bluuebunny/crossref_metadata_2025 huggingface dataset:
A 15-year follow-up study on schistosomiasis in a low-endemic area in Rio de Janeiro State, Brazil
Authors: Igreja R.P. , Gusmão M.F. , Barreto M.G.M. , Paulino M.T. , da Silva J.F. , Seck O.K. , Gonçalves M.M.L. , Soares M.S.
Published: September 2009

Fifteen years after our first investigation, a follow-up study was carried out with the purpose of assessing the evolution of schistosomiasis in the locality of Sabugo, Paracambi, state of Rio de Janeiro, Brazil, an area with low prevalence of the disease. The coprological techniques adopted were spontaneous sedimentation and Kato-Katz. Out of the 1356 individuals assessed, 13 (1%) were infected with Schistosoma mansoni. From those, 10 were males, 12 were over 15 years old, and at least 11 had been infected in Sabugo. All patients presented either the intestinal or the hepato-intestinal form of the disease, and 8 (61.5%) harboured light parasitic loads. In 1990, there were 27 (2.7%) infected individuals; less than half harboured light parasitic loads, with the predominance of moderate and heavy forms. Although our results indicate an improvement in the epidemiological situation of schistosomiasis in Sabugo, transmission of the disease in the locality is still active, especially among young males, and tends to be acquired during leisure activities.
New species and new records of Cryptothecia and Herpothallon (Arthoniales) from India
Authors: RAM T. A. M. JAGADEESH , SINHA G. P. , SINGH K. P.
Published: September 2009

Five new species of Cryptothecia: C. alboglauca, C. bengalensis, C. farinosa, C. multipunctata and C. verruculifera, and two new species of Herpothallon: H. granulosum and H. isidiatum are described from India. Herpothallon australasicum (Elix) Elix & G. Thor and H. granulare (Sipman) Aptroot & Lücking are also reported as new records.
Growth of the old forest lichen Usnea longissima at forest edges
Authors: JANSSON K. Ulrika , PALMQVIST Kristin , ESSEEN Per-Anders
Published: September 2009

The lichen Usnea longissima was used to examine how distance from forest edge and edge contrast influence growth of pendulous lichens. Thalli of two sizes (12 and 27 cm) were transplanted to the lower canopy of old Picea abies forest at 5, 25 and 100 m distance from cutovers. Sites represented three levels of edge contrast: high (clear-cut), intermediate (3 m tall saplings) and low (6–7 m tall young forest). Lichen growth was assessed as annual length and weight gain. Growth rates of intact thalli were size-dependent, with both growth variables being higher in long than in short thalli. Distance and edge contrast had significant effects on weight gain in long thalli but not in short ones. Weight gain in long thalli was twice as high near the edge (23%) compared to the forest interior (12%). The highest weight gain (31%) occurred at intermediate contrast edges with lower growth at both low (18%) and high contrast edges (20%). Chlorophyll a concentration was highest near the edge and positively correlated with weight gain, suggesting that growth was stimulated by both increased photosynthetic capacity and higher light availability near the edge. The lower part of the canopy in forest edges apparently have favourable growth conditions for U. longissima with growth being influenced by vegetation on adjoining cutovers. Therefore growth responses cannot explain the previously observed decline of pendulous lichens following edge creation. Our results suggest that vegetation buffers can improve conditions for pendulous lichens near forest edges.
A new species of Placocarpus (Verrucariaceae) from southern California
Authors: KNUDSEN Kerry , BREUSS Othmar , KOCOURKOVÁ Jana
Published: September 2009

A new species, Placocarpus americanus, is described from the Santa Monica Mountains in Southern California. It is a juvenile parasite on Protoparmeliopsis muralis and differs from Placocarpus schaereri in having smaller non-halonate ascospores, a negative iodine reaction of the medulla, lack of inspersion of the medulla with small crystals, and having a thallus of dispersed areoles.
Multivariate analysis of anatomical characters confirms the differentiation of two morphologically close species,Melanohalea olivacea(L.) O. Blancoet al.andM. septentrionalis(Lynge) O. Blancoet al.
Authors: TRUONG Camille , NACIRI Yamama , CLERC Philippe
Published: September 2009

This study investigates how anatomical characters can be used to differentiate two morphologically close species,Melanohalea olivacea(L.) O. Blancoet al.andM. septentrionalis(Lynge) O. Blancoet al. Although the two species are morphologically differentiated, mainly based on the position and shape of pseudocyphellae on the lobes, poorly-developed specimens can be difficult to identify based on morphology alone. For example, in Switzerland, both species are at the south-west limit of their distribution range and most specimens are small and not fully developed. In such cases, anatomical characters are particularly useful in separating the two species. Five anatomical characters were studied: spore length and width; hymenium, subhymenium and hypothecium height. A nested ANOVA showed that variation of spore length was 155 times greater between species than between individuals of the same species, itself 5 times higher than within individuals. In a Principal Component Analysis, despite a substantial variation of the anatomical characters within both species, a significant species differentiation appeared distinctly on the first axis (P< 0·001), which accounted for 62·35% of the total variance, and the type specimens nested within each species. Finally, a Discriminant Linear Analysis assigned 100% of the individuals to their species class, the best predictors to discriminate between the two species being subhymenium height and spore length. These characters proved to be powerful in identifying specimens with a poorly-developed morphology and confirmed the presence ofM. olivaceain Switzerland.
Exploring Women’s Attitudes and Intentions to Seek Care from Nurse Practitioners across Different Age Groups
Authors: Wasylkiw Louise , Gould Odette N. , Johnstone Dusty
Published: September 2009

Puisque l’acceptation publique est essentielle à une intégration réussie des infirmières praticiennes dans le système de soins de santé canadien, la présente étude examine de quelle manière les femmes de différents groupes d’âge perçoivent les infirmières praticiennes. Les femmes d’âge moyen avaient généralement une opinion plus positive des professionnels de la santé et étaient plus enclines à indiquer qu’elles demanderaient de l’aide des infirmières praticiennes que les femmes plus âgées et plus jeunes qu’elles. Les répondants des trois groupes d’âge étaient davantage portés à consulter des médecins que des infirmières praticiennes, particulièrement en ce qui concerne les problèmes de santé aigus (par opposition aux questions préventives).
Fear of Falling among Elderly Patients with Dizziness and Syncope in a Tilt Setting
Authors: Perez-Jara Javier , Enguix Alfredo , Fernandez-Quintas Jose Miguel , Gómez-Salvador Beatriz , Baz Rosa , Olmos Paloma , Rodríguez Alberto , Vilches Arturo , Reyes-Ortiz Carlos
Published: September 2009

Les objectifs de cette étude étaient de mesurer la prévalence de la crainte de tomber chez les patients âgés de plus de 60 ans à cause d’étourdissements, de chutes et de syncopes et d’analyser les facteurs de risque que l’on associe à ce syndrome, y compris les données provenant du test d’inclinaison. Cette étude transversale a inclus 200 patients qui ont été dirigés vers une clinique gériatrique externe spécialisée dans les étourdissements, les chutes et les syncopes. Le premier résultat mesuré a été la proportion de patients qui ont expérimenté la crainte de tomber (oui ou non) et si cette crainte causait une restriction au moment de sortir seuls ou d’effectuer les activités de la vie quotidienne. La crainte de tomber est apparue chez 50 pour cent des patients de cette population. Parmi eux, 44 pour cent avaient cessé de sortir seuls et 10 pour cent avaient cessé d’effectuer les activités de base de la vie quotidienne. Chez les patients de 75 ans et plus, les étourdissements à répétition, la dépression et les symptômes ressentis lorsqu’ils se lèvent ont été des facteurs associés à la crainte de tomber. Le fait d’avoir subi des chutes au préalable n’a pas été un facteur associé.
Exploring the Acceptability and Feasibility of Conducting a Large Longitudinal Population-Based Study in Canada
Authors: Kirkland Susan A. , Raina Parminder S. , Wolfson Christina , Strople Geoff , Kits Olga , Dukeshire Steven , Angus Camille L. , Szala-Meneok Karen , Uniat Jennifer , Keshavarz Homa , Furlini Linda , Pelletier Amélie
Published: September 2009

Le recrutement et la rétention réussis lors d’études longitudinales basées sur la population exigent la compréhension des facilitants et des barrières à la participation. Les points de vue des Canadiens(nes) concernant une telle étude proposée, l’Étude longitudinale canadienne sur le vieillissement (ÉLCV), ont été explorés. Des groupes de discussion de participants âgés de ≥ 40 ans ont été mis en place dans six emplacements proposés pour la collecte de données de l’ÉLCV (Halifax, Montréal, Hamilton, Winnipeg, Calgary et Vancouver) pour discuter de la participation possible à une étude à long terme sur le vieillissement en santé. Il y avait un soutien marqué pour la recherche longitudinale sur la santé et le vieillissement. L’altruisme était une motivation clée à la participation et les universités ont été perçues comme des institutions crédibles pour entreprendre de telles études. Les participants ont eu peu d’inquiétude à l’égard du don d’échantillons biologiques, mais ont exprimé quelques inquiétudes concernant l’utilisation inapproprié du matériel génétique, la commercialisation des données de participant et les questions reliées à la confidentialité et la vie privée. Ces résultats ont déjà eu un impact sur le travail actuel, et futur, de l’ÉLCV, et fourniront également des informations utiles aux chercheurs qui entreprennent d’autres études longitudinales basées sur la population.
Éditorial : Concrétisation de la vision. L’Étude longitudinale canadienne sur le vieillissement, une initiative stratégique des Instituts de recherche en santé du Canada
Authors: Martin-Matthews Anne , Mealing Linda
Published: September 2009

The Canadian Longitudinal Study on Aging has progressed from a vision initiated by the CIHR Institute of Aging in 2001 to a federally funded national research platform in 2008. The development of the CLSA protocol was enhanced through a series of international peer reviews, a multisectorial Steering Committee, and a CIHR Ethical, Legal, and Social Issues committee; each was essential to the excellence of the science and to making the CLSA relevant to multiple sectors. The CLSA research team, led by three co-principal investigators (Kirkland, Raina, and Wolfson), has developed a unique protocol focusing on aging from cell to society, designed to follow 50,000 people aged 45 to 85, for 20 years. A strategic partnership with Statistics Canada has been crucial to the development and launch of the CLSA. The CLSA will contribute to our understanding of transitions and trajectories within an aging population, and will differ from longitudinal studies of aging worldwide through the breadth of its scope, the early age of recruitment into the study (age 45), the ethno-cultural diversity of Canada’s population, and the potential to link collected data to health administrative data at the provincial level. The CIHR is a novel longitudinal population-based study that will be an unprecedented research resource underpinning multidisciplinary research and evidence-based decision making in aging in Canada.
The clinical neuropsychologist's dilemma
Authors: WILSON BARBARA A.
Published: September 2009

Academic neuropsychologists are increasingly engaged in (and are part of) cognitive neuroscience. Neuroimaging is currently high on the agenda, neuroplasticity is a very topical field within neuroscience, and a number of neuropsychologists work on animal models of brain injury. Clinical neuropsychologists, particularly those involved in rehabilitation, will usually tell you that their work needs to be guided by theory or else they risk the accusation of being simply pragmatic. The fundamental question for clinical neuropsychologists is which theory or theories are most relevant and useful for the patients and families with whom they work? While it would seem that most clinical neuropsychologists consider cognitive neuroscience to be of direct or at least indirect benefit to clinical neuropsychological practice, it is part of the argument of this paper to suggest that the benefits are less substantial than is sometimes claimed. As I work with both academic and clinical neuropsychologists, I hold the conviction that theory should be relevant to clinical practice while, at the same time, wanting neuropsychological rehabilitation to be respectable in the eyes of the academic community. However, when treating a patient with brain injury it is sometimes a struggle to implement, or even see the relevance of findings from cognitive neuroscience.
Numerical simulation of mean currents and water property anomalies at Endeavour Ridge: Hydrothermal versus topographic forcing
Authors: Thomson Richard E. , Subbotina Marina M. , Anisimov Mikhail V.
Published: September 2009

Numerical simulations based on realistic seafloor topography are used to examine near‐bottom currents in the region of the Endeavour segment of Juan de Fuca Ridge (Endeavour Ridge) in the northeast Pacific. Results support earlier findings that hydrothermal venting within the ∼2200‐m deep axial valley, rather than topographically modified, basin‐scale cross‐ridge geostrophic flow, is responsible for the near‐steady northward currents observed within the confines of the valley. Although it does not generate deep flow within the valley, the basin‐scale circulation determines the horizontal redistribution of the hydrothermal plumes once they rise above the ridge crest. Simulations of the near‐bottom temperature and salinity fields reveal that model runs that incorporate a deep westward background flow most closely reproduce the observed plume anomaly distributions above the ridge, indicating that bottom currents in the region are predominantly westward, counter to the prevailing southeasterly flow of the wind‐driven California Current in the upper half of the water column.
Effects of vegetation and soil moisture on the simulated land surface processes from the coupled WRF/Noah model
Authors: Hong Seungbum , Lakshmi Venkat , Small Eric E. , Chen Fei , Tewari Mukul , Manning Kevin W.
Published: September 2009

The coupled Weather Research and Forecasting (WRF) model with the Noah land surface model (Noah LSM) is an attempt of the modeling community to embody the complex interrelationship between land surface and atmosphere into numerical weather or climate prediction. This study describes coupled WRF/Noah model tests to evaluate the model sensitivity and improvement through vegetation fraction (Fg) parameterizations and soil moisture initialization. We utilized the 500 m 8‐day Moderate Resolution Imaging Spectroradiometer reflectance data to derive the model Fg parameter using two different methods: the linear and quadric methods. In addition, combining the Fg quadric method, we initialized soil moisture simulated by High‐Resolution Land Data Assimilation System, which has been developed for providing better soil moisture data in high spatial resolution by National Center for Atmospheric Research. We performed temporal comparisons of the simulated land surface variables: surface temperature (TS), sensible heat flux (SH), ground heat flux (GH), and latent heat flux (LH) to observed data during 2002 International H2O Project. Then these results were statistically validated with correlation coefficients and root mean square errors. The results indicate high sensitivity of the coupled model to vegetation fluctuations, showing overestimation of vegetation transpiration and very low variability of GH in highly vegetated area.
Tectonic model and fault segmentation of the Median Tectonic Line active fault system on Shikoku, Japan
Authors: Ikeda Michiharu , Toda Shinji , Kobayashi Shuji , Ohno Yuki , Nishizaka Naoki , Ohno Ichiro
Published: September 2009

Fault segmentation models have been developed by using various types of information about faults, including both geological and geophysical data, in order to predict the size of future cascade earthquakes. In these models, however, stress conditions within the fault systems have not been considered in sufficient detail. Major fault systems generally exhibit heterogeneous stress conditions. The Median Tectonic Line active fault system (MTLAFS) is the longest and most active arc‐parallel, right‐lateral, strike‐slip fault system in Japan. The stress conditions along the MTLAFS change from transpression on eastern Shikoku Island to transtension on Kyushu Island. The change of stress conditions along the fault system is caused by the counterclockwise rotation of the Nankai fore‐arc sliver in response to the relative motion of the Philippine Sea and Eurasian tectonic plates and back‐arc spreading in the Okinawa trough. Here, we propose “stress condition segmentation” as a concept that deals with the diversity of stress conditions and can be applied in seismic hazard assessment. According to this concept, the MTLAFS is divided into three segments: the East Shikoku, West Shikoku, and Kyushu segments. The East Shikoku and Kyushu segments are under compressional and tensional stress conditions, respectively. Stress in the West Shikoku segment, which is between the other two segments, is transitional from compressional to tensional conditions. In particular, change in the magnitude of fault‐normal stresses along strike is one of the key factors that govern the geometry of fault discontinuities, rupture propagation and termination, and, consequently, fault segmentation. Application of our stress condition segmentation concept to the MTLAFS suggests that future earthquakes in the West Shikoku and Kyushu segments will be of lower energy than those in the East Shikoku segment.
Evidence for a 3.45‐billion‐year‐old magnetic remanence: Hints of an ancient geodynamo from conglomerates of South Africa
Authors: Usui Yoichi , Tarduno John A. , Watkeys Michael , Hofmann Axel , Cottrell Rory D.
Published: September 2009

Paleomagnetic and rock magnetic analyses of ∼3445‐million‐year‐old dacite conglomerate clasts and parent body rocks from the Barberton greenstone belt, South Africa, define two dominant components of magnetization. One component, unblocked at low temperature, is an overprint acquired ∼180 million years ago. The other component is unblocked at high temperatures and passes a conglomerate test, indicating that this component is older than the depositional age of the conglomerate (∼3416 Ma). The high unblocking temperature component shows scatter in the parent body rocks that can be explained by the effects of modern lightning strikes, Archean overprinting, and the presence of multidomain magnetic grains that are conducive to carrying secondary magnetizations. Alternatively, this scatter can be explained by exotic magnetization scenarios in the absence of a dynamo, including magnetization by an external field related to solar wind interaction with the atmosphere. Such exotic mechanisms can be tested with the acquisition of paleointensity data. While more scattered than paleomagnetic data recording the more recent geomagnetic field, the high unblocking temperature component in the dacite parent body shows some consistency, and the simplest explanation of the data is that they reflect a geodynamo ∼3445 million years ago.
Clay mineral anomalies in the fault zone of the Chelungpu Fault, Taiwan, and their implications
Authors: Kuo Li‐Wei , Song Sheng‐Rong , Yeh En‐Chao , Chen Huei‐Fen
Published: September 2009

The Taiwan Chelungpu‐fault Drilling Project (TCDP) Hole‐A recovered continuous core samples across the rupture zone of the 1999 Chi‐Chi earthquake (Mw7.6). Studying in‐situ chemical properties sequentially from fresh‐fault‐zone materials of the Chelungpu fault provides insight into possible faulting mechanisms. Distinct anomalies of mineral assemblages at the 1111‐m fault zone of TCDP Hole‐A are found to be: (1) A decrease in clay content within the primary slip zone (PSZ); and (2) A significant decline of illite, disappearance of chlorite and kaolinite, and spike in smectite within the PSZ. Meanwhile, features relating to melting or amorphous material in the PSZ have been observed by SEM and TEM. The results suggest that the PSZ might have experienced generation of glassy materials such as pseudotachylyte by the expense of clay minerals due to strong shear heating, then prompt alteration of pseudotachylyte into smectite. Characteristics of clay minerals and images obtained from electronic microscopes in the PSZ thus imply that pseudotachylyte possibly developed during the 1999 Chi‐Chi earthquake, but quickly altered into smectite. This particular phenomenon may explain why pseudotachylyte is rarely found in exhumed hydrated fault zones.
Abrupt mid‐Holocene onset of centennial‐scale climate variability on the Peru‐Chile Margin
Authors: Chazen Caitlin R. , Altabet Mark A. , Herbert Timothy D.
Published: September 2009

Understanding the natural climate variations in the eastern tropical Pacific (ETP) is crucial for predicting the evolution of the El Niño‐Southern Oscillation (ENSO). Here we present the first continuous, decadal‐resolution Holocene climate record from the Peru‐Chile Margin, near the epicenter of the modern ENSO system. Geochemical proxies allow us to reconstruct sea surface temperature, phytoplankton productivity, and thermocline ventilation, variables that are tightly correlated to ENSO events today. Despite the observation that the mean state of all three variables did not change over the past 10,000 years, our data reveal a dramatic increase in climate variability near 5 ka; represented by prolonged periods (50–200 yrs) of climate extremes, which are absent in the early Holocene. These centennial‐scale oscillations do not show typical El Niño‐La Niña correlations between proxies. We therefore posit that a significant fraction of super‐ENSO variance may originate outside the tropics, through processes that ventilate the ETP subsurface waters.
Model of formation of double structure gas hydrates in Lake Baikal based on isotopic data
Authors: Hachikubo Akihiro , Khlystov Oleg , Manakov Andrey , Kida Masato , Krylov Alexey , Sakagami Hirotoshi , Minami Hirotsugu , Takahashi Nobuo , Shoji Hitoshi , Kalmychkov Gennadiy , Poort Jeffrey
Published: September 2009

We measured the isotopic compositions of methane (C1) and ethane (C2) of hydrate‐bound gas and of dissolved gas in pore water retrieved from bottom sediments in Lake Baikal. Both structure I (sI:3%C2) and II (sII:14%C2) gas hydrates are observed in the same sediment cores in Kukuy K‐2 mud volcano. We found that C2δD of sI gas hydrate is larger than that of sII, whereas C1δ13C, C1δD and C2δ13C values are practically the same in both hydrate structures. δ13C of C1 and C2 of hydrate‐bound gas are several permil smaller than those in pore water, showing that the current pore water is not the source of gas hydrates. These findings lead to a new model where the sII gas hydrates were formed prior to the sI hydrates.
Influence of sea surface temperature variability on global temperature and precipitation extremes
Authors: Alexander Lisa V. , Uotila Petteri , Nicholls Neville
Published: September 2009

The HadISST1 data set was used to categorize seasonal patterns of observed global sea surface temperature (SST) variability between 1870 and 2006 using the method of Self‐Organizing Maps (SOM). Eight patterns represented the majority of global SST variations associated with the El Niño–Southern Oscillation (ENSO). Time series of the eight patterns exhibited periods with “preferred” SST states since the late 19th century, i.e., when one or more patterns occurred more frequently than in other periods. The eight patterns were used to investigate the global land‐based response of observed extreme temperature and precipitation indices from the HadEX data set to different nodes of SST variability between 1951 and 2003. Results showed very strong statistically significant opposite temperature and precipitation extremes associated with the first pattern (strong La Niña) and the last pattern (strong El Niño). Extreme maximum temperatures were significantly cooler during strong La Niña events than strong El Niño events over Australia, southern Africa, India, and Canada while the converse was true for United States and northeastern Siberia. These responses were larger when global warming was retained. Even intermediate patterns representing a shift from a weak El Niño to a weak La Niña with associated variability in the North Atlantic were linked with statistically significant increases in warm nights and warm days particularly across Scandinavia and northwest Russia. While the link between precipitation extremes and global SST patterns was less spatially coherent, there were large areas across North America and central Europe, which showed statistically significant differences in the response to opposite phases of the El Niño–Southern Oscillation. These results confirm that the variability of global SST anomaly patterns is important for the modulation of extreme temperature and precipitation globally.
Segmentation of X‐ray computed tomography images of porous materials: A crucial step for characterization and quantitative analysis of pore structures
Authors: Iassonov Pavel , Gebrenegus Thomas , Tuller Markus
Published: September 2009

Nondestructive imaging methods such as X‐ray computed tomography (CT) yield high‐resolution, three‐dimensional representations of pore space and fluid distribution within porous materials. Steadily increasing computational capabilities and easier access to X‐ray CT facilities have contributed to a recent surge in microporous media research with objectives ranging from theoretical aspects of fluid and interfacial dynamics at the pore scale to practical applications such as dense nonaqueous phase liquid transport and dissolution. In recent years, significant efforts and resources have been devoted to improve CT technology, microscale analysis, and fluid dynamics simulations. However, the development of adequate image segmentation methods for conversion of gray scale CT volumes into a discrete form that permits quantitative characterization of pore space features and subsequent modeling of liquid distribution and flow processes seems to lag. In this paper we investigated the applicability of various thresholding and locally adaptive segmentation techniques for industrial and synchrotron X‐ray CT images of natural and artificial porous media. A comparison between directly measured and image‐derived porosities clearly demonstrates that the application of different segmentation methods as well as associated operator biases yield vastly differing results. This illustrates the importance of the segmentation step for quantitative pore space analysis and fluid dynamics modeling. Only a few of the tested methods showed promise for both industrial and synchrotron tomography. Utilization of local image information such as spatial correlation as well as the application of locally adaptive techniques yielded significantly better results.
Induction Profile of MANF/ARMET by Cerebral Ischemia and its Implication for Neuron Protection
Authors: Yu Yong-Qiang , Liu Lian-Cheng , Wang Fa-Cai , Liang Yan , Cha Da-Qin , Zhang Jing-Jing , Shen Yu-Jun , Wang Hai-Ping , Fang Shengyun , Shen Yu-Xian
Published: September 2009

Cerebral ischemia-induced accumulation of unfolded proteins in vulnerable neurons triggers endoplasmic reticulum (ER) stress. Arginine-rich, mutated in early stage tumors (ARMET) is an ER stress-inducible protein and upregulated in the early stage of cerebral ischemia. The purposes of this study were to investigate the characteristics and implications of ARMET expression induced by focal cerebral ischemia. Focal cerebral ischemia in rats was induced by right middle cerebral artery occlusion with a suture; ischemic lesions were assessed by magnetic resonance imaging and histology; neuronal apoptosis was determined by TUNEL staining; the expressions of proteins were measured by immunohistochemistry, immunofluorescent labeling, and Western blotting. ARMET was found to be extensively upregulated in ischemic regions in a time-dependent manner. The expression of ARMET was neuronal in all examined structures in response to the ischemic insult. We also found that ARMET expression is earlier and more sensitive to ischemic stimulation than C/EBP homologous protein (CHOP). ER stress agent tunicamycin induced ARMET and CHOP expressions in the primary cultured neurons. Treatment with recombinant human ARMET promoted neuron proliferation and prevented from neuron apoptosis induced by tunicamycin. These results suggest that cerebral ischemia-induced ARMET expression may be protective to the neurons.
Autologous Bone Marrow Mononuclear Cells Enhance Recovery after Acute Ischemic Stroke in Young and Middle-Aged Rats
Authors: Brenneman Miranda , Sharma Sushil , Harting Matthew , Strong Roger , Cox Charles S , Aronowski Jarek , Grotta James C , Savitz Sean I
Published: September 2009

We investigated intra-arterially administered autologous bone marrow mononuclear cells (MNCs) in rats with acute ischemic stroke. Long Evans rats (2 to 3 months or 12 months old) underwent tandem reversible common carotid artery (CCA)/middle cerebral artery (MCA) occlusion (CCAo/MCAo) for 3 h and then 24 h later underwent tibial bone marrow harvest. Ten million or 4 million cells were re-injected by an intra-carotid infusion. Control animals underwent marrow needle insertion and then saline injection into the carotid artery. Animals were assessed on a battery of neurological tests. MNCs in the ischemic brain were tracked using Q-dot nanocrystal labeling. Infarct volume and cytokines in the ischemia-affected brain were analyzed. Cell-treated animals in the younger and older groups showed improvement from 7 to 30 days after stroke compared with vehicle-treated animals. MNCs significantly reduced infarct volume compared with saline. There was a significant reduction in tumor necrosis factor-α, interleukin-1α (IL-1α), IL-β, IL-6, and a significant increase in IL-10 in injured brains harvested from the cell-treated groups compared with saline controls. Labeled MNCs were found in the peri-infarcted area at 1 h and exponentially decreased over the ensuing week after injection. Autologous bone marrow MNCs can be safely harvested from rodents after stroke, migrate to the peri-infarct area, enhance recovery, and modulate the post-ischemic inflammatory response.
Electrocaloric devices based on thin-film heat switches
Authors: Epstein Richard I. , Malloy Kevin J.
Published: September 2009

We describe a new approach to refrigeration, heat pumping, and electrical generation that allows one to exploit the attractive properties of thin films of electrocaloric materials. Layers of electrocaloric material coupled with thin-film heat switches can work as either refrigerators and heat pumps or electrical generators, depending on the phasing of the applied voltages and heat switching. With heat switches based on thin layers of liquid crystals, the efficiency of electrocaloric thin-film devices can be at least as high as that of current thermoelectric devices. Advanced heat switches that may use carbon nanotubes would enable thin-film refrigerators and generators to outperform conventional vapor-compression devices.
Growth and properties of epitaxial GdN
Authors: Ludbrook B. M. , Farrell I. L. , Kuebel M. , Ruck B. J. , Preston A. R. H. , Trodahl H. J. , Ranno L. , Reeves R. J. , Durbin S. M.
Published: September 2009

Epitaxial gadolinium nitride films with well-oriented crystallites of up to 30 nm have been grown on yttria-stabilized ziconia substrates using a plasma-assisted pulsed laser deposition technique. We observe that the epitaxial GdN growth proceeds on top of a gadolinium oxide buffer layer that forms via reaction between deposited Gd and mobile oxygen from the substrate. Hall effect measurements show the films are electron doped to degeneracy, with carrier concentrations of 4×1020 cm−3. Magnetic measurements establish a TC of 70 K with a coercive field that can be tuned from 200 Oe to as low as 10 Oe.
Observations of proton beam enhancement due to erbium hydride on gold foil targets
Authors: Offermann D. T. , Freeman R. R. , Van Woerkom L. D. , Foord M. E. , Hey D. , Key M. H. , Mackinnon A. J. , MacPhee A. G. , Patel P. K. , Ping Y. , Sanchez J. J. , Shen N. , Bartal T. , Beg F. N. , Espada L. , Chen C. D.
Published: September 2009

Recent theoretical work suggests that the conversion efficiency from laser to protons in laser irradiated thin foil experiments increases if the atomic mass of nonhydrogen atoms on the foil rear surface increases. Experiments were performed at the Lawrence Livermore National Laboratory Jupiter Laser Facility to observe the effect of thin foils coated with erbium hydride on the conversion efficiency from laser to protons. Gold foils with and without the rear surface coated with ErH3 were irradiated using the ultrashort pulse, 40 TW Callisto laser. An argon-ion etching system was used to remove naturally occurring nanometer thick surface layer contaminants from the hydride. With the etcher, gold with ErH3 showed a 25% increase in the conversion efficiency to protons above 3.4 MeV relative to contaminants, where C+4 and H+ were the dominant ion species. No difference in the ion signal was observed without first cleaning the hydrides. Simulations using the hybrid PIC code, LSP, revealed that the increase due to erbium hydride versus contaminants is 37% for protons above 3 MeV.
Internal residual stress studies and enhanced dielectric properties in La0.7Sr0.3CoO3 buffered (Ba,Sr)TiO3 thin films
Authors: Lu Shengbo , Xu Zhengkui
Published: September 2009

Ba 0.6 Sr 0.4 TiO 3 (BST) thin films were deposited on La0.7Sr0.3CoO3 (LSCO) buffered and unbuffered Pt (111)/Ti/SiO2/Si substrates by pulsed laser deposition. The former exhibits a (100) preferred orientation and the latter a random orientation, respectively. Grazing incident x-ray diffraction study revealed that the tensile residual stress observed in the latter is markedly reduced in the former. As a result, the dielectric property of the LSCO buffered BST thin film is greatly improved, which shows a larger dielectric constant and tunability, smaller loss tangent, and lower leakage current than those of the unbuffered BST thin film. The relaxation of the larger tensile residual stress is attributed to the larger grain size in the buffered BST thin film and to a closer match of thermal expansion coefficient between the BST and the LSCO buffer layer.
Metal clusters with hidden ground states: Melting and structural transitions in Al115+, Al116+, and Al117+
Authors: Cao Baopeng , Starace Anne K. , Judd Oscar H. , Bhattacharyya Indrani , Jarrold Martin F.
Published: September 2009

Heat capacities measured as a function of temperature for Al115+, Al116+, and Al117+ show two well-resolved peaks, at around 450 and 600 K. After being annealed to 523 K (a temperature between the two peaks) or to 773 K (well above both peaks), the high temperature peak remains unchanged but the low temperature peak disappears. After considering the possible explanations, the low temperature peak is attributed to a structural transition and the high temperature peak to the melting of the higher enthalpy structure generated by the structural transition. The annealing results show that the liquid clusters freeze exclusively into the higher enthalpy structure and that the lower enthalpy structure is not accessible from the higher enthalpy one on the timescale of the experiments. We suggest that the low enthalpy structure observed before annealing results from epitaxy, where the smaller clusters act as a nucleus and follow a growth pattern that provides access to the low enthalpy structure. The solid-to-solid transition that leads to the low temperature peak in the heat capacity does not occur under equilibrium but requires a superheated solid.
Time correlation functions via forward-backward quantum dynamics using Hamilton’s law of varying action
Authors: Chen Jonathan , Makri Nancy
Published: September 2009

We introduce a stable numerical procedure for solving Bohm’s equations of motion to compute quantum trajectories in the forward-backward quantum dynamics (FBQD) formulation of zero-temperature time correlation functions. Rather than integrating the differential equations forward in time, our method is based on a series expansion of the quantum trajectory, exploiting Hamilton’s law of varying action to determine the expansion coefficients. Because in FBQD the quantum trajectories generally are smooth and the quantum potential is well behaved, our method allows accurate determination of time correlation functions in strongly anharmonic bound systems over several oscillation periods.
Magnetic monopole and string excitations in two-dimensional spin ice
Authors: Mól L. A. , Silva R. L. , Silva R. C. , Pereira A. R. , Moura-Melo W. A. , Costa B. V.
Published: September 2009

We study the magnetic excitations of a square lattice spin ice recently produced in an artificial form as an array of nanoscale magnets. Our analysis, based on the dipolar interaction between the nanomagnetic islands, correctly reproduces the ground state observed experimentally. In addition, we find magnetic monopolelike excitations effectively interacting by means of the usual Coulombic plus a linear confining potential, the latter being related to a stringlike excitation binding the monopoles pairs, which indicates that the fractionalization of magnetic dipoles may not be so easy in two dimensions. These findings contrast this material with the three-dimensional analog, where such monopoles experience only the Coulombic interaction. We discuss, however, two entropic effects that affect the monopole interactions. First, the string configurational entropy may lose the string tension and then free magnetic monopoles should also be found in lower dimensional spin ices; second, in contrast to the string configurational entropy, an entropically driven Coulomb force, which increases with temperature, has the opposite effect of confining the magnetic defects.
Impurities in synthetic fluorite for deep ultraviolet optical applications
Authors: Sils J. , Hausfeld S. , Clauß W. , Pahl U. , Lindner R. , Reichling M.
Published: September 2009

The impurity content of synthetic calciumdifluoride (fluorite, CaF2) single crystals produced for optical applications in the deep ultraviolet (DUV) and infrared (IR) spectral regions are investigated by luminescence and absorption spectroscopy. Lead, oxygen, and rare earth (RE) ions, namely, trivalent (Ce3+, Pr3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, and Yb3+) and divalent (Eu2+) are identified as common impurities. RE ions are dominating impurities in the IR grade sample and the impurity concentration for this sample is found to be about 100 times higher than the one for DUV samples. Due to the strongly reduced RE luminescence background, we additionally identify lead and oxygen in DUV grade crystals. Remarkable differences in the luminescence spectra are found when comparing DUV grade crystals from different sources.
Concentration-dependent near-infrared quantum cutting in NaYF4:Pr3+, Yb3+ phosphor
Authors: Chen X. P. , Huang X. Y. , Zhang Q. Y.
Published: September 2009

Near-infrared quantum cutting phenomenon has been demonstrated in Pr3+–Yb3+-codoped NaYF4 microcrystals synthesized by a facile hydrothermal route, which involves the emission of two near-infrared photons from an absorbed blue photon via a cooperative downconversion process. The Pr3+–Yb3+ energy transfer mechanisms have been identified by the dependence of Yb3+ doping concentration on the visible and infrared emissions, decay lifetime, and quantum efficiency. Upon excitation of Pr3+ ions with a blue photon at 443 nm, Yb3+ ions emit two near-infrared photons at 977 nm with an optimal quantum efficiency of 133.6%. The excellent luminescence properties of NaYF4:Pr3+, Yb3+ microcrystal demonstrate its potentiality to become identified as a better candidate for application as downconversion layer on the top of crystalline silicon solar cell panels in order to reduce thermalization loss.
Effect of Mn doping on electric and magnetic properties of BiFeO3 thin films by chemical solution deposition
Authors: Huang Ji-Zhou , Wang Yao , Lin Yuanhua , Li Ming , Nan C. W.
Published: September 2009

The effect of Mn doping on crystal structure, electric and magnetic properties of BiFeO3 thin films prepared via a chemical deposition method on (111) Pt/Ti/SiO2/Si substrates was studied. The substitution of Fe ions by a small amount (5%) of Mn ions could facilitate the stabilization of Fe3+ in BiFeO3 thin films, while larger substitution (e.g., 10% and 15% Mn substitution) could lead to the increase in Fe2+ concentration. Well saturated polarization hysteresis loops were observed in the Mn-doped BiFeO3 films, with remanent polarization value of 32 μC/cm2 and 53 μC/cm2 for the 5% and 10% Mn-doped BiFeO3 films, respectively. Mn substitution also affect ferroelectric domain structures and microstructures of the films. It was observed that Mn substitution does not affect the intrinsic weak magnetism of BiFeO3. The enhanced ferroelectric and weak magnetic behaviors by Mn substitution were further studied through the analysis of the bonding state of Fe and Mn ions.
Maximum and overlapped photonic band gaps in both transverse electric and transverse magnetic polarizations in two-dimensional photonic crystals with low symmetry
Authors: Ohlinger Kris , Lin Yuankun , Qualls Jeremy S.
Published: September 2009

In this paper, photonic band gaps have been systematically calculated for two-dimensional photonic crystals in centered rectangular lattices with elliptical patterns for both transverse electric and transverse magnetic polarizations. Two-dimensional centered rectangular lattices can be considered to be a stretched or compressed form of the hexagonal lattice with lower symmetry. For infinitely thick two-dimensional photonic crystals, the maximum overlapped photonic band gaps for both transverse electric and transverse magnetic polarizations occur in the well-studied hexagonal lattice. However, the maximum overlapped band gap happens in centered rectangular lattices with elliptical patterns for two-dimensional photonic crystal slabs, supporting other studies that reducing symmetry can open overlapped photonic band gaps.
Mechanisms for high internal quantum efficiency of ZnO nanorods
Authors: Al-Suleiman M. A. M. , Bakin A. , Waag A.
Published: September 2009

We investigate the photoluminescence properties of ZnO nanorods grown by vapor phase epitaxy. The room temperature photoluminescence spectra exhibit an energy shift of about 80 meV to lower energy in comparison with that of bulk ZnO as well as ZnO epilayers. The emission band observed at 3.31 eV at low temperature dominates the photoluminescence at room temperature. The high internal quantum efficiency of about 33% is explained in terms of this band, which seems to result from excitons bound to surface defect states.
Avalanche photodiode punch-through gain determination through excess noise analysis
Authors: Liu Han-Din , Pan Huapu , Hu Chong , McIntosh Dion , Lu Zhiwen , Campbell Joe , Kang Yimin , Morse Mike
Published: September 2009

A new approach to determine the multiplication gain at punch-through for an avalanche photodiode with separate absorption and multiplication regions from excess noise measurement is discussed. Correctly determining the gain at punch-through is crucial for characterizing performance parameters of this type of avalanche photodiode. In order to illustrate the viability of this technique, in this work, a Ge on Si avalanche photodiode is analyzed. At a punch-through bias of 15 V, the multiplication gain was determined to be ∼1.54 while a simulation based on the device structure yielded a punch-through gain of 1.65.
Electrode effects on the conduction mechanisms in HfO2-based metal-insulator-metal capacitors
Authors: El Kamel F. , Gonon P. , Vallée C. , Jorel C.
Published: September 2009

The impact of top-electrode metal on the conduction mechanisms of HfO2 thin films-based metal-insulator-metal capacitors was investigated at temperature ranging from 25 to 150 °C. Al, Cr, and Au are considered as top electrodes whereas Pt constitutes the commune bottom electrode. It was found for both capacitors that in the high field region, the leakage mechanism is electrode-limited. The leakage current, measured at the Al/HfO2 and Cr/HfO2 interfaces, was largely governed by Fowler–Nordheim tunneling in the whole measured temperature range. The barrier heights, at the Al/HfO2 and the Cr/HfO2 interfaces, were around 0.77 and 0.95 eV, respectively. In the case of Au/HfO2/Pt capacitors, the Au/HfO2 interface acts as a Schottky barrier with a height of 1.06 eV.
Fermi acceleration and scaling properties of a time dependent oval billiard
Authors: Leonel Edson D. , Oliveira Diego F. M. , Loskutov Alexander
Published: September 2009

We consider the phenomenon of Fermi acceleration for a classical particle inside an area with a closed boundary of oval shape. The boundary is considered to be periodically time varying and collisions of the particle with the boundary are assumed to be elastic. It is shown that the breathing geometry causes the particle to experience Fermi acceleration with a growing exponent rather smaller as compared to the no breathing case. Some dynamical properties of the particle’s velocity are discussed in the framework of scaling analysis.
Single molecule power-law behavior on a crystalline surface
Authors: Schirra Laura K. , Tackett Brandon S. , Blumenfeld Michael L. , Monti Oliver L. A.
Published: September 2009

Single perylene bisimide molecules deposited onto Al2O3 (0001) and investigated under controlled ultrahigh vacuum conditions display fluorescence intermittency behavior characteristic of an interfacial charge transfer process. Remarkably, even though the molecules are deposited on a crystalline surface with reduced disorder, power-law-distributed bright and dark periods are observed. These data can be understood based on activated formation of localized small polaron states in Al2O3 (0001). We present a kinetic scheme capable of explaining the occurrence of power-law distributions for both “on” and “off” periods for single molecules on the sapphire substrate. These findings represent a first step toward understanding interfacial charge transfer processes under controlled conditions on crystalline surfaces and at the single molecule level.
Modeling the polaronic nature of p-type defects in Cu2O: The failure of GGA and GGA+U
Authors: Scanlon David O. , Morgan Benjamin J. , Watson Graeme W.
Published: September 2009

The exact nature of the hole traps reported deep in the band gap of Cu2O has been a topic of vigorous debate, with copper vacancies and oxygen interstitials both having been proposed as the relevant defects. In this article, the electronic structure of acceptor-forming defects in Cu2O, namely, copper vacancies and oxygen interstitials, is investigated using generalized gradient approximation (GGA) and GGA corrected for on-site Coulombic interactions (GGA+U). GGA produces notionally semimetallic defect complexes, which is not consistent with the experimentally known polaronic nature of conduction in Cu2O. GGA+U also predicts a semimetallic defect complex for the “simple” copper vacancy but predicts the “split” vacancy and both oxygen interstitials are characterized by localized polarons, with distinct single particle levels found in the band gap. For both methods, however, the positions of calculated transition levels are inconsistent with experimental ionization levels. Hence neither GGA nor GGA+U are successful in modeling p-type defects in Cu2O.