of betamethasone in PD.
Adiponectin Multimers and Metabolic Syndrome Traits: Relative Adiponectin Resistance in African Americans
Authors: Lara‐Castro Cristina , Doud Erin C. , Tapia Patrick C. , Munoz Andres J. , Fernandez Jose R. , Hunter Gary R. , Gower Barbara A. , Garvey W. Timothy
Published: September 2008

African Americans (AAs) tend to have lower total adiponectin levels compared to European Americans (EA); however, it is not known whether race affects adiponectin multimer distribution and their relationships to metabolic traits. We measured total adiponectin, high molecular weight (HMW), low molecular weight (LMW) (i.e., hexamer), and trimer adiponectin in 132 normoglycemic premenopausal women (75 AAs, 57 EAs), together with measures of total and abdominal fat, plasma lipids, insulin sensitivity (Si), and genetic admixture estimates. We found that lower total adiponectin in AAs was explained by reduced LMW, and trimer forms because levels of HMW did not differ between races. In EAs, HMW was highly correlated with multiple metabolic syndrome traits. In contrast, the LMW and trimer forms were most highly correlated with metabolic traits in AAs, including abdominal adiposity, lipids, and Si. At similar levels of visceral adiposity, AAs exhibited significantly lower LMW adiponectin than EAs. Similarly, at comparable levels of HMW and LMW adiponectin, AAs were more insulin resistant than their EA counterparts. In conclusion, (i) serum adiponectin is lower in AAs predominantly as a result of reduced concentrations of LMW and trimers multimeric forms; (ii) LMW and trimer, not HMW, are most broadly correlated with metabolic traits in AAs. Thus, HMW adiponectin may exert less bioactivity in explaining the metabolic syndrome trait cluster in populations of predominant African genetic background.
School-Based Speech-Language Pathologists' Perspectives on Dysphagia Management in the Schools
Authors: Bailey Rita L. , Stoner Julia B. , Angell Maureen E. , Fetzer Alycia
Published: September 2008

Purpose

Although provision of dysphagia services is within the scope of practice of speech-language pathologists (SLPs), little is known about the perspectives of school-based SLPs in relation to these services. The purpose of this study was to examine SLPs' perspectives related to school-based management of students with dysphagia.

Method

Focus group interviews were conducted with 33 SLPs who were employed by a large school district in the Midwest before development of district-supported policies and protocols related to dysphagia management. The interviews were analyzed using qualitative analysis methods.

Results

A variety of common perspectives emerged from the data, including a primary perceived difficulty in adapting practice in dysphagia from medical to educational service delivery models and settings. Additionally, 3 thematic categories of concerns emerged that were related to child characteristics, training, and support.

Implications

Information gained in this investigation may be used to develop effective service delivery models, policies, and protocols, as well as to identify necessary supports related to the management of students with dysphagia in school settings.
Phonemic Awareness Skill of Speech-Language Pathologists and Other Educators
Authors: Spencer Elizabeth J. , Schuele C. Melanie , Guillot Kathryn M. , Lee Marvin W.
Published: September 2008

Purpose

Educators rely on sufficient knowledge and skill to provide effective phonemic awareness instruction, an important component of early literacy instruction, particularly for children who experience difficulty learning to read. The purpose of this study was to evaluate and compare the phonemic awareness skill of several groups of educators, including speech-language pathologists (SLPs;
n
= 160), kindergarten teachers (
n
= 109), first-grade teachers (
n
= 112), reading teachers (
n
= 100), and special education teachers (
n
= 60).

Method

Participants completed a paper–pencil measure of phonemic awareness skill that included 3 tasks. The measure was designed to assess sophisticated explicit phonemic awareness skill within a print context, representing an advanced skill level that has been deemed critical to teaching.

Results

SLPs demonstrated superior performance on the measure of phonemic awareness skill when compared to other educators (
d
= 1.54). The performance of reading and special education teachers was comparable to that of kindergarten and first-grade teachers. Orthographic knowledge had an adverse impact on the performance of all groups. However, SLPs were far more proficient than other educators at segmenting words that had a complex relationship between speech and print (e.g.,
box, use
).

Clinical Implications

SLPs have relative expertise in phonemic awareness, yet their performance may not be proficient. Three recommendations are discussed: (a) Increase the phonemic awareness skill of all educators, (b) revise instructional materials to enhance educators' efforts to provide accurate and effective phonemic awareness instruction, and (c) include SLPs as members of the team responsible for phonemic awareness instruction and intervention.
Negative index metamaterials based on metal-dielectric nanocomposites for imaging applications
Authors: Menon L. , Lu W. T. , Friedman A. L. , Bennett S. P. , Heiman D. , Sridhar S.
Published: September 2008

Negative index metamaterials are demonstrated based on metal-dielectric nanocomposites prepared using a versatile bottom-up nanofabrication approach. The method involves the incorporation of vertically aligned metal nanowires such as Au and Ag inside dielectric aluminum oxide nanotemplates. Optical absorbance measurements show resonance peaks corresponding to the transverse and longitudinal surface plasmon modes. A quantitative model based on effective medium theory is in excellent agreement with experimental data, and points to specific composite configurations and wavelength regimes where such structures can have applications as negative refraction media for imaging.
The augmented Roothaan–Hall method for optimizing Hartree–Fock and Kohn–Sham density matrices
Authors: Høst Stinne , Olsen Jeppe , Jansík Branislav , Thøgersen Lea , Jørgensen Poul , Helgaker Trygve
Published: September 2008

We present a novel method for the optimization of Hartree–Fock and Kohn–Sham energies that does not suffer from the flaws of the conventionally used two-step Roothaan–Hall (RH) with direct inversion in iterative subspace (DIIS) acceleration scheme, improving the reliability of the optimization while reducing its cost. The key to its success is the replacement of the two separate steps of each RH/DIIS iteration by a single concerted step that fully exploits the Hessian information available from the previous iterations. It is a trust-region based method and therefore by design converges to an energy minimum. Numerical examples are given to illustrate that the algorithm is robust and cost efficient, converging smoothly to a minimum also in cases when the RH/DIIS algorithm fails to converge or when it converges to a saddle point rather than to a minimum. The algorithm is based on matrix multiplications and becomes linearly scaling for sufficiently large systems.
Dynamic response of polydomain ferroelectric barium titanate epitaxial thin films and its field dependence
Authors: Liu Zhifu , Meier A. L. , Wessels B. W.
Published: September 2008

The nature of ferroelectric domain dynamics in polydomain epitaxial barium titanate thin film was investigated using the linear electro-optic effect. The dynamic response was studied as a function of bias field under pulsed excitation. Upon removal of the bias pulse a millisecond long transient response was observed that is attributed to 90° domain reversal. The dynamic response and its field dependence are described by the Kohlrausch–Williams–Watts stretched exponential function in time with an average relaxation time ⟨τ⟩. This average time for polarization reversal is a function of applied electric field E and is given by ⟨τ⟩=τ0 exp(α/E), where τ0 is the prefactor and α is the activation field. The measured activation fields depended on bias. Activation fields of 2.0 and 0.7 V/μm measured under high and low bias conditions are comparable to those observed for bulk barium titanate.
Anisotropic strain state of the [11¯00] GaN quantum dots and quantum wires
Authors: Amstatt B. , Landré O. , Nicolin V. Favre , Proietti M. G. , Bellet-Amalric E. , Bougerol C. , Renevier H. , Daudin B.
Published: September 2008

The strain state of the [11¯00] GaN quantum dots and quantum wires has been studied by a combination of multiwavelength anomalous diffraction and diffraction anomalous fine structure under grazing incidence. The three components of the anisotropic deformation have been independently determined. On one hand, a weak residual strain state along the c-axis, similar for quantum dots and quantum wires, is found. On the other hand, along the [112¯0] direction, quantum wires appear to be more relaxed than quantum dots. Based on high resolution transmission electron microscopy, this is assigned to elastic strain relaxation of GaN governed by either misfit dislocation formation or three-dimensional islanding, depending on the anisotropic strain state of the [11¯00] AlN buffer layer.
Optical, magnetic, and transport behaviors of Ge1−xMnxTe ferromagnetic semiconductors grown by molecular-beam epitaxy
Authors: Chen W. Q. , Lim S. T. , Sim C. H. , Bi J. F. , Teo K. L. , Liew T. , Chong T. C.
Published: September 2008

The optical, magnetic, and transport behaviors of Ge1−xMnxTe (x=0.24 and 0.55) grown by solid-source molecular-beam epitaxy are investigated. X-ray diffraction shows that Ge1−xMnxTe crystallizes in rocksalt structure. The temperature-dependent magnetization (M-T) for x=0.55 sample gives a Curie paramagnetic temperature of θp∼180 K, which is consistent with the temperature-dependent resistivity ρ(T) measurement. Anomalous Hall effect is clearly observed in the samples and can be attributed to extrinsic skew scattering based on the scaling relationship of ρxy∝ρxx1.06. The magnetoresistance of Ge1−xMnxTe is isotropic and displays a clear hysterestic loop at low temperature, which resembles that of giant-magnetoresistance granular system in solids.
Molecular dynamics study on DNA oligonucleotide translocation through carbon nanotubes
Authors: Pei Q. X. , Lim C. G. , Cheng Y. , Gao Huajian
Published: September 2008

Molecular dynamics simulations are performed to study the translocation of a DNA oligonucleotide in a carbon nanotube (CNT) channel consisting of CNTs of two different diameters. A strong gravitational acceleration field is applied to the DNA molecule and water solvent as an external driving force for the translocation. It is observed that both the CNT channel size and the strength of gravitational field have significant influence on the DNA translocation process. It is found that the DNA oligonucleotide is unable to pass through the (8,8) CNT even under strong gravitational fields, which extends previous finding that DNA cannot be self-inserted into a (8,8) CNT. It is shown that the DNA can pass through the (10,10)-(12,12) and (12,12)-(14,14) CNTs with stronger gravitational field resulting in faster translocation. The translocation time τ is found to follow the inverse power law relationship with the gravitational acceleration a as τ∼a−1.21. The energetic analysis of the translocation process shows that there is an energy barrier for DNA translocation into the (10,10) tube from the (14,14) tube, which is in contrast to previous report that DNA can be self-inserted into a (10,10) tube from outside the CNT. This difference with previous report shows that the dynamic behavior of DNA translocation inside a CNT channel is quite different from that of DNA translocation into a CNT from outside the CNT.
Characteristics of cylindrical flame acceleration in outward expansion
Authors: Pan Kuo-Long , Fursenko Roman
Published: September 2008

We have studied the outward propagation of a cylindrical flame by means of a flame-tracking numerical method and direct computation of the Sivashinsky equation. The flame speed is modified by the local curvature, via a Markstein length ℓ, that somehow groups the complicated physiochemical effects and can be monotonically relevant to the system pressure. The flame is found to accelerate in a universal profile as a function of time, which is insensitive to initial perturbations after a self-similar regime is reached. The extent of acceleration can be quantified by an exponent of a power law that approximates the dependency of the average flame radius on time. It is shown that the growth exponent is invariant with respect to ℓ while it increases with the density ratio between the unburned and burned gases (q). Furthermore, various fitting approaches are discussed and the proper one is found to satisfy the formal relation according to the fractal analysis. Therefore the diversity of the exponent that was supposed to be invariant as reported in the literature, ranging from 1.25 to 1.5, would be realized via the variation in q as well as the fitting methods, while other factors might also be involved such as the sampling and uncertainty of fitted data.