bluuebunny/crossref_metadata_2025 huggingface dataset:
Foxes and Myxomatosis in Kent
Authors: Cobnut G.
Published: September 2009

We shot or otherwise took over 100 foxes in this area during the spring. I opened a great many of them and, apart from a few odd ones, the diet appeared to have gone over to the same as the badger, omnivorous. There is no doubt that foxes are eating quite a lot of vegetable matter where the rabbits have disappeared due to disease, but I have never seen better and healthier foxes than of late, with two exceptions, which, of course, one normally expects, for there are always odd wasters in all species of animals and birds. Those which had full stomachs have invariably contained poultry and/or game, and once a coot, but by far the greater number had empty stomachs with intestines usually full of faeces, mostly vegetable matter. From this I deduce that their varied diet goes through them quickly but is ample to keep them in first-class order. The one exceptional stomach, of a vixen, was full of grass! There has been no case of malnutrition or food-crazy foxes, they are behaving quite normally.
Animal Ways
Authors: Poles W. E.
Published: September 2009

Lions.—One day I found a pride of fifteen lions gathered round the putrid remains of a hippo cow, lying in shallow water at the edge of a wide sand bank. Dozens of crocodiles, attracted by the tainted air and water, lay basking on the sand, the nearest within twenty yards of the lions. The animals were so engrossed in their affairs, two old males growling and snarling at one another across the carcase, that I was able to stalk them over the bare sand and approach sufficiently closely to photograph them, though not so near as to anything like fill my viewfinder.
The Plight of the Barren-Ground Caribou
Authors: Banfield A. W. F.
Published: September 2009

The caribou is a typical Arctic animal, like a reindeer but with longer legs. In late autumn both animals appear very sturdy because of lengthening hair and accumulating fat. The caribou is specially adapted to its environment in many ways; its large broad hoofs support its weight on crusted snow and the concavity of the sole of the hoof makes it sure-footed on ice.
Some National Parks of North America
Authors: Gee E. P.
Published: September 2009

There was a story told sometime during the last century of an old and impoverished North American prospector, who was asked on his return, what he had to show for all the time he had spent out west. His answer was “I have seen the Rocky Mountains”. I myself have recently returned from a tour of some of the national parks of North America and the impression of wildness, grandeur and beauty remains.
Exploitation and Conservation of Seals in South Georgia
Authors: Bonner W. Nigel
Published: September 2009

Almost from the date of their discovery by Captain Cook in 1775 the seal stocks of South Georgia have formed the basis of a lucrative, though initially sporadic, industry.

South Georgia lies between 54 degrees and 55 degrees South and between 36 degrees and 38 degrees West. Despite its low latitude it has an antarctic climate, being south of the Antarctic Convergence at all seasons of the year. True sea ice is probably never formed on any of its coasts though enormous quantities of brash ice from the many glaciers may frequently obstruct access to certain beaches. Meteorological observations are made at King Edward Cove, a sheltered spot on the north-east coast, which does not perhaps represent truly the severity of the climate. In 1953 the average temperature throughout the year was 35·6 degrees F. and the extreme minimum recorded was 10 degrees F. in July. Almost certainly the exposed parts of the coast, particularly on the south-west side, frequently experience temperatures below zero. Violent winds are common. In 1953 the mean wind-speed was 8·9 knots and precipitation, mostly in the form of snow, amounted to 1,257·6 mm. The pattern of the climate of South Georgia is delineated by the relatively low temperatures, the prevailing high winds and the heavy precipitation.
Through the lens of the polar years: changing characteristics of polar research in historical perspective
Authors: Elzinga Aant
Published: September 2009

The four polar years are used as windows for highlighting changes in the character of polar research over the past 125 years. The approach taken may be seen as one of an archaeology of knowledge. As such it fixes on four separate strata in the history of science and seeks to lay bare distinctive features in each of these. To simplify, the focus is selective, mainly presenting three types of aspect for each year. The first is the character of the instruments and research technologies employed in each, and the second is the kinds of problems tackled, while the third is the associated view or ideal of science that stands out. The latter aspect has to do with epistemology. The paper suggests that whereas work during the first International Polar Year (IPY) reflected an empirical inductivist philosophy of science, during the second IPY a mix of problem oriented, and hypothesis driven, approaches existed alongside inductivism. By the time of the International Geophysical Year (IGY) the theoretical foundations of polar research had grown stronger and much of the focus had shifted to larger scale geophysical processes. Finally, today's ambition to develop an integrated Earth system science reflects an ideal that is systemic, constructivist and predictive. Such epistemological features are evident in some of the most advanced forms of computer aided analysis of Arctic and Antarctic processes, as well as in visualisation methodologies used to interpret and present data, concepts, models and theories. This latest approach is evident in some of the planning and agenda setting documents generated under the auspices of the current IPY.
Emperor penguin colonies in the Australian Antarctic Territory: how many are there?
Authors: Wienecke Barbara
Published: September 2009

Emperor penguinsAptenodytes forsteriare endemic to Antarctica. Their breeding colonies are located in the coastal areas of the continent. The precise number of breeding locations is uncertain. This paper examines what is known about the colonies in the Australian Antarctic Territory and examines which colonies are without doubt breeding locations and which ones require further examination in order to determine their existence and status. Several colonies have not been seen since they were first reported. This begs the question of whether the reported sightings were indeed of breeding colonies. Given the extent of uncertainty with regard to the number of colonies, it is suggested that the listing of the species by the International Union for the Conservation of Nature be changed from ‘of least concern’ to ‘data deficient’.
Incomplete search effort: a potential source of bias in estimates of Adélie penguin breeding populations in the Australian Antarctic Territory
Authors: Southwell Colin , Smith David , Bender Angela
Published: September 2009

Potential Adélie penguin Pygoscelis adeliae breeding habitat in the Australian Antarctic Territory (AAT: 45°E–136°E, 142°E–160°E) was mapped using a geographic information system (GIS), and the literature reviewed for evidence of the mapped habitat being searched for presence or absence of breeding Adélie penguins. It is concluded that incomplete search effort is a possible source of substantial negative bias of Adélie penguin breeding abundance derived from published count data in some regions of the AAT. The extent of search effort in other regions of Antarctica could be determined using the same approach applied here, because GIS data required for mapping potential habitat are available for the entire continent. We would expect that regions with more scientific and tourist activity, such as the Antarctic Peninsula, are likely to have greater search effort than the AAT.
Making Choices
Authors: Caprioli Mary
Published: September 2009

Not everything that counts can be counted, and not everything that can be counted counts.

— Albert Einstein

I never thought I would be considered a quantitative scholar. When I took my first statistics course in graduate school, I just did not ask the types of questions that required statistical analysis. I was interested in women in development, issues of power and powerlessness, and violence against women—not issues that are readily quantifiable. As you can imagine, I quickly learned how to ask the “right” questions. This all occurred when the democratic peace thesis began to take on a life of its own, and I reasoned that norms of inequality and injustice must surely transfer to the international arena, much the same way as those positive democratic norms are theorized to do (see Hudson et al. 2008/9). So I decided I would study conflict and war, which were readily quantifiable. And I would incorporate measures of women's equality. Thus, by some twist of fate, I chose quantitative methods as one of my testing fields and became a scholar interested in bridging the gap between feminist international relations theory and traditional international relations theory using quantitative methods.
Global hydrographic variability patterns during 2003–2008
Authors: von Schuckmann K. , Gaillard F. , Le Traon P.‐Y.
Published: September 2009

Monthly gridded global temperature and salinity fields from the near‐surface layer down to 2000 m depth based on Argo measurements are used to analyze large‐scale variability patterns on annual to interannual time scales during the years 2003–2008. Previous estimates of global hydrographic fluctuations have been derived using different data sets, partly on the basis of scarce sampling. The substantial advantage of this study includes a detailed summary of global variability patterns based on a single and more uniform database. In the upper 400 m, regions of strong seasonal salinity changes differ from regions of strong seasonal temperature changes, and large amplitudes of seasonal salinity are observed in the upper tropical and subpolar global ocean. Strong interannual and decadal changes superimpose long‐term changes at northern midlatitudes. In the subtropical and tropical basin, interannual fluctuations dominate the upper 500 m depth. At southern midlatitudes, hydrographic changes occur on interannual and decadal time scales, while long‐term changes are predominantly observed in the salinity field. Global mean heat content and steric height changes are clearly associated with a positive trend during the 6 years of measurements. The global 6‐year trend of steric height deduced from in situ measurements explains 40% of the satellite‐derived quantities. The global freshwater content does not show a significant trend and is dominated by interannual variability.
A comparison of low pressure system statistics derived from a high‐resolution NWP output and three reanalysis products over the Southern Ocean
Authors: Uotila P. , Pezza A. B. , Cassano J. J. , Keay K. , Lynch A. H.
Published: September 2009

Low pressure system statistics derived from the Antarctic Mesoscale Prediction System (AMPS) and NCEP, NCEP2, and JRA25 reanalysis products are compared by using an automatic cyclone tracking scheme. Since AMPS model spatial and temporal resolutions are much higher than the ones of the reanalyses, this study provides a valuable insight of the ability of numerical models to simulate low pressure systems with an increasing resolution. Results based on AMPS data agree relatively well with reanalyses‐based results when looking at the seasonal variability and spatial patterns of low pressure system properties over large scales. Results differ systematically close to the Antarctic ice sheet, where the horizontal resolution is important in resolving the continental topography. This appears as lower AMPS system densities and smaller system sizes close to the Antarctic coast. Results differ most during winter when the correct parameterization of surface energy balance is crucial over the sea‐ice covered ocean. AMPS data show more systems at around and south of 60°S in the Antarctic Circumpolar Trough, where reanalyses display systems of larger size. Earlier studies of cyclonic systems over the Southern Ocean show that there is a spectrum of atmospheric systems, where small synoptic systems merge into mesoscale lows. Accordingly, a high‐resolution model setup with appropriate physics parameterization, like AMPS, is required to generate small systems. This study highlights that when new data become available it is important to update low pressure system statistics to gain a better understanding of high‐latitude processes over intermediate scales.
Extratropical stratosphere‐troposphere exchange in an AGCM with the horizontal grid size of 20 km
Authors: Mizuta Ryo , Yoshimura Hiromasa
Published: September 2009

The transport and exchange process across the extratropical tropopause is investigated using an atmospheric global climate model with a horizontal grid size of about 20 km, which can depict filamental structures near the tropopause. The advection of an idealized passive tracer, which is initialized to have a nonzero value only above the tropopause, is calculated in January and July in the Northern Hemisphere. A version of the model with coarse resolution is used to examine the horizontal resolution dependence. The exchange between the stratosphere and the troposphere has its maximum amounts at 300 hPa in January and at 200–250 hPa in July. Above 400 hPa, the amount of exchange in the 20‐km model is about one‐half of that of the 180‐km model, in accordance with the existence of a sharp tropopause. In contrast, the amount in the 20‐km model below 400 hPa is more than that in the 180‐km model, partly due to the inability of simulating filamental structures along with the storms in the 180‐km model. However, the net transport across the tropopause does not have large dependence on the horizontal resolution. The net transport below 400 hPa is from the stratosphere to the troposphere and is large over the Pacific and Atlantic storm track in January. The net troposphere to stratosphere transport is seen above 300 hPa and is large near the subtropical jet over the Eurasian continent. A large part of this transport is attributed to the temporal change of the potential vorticity estimated from a vertical difference in the longwave radiation.
Analysis of planetary boundary layer fluxes and land‐atmosphere coupling in the regional climate model CLM
Authors: Jaeger E. B. , Stöckli R. , Seneviratne S. I.
Published: September 2009

Land‐atmosphere interactions and associated boundary layer processes are crucial elements of the climate system and play a major role in several feedback processes, in particular for extreme events. In this article, we provide a detailed validation of land surface processes and land‐atmosphere interactions in the climate version of the Lokal Modell (CLM), a regional climate model that has been recently developed and is now used by a wide research community. For the evaluation of the model, we use observations from the FLUXNET network and meteorological data. Moreover, we also compare the performance of the CLM with that of its driving data set, the European Centre for Medium‐Range Weather Forecasts (ECMWF) operational analysis, and simulations of the Inter‐Continental Transferability Study (ICTS). The results show that most of the land‐atmosphere coupling characteristics are consistent in CLM and the observations. Nonetheless, the analysis also allows identification of specific weaknesses of the CLM such as an underestimation of the incoming surface shortwave radiation due to cloud cover overestimation, leading to an underestimation of the sensible heat flux. The comparisons with the ECMWF operational analysis and the ICTS models suggest, however, that all models have biases of comparable magnitude. This study demonstrates the utility of flux observations for diagnosing biases in land‐atmosphere exchanges and interactions in current climate models and highlights perspectives for our improved understanding of the relevant processes.
Giving Advice: Enough Is Enough After Three Solar Cycles
Authors: Mendillo Michael
Published: September 2009

On 1 July 2008, I concluded my 6‐year term of service as president‐elect, president, and past‐president of AGU's Space Physics and Aeronomy (SPA) section. I truly appreciated the trust and confidence placed in me by the SPA electorate, and I greatly enjoyed this unique period of professional service. To have sufficient time to be fully engaged in SPA and AGU matters, I had taken a 6‐year leave of service from advisory committees at NASA, the U.S. National Science Foundation, the Space Studies Board of the U.S. National Academy of Sciences (NAS), Department of Defense laboratories, and grant panels at all U.S. federal agencies.
Planning for a Soil Moisture Satellite Mission: SMAP Algorithms & Cal/Val Workshop; Oxnard, California, 9–11 June 2009
Authors: Moghaddam Mahta , Jackson Thomas
Published: September 2009

The Soil Moisture Active and Passive (SMAP) mission aims to gather high‐resolution global soil moisture and freeze/thaw state data, which should enable improvements to weather and climate forecasts, flood prediction and drought monitoring, and estimations of net carbon dioxide (CO2) uptake in forested regions. Targeted for launch in 2014, SMAP is one of four missions recommended by the U.S. National Research Council Committee on Earth Science and Applications From Space for launch in the early part of the next decade (Earth Science and Applications From Space: National Imperatives for the Next Decade and Beyond, Natl. Acad. Press, 2007).

The SMAP mission concept utilizes an L‐band (1.20–1.41 gigahertz) radar and a radiometer that share a rotating 6‐meter mesh reflector antenna to provide high‐resolution and high‐accuracy global maps of soil moisture and freeze/thaw state every 2–3 days.
New Methods to Integrate Paleodata Into Climate Models: Data‐Assimilation Techniques for Paleoclimate Data; Vienna, Austria, 25 April 2009
Authors: Otto‐Bliesner Bette L. , Schulz Michael
Published: September 2009

Data assimilation has become an important approach for estimating or forecasting the state of the atmosphere and oceans. This method, though, is difficult to apply to paleodata due to their sparse spatial distribution and the uncertainties associated with proxy reconstructions. To debate the applicability of the various techniques in a paleoclimate context, a group of 12 scientists from Europe, Japan, and the United States convened at a workshop in Vienna.
The Importance of Long‐term Preservation and Accessibility of Geophysical Data
Authors: Anonymous
Published: September 2009

Earth and space science data collection, analysis, and archiving are essential to our understanding of the natural environment and how it changes with time. AGU policy is grounded in the principle of full and open sharing of such data and associated metadata for research and education. Adherence to this policy will foster scientific advances, yield economic benefits, improve decision‐making, enhance public safety and wellbeing, contribute to national and global security, and lead to a more informed public.
Atmospheric Science for Environmental Scientists
Authors: Anyah Richard
Published: September 2009

Concepts in atmospheric and environmental sciences are intimately connected, but the two disciplines are often treated as if they are only thinly interrelated. Atmospheric Science for Environmental Scientists dispenses with such unrealistic separations between the atmosphere and the environment by delving into concepts that link atmospheric dynamics, chemistry, and dispersion to the environment. With a fashionable and consistent layout, the book comprises 11 well‐written chapters contributed by renowned experts in atmospheric chemistry, air pollution, climate change science, and boundary layer physics. In an uncommonly detailed fashion, the book weaves together atmospheric and environmental science concepts, especially those related to atmospheric chemistry and dispersion as well as the long‐term climatic factors and short‐term planetary boundary layer dynamics and physics that affect coupled biosphere‐atmosphere variability.
Reactivation of an Archean craton: Constraints from P‐ and S‐wave tomography in North China
Authors: Zhao Liang , Allen Richard M. , Zheng Tianyu , Hung Shu‐Huei
Published: September 2009

The unusual reactivation of the North China Craton (NCC) challenges the classical views concerning the strength and stability of cratonic lithosphere. By using teleseismic body‐waves recorded at 250 seismic stations, this paper presents high‐resolution North China Models of P‐ and S‐wave velocity based on finite‐frequency kernel tomography. Both P‐ and S‐wave velocity models reveal that: (1) an obvious N–S trending narrow low‐velocity region is located at the base of the lithosphere beneath the Central Block (CB) of the NCC, which extends to more than 500 km depth; (2) a region of high‐velocity extends to more than 250–300 km depth beneath the Western Block, in contrast to the much shallower high‐velocity zones beneath the CB and shallower high‐velocities beneath the Eastern Block. These features suggest that warm mantle material with a source at least as deep as the transition zone, possibly a mantle plume, may be responsible for the reactivation of the NCC. The Central Block may have behaved as a sublithospheric corridor for the warm mantle material due to its pre‐existing weakness.
Retrieval characteristics of non‐linear sea surface temperature from the Advanced Very High Resolution Radiometer
Authors: Merchant C. J. , Harris A. R. , Roquet H. , Le Borgne P.
Published: September 2009

Criteria are proposed for evaluating sea surface temperature (SST) retrieved from satellite infra‐red imagery: bias should be small on regional scales; sensitivity to atmospheric humidity should be small; and sensitivity of retrieved SST to surface temperature should be close to 1 K K−1. Their application is illustrated for non‐linear sea surface temperature (NLSST) estimates. 233929 observations from the Advanced Very High Resolution Radiometer (AVHRR) on Metop‐A are matched with in situ data and numerical weather prediction (NWP) fields. NLSST coefficients derived from these matches have regional biases from −0.5 to +0.3 K. Using radiative transfer modelling we find that a 10% increase in humidity alone can change the retrieved NLSST by between −0.5 K and +0.1 K. A 1 K increase in SST changes NLSST by <0.5 K in extreme cases. The validity of estimates of sensitivity by radiative transfer modelling is confirmed empirically.
Isotopic ratios in gas‐phase HNO3 and snow nitrate at Summit, Greenland
Authors: Jarvis Julia C. , Hastings Meredith G. , Steig Eric J. , Kunasek Shelley A.
Published: September 2009

Measurements of the isotope ratios of snow nitrate and atmospheric gas‐phase HNO3 (15N/14N and 18O/16O) from Summit, Greenland provide new observational constraints on postdepositional processing of snowpack nitrate. The δ15N of NO3− is similar in surface snow and in air sampled 1.5 m above the snow surface during Spring and Summer 2006, ranging between −15 and +6‰ versus N2. The δ18O of NO3−, however, is ∼40‰ higher in surface snow than air samples. Photochemical box modeling of HNO3 chemistry at Summit suggests that the δ18O of the air samples is derived predominantly from gas‐phase HNO3 originating from photolyzed snow nitrate. Measurements of isotopically labeled nitrate in surface snow confirm that photolytic recycling of snowpack nitrate, in which photolyzed nitrate products recombine to form HNO3 that is subsequently redeposited to the snow surface, does occur at Summit. Calculations incorporating these measurements suggest that photolytic recycling of snow nitrate at Summit will have a maximum −7.5‰ change on the δ18O of nitrate buried in snow, while photolytic loss of snow nitrate will decrease the δ18O of buried nitrate by 0.9‰. Photolytic recycling and loss will increase the δ15N of buried snow nitrate, the degree to which depends on the nitrogen isotope fractionation of nitrate photolysis. Finally, a comparison of surface snow and snowpit samples demonstrates the preservation of the seasonal cycle in isotope ratios of snow nitrate.
Factors influencing immature Dermacentor variabilis burdens on white-footed mice (Peromyscus leucopus)
Authors: Dallas Tad , Fore Stephanie , Kim Hyun-Joo , Peng Mary , Henderson Jake , Mueller Georgia , Fielden Laura
Published: September 2009

The host-parasite relationship is an important and complex ecological interaction.Parasite load affects pathogen transfer and can influence host fitness. Mice werelive trapped in three night trapping sessions conducted on two permanent gridsevery other month from June 2006 to December 2008. Grids were established inan old field and an early successional forest each with 104 sampling points. Datawere analyzed with negative binomial regression. Gender and body size both hadsignificant effects on tick load (P =0.012 and P =0.029, respectively), with males andlarger hosts harboring more immature ticks. However, body size and gender werenot significantly related with one another (P = 0.234). The data were also found tofollow the 80/20 rule, in which less than 20% of the hosts harbor 80% of on-hostimmature D. variabilis.
Invasional conflict: Do invasive insect herbivores mediate the effects of enemy release for their invasive plant hosts?
Authors: Bohl Kerry , Stiling Peter
Published: September 2009

Although many factors have been proposed that potentially contribute to invasion success in plants, it remains unclear why some species successfully establish and become dominant while others do not. The most often cited explanation for the success of invasive plants worldwide is the enemy release hypothesis (ERH), which maintains that populations are kept in check by their co-evolved natural enemies in their native range, but are released from this regulation in the new range. Although there is evidence that introduced plant species often experience a decrease in damage by herbivores in the novel range, it is uncertain if this decrease affects plant productivity. The purpose of this study was 1) to determine if the invasive plant _Eugenia uniflora_ (Myrtaceae) experiences release from enemies and 2) if enemy release increases growth and survival for this species relative to co-occurring native congeners E. axillaris and E. foetida. An insect herbivore exclusion experiment using insecticide was conducted in the field to assess differences in insect herbivore damage, leaf number, height, and survival for all three species. The results contradict the ERH, showing that E. uniflora has a greater proportion of damaged leaves and experiences a greater reduction in this damage when herbivores are excluded from the system, relative to the two native congeners. A trend exhibited by the data also demonstrates that exclusion of enemies positively affects growth and survival for all three species, indicating that E. uniflora has not experienced enemy release in its new range. This may be explained by the fact that E. uniflora exhibits, with few exceptions, mostly damage characteristic of a notching weevil, Myllocerus undatus, a recent import from Sri Lanka. E. uniflora originates in Brazil, so these species share no coevolutionary history. The results of this study indicate that M. undatus may have a negative effect on E. uniflora, potentially benefitting the native species by reducing competition. In contrast to invasional meltdown, this is a potential example of another type of interaction, which we have termed “invasional conflict”. This interaction will undoubtedly become much more prevalent as more species are introduced, become established, and interact with one another, forming new biological associations.
The human urocortin 2 gene is regulated by hypoxia: identification of a hypoxia-responsive element in the 3′-flanking region
Authors: Bühler Katrin , Plaisance Isabelle , Dieterle Thomas , Brink Marijke
Published: September 2009

Ucn2 (urocortin 2) has been shown to exert potent beneficial effects in the cardiovascular system, including inhibition of apoptosis, improvement of cardiomyocyte contractility and decrease of oxidative stress. The mechanisms that contribute to the regulation of hUcn2 (human Ucn2) expression in cardiovascular pathologies are not known. In the present study, we analysed the mechanism by which hypoxia, a major stimulus in ischaemic heart disease, regulates Ucn2 gene expression. Hypoxia and CPX (ciclopirox olamine), which prevents proteolytic degradation of HIF (hypoxia-inducible factor), significantly increased hUcn2 mRNA levels in TE-671 cells. Gene silencing of endogenous HIF1α abolishes this increase. Hypoxia and CPX activated a luciferase-linked fragment of the 3′FLR (3′-flanking region) of the hUcn2 gene containing two putative HREs (hypoxia-response elements), HRE1 and HRE2. Site-directed mutagenesis experiments demonstrated that HRE1 is required for HIF1α-dependent luciferase activation. This activation was conserved in constructs with the 3′FLR fragment placed upstream of the luciferase gene, indicating an enhancer function for HRE1. Competition assays revealed direct binding between HRE1 and HIF1α. Regulation of Ucn2 by hypoxia was confirmed in rat neonatal cardiomyocytes and in cardiac-derived H9c2 cells transfected with constructs of the 3′FLR of the hUcn2 gene. In conclusion, our study demonstrates that hypoxia induces hUcn2 expression via a specific HRE in the 3′FLR of the hUcn2 gene, which interacts with the transcription factor HIF1α. Hypoxia-mediated stimulation of cardioprotective Ucn2 may help to preserve cardiac function and prevent apoptosis in ischaemic conditions in the heart.
Active-site determinants of substrate recognition by the metalloproteinases TACE and ADAM10
Authors: Caescu Cristina I. , Jeschke Grace R. , Turk Benjamin E.
Published: September 2009

The metalloproteinases TACE [tumour necrosis factor α-converting enzyme; also known as ADAM17 (a disintegrin and metalloproteinase 17)] and ADAM10 are the primary enzymes responsible for catalysing release of membrane-anchored proteins from the cell surface in metazoan organisms. Although the repertoire of protein substrates for these two proteases is partially overlapping, each one appears to target a subset of unique proteins in vivo. The mechanisms by which the two proteases achieve specificity for particular substrates are not completely understood. We have used peptide libraries to define the cleavage site selectivity of TACE and ADAM10. The two proteases have distinct primary sequence requirements at multiple positions surrounding the cleavage site in their substrates, which allowed us to generate peptide substrates that are highly specific for each of these proteases. The major difference between the two protease specificities maps to the P1′ position (immediately downstream of the cleavage site) of the substrate. At this position, TACE is selective for smaller aliphatic residues, whereas ADAM10 can accommodate aromatic amino acids. Using mutagenesis we identified three residues in the S1′ pockets of these enzymes that dramatically influence specificity for both peptide and protein substrates. Our results suggest that substrate selectivity of TACE and ADAM10 can be at least partly rationalized by specific features of their active sites.
Obesity is the major contributor to vascular dysfunction and inflammation in high-fat diet hypertensive rats
Authors: Elmarakby Ahmed A. , Imig John D.
Published: September 2009

Obesity and hypertension are the two major risk factors that contribute to the progression of end-stage renal disease. To examine whether hypertension further exacerbates oxidative stress and vascular dysfunction and inflammation in obese rats, four groups of male Sprague–Dawley rats were fed either a normal (7% fat) or high-fat (36% fat) diet for 6 weeks and osmotic pumps were implanted to deliver ANG (angiotensin II) or vehicle for an additional 4 weeks. Treatment with the high-fat diet did not alter ANG-induced hypertension compared with the normal diet (174±6 compared with 170±5 mmHg respectively). Treatment with the high-fat diet increased body weight gain and plasma leptin levels and induced insulin resistance in normotensive and ANG-induced hypertensive rats. Plasma TBARS (thiobarbituric acid-reacting substances), a measure of oxidative stress, were elevated in high-fat diet-fed rats compared with controls (11.2±1 compared with 8.4±1 nmol/ml respectively) and was increased further in ANG-induced hypertensive rats fed a high-fat diet (18.8±2.2 nmol/ml). Urinary nitrite excretion was also decreased in rats fed a high-fat diet without or with ANG infusion compared with controls. Afferent arteriolar relaxation to acetylcholine was impaired in rats fed the high-fat diet without or with ANG infusion. Renal cortical TNF-α (tumour necrosis factor-α), COX-2 (cyclo-oxygenase-2) and phospho-IKK (inhibitor of nuclear factor κB kinase) expression increased in high-fat diet-fed rats compared with normal diet-fed rats. The increases in phospho-IKK and COX-2 expression were elevated further in ANG-induced hypertensive rats fed the high-fat diet. These results suggest that ANG-induced hypertension exacerbates oxidative stress and renal inflammation without further impairment in vascular dysfunction in high-fat diet-induced obesity.
Analytical model for low-frequency noise in amorphous chalcogenide-based phase-change memory devices
Authors: Betti Beneventi G. , Calderoni A. , Fantini P. , Larcher L. , Pavan P.
Published: September 2009

Low-frequency noise has been experimentally characterized in the disordered insulating phase of chalcogenide-based phase-change memory (PCM) devices. An analytical model of noise based on the two-level systems (TLS) theory has been developed. In this framework we suggest that the origin of the 1/fγ noise in the conductivity of amorphous chalcogenides has to be ascribed to the TLS-induced fluctuations of the mean trap energy in the material. The model allows to quantitatively account for noise magnitude dependence on both voltage and temperature in the readout region of the memory device. Besides, our equations well describe the noise behavior as a function of the drift phenomenon, coherently with existing structural relaxation theories. Measurements and model results show that the noise-to-signal ratio (N/S) in the readout region of the cell is constant with respect to bias; hence there is no particular readout voltage that minimizes N/S. Furthermore, the analysis of noise data with cell scaling confirms that noise in PCMs is mainly due to the bulk properties of the chalcogenide employed rather than to interfacial effects.
The global wave stability and selection criterion of dendritic growth from a system of binary mixture with enforced flow
Authors: Li Xiang Ming , Wang Zi Dong , Wang Qing Yun
Published: September 2009

The present paper is concerned with the oscillatory stability and selection condition of dendritic growth from a system of binary mixture with enforced flow. We consider the case of large Schmidt number (Sc⪢1) and obtain the uniformly valid asymptotic solution by following the approach of the interfacial wave (IFW) theory of dendritic growth developed by Xu in the 1990s [Phys. Rev. A 43, 930 (1991); Phys. Rev. E 53, 5051 (1996)]. The results obtained show that the oscillatory wave instability mechanism explored in the IFW theory remains in the case under study. The quantitative changes in the critical number of stability criterion and selected condition for the velocity of the dendrite tip affected by the strength of the enforced flow are given under various growth conditions and material properties.
Experimental investigation of the R85b2 a Σ3u+ triplet ground state: Multiparameter Morse long range potential analysis
Authors: Beser Bediha , Sovkov V. B. , Bai J. , Ahmed E. H. , Tsai C. C. , Xie F. , Li Li , Ivanov V. S. , Lyyra A. M.
Published: September 2009

Using perturbation facilitated infrared-infrared double resonance excitation of the R85b2 molecule, we have observed spectrally resolved fluorescence to the a Σ3u+ state. We have analyzed the rovibrational energy level structure of the R85b2 a Σ3u+ state and derived a multiparameter Morse Long Range (MLR) potential and molecular constants for this state, which can be used to predict term values without needing to solve the radial Schrödinger equation.
Surface-plasmon distributed-feedback quantum cascade lasers operating pulsed, room temperature
Authors: Bousseksou A. , Chassagneux Y. , Coudevylle J. R. , Colombelli R. , Sirtori C. , Patriarche G. , Beaudoin G. , Sagnes I.
Published: September 2009

We report distributed-feedback surface-plasmon quantum cascade lasers operating at λ≈7.6μm. The distributed feedback is obtained by the sole patterning of the top metal contact on a surface plasmon waveguide. Single mode operation with more than 30dB side mode suppression ratio is obtained in pulsed mode and at room temperature. A careful experimental study confirms that by varying the grating duty cycle, one can reduce the waveguide losses with respect to standard, unpatterned surface-plasmon devices. This allows one to reduce the laser threshold current of more than a factor of 2 in the 200–300K temperature range. This approach may lead to a fabrication technology for midinfrared distributed-feedback lasers based on a very simple processing.
Full-quantum simulation of hole transport and band-to-band tunneling in nanowires using the k⋅p method
Authors: Shin Mincheol
Published: September 2009

We have developed a three-dimensional, self-consistent full-quantum transport simulator for nanowire field effect transistors based on the eight-band k⋅p method. We have constructed the mode-space Hamiltonian via a unitary transformation from the Hamiltonian discretized in the k-space, and reduced its size significantly by selecting only the modes that contribute to the transport. We have also devised an approximate but highly accurate method to solve the cross-sectional eigenvalue problems, thereby overcoming the numerical bottleneck of the mode-space approach. We have therefore been able to develop a highly efficient device simulator. We demonstrate the capability of our simulator by calculating the hole transport in a p-type Si nanowire field effect transistor and the band-to-band tunneling current in a InAs nanowire tunnel field effect transistor.
On generation of Alfvénic-like fluctuations by drift wave–zonal flow system in large plasma device experiments
Authors: Horton W. , Correa C. , Chagelishvili G. D. , Avsarkisov V. S. , Lominadze J. G. , Perez J. C. , Kim J.-H. , Carter T. A.
Published: September 2009

According to recent experiments, magnetically confined fusion plasmas with “drift wave–zonal flow turbulence” (DW-ZF) give rise to broadband electromagnetic waves. Sharapov et al. [Europhysics Conference Abstracts, 35th EPS Conference on Plasma Physics, Hersonissos, 2008, edited by P. Lalousis and S. Moustaizis (European Physical Society, Switzerland, 2008), Vol. 32D, p. 4–071] reported an abrupt change in the magnetic turbulence during L-H transitions in Joint European Torus [P. H. Rebut and B. E. Keen, Fusion Technol. 11, 13 (1987)] plasmas. A broad spectrum of Alfvénic-like (electromagnetic) fluctuations appears from E×B flow driven turbulence in experiments on the large plasma device (LAPD) [W. Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)] facility at UCLA. Evidence of the existence of magnetic fluctuations in the shear flow region in the experiments is shown. We present one possible theoretical explanation of the generation of electromagnetic fluctuations in DW-ZF systems for an example of LAPD experiments. The method used is based on generalizing results on shear flow phenomena from the hydrodynamics community. In the 1990s, it was realized that fluctuation modes of spectrally stable nonuniform (sheared) flows are non-normal. That is, the linear operators of the flows modal analysis are non-normal and the corresponding eigenmodes are not orthogonal. The non-normality results in linear transient growth with bursts of the perturbations and the mode coupling, which causes the generation of electromagnetic waves from the drift wave–shear flow system. We consider shear flow that mimics tokamak zonal flow. We show that the transient growth substantially exceeds the growth of the classical dissipative trapped-particle instability of the system.
Effect of Zn doping on SnAg solder microstructure and electromigration stability
Authors: Lu Minhua , Shih Da-Yuan , Kang Sung K. , Goldsmith Charles , Flaitz Philip
Published: September 2009

A comprehensive study on the effect of Zn-doped SnAg solders on microstructure and electromigration (EM) is reported. Minor Zn doping, about 0.6 wt %, in a SnAg solder alloy is found to be effective in stabilizing solder microstructure and improving EM reliability. Early EM failure modes in Zn-doped solders are significantly suppressed, resulting in a longer EM lifetime with tight distributions. Analyses using optical microscopy, scanning electron microcopy, transmission electron microscopy, electron microprobe analysis, and electron backscattering diffraction were conducted. Zn addition in SnAg leads to significant changes in solder microstructure, grain structure, and thermal and EM stabilities. The strong reaction of Zn with Cu atoms effectively slowed down the Cu diffusion in β-Sn grains, thus improved the EM stability of Sn-rich solder joints.
Determination of the critical coupling for oscillators in a ring
Authors: El-Nashar Hassan F. , Cerdeira Hilda A.
Published: September 2009

We study a model of coupled oscillators with bidirectional first nearest neighbors coupling with periodic boundary conditions. We show that a stable phase-locked solution is decided by the oscillators at the borders between the major clusters, which merge to form a larger one of all oscillators at the stage of complete synchronization. We are able to locate these four oscillators depending only on the set of the initial frequencies. Using these results plus an educated guess (supported by numerical findings) of the functional dependence of the corrections due to periodic boundary conditions, we are able to obtain a formula for the critical coupling, at which the complete synchronization state occurs. Such formula fits well in very good accuracy with the results that come from numerical simulations. This also helps to determine the sizes of the major clusters in the vicinity of the stage of full synchronization.
Retroreflecting polarization spectroscopy enabling miniaturization
Authors: Groswasser D. , Waxman A. , Givon M. , Aviv G. , Japha Y. , Keil M. , Folman R.
Published: September 2009

We describe and characterize alternative configurations for Doppler-free polarization spectroscopy. The suggested apparatus enables complete pump/probe beam overlap and allows substantial miniaturization. Its utility and performance for narrow linewidth, high-stability frequency locking is discussed for the |5S1/2F=2⟩→|5P3/2F′⟩D2 transition in R87b.
Quantitative grating-based x-ray dark-field computed tomography
Authors: Wang Zhen-Tian , Kang Ke-Jun , Huang Zhi-Feng , Chen Zhi-Qiang
Published: September 2009

Grating-based x-ray dark-field computed tomography is a functional method that utilizes the scattering contrast mechanism to explore the inaccessible spatially resolved internal structure of the sample. In this letter, we show that the second moment of the scattering angle distribution can be expressed as the minus logarithm of the visibility degradation of the oscillation curve in grating-based imaging. According to the conclusion of Khelashvili et al. [Phys. Med. Biol. 51, 221 (2006)], the minus logarithm of the visibility ratio fulfills the line integral condition; consequently the scattering information can be reconstructed quantitatively by conventional computed tomography algorithms. Results from a computer simulation and from an actual experiment both validate our deduction.
Chaos enhancing tunneling in a coupled Bose–Einstein condensate with a double driving
Authors: Rong Shiguang , Hai Wenhua , Xie Qiongtao , Zhu Qianquan
Published: September 2009

We study the effects of chaotic dynamics on atomic tunneling between two weakly coupled Bose–Einstein condensates driven by a double-frequency periodic field. Under the Melnikov’s chaos criterion, we divide the parameter space into three parts of different types, regular region, low-chaoticity region, and high-chaoticity region, and give the accurate boundaries between the different regions. It is found that the atomic tunneling can be enhanced in the presence of chaos. Particularly, in the high-chaoticity regions, the chaos-induced inversion of the population imbalance is observed numerically.
On the difficulties of present theoretical models to predict the oxidation state of atomic Au adsorbed on regular sites of CeO2(111)
Authors: Branda María Marta , Castellani Norberto J. , Grau-Crespo Ricardo , de Leeuw Nora H. , Hernandez Norge C. , Sanz Javier F. , Neyman Konstantin M. , Illas Francesc
Published: September 2009

The electronic structure and oxidation state of atomic Au adsorbed on a perfect CeO2(111) surface have been investigated in detail by means of periodic density functional theory-based calculations, using the LDA+U and GGA+U potentials for a broad range of U values, complemented with calculations employing the HSE06 hybrid functional. In addition, the effects of the lattice parameter a0 and of the starting point for the geometry optimization have also been analyzed. From the present results we suggest that the oxidation state of single Au atoms on CeO2(111) predicted by LDA+U, GGA+U, and HSE06 density functional calculations is not conclusive and that the final picture strongly depends on the method chosen and on the construction of the surface model. In some cases we have been able to locate two well-defined states which are close in energy but with very different electronic structure and local geometries, one with Au fully oxidized and one with neutral Au. The energy difference between the two states is typically within the limits of the accuracy of the present exchange-correlation potentials, and therefore, a clear lowest-energy state cannot be identified. These results suggest the possibility of a dynamic distribution of Au0 and Au+ atomic species at the regular sites of the CeO2(111) surface.
Full wave simulation of lower hybrid waves in Maxwellian plasma based on the finite element method
Authors: Meneghini O. , Shiraiwa S. , Parker R.
Published: September 2009

A full wave simulation of the lower-hybrid (LH) wave based on the finite element method is presented. For the LH wave, the most important terms of the dielectric tensor are the cold plasma contribution and the electron Landau damping (ELD) term, which depends only on the component of the wave vector parallel to the background magnetic field. The nonlocal hot plasma ELD effect was expressed as a convolution integral along the magnetic field lines and the resultant integro-differential Helmholtz equation was solved iteratively. The LH wave propagation in a Maxwellian tokamak plasma based on the Alcator C experiment was simulated for electron temperatures in the range of 2.5–10 keV. Comparison with ray tracing simulations showed good agreement when the single pass damping is strong. The advantages of the new approach include a significant reduction of computational requirements compared to full wave spectral methods and seamless treatment of the core, the scrape off layer and the launcher regions.
Scanning capacitance microscopy investigation on InGaAs/InP avalanche photodiode structures: Light-induced polarity reversal
Authors: Yin Hao , Li Tianxin , Wang Wenjuan , Hu Weida , Lin Le , Lu Wei
Published: September 2009

Cross-sectional scanning capacitance microscopy is applied to study the carrier distribution as well as its variation under irradiation in an InGaAs/InP avalanche photodiode. The photocarriers excited by the stray light of atomic force microscope laser beam lead to a dramatic deviation of the dC/dV profile in the unintended-doped absorption layer, and even cause the reversal of signal polarity. The existence of surface potential and its impact on the spreading of photocarriers near the cleaved face are demonstrated as the main origins of the light-induced dC/dV reversal. The effect provides experimental information on the distribution property of photoelectric process in devices.