bluuebunny/crossref_metadata_2025 huggingface dataset:
The use of a test battery in marine ecotoxicology: The acute toxicity of sodium dodecyl sulfate
Authors: Mariani Livia , De Pascale Domenica , Faraponova Olga , Tornambè Andrea , Sarni Angela , Giuliani Silvia , Ruggiero Giordano , Onorati Fulvio , Magaletti Erika
Published: July 2006

For a toxicity assessment of substances entering the marine environment, it is preferable to carry out ecotoxicological tests on a base‐set of taxa utilizing target species belonging to different trophic levels. In this study a battery composed of Vibrio fischeri (bacteria), Dunaliella tertiolecta (algae), Tigriopus fulvus (crustacea), Paracentrotus lividus (echinodermata), and Dicentrarchus labrax (pisces) was used for acute toxicity testing of sodium dodecyl sulfate (SDS). SDS is an anionic surfactant widely employed in industry, agriculture, and domestic usage and therefore is found in abundance in the environment, particularly in the sea. The mean values of EC50 obtained were 2.6, 4.8, 7.4, 3.2, 7.3 mg L−1, respectively, for V. fischeri, D. tertiolecta, T. fulvus, P. lividus, and D. labrax. The results indicate the high acute toxicity of SDS with respect to all the trophic levels represented by the target species. In addition, they highlight the usefulness of employing a base‐set of taxa rather than a single species in toxicological tests, in order to obtain more reliable information for the evaluation of toxicity and potential hazards to the marine environment of selected substances. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 373–379, 2006.
On the relaxation of some classes of pointwise gradient constrained energies
Authors: De Arcangelis Riccardo
Published: July 2006

The integral representation problem on

\mathrm{BV}(\Omega )

for the

L^{1}(\Omega )

-lower semicontinuous envelope

\overline{F}

of the functional

F\:\text{:}u \in W^{1,\infty }(\Omega )\mapsto \int _{\Omega }f(\mathrm{∇}u)\:\mathrm{d}x

is approached when

f

is a Borel function, not necessarily convex, with values in

[0, + \infty ]

. The presence of the value +∞ in the image of

f

involves a pointwise gradient constraint on the admissible configurations, since those generating the relaxation process must satisfy the condition

\mathrm{∇}u(x) \in \mathrm{dom}f

for a.e.

x \in \Omega

. The main novelty relies in the absence of any convexity assumption on the domain of

f

. For every convex bounded open set

Ω

,

\overline{F}

is represented on the whole

\mathrm{BV}(\Omega )

as an integral of the calculus of variations by means of the convex lower semicontinuous envelope of

f

. Due to the lack of the convexity properties of

\operatorname{dom}\,f

, the classical integral representation techniques, based on measure theoretic arguments, seem not to work properly, thus an alternative approach is proposed. Applications are given to the relaxation of Dirichlet variational problems and to first order differential inclusions.

Le problème de représentation intégrale sur

\mathrm{BV}(\Omega )

pour l'enveloppe

L^{1}(\Omega )

-semi-continue inférieurement

\overline{F}

de la fonctionnelle

F\:\text{:}u \in W^{1,\infty }(\Omega )\mapsto \int _{\Omega }f(\mathrm{∇}u)\:\mathrm{d}x

est considéré dans le cas où

f

est Borelienne non nécessairement convexe, à valeurs dans

[0, + \infty ]

. La présence de la valeur +∞ dans l'image de

f

implique une contrainte ponctuelle sur le gradient des configurations admissibles, puisque celles qui jouent un rôle dans le processus de relaxation doivent satisfaire la condition

\mathrm{∇}u(x) \in \mathrm{dom}f

p.p. dans

Ω

. La nouveauté principale consiste en l'absence d'hypothèses de convexité sur le domaine de

f

. Pour tout ensemble ouvert borné et convexe

Ω

,

\overline{F}

admet une représentation sur

\mathrm{BV}(\Omega )

tout entier comme une intégrale du calcul des variations au moyen de l'enveloppe convexe et semi-continue inférieurement de

f

. En raison du manque des propriétés de convexité de

\operatorname{dom}\,f

, les techniques classiques de représentation intégrale, basées sur des arguments de théorie de la mesure, semblent ne pas fonctionner convenablement, donc une approche alternative est proposée. Des applications sont données à la relaxation des problèmes variationnels de type Dirichlet et aux inclusions différentielles du premier ordre.
Women's access to modern methods of fertility regulation
Authors: Simelela N.
Published: July 2006

Preventing unintended pregnancies through access to modern family planning could avert 20–35% of maternal deaths, saving the lives of more than 100,000 women each year. Obstacles to wider access still exist, but they may be overcome by overt policy commitment to reproductive health services, partnership between stakeholders, community involvement and quality programs.
Access to emergency contraception
Authors: Schiappacasse V. , Diaz S.
Published: July 2006

The introduction of emergency contraception (EC) has encountered barriers derived from the erroneous perception of EC as an abortificient and conservative attitudes. In several countries, “prolife” groups have initiated lawsuits against national regulatory bodies for approving EC. Other barriers are limited availability and high price of dedicated products, lack of information among providers about EC and the requirement of medical prescription for EC. The availability of EC has increased in the last years due to efforts of multiple stakeholders. Facilitating factors include the acceptability of EC by users and providers; dissemination of information about EC; advocacy among policymakers; training of providers; registration of dedicated products; over the counter sales and inclusion of EC in the national norms. By 2005, 109 countries have registered around 50 dedicated products that are available in public services, pharmacies, NGOs or through social marketing and 45 countries have included EC in their national norms.
Violence against women and the Millennium Development Goals: Facilitating women's access to support
Authors: Ellsberg M.
Published: July 2006

Violence against women is a serious health and development concern, as well as a violation of women's human rights. Violence against women has a devastating effect on women's sexual and reproductive health, as well as the health of their children, and is rooted in gender inequality. Reducing violence against women is therefore a key strategy for the achievement of the Millennium Development Goals. Key lessons have emerged from more than two decades of experiences dealing with violence against women within the health sector. Interventions must go beyond training and curricula reform and utilize a system‐wide approach, including changes in policies, procedures and attention to privacy and confidentiality. Providers must work together with other sectors, particularly at a community level, to strengthen local networks for support of survivors of violence. Prevention activities are critical, particularly those that seek to change cultural norms and laws that encourage violence and discriminate against women and girls.
Interdependence of udder quarters for new intramammary infection during the dry period in cows submitted to selective antibiotic therapy
Authors: Robert Aurélie , Bareille Nathalie , Roussel Philippe , Poutrel Bernard , Heuchel Vincent , Seegers Henri
Published: July 2006

The aim was to investigate the interdependence of udder quarters within cow towards the incidence of intramammary infections during the dry period in herds under selective dry-cow antibiotic therapy. A total of 368 cows among 28 herds were included in a survey. Quarter milk samples collected at the last milking before drying-off and on day 3 after calving were submitted to microbiological procedures. An expected distribution of cows according to their number of newly infected quarters was calculated based on a binomial probability distribution from the overall quarter incidence (or from the quarter incidence in each herd) and compared with the observed distribution. Incidence of newly infected quarters ranged from 0·0 to 39·3%, depending on the herd (median: 17·7%). Interdependence of quarters towards new infection during the dry period was observed whatever the pathogen type, for both treated and untreated cows. Calculation of an expected distribution of cows according to their number of newly infected quarters using the quarter incidence in each herd (instead of the overall quarter incidence) reduced the distance to the observed distribution, but interdependence was still observed. Our results support the application of selective antibiotic therapy at the cow level rather than at the quarter level.
Legal Pluralism and the Rule of Law in Timor Leste
Authors: GRENFELL LAURA
Published: July 2006

Many transitional countries face the problem of establishing the rule of law in a weak justice sector where a gulf separates local legal norms from national, constitutional norms that are drawn largely from the international sphere. As a case study of East Timor this article challenges simplistic positivist notions about the normative hierarchy of laws within a constitutionally bounded polity. It argues that in transitional countries such as East Timor legal pluralism is important but must be properly tuned to serve the rule of law. Legal pluralism poses certain dangers when it operates without any of the checks or balances that ensure accountability and the promotion of constitutional values such as equality. The rule of law is not served by an informal system where there are no formal avenues of appeal and thus minimal accountability and transparency. A more promising version of legal pluralism that comports with the rule of law is one that empowers the state to monitor local decisions to ensure that they observe the norms set out in East Timor's Constitution.
State-Centrism, International Law, and the Anxieties of Influence
Authors: MARKS SUSAN
Published: July 2006

State-centrism is a key concept in discussions of sovereignty, justice, and the global political order and of changes within that order. Thus we routinely hear: ‘that analysis is far too state-centric!’ Or: ‘earlier approaches were marred by excessive state-centrism, and need to be reconsidered in the light of contemporary circumstances’. Or even: ‘I'm state-centrist and proud of it’. This article brings into focus some of the themes associated with state-centrism in international legal writing, and suggests something of the limits of this way of framing issues. It also raises the possibility that these themes may provide clues to certain characteristic and apparently deep-rooted, but not always clearly recognized, anxieties on the part of those who work in this field. Borrowing a phrase from Harold Bloom, the article refers to these as anxieties of influence.
The ‘Feminizing’ of Torture under International Human Rights Law
Authors: EDWARDS ALICE
Published: July 2006

International human rights law has been the subject of much scrutiny by feminist scholars over the past two decades, principally because of the way in which it is seen as privileging the realities of men's lives while ignoring or marginalizing those of women. The international prohibition on torture is identified by feminist writers as a classic example of this ‘male’-gendered nature of human rights law. This article explores the extent to which key feminist critiques of the 1980s and 1990s are now reflected in the commentary and jurisprudence on torture of various international human rights bodies. It asks: have the critiques of international human rights law been satisfied by interpretations applied by international and regional bodies to this so-called ‘male’ right? It concludes by offering both caution and counsel – it cautions against the potentiality of new interpretations simply replacing old gender-based stereotypes with new ones and counsels international decision-makers to focus on the individual or personalized characteristics and circumstances of each claim, of which sex/gender may be but one factor.
The Construction of a Wall between The Hague and Jerusalem: The Enforcement and Limits of Humanitarian Law and the Structure of Occupation
Authors: GROSS AEYAL M.
Published: July 2006

The ICJ considered the Wall in terms of the structure of the Israeli occupation and the settlements, which is one of de facto annexation. By contrast, the Israeli HCJ uses proportionality to regulate within the occupation. This approach may be inherent in humanitarian law, but involves a misplaced transplantation of the proportionality doctrine and an imbalanced rights/security equation. Contrary to the HCJ's determination, which attributes the different conclusions of the two courts to the different factual backgrounds available to them, this article argues that they reflect the courts' variant attitudes towards the barrier and its place within the broader context of the occupation and its structure. The looming shadow of the ICJ affected the HCJ's decision. On critical questions of international law, however, a wall separates international law as articulated in The Hague and the decisions issued in Jerusalem, pointing to the need for a new articulation of existing theories on transnational legal processes.
The Moiwana Village Case: A New Trend in Approaching the Rights of Ethnic Groups in the Inter-American System
Authors: MARTIN CLAUDIA
Published: July 2006

Moiwana Village is the second case to be decided by the Inter-American Court on Human Rights against Suriname in which the victims are members of an ethnic community that descends from ‘Bush Negroes’ or ‘Maroons’, namely escaped former slaves who established new autonomous communities in the eastern part of Suriname. In contrast to its prior judgment, in Moiwana the Court shows a striking evolution in its case law regarding the treatment of ethnic or group rights. This approach, which may be traced back to previous case law on the rights of indigenous communities, affords an enhanced protection to members of an ethnic community in the light of their disadvantaged position as a vulnerable group and taking into account the ancestral traditions followed by the community. After the Moiwana case, the Court decided Yakye Axa and Yatama, two cases regarding indigenous and ethnic communities in which this tribunal consolidated its approach towards the protection of these vulnerable groups.
Between Harmonization and Fragmentation: New Groundwork on Ad Hoc Criminal Courts and Tribunals
Authors: STAHN CARSTEN
Published: July 2006

Guénaël Mettraux, International Crimes and the Ad Hoc Tribunals, Oxford, Oxford University Press, 2005, ISBN 0199271550, 474 pp., £75.00 (hb).

Cesare P. R. Romano, André Nollkaemper, and Jann Kleffner (eds.), Internationalized Criminal Courts: Sierra Leone, East Timor, Kosovo and Cambodia, Oxford, Oxford University Press, 2005, ISBN 0199276730, 550 pp., £75.00 (hb).
Implications of agricultural policy for species invasion in shifting cultivation systems
Authors: ALBERS HEIDI J. , GOLDBACH MICHAEL J. , KAFFINE DANIEL T.
Published: July 2006

Policies to influence land use decisions in agriculture or grazing can increase the ability of invasive species to out-compete native species and thereby disrupt seemingly stable ecological-economic systems. Building off of models of interdependent resources, invasive species and soil fertility, this paper develops a model of shifting cultivation decisions for two types of farmers, one who sees the threat of invasive grasses and one who does not. The paper uses numerical solutions to this dynamic decision problem to examine the impact of various policies on farmer welfare and on the stability of the economic-ecological system. Some policies undermine the resilience of the system, while other policies augment the system's ability to withstand species invasions.
The bioeconomics of controlling an African rodent pest species
Authors: SKONHOFT ANDERS , LEIRS HERWIG , ANDREASSEN HARRY P. , MULUNGU LOTH S.A. , STENSETH NILS CHR.
Published: July 2006

The paper treats the economy of controlling an African pest rodent, the multimammate rat, causing major damage in maize production. An ecological population model is presented and used as a basis for the economic analyses carried out at the village level using data from Tanzania. This model incorporates both density-dependent and density-independent (stochastic) factors. Rodents are controlled by applying poison, and the costs are made up of the cost of poison plus the damage to maize production. We analyse how the present-value costs of maize production are affected by various rodent control strategies, by varying the duration and timing of rodenticide application. Our numerical results suggest that it is economically beneficial to control the rodent population. In general, the most cost-effective duration of controlling the rodent population is 3–4 months every year, and especially at the end of the dry season/beginning of rainy season. The paper demonstrates that changing from today's practice of symptomatic treatment when heavy rodent damage is noticed to a practice where the calendar is emphasized, may substantially improve the economic conditions for the maize producing farmers. This main conclusion is highly robust and not much affected by changing prices of maize production.
Multiple equilibria, soil conservation investments, and the resilience of agricultural systems
Authors: ANTLE JOHN M. , STOORVOGEL JETSE J. , VALDIVIA ROBERTO O.
Published: July 2006

This paper provides a new explanation for the persistent land degradation in some parts of the world, despite the availability of seemingly effective soil conservation technologies. We demonstrate that soil conservation technologies may induce agricultural systems to exhibit equilibria characterized by both low and high levels of soil degradation. These two equilibria are separated by a threshold level of soil degradation beyond which a conservation investment will not yield a positive return. Once a parcel of land crosses this productivity threshold, soil degradation becomes economically irreversible (it is not profitable to invest in soil conservation) even though the degradation may be technically reversible. A case study of terracing investments in Peru is used to demonstrate the existence of multiple equilibria under conditions typical of many marginal agricultural areas. These findings help explain why attempts to encourage permanent adoption of soil conservation practices often fail, and how more successful policies could be designed.
Fragmented landholding, productivity, and resilience management
Authors: SENGUPTA NIRMAL
Published: July 2006

The operation of a number of non-contiguous parcels of land as a single farming unit is known as land fragmentation. It is a widespread and persistent phenomenon and, at the same time, widely criticized by development agencies. Available evidence clearly suggests that the unqualified faith in the merit of consolidation is not justified; fragmentation may have some rationale. This paper substantiates the latter position with a case study of an irrigated agricultural system. Thereafter, it locates fragmentation within the broader context and analyses its role within a hierarchy of phenomena in the linked social and ecological local system. For this analysis an evolutionary game model is used. It is shown that fragmentation increases the resilience of the system of cooperation. The study concludes by suggesting an appropriate strategy for resilience management.
Asymmetric Reduction of o‐Chloroacetophenone with Candida pseudotropicalis104
Authors: Xie Qing , Wu Jianping , Xu Gang , Yang Lirong
Published: July 2006

The asymmetric reduction of o‐chloroacetophenone 1 with Candida pseudotropicalis 104 produced the corresponding (S)‐1‐(2‐chloro‐phenyl)‐ethanol 2 with the enantiomeric excess (ee >99%) without addition of any cosolvent. The cell could tolerate high ketone 1 concentration of 233.8 mmol/L (i.e., 36 g/L) with considerable reduction activity in this method. The product 2 concentration achieved 38.9 and 58.4 mmol/L with cells of 40 and 60 gDCW (dry cell weight)'L, respectively, in 24 h. The optimum reaction time, the effect of substrate concentration, cosubstrate type and concentration, and cell concentration in the reaction were investigated in this paper.
Design of Adsorptive Columns for Specific Pathogen Removal: Application to Staphylococcal Enterotoxin B
Authors: Wang Guangquan , Carbonell Ruben G.
Published: July 2006

The removal of pathogens such as toxins, viruses, bacteria, and prions in human blood, mammalian cell culture media, fermentation broths, food items, and water streams has gained increasing importance in ensuring product safety and in combatting acts of terrorism. Adsorption processes can play an important role in removing such pathogens from solution without affecting other desirable components. Adsorptive columns that can remove specific families of pathogens would need to achieve a reduction of several logs in pathogen concentration. This requirement is much more stringent than the normal yield requirements associated with adsorptive separations aimed at product recovery and purification in a process stream. This paper considers the design of an adsorptive column aimed at reducing the concentration of infectious agents from a known volume of solution by several logs in a fixed amount of time. The general rate (GR) model of chromatography is used in the analysis, including all major transport and kinetic steps in the adsorption process. The theory, with no adjustable parameters, is shown to predict with great accuracy the effect of residence time on the log removal of staphylococcal enterotoxin B (SEB) from solution using an affinity resin with a small peptide (YYWLHH) that has been found to bind specifically to this toxin.
Real‐time monitoring of nutrient concentrations and red‐tide outbreaks in the southern sea of Korea
Authors: Kim Guebuem , Lee Yong‐Woo , Joung Dong‐Joo , Kim Kyung‐Ryul , Kim Kuh
Published: July 2006

In order to determine the physical and chemical factors controlling the outbreak of red tides, we monitored nutrients and other environmental parameters using a novel real‐time monitoring buoy system during the summer of 2003 in the southern sea of Korea, where red‐tide outbreaks occur every year. The real‐time monitoring data on bioluminescence, which may indicate the presence of bioluminescent dinoflagellate species, showed a sudden increase under the lowest concentrations of dissolved inorganic nutrients. Our monitoring system for the first time provides real‐time variations in nutrients and associated outbreaks of dinoflagellate red tides. This result supports the previous hypothesis by others that the outbreak of dinoflagellate red tides is associated with the limited growth of diatoms under depleted DIP or DIN conditions. We suggest that this real‐time monitoring system can be utilized as a powerful tool for studying and predicting harmful dinoflagellate red tides in the coastal ocean.
Spatial and temporal variability of the surface water pCO2 and air‐sea CO2 flux in the equatorial Pacific during 1980–2003: A basin‐scale carbon cycle model
Authors: Wang Xiujun , Christian James R. , Murtugudde Ragu , Busalacchi Antonio J.
Published: July 2006

The surface water pCO2 data from the past two decades indicate significant seasonal to interannual variability, and the size of the equatorial Pacific CO2 source is strongly influenced by El Niño and La Niña events. A basin‐scale ocean circulation‐biogeochemistry model is developed to study the carbon cycle in the equatorial Pacific for the period of 1980–2003. The model produces strong spatial and temporal variability in sea minus air pCO2 (50–170 μatm) and sea‐to‐air CO2 flux (1–5 mol C m−2 yr−1). The magnitude, spatial pattern, and seasonal to interannual variability in the model fields are in general agreement with the observations. Our analyses have demonstrated that dissolved inorganic carbon (DIC) plays a dominant role in determining the interannual variability of the sea surface pCO2 in the equatorial Pacific. However, sea surface temperature (SST) also has significant influence on the spatial and temporal variability of the sea surface pCO2 in particular during warm periods. At seasonal timescales, the sea surface pCO2 is relatively high both in boreal spring and fall, but low in boreal summer in the eastern equatorial Pacific. While the high sea surface pCO2 in boreal fall is associated with the seasonal upwelling of carbon‐rich water, the high sea surface pCO2 in boreal spring results mainly from the seasonal warming (e.g., high SST). At interannual timescales, the sea surface pCO2 is largely associated with the El Niño–Southern Oscillation (ENSO) phenomenon, showing high values during cold ENSO phase but low ones during warm ENSO phase. The overall spatial and temporal variations of the sea surface pCO2 are dominated by physical processes (e.g., seasonal upwelling and the ENSO cycle). However, biological uptake also plays an important role in modulating the variability of the sea surface pCO2, and determining the strength of the equatorial Pacific CO2 source. On an annual basis, the integrated DIC over the top 50 m of the equatorial Pacific is approximately balanced between the supply due to physical processes (1.47 Pg C) and removal due to the biological activity (0.87 Pg C) and outgassing (0.6 Pg C).
Nonequilibrium radiative heat flux modeling for the Huygens entry probe
Authors: Magin T. E. , Caillault L. , Bourdon A. , Laux C. O.
Published: July 2006

An electronic collisional‐radiative model is proposed to predict the nonequilibrium populations and the radiation of the excited electronic states CN(A, B) and N2(A, B, C) during the entry of the Huygens probe into the atmosphere of Titan. The model is loosely coupled with flow solvers using a Lagrangian method. First, the model was tested against measurements obtained with the shock‐tube of NASA Ames Research Center. Then, the model was applied to the simulation of Huygen's entry. Our simulations predict that the population of the CN(B) state is lower than the Boltzmann population by a factor 40 at trajectory time t = 165 s and by a factor 2 at t = 187 s and that the population of the CN(A) state remains close to the Boltzmann population for both trajectory points. The radiative heat fluxes, driven by the CN(A, B) states, are lower than predictions based on the Boltzmann populations by a factor 15 at t = 165 s and a factor 2 at t = 187 s.
Physical and biological regulation of the soft tissue carbon pump
Authors: Parekh P. , Follows M. J. , Dutkiewicz S. , Ito T.
Published: July 2006

We examine the relationship between aeolian iron deposition, ocean circulation, and atmospheric CO2 in the context of a global ocean circulation and biogeochemistry model with a coupled atmospheric reservoir of CO2. In common with previous models we find only a small reduction of atmospheric pCO2 in response to an enhanced aeolian iron source consistent with Last Glacial Maximum conditions. We show this to be due to a combination of limiting factors including control of deep ocean iron concentrations by complexation to an organic ligand, regional compensation in changes to export production, and the maintenance of high preformed nutrient concentrations in deep water formation regions. We also demonstrate a significant sensitivity of atmospheric pCO2 to changes in the residual mean overturning circulation of the Southern Ocean dominated by its regulation of the accumulation of biogenic carbon in the deep ocean. Although it is not enough to explain the full drawdown of pCO2 to glacial levels, a reduction in overturning can lead to significant reduction in atmospheric pCO2, providing mechanistic basis for the control by “vertical mixing” inferred from box models.
GPS scintillation channel model for the disturbed low‐latitude ionosphere
Authors: Keskinen M. J.
Published: July 2006

A Global Positioning System (GPS) scintillation channel model for the disturbed low‐latitude ionosphere is developed by combining first‐principles physics‐based simulated low‐latitude ionospheric irregularities together with an electromagnetic wave propagation model. Using this combined model, basic channel parameters, that is, phase variance, decorrelation length, decorrelation time, and coherence bandwidth, are computed and are favorably compared with recent ground‐based low‐latitude GPS experimental observations.
Bayesian neural network for rainfall‐runoff modeling
Authors: Khan Mohammad Sajjad , Coulibaly Paulin
Published: July 2006

In this paper, a Bayesian learning approach is introduced to train a multilayer feed‐forward network for daily river flow and reservoir inflow simulation in a cold region river basin in Canada. In Bayesian approach, uncertainty about the relationship between inputs and outputs is initially taken care of by an assumed prior distribution of parameters (weights and biases). This prior distribution is updated to posterior distribution using a likelihood function following Bayes' theorem while data are observed. This posterior distribution is called the objective function of a network in the Bayesian learning approach. The objective function is maximized using a suitable optimization technique. Once the network is trained, the predictive distribution of the network outputs is obtained by integrating over the posterior distribution of weights. In this study, Gaussian prior distribution and a Gaussian noise model are used in defining posterior distribution. The network has been optimized using a scaled conjugate gradient technique. Posterior distribution of weights is approximated to Gaussian during prediction. Prediction performance of the Bayesian neural network (BNN) is compared with the results obtained from a standard artificial neural network (ANN) model and a widely used conceptual rainfall‐runoff model, namely, HBV‐96. The BNN model outperformed the conceptual model and slightly outperformed the standard ANN model in simulating mean, peak, and low river flows and reservoir inflows. The significant contribution of the Bayesian method over the conventional ANN approach, among others, is the uncertainty estimation of the outputs in the form of confidence intervals which are particularly needed in practical water resources applications. Prediction confidence limits (or intervals) indicate the extent to which one can rely on predictions for decision making. It is shown that the BNN can provide reliable streamflow and reservoir inflow forecasts without a loss in model prediction accuracy as compared to standard ANN and conceptual model HBV. Another significant advantage of BNN approach is that the overfitting and underfitting problems are automatically taken care of by the Bayesian learning algorithm, which conversely remain serious problems with conventional ANN learning algorithm.
Hurricane forecasts with a global mesoscale‐resolving model: Preliminary results with Hurricane Katrina (2005)
Authors: Shen B.‐W. , Atlas R. , Reale O. , Lin S.‐J. , Chern J.‐D. , Chang J. , Henze C. , Li J.‐L.
Published: July 2006

It is known that General Circulation Models (GCMs) have insufficient resolution to accurately simulate hurricane near‐eye structure and intensity. The increasing capabilities of high‐end computers have changed this. The mesoscale‐resolving finite‐volume GCM (fvGCM) has been experimentally deployed on the NASA Columbia supercomputer, and its performance is evaluated in this study by choosing hurricane Katrina as an example. In late August 2005, Katrina underwent two stages of rapid intensification, and became the sixth most intense hurricane in the Atlantic. Six 5‐day simulations of Katrina at both 0.25° and 0.125° show comparable track forecasts but the 0.125° runs provide much better intensity forecasts, producing the center pressure with errors of only ±12 hPa. In the runs examined in this study, the 0.125° simulates better near‐eye wind distributions and a more realistic average intensification rate. To contribute to the ongoing research on the effects of disabling convection parameterization (CP), we present promising results by comparing 0.125° runs with disabled CPs against runs with enabled CPs.
On the variability of African dust transport across the Atlantic
Authors: Riemer N. , Doherty O. M. , Hameed S.
Published: July 2006

We investigate the interannual variability of Saharan dust transport over the Atlantic by using the TOMS/Nimbus‐7 and TOMS/Earth Probe daily aerosol data. We focus on the winter season, and on the area off the North‐West African coast (15–30°N, 30–5°W). Previous studies have suggested that the variability of the Saharan dust can be partially explained by the North Atlantic Oscillation. In an alternative approach, we correlate the aerosol data with the positions and the surface pressure values of the two “Centers of Action” in the Atlantic, the Azores High and the Icelandic Low. This approach decouples the two semi‐permanent pressure systems, and it reveals that the Icelandic Low does not play a role in the dust concentration for our region of interest. Instead, the position of the Azores High turns out to be the most important factor, with the Azores High latitude yielding the highest correlation (r = 0.48).
Potential bias of model projected greenhouse warming in irrigated regions
Authors: Lobell D. B. , Bala G. , Bonfils C. , Duffy P. B.
Published: July 2006

Atmospheric general circulation models (GCMs) used to project climate responses to increased CO2 generally omit irrigation of agricultural land. Using the NCAR CAM3 GCM coupled to a slab‐ocean model, we find that inclusion of an extreme irrigation scenario has a small effect on the simulated temperature and precipitation response to doubled CO2 in most regions, but reduced warming by as much as 1°C in some agricultural regions, such as Europe and India. This interaction between CO2 and irrigation occurs in cases where agriculture is a major fraction of the land surface and where, in the absence of irrigation, soil moisture declines are projected to provide a positive feedback to temperature change. The reduction of warming is less than 25% of the temperature increase modeled for doubled CO2 in most regions; thus greenhouse warming will still be dominant. However, the results indicate that land use interactions may be an important component of climate change uncertainty in some agricultural regions. While irrigated lands comprise only ∼2% of the land surface, they contribute over 40% of global food production. Climate changes in these regions are therefore particularly important to society despite their relatively small contribution to average global climate.
Electron temperature enhancement beneath the magnetospheric cusp
Authors: Prölss Gerd W.
Published: July 2006

In the dayside polar region, soft electron precipitation and heat conduction cause a significant increase in the electron temperature of the upper ionosphere. Using DE‐2 satellite data, the properties of this remarkable cusp signature are investigated. First, the location of the temperature enhancement is determined. It is found that this location is primarily dependent on the substorm activity. For geomagnetically quiet conditions (AE ≃ 0) the temperature peak is located near 79° invariant latitude. For each increase in the AE index by 100 nT it moves equatorward by about 1 degree. During strongly disturbed conditions it may be observed at a latitude as low as 61 degrees. Since the substorm activity is controlled by the Bz component of the interplanetary magnetic field, the location of the temperature peak is also dependent on this parameter. Besides the location, the magnitude of the temperature increase is of interest. This magnitude is found to be strongly dependent on altitude. Within the height range 280 to 940 km it increases by a factor of almost 5. Compared with altitude, other parameters like the dynamic pressure of the solar wind or the geomagnetic activity are only of secondary importance. To obtain mean latitudinal profiles of the cusp‐related temperature enhancement, a superposed epoch type of averaging procedure is used. This way the basic latitudinal structure of this narrow feature is preserved. For an altitude of 700 km the following mean properties are derived: amplitude ≃1200 K; width at half this maximum value ≃2.5 degrees; distance between equatorward boundary and maximum of the temperature increase ≃3.5 degrees. In general, a decrease in the electron density is observed at the location of the temperature peak. Only in the uppermost ionosphere and during geomagnetically quiet conditions is the density observed to increase, on average. The results obtained in this study should prove very useful for both empirical and theoretical modeling of the dayside polar ionosphere. They may also shed some light on the reconfiguration of the magnetosphere in the cusp region during substorm activity.
Unsaturated hydraulic conductivity from nuclear magnetic resonance measurements
Authors: Ioannidis M. A. , Chatzis I. , Lemaire C. , Perunarkilli R.
Published: July 2006

Gravity‐driven drainage of water from a column of glass beads of uniform size is studied using nuclear magnetic resonance (NMR). The evolution of proton magnetization and its spin‐spin relaxation time is measured as a function of drainage time at different locations within the column. On the basis of these measurements a model for calculating water relative permeability directly from relaxation time data at various saturations, originally proposed by Chen et al. (1994), is successfully tested for the first time.
Measuring direction in the coupling of biological oscillators: A case study for electroreceptors of paddlefish
Authors: Brea Jorge , Russell David F. , Neiman Alexander B.
Published: July 2006

Recently developed methods for estimating directionality in the coupling between oscillators were tested on experimental time series data from electroreceptors of paddlefish, because each electroreceptor contains two distinct types of noisy oscillators. One type of oscillator is in the sensory epithelia, and another type is in the terminals of afferent neurons. Based on morphological organization and our previous work, we expected unidirectional coupling, whereby epithelial oscillations synaptically influence the spiking oscillators of afferent neurons. Using directionality analysis we confirmed unidirectional coupling of oscillators embedded in electroreceptors. We studied the performance of directionality algorithms for decreasing length of data. Also, we experimentally varied the strength of oscillator coupling, to test the effect of coupling strength on directionality algorithms.
Statistics of subthreshold neuronal voltage fluctuations due to conductance-based synaptic shot noise
Authors: Richardson Magnus J. E. , Gerstner Wulfram
Published: July 2006

Neurons in the central nervous system, and in the cortex in particular, are subject to a barrage of pulses from their presynaptic populations. These synaptic pulses are mediated by conductance changes and therefore lead to increases or decreases of the neuronal membrane potential with amplitudes that are dependent on the voltage: synaptic noise is multiplicative. The statistics of the membrane potential are of experimental interest because the measurement of a single subthreshold voltage can be used to probe the activity occurring across the presynaptic population. Though the interpulse interval is not always significantly smaller than the characteristic decay time of the pulses, and so the fluctuations have the nature of shot noise, the majority of results available in the literature have been calculated in the diffusion limit, which is valid for high-rate pulses. Here the effects that multiplicative conductance noise and shot noise have on the voltage fluctuations are examined. It is shown that both these aspects of synaptic drive sculpt high-order features of the subthreshold voltage distribution, such as the skew. It is further shown that the diffusion approximation can only capture the effects arising from the multiplicative conductance noise, predicting a negative voltage skew for excitatory drive. Exact results for the full dynamics are derived from a master-equation approach, predicting positively skewed distributions with long tails in voltage ranges typical for action potential generation. It is argued that, although the skew is a high-order feature of subthreshold voltage distributions, the increased probability of reaching firing threshold suggests a potential role for shot noise in shaping the neuronal transfer function.
Frequency domain analysis of noise in simple gene circuits
Authors: Cox Chris D. , McCollum James M. , Austin Derek W. , Allen Michael S. , Dar Roy D. , Simpson Michael L.
Published: July 2006

Recent advances in single cell methods have spurred progress in quantifying and analyzing stochastic fluctuations, or noise, in genetic networks. Many of these studies have focused on identifying the sources of noise and quantifying its magnitude, and at the same time, paying less attention to the frequency content of the noise. We have developed a frequency domain approach to extract the information contained in the frequency content of the noise. In this article we review our work in this area and extend it to explicitly consider sources of extrinsic and intrinsic noise. First we review applications of the frequency domain approach to several simple circuits, including a constitutively expressed gene, a gene regulated by transitions in its operator state, and a negatively autoregulated gene. We then review our recent experimental study, in which time-lapse microscopy was used to measure noise in the expression of green fluorescent protein in individual cells. The results demonstrate how changes in rate constants within the gene circuit are reflected in the spectral content of the noise in a manner consistent with the predictions derived through frequency domain analysis. The experimental results confirm our earlier theoretical prediction that negative autoregulation not only reduces the magnitude of the noise but shifts its content out to higher frequency. Finally, we develop a frequency domain model of gene expression that explicitly accounts for extrinsic noise at the transcriptional and translational levels. We apply the model to interpret a shift in the autocorrelation function of green fluorescent protein induced by perturbations of the translational process as a shift in the frequency spectrum of extrinsic noise and a decrease in its weighting relative to intrinsic noise.
Phase behavior and particle size cutoff effects in polydisperse fluids
Authors: Wilding Nigel B. , Sollich Peter , Fasolo Moreno , Buzzacchi Matteo
Published: July 2006

We report a joint simulation and theoretical study of the liquid-vapor phase behavior of a fluid in which polydispersity in the particle size couples to the strength of the interparticle interactions. Attention is focused on the case in which the particle diameters are distributed according to a fixed Schulz form with degree of polydispersity δ=14%. The coexistence properties of this model are studied using grand canonical ensemble Monte Carlo simulations and moment free energy calculations. We obtain the cloud and shadow curves as well as the daughter phase density distributions and fractional volumes along selected isothermal dilution lines. In contrast to the case of size-independent interaction [N. B. Wilding et al., J. Chem. Phys. 121, 6887 (2004)], the cloud and shadow curves are found to be well separated, with the critical point lying significantly below the cloud curve maximum. For densities below the critical value, we observe that the phase behavior is highly sensitive to the choice of upper cutoff on the particle size distribution. We elucidate the origins of this effect in terms of extremely pronounced fractionation effects and discuss the likely appearance of new phases in the limit of very large values of the cutoff.
Stochastic modeling of neurobiological time series: Power, coherence, Granger causality, and separation of evoked responses from ongoing activity
Authors: Chen Yonghong , Bressler Steven L. , Knuth Kevin H. , Truccolo Wilson A. , Ding Mingzhou
Published: July 2006

In this article we consider the stochastic modeling of neurobiological time series from cognitive experiments. Our starting point is the variable-signal-plus-ongoing-activity model. From this model a differentially variable component analysis strategy is developed from a Bayesian perspective to estimate event-related signals on a single trial basis. After subtracting out the event-related signal from recorded single trial time series, the residual ongoing activity is treated as a piecewise stationary stochastic process and analyzed by an adaptive multivariate autoregressive modeling strategy which yields power, coherence, and Granger causality spectra. Results from applying these methods to local field potential recordings from monkeys performing cognitive tasks are presented.
Interplay between two phase transitions: Crystallization and liquid-liquid phase separation in a polyolefin blend
Authors: Zhang Xiaohua , Wang Zhigang , Dong Xia , Wang Dujin , Han Charles C.
Published: July 2006

The interplay between liquid-liquid phase separation (LLPS) and crystallization at several compositions in statistical copolymer blends of poly(ethyleneco-hexene) and poly(ethylene-cobutene) has been examined by optical microscopy (OM), atomic force microscopy (AFM), and differential scanning calorimetry (DSC). The phase contrast optical microscopy shows interconnected bicontinuous structures for deeply quenched LLPS, characteristic of spinodal decomposition. After a second quench to a temperature below the melting point, an overwhelming change in crystallization kinetics has been clearly observed, which is caused by the increase of the nucleation rate assisted by concentration fluctuations due to the spontaneous spinodal LLPS. We propose a new mechanism of “fluctuation assisted nucleation” in the crystallization process for such interactive process in a blend system. The experimental results from OM, AFM, and DSC measurements at various conditions are all consistent with the fluctuation assisted nucleation model.
Ab initiononadiabatic dynamics study of ultrafast radiationless decay over conical intersections illustrated on the Na3F cluster
Authors: Mitrić Roland , Bonačić-Koutecký Vlasta , Pittner Jiří , Lischka Hans
Published: July 2006

We present a theoretical approach for the ultrafast nonadiabatic dynamics based on the ab initio molecular dynamics carried out “on the fly” in the framework of the configuration interaction method combined with Tully’s surface hopping algorithm for nonadiabatic transitions. This approach combined with our Wigner distribution approach allows us to perform accurate simulations of femtosecond pump-probe spectra in the systems where radiationless transitions among electronic states take place. In this paper we illustrate this by theoretical simulation of ultrafast processes and nonradiative relaxation in the Na3F cluster, involving three excited states and the ground electronic state. Furthermore, we show that our accurate simulation of the photoionization pump-probe spectrum is in full agreement with the experimental signal. Based on the nonadiabatic dynamics at high level of accuracy and taking into account all degrees of freedom, the nonradiative lifetime for the 1B11 excited state of Na3F has been determined to be ∼900fs.