bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy flow and nutrient cycling in the Marion Island terrestrial ecosystem: 30 years on
Authors: Smith Valdon R.
Published: May 2008

This article is a sequel to a word-model description of the ecosystem of sub-Antarctic Marion Island, published in this journal 30 years ago (Smith 1977). It expands on the qualitative considerations of patterns of energy flow and nutrient cycling presented in that paper, by providing quantitative information from subsequent research at the island. Primary production of the island's lowland plant communities is high on an annual basis, because the vegetation has a long growing season due to the lack of severely cold winters or drought. Daily productivity is actually low due to low radiation levels and a cool growing season. The vegetation is particularly efficient regarding its use of nutrients for its growth, but still requires substantial amounts of nutrients to support the high annual production. Seabirds and seals import large quantities of nutrients from the ocean when they breed and moult on the island. They markedly enhance soil and plant nutrient status in the areas in which they occur, and also in adjacent areas. However, by far the greater part of the island's inland vegetation is not directly influenced by birds or seals and most of the nutrients required for plant growth are provided by decomposition of plant litter and peat. Soil invertebrates are crucial facilitators of decomposition processes, which are otherwise restricted by low soil temperatures and high soil moisture contents. Introduced house mice have invaded almost all parts of the island and predate heavily on the invertebrates, thus affecting nutrient mineralisation. This threatens not only the functioning (lowered nutrient availability leading to slower plant growth and the production of a lower quality, more decomposition-recalcitrant plant litter), but also the structure (an altered balance between production and decomposition leads to a change in the relation between peat formation and degradation, which is an important determinant of vegetation succession) of the island's ecosystem. It is suggested that mice may also affect the island's ecology by predating on seabird chicks.
Communicating traditional environmental knowledge: addressing the diversity of knowledge, audiences and media types
Authors: Bonny Eleanor , Berkes Fikret
Published: May 2008

Although there are a number of distinct audiences (for example students, hunter and trapper organisations, and co-management agencies) for traditional environmental knowledge, little work has been done in analysing how indigenous knowledge can be best communicated to these different groups. Using examples mainly from northern Canada and Alaska, we explore the challenge of collecting and communicating different kinds of traditional environmental knowledge; the media types or communication modes that can be used; and the appropriateness of these kinds of media for communicating with different audiences. A range of communication options is available, including direct interaction with knowledge holders, use of print media, maps, DVD/video, audio, CD ROM, and websites. These options permit a mix-and-match to find the best fit between kinds of knowledge, the intended audience, and the media type used. This paper does not propose to replace traditional methods of communication with technology. Rather, we examine how technology can serve community and other needs. No single option emerges as a clear best choice for communicating indigenous knowledge. Nevertheless, various media types offer avenues through which northern people can meet their educational, cultural, and political needs, and build cross-cultural understanding.
Benjamin Leigh Smith's second Arctic expedition: Svalbard and Jan Mayen, 1872
Authors: Capelotti P.J.
Published: May 2008

In 1872, the British yachtsman and explorer Benjamin Leigh Smith led his second expedition to the Arctic. Seeking to further the impressive oceanographic and geographic research of his first expedition in the summer of the previous year, Leigh Smith first explored Jan Mayen and then sailed to Svalbard. There, after investigating Moffen, adverse ice conditions precluded effective continuation of the voyage and almost wrecked his research vessel,Sampson. During a brief meeting with Adolf Erik Nordenskiöld's Swedish polar expedition, a bond was formed between the two explorers with fortuitous benefits for the Swedish expedition the following year as it struggled to escape from the north coast of Svalbard. Leigh Smith was forced to make for England in September 1872, without sailing nearly as far to the north or east as during his first expedition. His 1872 experiences led him to reconsider his method for Arctic exploration, and consequently, for his third expedition in 1873, he decided to include a chartered steamer as his primary research vessel withSampsonrelegated to the role of support vessel.
The frozen continent: an Antarctic play
Authors: Moore Jason Kendall , Wöppke Consuelo León
Published: May 2008

This one-act play was recently presented at an Antarctic workshop held at Universidad Marítima de Chile, Viña del Mar, Chile. Apart from being entertaining, it provided an example of how theatre can be used to generate or reinforce interest in polar studies. The script has been translated from Spanish by the playwright.
Fairness in multi-agent systems
Authors: JONG STEVEN DE , TUYLS KARL , VERBEECK KATJA
Published: May 2008

Multi-agent systems are complex systems in which multiple autonomous entities, called agents, cooperate in order to achieve a common or personal goal. These entities may be computer software, robots, and also humans. In fact, many multi-agent systems are intended to operate in cooperation with or as a service for humans. Typically, multi-agent systems are designed assuming perfectly rational, self-interested agents, according to the principles of classical game theory. Recently, such strong assumptions have been relaxed in various ways. One such way is explicitly including principles derived from human behavior. For instance, research in the field of behavioral economics shows that humans are not purely self-interested. In addition, they strongly care aboutfairness. Therefore, multi-agent systems that fail to take fairness into account, may not be sufficiently aligned with human expectations and may not reach intended goals. In this paper, we present an overview of work in the area of fairness in multi-agent systems. More precisely, we first look at the classical agent model, that is, rational decision making. We then provide an outline of descriptive models of fairness, that is, models that explain how and why humans reach fair decisions. Then, we look at prescriptive, computational models for achieving fairness in adaptive multi-agent systems. We show that results obtained by these models are compatible with experimental and analytical results obtained in the field of behavioral economics.
Solutions of second order multi-point boundary value problems
Authors: GRAEF JOHN R. , KONG LINGJU
Published: May 2008

We consider classes of second order boundary value problems with a nonlinearity f(t, x) in the equations and subject to a multi-point boundary condition. Criteria are established for the existence of nontrivial solutions, positive solutions, and negative solutions of the problems under consideration. The symmetry of solutions is also studied. Conditions are determined by the relationship between the behavior of the quotient f(t, x)/x for x near 0 and ∞ and the largest positive eigenvalue of a related linear integral operator. Our analysis mainly relies on the topological degree and fixed point index theories.
The threefold containing the Bordiga surface of degree ten as a hyperplane section
Authors: MAEDA HIDETOSHI
Published: May 2008

Let be a very ample vector bundle of rank 2 on $\Bbb P^2$ with c1() = 4 and c2() = 6. Then it is proved that is the cokernel of a bundle monomorphism $\mathcal O_{\Bbb P^2}(1)^{\oplus 2}\to T_{\Bbb P^2}^{\oplus 2}$, where $T_{\Bbb P^2}$ is the tangent bundle of $\Bbb P^2$. This gives a new example of a threefold containing a Bordiga surface as a hyperplane section.
Impact of the B-15 iceberg “stranding event” on the physical and biological properties of sea ice in McMurdo Sound, Ross Sea, Antarctica
Authors: Remy J.-P. , Becquevort S. , Haskell T.G. , Tison J.-L.
Published: May 2008

Ice cores were sampled at four stations in McMurdo Sound (Ross Sea) between 1999 and 2003. At the beginning of year 2000, a very large iceberg (B-15) detached itself from the Ross Ice Shelf and stranded at the entrance of the Sound, preventing the usual oceanic circulation purging of the annual sea ice cover from this area. Ice textural studies showed that a second year sea ice cover was built-up at three out of the four stations: ice thickness increased to about 3 m. Repeated alternation of columnar and platelet ice appeared, and bulk salinity showed a strong decrease, principally in the upper part of the ice sheet, with associated brine volume decrease. Physical modification influenced the biology as well. By decreasing the light and space available for organisms in the sea ice cover, the stranding of B-15 has i) hampered autotrophic productivity, with chlorophyllaconcentration and algae biomass significantly lower for second year ice stations, and ii) affected trophic relationships such as the bacterial biomass/chlaconcentration correlation, or the autotrophic to heterotrophic ratio.
On the Minimal Density of Triangles in Graphs
Authors: RAZBOROV ALEXANDER A.
Published: May 2008

For a fixed ρ ∈ [0, 1], what is (asymptotically) the minimal possible density g3(ρ) of triangles in a graph with edge density ρ? We completely solve this problem by proving thatwhere$t\df \lfloor 1/(1-\rho)\rfloor$is the integer such that$\rho\in\bigl[ 1-\frac 1t,1-\frac 1{t+1}\bigr]$.
The Rise and Fall of Constructions and the History of EnglishDo-Support
Authors: Culicover Peter W.
Published: May 2008

Do-support is a unique characteristic of English. Many languages other than English havedo-periphrasis but not English-typedo-support. This raises the obvious question: What is special about English? The goal of this paper is to provide an account of Englishdo-support that explains whydo-support, with its attendant properties, is found uniquely in English. I review the classical derivational approaches todo-support and argue that they do not satisfactorily capture the generalizations. I suggest an alternative, non-derivational account of contemporarydo-support that makes crucial use of constructions. Finally, I propose an account of the history ofdo-support in English that characterizes the changes in terms of the content and scope of constructions. The rise ofdo-support can be understood as a consequence of the contraction and re-specialization of particular constructions in the wake of well-documented changes in the overt morphological system of the language.*
On the Emergent Trochaic Cadence / × in Old NorseFornyrðislagMeter: Statistical and Comparative Perspectives
Authors: Suzuki Seiichi
Published: May 2008

Through statistical and comparative investigations of eddic poetry, I show that Old Norsefornyrðislagmeter is sharply distinguished from its West Germanic cognates by its strong preference for the trochaic cadence lift + drop in the b-verse. This unique feature is claimed to have induced the radical redistribution and reorganization of the major metrical types, types A, B, and C infornyrðislag. Furthermore, I suggest that this favored cadence served as a basis for the fixed cadence ofdróttkvættmeter by generalization and reanalysis.*
Psychometric evaluation of the German version of the Life Attitude
Profile–Revised (LAP-R) in prostate cancer patients
Authors: Mehnert Anja , Koch Uwe
Published: May 2008

Objective:

There has been an increasing interest in the measurement of patients efforts
to find meaning during the experience of a life-threatening illness. The aim
of this study was to validate the German version of the Life Attitude
Profile–Revised (LAP-R), a multidimensional measure of meaning
and purpose.

Methods:

A total of 511 prostate cancer patients with an average age of 64 years
filled in the questionnaire during outpatient follow up care (response rate
70%).

Results:

Five of the original six dimensions were replicated by exploratory and
confirmatory factor analysis: Coherence, Existential Vacuum,
Choice/Responsibleness, Death Acceptance, and Goal Seeking. The Purpose
dimension was not replicated. Most LAP-R subscales showed good internal
consistencies with Cronbach's α between .80 and .82,
whereas the reliability for Existential Vacuum
(α = .69) and Goal Seeking
(α = .74) was less sufficient,
but still acceptable. Results show significant concurrent associations
between all LAP-R dimensions and measures of emotional distress, coping, and
health-related quality of life; however, moderate correlations were found
only for Existential Vacuum and depression, and inversely for depressive
coping and the mental health subscale.

Significance of research:

The German LAP-R is a reliable and valid instrument that can be recommended
for further use in research and clinical cancer care.
General practitioners' experiences of the psychological aspects in the care of a dying patient
Authors: Kelly Brian , Varghese Francis T , Burnett Paul , Turner Jane , Robertson Marguerite , Kelly Patricia , Mitchell Geoffrey , Treston Pat
Published: May 2008

Objective:

General practitioners (GPs) play an integral role in addressing the psychological needs of palliative care patients and their families. This qualitative study investigated psychosocial issues faced by GPs in the management of patients receiving palliative care and investigated the themes relevant to the psychosocial care of dying patients.

Method:

Fifteen general practitioners whose patient had been recently referred to the Mt. Olivet Palliative Home Care Services in Brisbane participated in an individual case review discussions guided by key questions within a semistructured format. These interviews focused on the psychosocial aspects of care and management of the referred patient, including aspects of the doctor/patient relationship, experience of delivering diagnosis and prognosis, addressing the psychological concerns of the patients' family, and the doctors' personal experiences, reactions, and responses. Qualitative analysis was conducted on the transcripts of these interviews.

Results:

The significant themes that emerged related to perceived barriers to exploration of emotional concerns, including spiritual issues, and the discussion of prognosis and dying, the perception of patients' responses/coping styles, and the GP's personal experience of the care (usually expressed in terms of identification with patient).

Significance of results:

The findings indicate the significant challenges facing clinicians in discussions with patients and families about death, to exploring the patient's emotional responses to terminal illness and spiritual concerns for the patient and family. These qualitative date indicate important tasks in the training and clinical support for doctors providing palliative care.
Psychiatric issues in palliative care: Recognition of delirium in patients enrolled in hospice care
Authors: Irwin Scott A. , Rao Sanjai , Bower Kimberly A. , Palica Joanna , Rao Sanjay S. , Maglione Jeanne E. , Soskins Matt , Betterton Amy E. , Ferris Frank D.
Published: May 2008

Objectives:

Delirium is prevalent, difficult to assess, under-recognized, and undertreated in hospice and palliative care settings. Furthermore, it is associated with significant morbidity and mortality. Under-recognition of delirium results in under-treatment and increased suffering. The intent of this study was to retrospectively evaluate the recognition of delirium in a large cohort of hospice patients by interdisciplinary hospice care teams.

Methods:

A retrospective chart review of 2,716 patients receiving hospice care was conducted in order to determine the baseline rate of recognition of delirium in patients with advanced, life-threatening illnesses by front-line hospice clinicians. Documentation of “delirium” as either a diagnosis or problem was used as an estimate of how often these disorders were considered significant issues by the treating interdisciplinary team.

Results:

Of the patients receiving home/long-term care, 17.8% (386/2168) had delirium documented as a diagnosis or significant problem. The presence of recognized delirium in this setting was associated with significant differences in marital status, ethnicity, hospice diagnosis, and age. Total length of hospice care was also significantly longer. Of patients receiving inpatient care, 28.3% (614/548) had delirium documented as a diagnosis or significant problem. Recognized delirium in this setting was associated with significant differences in gender, ethnicity, hospice diagnosis, and length of inpatient stay.

Significance of results:

If documentation is representative of the care that the interdisciplinary teams provide, delirium of any kind appears to be under-recognized in this population. In fact, it is on the low end of prevalence estimates in the literature. Improved delirium assessment is needed in order to minimize the impact of delirium on patients living with advanced, life-threatening illnesses and their caregivers.
Consensus guideline on parenteral methadone use in pain and palliative care
Authors: Shaiova Lauren , Berger Ann , Blinderman Craig D. , Bruera Eduardo , Davis Mellar P. , Derby Susan , Inturrisi Charles , Kalman Jill , Mehta Davendra , Pappagallo Marco , Perlov Eugene
Published: May 2008

Once used only as third-line therapy for chronic pain management, methadone is now being used as first- and second-line therapy in palliative care. The risks and stigma associated with methadone use are known, but difficulties with dosing methadone and lack of an established conversion protocol from other opiates have limited the access for patient populations who could potentially benefit from this medication. For palliative care patients, the benefits of methadone can far outweigh its risks. This article provides an overview and specific recommendations on the use of parenteral methadone in pain and palliative care, with a focus on the transition from hospital to home/hospice care. The goal of this consensus guideline is to assist clinicians who are providing chronic pain management in acute care hospital and nonhospital settings (i.e., hospice, long-term care facilities, and community) for patients with life-limiting illnesses, where the goals of care are focused on comfort (i.e., palliative care). The recommendations in this article intend to promote a standard of care involving the use of intravenous methadone with the aim of reaching a broader population of patients for whom this drug would provide important benefits.
Activation syndrome caused by paroxetine in a cancer patient
Authors: Nishida Tomomi , Wada Makoto , Wada Mei , Ito Hiroshi , Narabayashi Masaru , Onishi Hideki
Published: May 2008

Individuals with cancer have two to four times an increased risk of depressive disorders compared to the general population. Depressive symptoms are related to impaired daily life functioning and a rise in health care utilization. Pharmacological treatments for depression are usually effective to reduce depressive symptoms, but sometimes lead to serious adverse reactions. We describe a cancer patient who developed sudden psychological and behavioral abnormalities after administration of the antidepressant paroxetine. Impulsive and aggressive symptoms are a so-called activation syndrome that can cause violent or suicidal tendencies. Palliative care staff should pay close attention to these potentially lethal reactions and make an immediate and correct diagnosis.
Geographic information systems database, Walnut Gulch Experimental Watershed, Arizona, United States
Authors: Heilman P. , Nichols M. H. , Goodrich D. C. , Miller S. N. , Guertin D. P.
Published: May 2008

The geographic information systems (GIS) database complementing the Walnut Gulch Experimental Watershed (WGEW) special section papers in this issue of Water Resources Research is described. Spatial data layers discussed here will be especially useful to modelers interested in simulating the spatial and temporal characteristics of rainfall, runoff, erosion, and sedimentation processes on the WGEW. All data are available as either images or individual GIS data layers (vector or raster format) via the U.S. Department of Agriculture Agricultural Research Service Southwest Watershed Research Center at http://www.tucson.ars.ag.gov/dap/. Standard metadata are provided with attending projection information and restrictions on use.
Earthquake triggering in southern Iceland following the June 2000 Ms 6.6 doublet
Authors: Daniel G. , Marsan D. , Bouchon M.
Published: May 2008

In June 2000, two remarkably similar Ms 6.6 earthquakes stroke southern Iceland in the space of 3 d. Here this doublet is analyzed to test whether aftershock triggering is linear, that is, if the triggering patterns of these two similar main shocks are also similar. Methodologically, the key issue is to separate the two contributions to the overall seismicity patterns. For this purpose, we model the first 3 d (17–21 June) of this aftershock sequence with an Omori‐Utsu law. We then extrapolate it beyond 21 June in order to estimate the variations linked with the second shock. We correct for the large transient changes in catalogue completeness. Our results indicate that instantaneous short‐lived (hours to days) dynamic triggering took place at the Hengill Triple Junction, on the Reykjanes Peninsula, and around the Árnes fault plane that ruptured on 17 June. We observe delayed, long‐lasting (longer than weeks) episodes of quiescence at Hengill and on the Árnes fault plane. At Hengill this quiescence remains significant up to at least the end of 2000. These quiescences are more consistent with Coulomb stress calculations than the preceding episodes of triggering. Comparison between the number of triggered events by the two main shocks reveals that the second one triggered only 2.1% at Hengill and 0.3% at Reykjanes of the number (3.6% and 0.1%, respectively, of the seismic moment) that could be expected with a simple stress threshold model of dynamic triggering. This clear nonlinearity in patterns of dynamic triggering is consistent with a model in which the population of nucleating earthquakes is depleted by the first trigger.
Probabilistic seismic hazard in the San Francisco Bay area based on a simplified viscoelastic cycle model of fault interactions
Authors: Pollitz Fred F. , Schwartz David P.
Published: May 2008

We construct a viscoelastic cycle model of plate boundary deformation that includes the effect of time‐dependent interseismic strain accumulation, coseismic strain release, and viscoelastic relaxation of the substrate beneath the seismogenic crust. For a given fault system, time‐averaged stress changes at any point (not on a fault) are constrained to zero; that is, kinematic consistency is enforced for the fault system. The dates of last rupture, mean recurrence times, and the slip distributions of the (assumed) repeating ruptures are key inputs into the viscoelastic cycle model. This simple formulation allows construction of stress evolution at all points in the plate boundary zone for purposes of probabilistic seismic hazard analysis (PSHA). Stress evolution is combined with a Coulomb failure stress threshold at representative points on the fault segments to estimate the times of their respective future ruptures. In our PSHA we consider uncertainties in a four‐dimensional parameter space: the rupture peridocities, slip distributions, time of last earthquake (for prehistoric ruptures) and Coulomb failure stress thresholds. We apply this methodology to the San Francisco Bay region using a recently determined fault chronology of area faults. Assuming single‐segment rupture scenarios, we find that future rupture probabilities of area faults in the coming decades are the highest for the southern Hayward, Rodgers Creek, and northern Calaveras faults. This conclusion is qualitatively similar to that of Working Group on California Earthquake Probabilities, but the probabilities derived here are significantly higher. Given that fault rupture probabilities are highly model‐dependent, no single model should be used to assess to time‐dependent rupture probabilities. We suggest that several models, including the present one, be used in a comprehensive PSHA methodology, as was done by Working Group on California Earthquake Probabilities.
Factors influencing spatial pattern in tropical forest clearance and stand age: Implications for carbon storage and species diversity
Authors: Helmer E. H. , Brandeis Thomas J. , Lugo Ariel E. , Kennaway Todd
Published: May 2008

Little is known about the tropical forests that undergo clearing as urban/built‐up and other developed lands spread. This study uses remote sensing‐based maps of Puerto Rico, multinomial logit models and forest inventory data to explain patterns of forest age and the age of forests cleared for land development and assess their implications for forest carbon storage and tree species richness. Accessibility, arability and spatial contagion emerge strongly as overriding spatial controls on tropical forest age, determining (1) the pattern of agricultural abandonment that permits forest regrowth, and (2) where humans leave old‐growth forest remnants. Covariation between the factors patterning forest age and land development explains why most forest cleared for land development is younger. Forests are increasingly younger in more accessible and fertile areas where agriculture has lasted longer and land development is most common. All else equal, more species‐rich older forest on less arable lands are somewhat less likely to undergo development, but they are still vulnerable to clearing for land development if close to urban centers and unprotected. Accounting for forest age leads to a 19% lower estimate of forest biomass cleared for land development than if forest age is not accounted for.
Fates of methane from different lake habitats: Connecting whole‐lake budgets and CH4 emissions
Authors: Bastviken David , Cole Jonathan J. , Pace Michael L. , Van de Bogert Matthew C.
Published: May 2008

Methane (CH4) represents a major product of organic matter decomposition in lakes. Once produced in the sediments, CH4 can be either oxidized or emitted as a greenhouse gas to the atmosphere. Lakes represent an important source of atmospheric CH4, but the relative magnitudes of the internal pathways that lead to CH4 emissions are not yet clear. We quantified internal cycling and methane emissions in three lakes during summer stratification. These methane budgets included: sediment release of CH4 at different depths; water column transport patterns and methane oxidation; methane storage in the water column; and methane emissions to the atmosphere by diffusion and ebullition. The contribution of CH4 carbon, via oxidation by methanotrophic bacteria, to pelagic food webs was also estimated. Despite the very low concentration of CH4 in surface waters, shallow, epilimnetic sediments were major contributors of CH4 to the atmosphere. While 51–80% of the CH4 produced in deep sediments was oxidized in the water column, most of the CH4 released from shallow sediment escaped oxidation and reached the atmosphere. Epilimnetic sediments accounted for 100% of CH4 emitted during summer stratification, and 14–76% considering the release of CH4 stored in deep water layers during lake circulation after the stratification period; diffusive emission accounted for 26–48% and ebullition the remainder. These results indicate that it is important to address transport rates of CH4 from the shallow sediment along with the production‐consumption processes when trying to understand methane dynamics and the regulation of lake methane emissions.
Method for estimating spatially variable seepage loss and hydraulic conductivity in intermittent and ephemeral streams
Authors: Niswonger R. G. , Prudic D. E. , Fogg G. E. , Stonestrom D. A. , Buckland E. M.
Published: May 2008

A method is presented for estimating seepage loss and streambed hydraulic conductivity along intermittent and ephemeral streams using streamflow front velocities in initially dry channels. The method uses the kinematic wave equation for routing streamflow in channels coupled to Philip's equation for infiltration. The coupled model considers variations in seepage loss both across and along the channel. Water redistribution in the unsaturated zone is also represented in the model. Sensitivity of the streamflow front velocity to parameters used for calculating seepage loss and for routing streamflow shows that the streambed hydraulic conductivity has the greatest sensitivity for moderate to large seepage loss rates. Channel roughness, geometry, and slope are most important for low seepage loss rates; however, streambed hydraulic conductivity is still important for values greater than 0.008 m/d. Two example applications are presented to demonstrate the utility of the method.
Helium isotopes on the Pacific‐Antarctic ridge (52.5°–41.5°S)
Authors: Moreira Manuel A. , Dosso Laure , Ondréas Hélène
Published: May 2008

The first isotopic data and concentrations of helium are reported for the Pacific‐Antarctic ridge between 52.5°S and 41.5°S. The 4He/3He ratio is extremely homogeneous over more than 1200 km, with a mean ratio of 99,275 (R/Ra = 7.29) and a standard deviation of 2719 (0.19), which is the lowest dispersion observed for the global mid oceanic ridge system. Moreover, the Menard T.F. is a frontier between two mantles with slightly different helium isotopic ratios (96,595 ± 1520 and 100,347 ± 2330). No difference in the helium concentration between the two ridge segments defined by the Menard T.F. can be observed, as well as no significant difference in the U and Th contents suggesting that the difference in helium isotopic ratio is old (>500 My) and may represent a slight difference in degassing or/and trace element depletion history.
Subsurface stormflow is important in semiarid karst shrublands
Authors: Wilcox Bradford P. , Taucer Phillip I. , Munster Clyde L. , Owens M. Keith , Mohanty Binayak P. , Sorenson Joshua R. , Bazan Roberto
Published: May 2008

In this paper we describe hillslope‐scale, rainfall‐simulation experiments on karst shrublands dominated by Ashe juniper. These simulations, designed to mimic flood‐producing rainfall events, were carried out at two sites separated by 206 km within the Edwards Plateau of Central Texas. Five hillslope plots were instrumented—two shrub‐covered (canopy) plots and three intercanopy plots measuring 12–14 m in length. We repeated the experiments on the canopy plots after removing the shrubs. For the canopy plots, both before and after shrub removal, 50% or more of the water applied exited the plots as subsurface stormflow and no overland flow occurred. For the intercanopy plots, subsurface stormflow amounted to less than 10% of the water applied and overland flow was between 10 and 50%. These experiments demonstrate the importance of subsurface stormflow in semiarid karst shrublands during flood events, and more generally highlight the fact that subsurface stormflow is important in some semiarid landscapes.
New dimensions in early flood warning across the globe using grand‐ensemble weather predictions
Authors: Pappenberger Florian , Bartholmes Jens , Thielen Jutta , Cloke Hannah L. , Buizza Roberto , de Roo Ad
Published: May 2008

Early and effective flood warning is essential to initiate timely measures to reduce loss of life and economic damage. The availability of several global ensemble weather prediction systems through the “THORPEX Interactive Grand Global Ensemble” (TIGGE) archive provides an opportunity to explore new dimensions in early flood forecasting and warning. TIGGE data has been used as meteorological input to the European Flood Alert System (EFAS) for a case study of a flood event in Romania in October 2007. Results illustrate that awareness for this case of flooding could have been raised as early as 8 days before the event and how the subsequent forecasts provide increasing insight into the range of possible flood conditions. This first assessment of one flood event illustrates the potential value of the TIGGE archive and the grand‐ensembles approach to raise preparedness and thus to reduce the socio‐economic impact of floods.
SAPS measurements around the magnetic equator by CRRES
Authors: Nishimura Y. , Wygant J. , Ono T. , Iizima M. , Kumamoto A. , Brautigam D. , Friedel R.
Published: May 2008

Enhancements of convection electric fields during two substorms have been analyzed using CRRES satellite data measured in the premidnight inner magnetosphere. The electric field, related to subauroral polarization streams (SAPS), begins to increase within 30 sec after the substorm onset, indicating a quicker response of convection in the inner magnetosphere to substorms than has been reported (∼10 min) before. A prompt response of the ion pressure and the following decrease in the cold plasma density supports the fact that the electric field enhances just after the substorm onset and drives accelerations of energetic ions and plasmapause erosion. The SAPS electric field enhances between the earthward edges of the ring current and plasmasheet, and the plasmapause coincides with the earthward edge of the electron plasmasheet. The plasmapause location deviates from the stagnation point, and the SAPS electric field penetrates into the plasmasphere, driving a sunward plasma drift of the plasmaspheric plasma.
Reply to comment by S. W. H. Cowley et al. on “Jupiter: A fundamentally different magnetospheric interaction with the solar wind”
Authors: McComas D. J. , Bagenal F.
Published: May 2008

We welcome the comments by Cowley et al. [2008] (hereinafter referred to as CBIM), and discussion of McComas and Bagenal [2007]. In our paper we pointed out a variety of problems with the operation of an Earth‐like Dungey cycle at Jupiter including the large spatial and long temporal scales over which a solar‐wind‐driven convection system would need to operate, the presence of a high beta plasma sheet of iogenic material inhibits closing of open (lobe) flux in the magnetotail, the ejection of plasma sheet material down the tail inhibits planetward motion of closed (reconnected) flux tubes, and the lack of a signature of a polar cap in Jovian auroral emissions. We suggested an alternate process that would close open magnetic flux at the magnetopause any time a solar wind flux tube connects with open flux anchored in both poles. While we do not pretend to have fully proven that our process is the dominant method for closing off open magnetic flux in the Jovian magnetosphere, we do believe that it is an interesting and new idea that is worth serious consideration. In addition, there are already a variety of observations that support our general concept, as described in our paper. Ultimately, which process is the primary one will have to be settled by these and other observations – it will not be settled by conflicting models or theoretical arguments.
A mutation (R826W) in nucleotide‐binding domain 1 of ABCC8 reduces ATPase activity and causes transient neonatal diabetes
Authors: de Wet Heidi , Proks Peter , Lafond Mathilde , Aittoniemi Jussi , Sansom Mark S P , Flanagan Sarah E , Pearson Ewan R , Hattersley Andrew T , Ashcroft Frances M
Published: May 2008

Activating mutations in the pore‐forming Kir6.2 (KCNJ11) and regulatory sulphonylurea receptor SUR1 (ABCC8) subunits of the KATP channel are a common cause of transient neonatal diabetes mellitus (TNDM). We identified a new TNDM mutation (R826W) in the first nucleotide‐binding domain (NBD1) of SUR1. The mutation was found in a region that heterodimerizes with NBD2 to form catalytic site 2. Functional analysis showed that this mutation decreases MgATP hydrolysis by purified maltose‐binding protein MBP–NBD1 fusion proteins. Inhibition of ATP hydrolysis by MgADP or BeF was not changed. The results indicate that the ATPase cycle lingers in the post‐hydrolytic MgADP·Pi‐bound state, which is associated with channel activation. The extent of MgADP‐dependent activation of KATP channel activity was unaffected by the R826W mutation, but the time course of deactivation was slowed. Channel inhibition by MgATP was reduced, leading to an increase in resting whole‐cell currents. In pancreatic beta cells, this would lead to less insulin secretion and thereby diabetes.
Random lasers with coherent feedback from highly transparent polymer films embedded with silver nanoparticles
Authors: Meng Xiangeng , Fujita Koji , Zong Yanhua , Murai Shunsuke , Tanaka Katsuhisa
Published: May 2008

We report on observations of random lasers with coherent feedback in highly transparent polymer films embedded with silver nanoparticles. The hybrid materials were fabricated via in situ synthesis method, through which silver nanoparticles were precipitated by thermal treatment. Sharp peaks with linewidth ∼0.5nm were observed to emerge on the broad emission background when the pump energy reached a threshold, together with unidirectional laser irradiation. Random lasers with coherent feedback induced by silver nanoparticles have been rarely reported, hence, we expect that this work will add an aspect to random lasers by using metal nanostructures to obtain coherent feedback.
Influence of the substrate orientation on the electrical and material properties of GaAs metal-oxide-semiconductor capacitors and self-aligned transistors using HfO2 and silicon interface passivation layer
Authors: Ok InJo , Kim H. , Zhang M. , Zhu F. , Park S. , Yum J. , Zhao H. , Garcia Domingo , Majhi Prashant , Lee Jack C.
Published: May 2008

In this work, we studied the effects of postdeposition anneal (PDA) time and Si interface passivation layer on the material and electrical characteristics of the metal-oxide-semiconductor (MOS) capacitor with high-k (HfO2) material on different orientation substrates with (100), (110), and (311). The interfacial change of HfO2∕Si∕GaAs gate stacks after PDA has been characterized using x-ray photoelectron spectroscopy (XPS) and Dit measurement using conductance method and frequency dispersion. XPS measurement shows the formation of gallium and arsenic oxides with increasing annealing temperature. Unoxidized Si and gallium and arsenic oxides formation in the interface might act as traps. Self-aligned MOS field effect transistors using PDA at 600°C and post-metal-annealing at 800°C have also been fabricated and characterized. The (100) substrate has lower density of interface traps and higher mobility due to reduced Ga2O3 formation.
UV-induced surface electrical conductivity jump of polymer nanocomposites
Authors: Chen Guang-Xin , Miyauchi Masahiro , Shimizu Hiroshi
Published: May 2008

A method of improving the electrical conductivity of polymer nanocomposites under UV irradiation was described. An anatase TiO2-grafted carbon nanotube could function as a conductive filler and a photocatalyst when it compounds with a poly(L-lactide) to produce a composite. After UV irradiation, the decomposition of the polymer only occurred on the surface of a poly(L-lactide)/TiO2 grafted carbon nanotube composite and not on bulk, resulting in an electrical conductivity jump as high as six orders of magnitude.
Magnetostatic and magnetohydrodynamic modeling of planar wire arrays
Authors: Esaulov A. A. , Kantsyrev V. L. , Safronova A. S. , Velikovich A. L. , Cuneo M. E. , Jones B. , Struve K. W. , Mehlhorn T. A.
Published: May 2008

For the past 2 years the planar wire array loads have proven their ability to create powerful x-ray radiation sources at the pulsed power facilities with the current level ranging from 1to3MA. Several key features of the implosion and ablation dynamics of the planar wire arrays distinguish them from the wire arrays of the conventional cylindrical design. The uneven current partition through the array wires in planar geometry results in a significant difference between the ablation rates of the outermost and the innermost array wires. This difference is even higher in a double row planar array geometry. According to the three-dimensional magnetohydrodynamic simulations the effect of the delayed ablation of the inner array wires can result in effective mitigation of the Rayleigh–Taylor instability modes. The high number (200–300) of wires in a cylindrical array is preferable to ensure fine azimuthal symmetry of an array implosion. However this requirement is not a great concern for the planar wire array loads, which implode along the plane of wires. Hence, the low-wire-number planar array loads are naturally optimized for the Z-pinch experiments at short pulse (100ns) 1MA facilities. The application of planar wire array loads at high current accelerators is attractive for the purposes of the inertial confinement fusion because of the relative compactness of these loads and their potential for radiation pulse shaping.
A constant-time kinetic Monte Carlo algorithm for simulation of large biochemical reaction networks
Authors: Slepoy Alexander , Thompson Aidan P. , Plimpton Steven J.
Published: May 2008

The time evolution of species concentrations in biochemical reaction networks is often modeled using the stochastic simulation algorithm (SSA) [Gillespie, J. Phys. Chem. 81, 2340 (1977)]. The computational cost of the original SSA scaled linearly with the number of reactions in the network. Gibson and Bruck developed a logarithmic scaling version of the SSA which uses a priority queue or binary tree for more efficient reaction selection [Gibson and Bruck, J. Phys. Chem. A 104, 1876 (2000)]. More generally, this problem is one of dynamic discrete random variate generation which finds many uses in kinetic Monte Carlo and discrete event simulation. We present here a constant-time algorithm, whose cost is independent of the number of reactions, enabled by a slightly more complex underlying data structure. While applicable to kinetic Monte Carlo simulations in general, we describe the algorithm in the context of biochemical simulations and demonstrate its competitive performance on small- and medium-size networks, as well as its superior constant-time performance on very large networks, which are becoming necessary to represent the increasing complexity of biochemical data for pathways that mediate cell function.
Electrical conductivity and carrier concentration control in β-Ga2O3 by Si doping
Authors: Víllora Encarnación G. , Shimamura Kiyoshi , Yoshikawa Yukio , Ujiie Takekazu , Aoki Kazuo
Published: May 2008

Electrical conductivity of β-Ga2O3 has been attributed so far to an oxygen deficiency, the donors presumably being oxygen vacancies. This letter shows, however, that the conductivity can be intentionally controlled over three orders of magnitude by Si doping. The related free-carrier concentration, which varies between 1016–1018cm−3, corresponds to a 25%–50% effective Si donors. Since Si is the main impurity present in Ga2O3 powders—in the order of the studied doping levels—we conclude that the electrical conductance of β-Ga2O3 can be attributed to Si impurities, and that the contribution of oxygen vacancies, if any, is not dominant.
Virial exchange energies from model exact-exchange potentials
Authors: Gaiduk Alex P. , Staroverov Viktor N.
Published: May 2008

It is shown by the example of Slater’s averaged exchange potential that a poor approximation to the optimized effective potential (OEP) can yield a deceptively accurate energy via the conventional Kohn–Sham energy functional. For a trial exchange potential to be correct, its Kohn–Sham energy must coincide with the value obtained by the Levy–Perdew virial relation. Significant discrepancies between Kohn–Sham and the virial exchange energies are found for self-consistent Slater, Becke–Johnson, and effective local potentials (ELPs); their relative magnitudes are used to argue that, as approximations to the exact-exchange OEP, ELPs are the most accurate. Virial energy discrepancies vanish for Yang–Wu OEPs when the orbital and auxiliary basis sets are balanced, and remain surprisingly small for oscillatory OEPs obtained with unbalanced basis sets.
Effect of electric field distribution uniformity on electrospinning
Authors: Yang Ying , Jia Zhidong , Liu Jianan , Li Qiang , Hou Lei , Wang Liming , Guan Zhicheng
Published: May 2008

Recent experiments demonstrated that the essential electrospinning mechanism is a rapidly whipping dielectric liquid jet in an electric field. The effects of three kinds of electric field distributions including a very nonuniform electric field, a slightly nonuniform electric field, and a uniform electric field were studied to analyze the influence of the electric field distribution on the electrospinning process and the fiber morphology. The average electric field strength Eav and the electric field nonuniformity coefficient f were used to describe the electric field. The results show that the length range of the straight jet path for stable electrospinning process was a function of the electric field distribution. The length of the jet straight part increased with the decreasing f. The initial angle of the looping envelope and the helical pitch decreased with decreasing f. The results also show that higher voltages can be used at the nozzle for a stable electrospinning when f is small. A higher voltage at the nozzle can produce a larger average electric field strength which will help produce smaller fiber diameters for the large bending frequency.
Spectroscopic data for the LiH molecule from pseudopotential quantum Monte Carlo calculations
Authors: Trail J. R. , Needs R. J.
Published: May 2008

Quantum Monte Carlo and quantum chemistry techniques are used to investigate pseudopotential models of the lithium hydride (LiH) molecule. Interatomic potentials are calculated and tested by comparing with the experimental spectroscopic constants and well depth. Two recently developed pseudopotentials are tested, and the effects of introducing a Li core polarization potential are investigated. The calculations are sufficiently accurate to isolate the errors from the pseudopotentials and core polarization potential. Core-valence correlation and core relaxation are found to be important in determining the interatomic potential.
Orientation dependence on electromechanical coupling behavior of ferroelectrics under compression
Authors: Zhao Ping , Li Jackie
Published: May 2008

When a compression is applied to a fully poled ferroelectric polycrystal at an angle θ to the original poling direction, its nonlinear electromechanical response is dependent on such an angle. Here we report our investigation on such an orientation dependence on the electromechanical behavior of lead zirconium titanate (PZT) under compression. The measured stress-electric displacement and stress-strain curves exhibit strong angle dependence and nonlinear behavior under compression. The experimental results indicate that as the loading direction changes from 0°, to 30°, 45°, 60°, and finally 90° to the initial poling direction, the magnitude of the electric displacement and mechanical strain all decrease. Then a micromechanics theory based on irreversible thermodynamics and physics of domain switch was applied to study this orientation effect on the electromechanical coupling behavior under compression. The comparisons between our experimental data and theoretical prediction are found to be in reasonable agreement.