bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic interaction of multiple buoyant jets
Authors: Lai Adrian C. H. , Lee Joseph H. W.
Published: August 2012

An array of closely spaced round buoyant jets interact dynamically due to the pressure field induced by jet entrainment. Mutual jet attraction can result in a significant change in jet trajectories. Jet merging also leads to overlapping of the passive scalar fields associated with the individual jets, resulting in mixing characteristics that are drastically different from those of an independent free jet. A general semi-analytical model for the dynamic interaction of multiple buoyant jets in stagnant ambient conditions is proposed. The external irrotational flow field induced by the buoyant jets is computed by a distribution of point sinks with strength equal to the entrainment per unit length along the unknown jet trajectories and accounting for boundary effects. The buoyant jet trajectories are then determined by an iterative solution of an integral buoyant jet model by tracking the changes in the external entrainment flow and dynamic pressure fields. The velocity and concentration fields of the jet group are obtained by momentum or kinetic energy superposition for merged jets and plumes, respectively. The modelling approach is supported by numerical solution of the Reynolds-averaged Navier–Stokes equations. The model shows that jet merging and mixing can be significantly affected by jet interactions. Model predictions of the multiple jet trajectories, merging height, as well as the centreline velocity and concentration of the buoyant jet group are in good agreement with experimental data for: (i) a clustered momentum jet group; (ii) a turbulent plume pair; and (iii) a rosette buoyant jet group. Dynamic interactions between a jet group are shown to decrease with the addition of an ambient cross-flow.
Dietary linoleic acid elevates endogenous 2-arachidonoylglycerol and anandamide in Atlantic salmon (Salmo salarL.) and mice, and induces weight gain and inflammation in mice
Authors: Alvheim Anita R. , Torstensen Bente E. , Lin Yu Hong , Lillefosse Haldis H. , Lock Erik-Jan , Madsen Lise , Hibbeln Joseph R. , Malde Marian K.
Published: August 2012

Dietary intake of linoleic acid (LA) has increased dramatically during the twentieth century and is associated with a greater prevalence of obesity. Vegetable oils are recognised as suitable alternatives to fish oil (FO) in feed for Atlantic salmon (Salmo salarL.) but introduce high amounts of LA in the salmon fillet. The effect on fish consumers of such a replacement remains to be elucidated. Here, we investigate the effect of excessive dietary LA from soyabean oil (SO) on endocannabinoid levels in Atlantic salmon and mice, and study the metabolic effects in mice when SO replaces FO in feed for Atlantic salmon. Atlantic salmon were fed FO and SO for 6 months, and the salmon fillet was used to produce feed for mice. Male C57BL/6J mice were fed diets of 35 % of energy as fat based on FO- and SO-enriched salmon for 16 weeks. We found that replacing FO with SO in feed for Atlantic salmon increased LA, arachidonic acid (AA), decreased EPA and DHA, elevated the endocannabinoids 2-arachidonoylglycerol (2-AG) and anandamide (AEA), and increased TAG accumulation in the salmon liver. In mice, the SO salmon diet increased LA and AA and decreased EPA and DHA in the liver and erythrocyte phospholipids, and elevated 2-AG and AEA associated with increased feed efficiency, weight gain and adipose tissue inflammation compared with mice fed the FO salmon diet. In conclusion, excessive dietary LA elevates endocannabinoids in the liver of salmon and mice, and increases weight gain and counteracts the anti-inflammatory properties of EPA and DHA in mice.
A checklist of turtle and whale barnacles (Cirripedia: Thoracica: Coronuloidea)
Authors: Hayashi Ryota
Published: August 2012

A checklist of published records of coronuloid barnacles (Cirripedia: Thoracica: Coronuloidea) attached to marine vertebrates is presented, with 44 species (including 15 fossil species) belonging to 14 genera (including 3 fossil genera) and 3 families recorded. Also included is information on their geographical distribution and the hosts with which they occur.
Combined role of childhood maltreatment, family history, and gender in the risk for alcohol dependence
Authors: Fenton M. C. , Geier T. , Keyes K. , Skodol A. E. , Grant B. F. , Hasin D. S.
Published: August 2012

Background

Studies of the relationship between childhood maltreatment and alcohol dependence have not controlled comprehensively for potential confounding by co-occurring maltreatments and other childhood trauma, or determined whether parental history of alcohol disorders operates synergistically with gender and maltreatment to produce alcohol dependence. We addressed these issues using national data.

Method

Face-to-face surveys of 27 712 adult participants in a national survey.

Results

Childhood physical, emotional and sexual abuse, and physical neglect were associated with alcohol dependence (p<0.001), controlling for demographics, co-occurring maltreatments and other childhood trauma. Attributable proportions (APs) due to interaction between each maltreatment and parental history revealed significant synergistic relationships for physical abuse in the entire sample, and for sexual abuse and emotional neglect in women (APs, 0.21, 0.31, 0.26 respectively), indicating that the odds of alcohol dependence given both parental history and these maltreatments were significantly higher than the additive effect of each alone (p<0.05).

Conclusions

Childhood maltreatments independently increased the risk of alcohol dependence. Importantly, results suggest a synergistic role of parental alcoholism: the effect of physical abuse on alcohol dependence may depend on parental history, while the effects of sexual abuse and emotional neglect may depend on parental history among women. Findings underscore the importance of early identification and prevention, particularly among those with a family history, and could guide genetic research and intervention development, e.g. programs to reduce the burden of childhood maltreatment may benefit from addressing the negative long-term effects of maltreatments, including potential alcohol problems, across a broad range of childhood environments.
Output voltage waveform analysis of an intense electron beam accelerator based on strip spiral Blumlein line
Authors: Cheng Xin-Bing , Liu Jin-Liang , Zhang Hong-Bo , Hong Zhi-Qiang , Qian Bao-Liang
Published: August 2012

The Blumlein pulse forming line (BPFL) consisting of an inner coaxial pulse forming line (PFL) and an outer coaxial PFL is widely used in the field of pulsed power, especially for intense electron-beam accelerators (IEBA). The output voltage waveform determines the quality and characteristics of the output beam current of the IEBA. Comparing with the conventional BPFL, an IEBA based on a strip spiral type BPFL can increase the duration of the output voltage in the same geometrical volume. However, for the spiral type BPFL, the voltage waveform on a matched load may be distorted, which influences the electron-beam quality. In this paper, the output waveform of an IEBA based on strip spiral BPFL is analyzed. It is found that there is fluctuation on the flattop of the main pulse, and the flatness is increased with the increment of the output voltage. According to the time integrated pictures of the cathode holder during the operation of the IEBA, the electron emission of the cathode holder is one of the reasons to cause the variance of the flatness. Furthermore, the distribution of the current density of spiral middle cylinder of the BPFL is calculated by using electromagnetic simulation software, and it is obtained that the current density is not uniform, and which leads to the nonuniformity of the impedance of BPFL. Meanwhile, when the nonuniformity of the BPFL is taken into account, the operation of the whole accelerator is simulated using a circuit-simulation code called PSpice. It is obtained that the nonuniformity of the BPFL influences the flatness of the output voltage waveform. In order to get an ideal square pulse voltage waveform and to improve the electron beam quality of such an accelerator, the uniformity of the spiral middle cylinder should be improved and the electron emission of the cathode holder should be avoided. The theoretical analysis and simulated output voltage waveform shows reasonable agreement with that of the experimental results.
Testing Odd-Cycle-Freeness in Boolean Functions
Authors: BHATTACHARYYA ARNAB , GRIGORESCU ELENA , RAGHAVENDRA PRASAD , SHAPIRA ASAF
Published: August 2012

A functionf:2n→ {0,1} isodd-cycle-freeif there are nox1,. . .,xk∈2nwithkan odd integer such thatf(x1) = ··· =f(xk)= 1 andx1+ ··· +xk= 0. We show that one can distinguish odd-cycle-free functions from those ε-far from being odd-cycle-free by making poly(1/ε) queries to an evaluation oracle. We give two proofs of this result, each shedding light on a different connection between testability of properties of Boolean functions and of dense graphs.

The first issue we study is directly reducing testing of linear-invariant properties of Boolean functions to testing associated graph properties. We show a black-box reduction from testing odd-cycle-freeness to testing bipartiteness of graphs. Such reductions have already been shown (Král’, Serra and Vena, and Shapira) for monotone linear-invariant properties defined by forbidding solutions to afinitenumber of equations. But for odd-cycle-freeness whose description involves an infinite number of forbidden equations, a reduction to graph property testing was not previously known. If one could show such a reduction more generally for any linear-invariant property closed under restrictions to subspaces, then it would likely lead to a characterization of the one-sided testable linear-invariant properties, an open problem raised by Sudan.

The second issue we study is whether there is an efficientcanonicaltester for linear-invariant properties of Boolean functions. A canonical tester for linear-invariant properties operates by picking a random linear subspace and then checking whether the restriction of the input function to the subspace satisfies a fixed property. The question is if, for every linear-invariant property, there is a canonical tester for which there is only a polynomial blow-up from the optimal query complexity. We answer the question affirmatively for odd-cycle-freeness. The general question remains open.
Model for Pre-Hospital Disaster Response
Authors: Kelly Joseph T.
Published: August 2012

I will discuss the need for a viable pre-hospital contingency plan applicable to mass casualty or disaster mode situations.

It is my experience, during eighteen years in public safety and emergency services, that most organizations are highly competent and responsive to the daily expectations which are placed upon them. As most emergency services managers will tell you, they generally plan for the expected. After all, analysis in such areas as population growth, economic levels, unemployment and criminal trends are the lifeblood of any emergency service agency's personnel, equipment and budgetary allocations. Our level of sophistication today allows us to predict, with some degree of certainty, what demand will be placed on our organizations and how we will meet that demand. The point is this: we in emergency services have been extremely efficient and proficient in addressing the expected needs of the public we serve.
The Model of Hospital Emergency Departments in 2,000 Bed Hospital in Hungary
Authors: Csepanyi Attila , Sebestyen Mihaly
Published: August 2012

The first emergency department in Hungary was established in Hetenyi Geza County Hospital in 1976. It was organized as part of a research program commissioned by the Ministry of Health. Initially, the hospital had 1400 beds which have now increased to 2,000.

The Emergency Department is located on the ground floor of a new building and occupies 1,100 square meters of surface. The operation of the department is divided into three main areas.
Emergency Telemedical Dispatching Centers the Flow Chart of French S.A.M.U.
Authors: Martinez-Almoyna M. , Gondi F. , Playe E.
Published: August 2012

For one hundred years medical and hospital care have developed as telecommunications have been disseminated throughout the industrialized societies.

Telecommunications have a number of important contributions to make in emergency medicine:

1. To permit reporting of all illness or incident to the rescue and medical services.

2. To permit physicians to offer advice and communicate with the patient and/or his rescuers or paramedical attendants.

3. To permit direct observation of the patient's condition by the physician through telemetry of the E.C.G., etc.

4. To permit co-ordination between rescue services and receiving hospitals and between district hospitals and regional centres.
What is a Disaster?
Authors: Korver Adriaan J. H.
Published: August 2012

One of the most serious bottle-necks in the discussions concerning the medical disaster relief is the lack of any uniformity of the concept “Disaster.”

In the summary of the International Congress on Disaster Medicine (Mainz 1977) (1) we can read “The definition of a disaster. This question hung over many of the discussions of the Congress. Several speakers drew attention to the fundamental differences between relief services for an air or train crash and those for an earthquake or flood. Armed conflicts can present different problems again which in themselves vary enormously. While numbers of victims were submitted as a basis for one classification, numbers alone are not enough.”
Resuscitation by Lay Bystanders: Are We Heading in the Right Direction?
Authors: Hart H.N. , Slooff R.
Published: August 2012

In Rotterdam with half a million inhabitants in 1974, we set up an integrated approach to pre-hospital coronary care consisting of ambulances equipped with monitoring and resuscitation equipment and staffed with specially trained nurses, who have a central role in cardiac emergencies (Figure 1). In 1979 we started a training program in cardiopulmonary resuscitation for the lay public, with training courses of three hours duration, following the Seattle model.
The impact of climate change on agro-ecological zones: evidence from Africa
Authors: Kala Namrata , Kurukulasuriya Pradeep , Mendelsohn Robert
Published: August 2012

This study predicts the impact of climate change on African agriculture. We use a generalized linear model (GLM) framework to estimate the relationship between the proportion of various Agro-Ecological Zones (AEZs) in a district and climate. Using three climate scenarios, we project how climate change will cause AEZs to shift, causing changes in acreage and net revenue per hectare of cropland. Our results predict that Africa will suffer heavy annual welfare losses by 2070–2100, ranging between US$14 billion and US$70 billion, depending on the climate scenario and cropland measure considered.
Caregiver food behaviours are associated with dietary intakes of children outside the child-care setting
Authors: Erinosho Temitope O , Beth Dixon L , Young Candace , Brotman Laurie Miller , Hayman Laura L
Published: August 2012

Objective

To evaluate whether food behaviours of parents are associated with children's dietary intakes outside the child-care setting, and to compare children's dietary intakes at home with foods and beverages consumed when they are at child-care centres.

Design

In 2005–2006, a survey was completed by parents of at least one child between 3 and 5 years old who attended group child-care centres. Surveys about nutrition practices were completed by centre directors. Research assistants observed foods and beverages consumed by children at lunchtime at the centres.

Setting

Sixteen licensed group child-care centres in three underserved New York City communities (South Bronx, East/Central Harlem, Central Brooklyn) and the Lower East Side of Manhattan.

Subjects

Two hundred parents.

Results

Children were more likely to consume healthful foods including fruits or vegetables if parents reported purchasing food from produce stands/farmers’ markets, shopped for frozen or canned fruits frequently and ate family meals or meals prepared at home daily. Children were more likely to consume less healthful foods such as French fries, or fruit drinks, more frequently if parents reported eating meals from fast-food or other restaurants at least once weekly, or if children ate while watching television. Types of foods and beverages offered to children at home (e.g. higher-fat milk, soft drinks and desserts) were less healthful than those offered at child-care centres.

Conclusions

Children's dietary intakes at home need to be improved. Parents need to understand the importance of providing home environments that support healthful food behaviours in children.
Infant BMI trajectories are associated with young adult body composition
Authors: Slining M. M. , Herring A. H. , Popkin B. M. , Mayer-Davis E. J. , Adair L. S.
Published: August 2012

The dynamic aspect of early life growth is not fully captured by typical analyses, which focus on one specific time period. To better understand how infant and young child growth relate to the development of adult body composition, the authors characterized body mass index (BMI) trajectories using latent class growth analysis (LCGA) and evaluated their association with adult body composition. Data are from the Cebu Longitudinal Health and Nutrition Survey, which followed a birth cohort to age 22 years (n = 1749). In both males and females, LCGA identified seven subgroups of respondents with similar BMI trajectories from 0 to 24 months (assessed with bimonthly anthropometrics). Trajectory groups were compared with conventional approaches: (1) accelerated growth between two time points (0–4 months), (2) continuous BMI gain between two points (0–4 months and 0–24 months) and (3) BMI measured at one time point (24 months) as predictors of young adult body composition measures. The seven trajectory groups were distinguished by age-specific differences in tempo and timing of BMI gain in infancy. Infant BMI trajectories were better than accelerated BMI gain between 0 and 4 months at predicting young adult body composition. After controlling for BMI at age 2 years, infant BMI trajectories still explained variation in adult body composition. Using unique longitudinal data and methods, we find that distinct infant BMI trajectories have long-term implications for the development of body composition.
Psychotherapie und Wissenschaft
Authors: Seehagen Sabine , Pflug Verena , Schneider Silvia
Published: August 2012

Klinische Praxis und Psychotherapieforschung werden häufig als Spannungsfelder mit wenigen Berührungspunkten angesehen. Trotz erheblicher empirischer Erkenntnisgewinne über die letzten Jahrzehnte hinweg spielen in der klinischen Praxis oft Forschungsergebnisse nur eine untergeordnete Rolle für das Fällen von Therapieentscheidungen oder die Auswahl von Behandlungsstrategien. Stattdessen vertrauen Therapeuten häufig auf das eigene klinische Urteil, was beispielsweise zu einer Unterschätzung der Wahrscheinlichkeit von Therapiemisserfolgen führen kann. Flexible Behandlungskonzepte werden in der Praxis häufig standardisierten Interventionen bevorzugt, beispielsweise in der Annahme, letztere würden von Patienten nicht akzeptiert. Jedoch gibt es neben überzeugenden Wirksamkeitsnachweisen auch aktuelle Daten, die eine hohe Wertschätzung standardisierter Interventionen wie strukturierte Interviews durch Patienten belegen. Neue Studien zeigen, dass eine wissenschaftlich orientierte Ausbildung sowohl die Akzeptanz evidenzbasierter Behandlungsmöglichkeiten durch Therapeuten als auch den Therapieerfolg erhöhen können. Um eine breitere Dissemination von Ergebnissen aus der Forschung zu erreichen sowie evidenzbasierte Behandlung zu fördern, sollten Psychotherapieforscher ihre Ergebnisse Praktikern leichter zugänglich machen und angehende Psychotherapeuten müssen eine wissenschaftlich fundierte Ausbildung erhalten.
Suchtartige Internetnutzung als komorbide Störung im jugendpsychiatrischen Setting
Authors: Müller Kai W. , Ammerschläger Marcella , Freisleder Franz Joseph , Beutel Manfred E. , Wölfling Klaus
Published: August 2012

Einleitung: Die exzessiv suchtartige Internetnutzung bei Kindern und Jugendlichen, welche sich in ähnlichen Symptomen äußern kann wie klassische Abhängigkeitserkrankungen, ist ein Phänomen, dem Wissenschaft und Praxis immer mehr Beachtung schenken. Prävalenzen von 3 % unter Kindern und Jugendlichen deuten auf ein häufig vorkommendes Problem hin, das bei Betroffenen zu Funktionseinschränkungen führt und mit hohem Leidensdruck einhergeht. Ungeklärt ist, wie häufig Internetsucht unter Patienten jugendpsychiatrischer Einrichtungen auftritt. Methodik: Zur erstmaligen Bestimmung der Prävalenz von Internetsucht unter psychiatrisch behandelten Jugendlichen wurde ein standardisiertes Screening-Instrument (OSV-S) zur Klassifikation der Internetnutzung an 81 Patienten zwischen 8 und 17 Jahren eingesetzt. Eine weitere klinische Beschreibung erfolgte mittels des Youth Self-Reports und der Child Behavior Checkliste. Ergebnisse: 11.3 % der Patienten erfüllten die Kriterien der Internetsucht. Diese Patienten haben ein höheres Durchschnittsalter und wiesen erhöhte Werte in Ängstlichkeit und Depressivität auf. Schlussfolgerungen: Diese Pilotstudie verdeutlicht, dass in jugendpsychiatrischen Einrichtungen komorbide Internetsucht häufig vorkommt. Patienten mit komorbider Internetsucht zeichnen sich durch spezifische Symptombelastungen aus. Eine gezielte störungsspezifische Psychotherapie ist zu diskutieren.
Synergistic multi‐wavelength remote sensing versus a posteriori combination of retrieved products: Application for the retrieval of atmospheric profiles using MetOp‐A
Authors: Aires F. , Aznay O. , Prigent C. , Paul M. , Bernardo F.
Published: August 2012

In this paper, synergy refers to a process where the use of multiple satellite observations makes the retrieval more precise than the best individual retrieval. Two general strategies can be used in order to use multi‐wavelength observations in an inversion scheme. First, the multi‐wavelength observations are merged in the input of the retrieval scheme. This means that the various satellite observations are used simultaneously and that their possible interactions can be exploited by the retrieval scheme. Second, each multi‐wavelength observations are used independently to retrieve a same geophysical variable and then, these independent retrievals are combined a posteriori using for example a simple weighted averaging. In this paper, it is shown that the first approach provides better synergy results: The retrieval is better suited to optimize the use of all the information available because they are provided to the algorithm simultaneously. In particular, the retrieval process is able, in this case, to exploit the possible interactions between the various input information. The two retrieval approaches are tested and compared using an application for the retrieval of atmospheric profiles and integrated column quantities (temperature, water vapor, and ozone) using MetOp‐A observations from IASI, AMSU‐A and MHS instruments. Although real satellite observations are considered in this analysis, the results are dependent on the correlation structure in the training data set (i.e. ECMWF analysis) used to calibrate the retrieval algorithm. However, it can be seen that the infrared and microwave observations have a good synergy for the retrieval of atmospheric temperature, water vapor, and for ozone thanks to an indirect synergy.
Characteristics of tropical cyclone precipitation features over the western Pacific warm pool
Authors: Thatcher Levi , Takayabu Yukari N. , Yokoyama Chie , Pu Zhaoxia
Published: August 2012

In this study, ten years (1998–2007) of the Tropical Rainfall Measuring Mission (TRMM)‐derivative radar precipitation feature (PF) product are analyzed in order to determine the differences between tropical cyclone‐related precipitation characteristics compared with those of the tropical Pacific warm pool (10 to 30°N and 130 to 150°E) in general. The PF data, from the University of Utah's archive, are based on the TRMM precipitation radar's 2A25 product, where one PF consists of a single or group of contiguous pixels with near surface rainfall greater than zero. Using the PF database, the height and area of tropical background PFs versus those within 500 km of tropical cyclones (TCs) are compared. It is found that TC‐related PFs are markedly more frequent from 5 to 10 km altitude than are background tropical PFs. The enhanced midlevel TC‐related populations not only exist in stratiform precipitation around the melting level at 5.5 km, but also from 6 to 9 km in stratiform regions, in convective precipitation, and when culling the smallest features from the data set. This increase in congestus‐like echoes in TC environments aligns well with observations regarding mesoscale convective systems (MCSs), in which the enhanced ice present in MCS (and TC) environments creates a stabilized melting layer through cooling immediately below 0°C. This stable layer appears to enhance the detrainment of convective PFs in our TC data set at and for a few kilometers above the melting level.
On the effect of wind speed on submicron sea salt mass concentrations and source fluxes
Authors: Ovadnevaite Jurgita , Ceburnis Darius , Canagaratna Manjula , Berresheim Harald , Bialek Jakub , Martucci Giovanni , Worsnop Douglas R. , O'Dowd Colin
Published: August 2012

A High Resolution Time of Flight Aerosol Mass Spectrometer (HR‐ToF‐AMS) was evaluated for its ability to quantify submicron sea salt mass concentrations. The evaluation included both laboratory and field studies. Quantification of the sea salt signal in the HR‐ToF‐AMS was achieved by taking the23Na35Cl+ion as a surrogate for sea salt and then identifying a calibration scaling factor through a comparison with mono‐disperse laboratory generated sea salt aerosol. Ambient sea salt concentrations calculated using this method agreed well with those obtained by ion chromatography of filter samples, following a 1:1 regression slope and a correlation coefficientR= 0.93. A key advantage of this AMS‐based method is that it allows for high time resolution measurements of sea salt (5 min) along with the speciation of other chemical compounds, including primary organics contributing to sea spray. The high‐time resolution sea salt measurement capability enabled the quantification of sea salt mass in both increasing and decreasing wind speed regimes up to 26 m s−1. A mass flux source function was also derived and found to have a power law wind speed dependency with an exponent of 3.1 for increasing winds and 2.3 for decreasing winds. Comparison of the mass flux relationship in this study suggests that previous schemes based on the Monahan whitecap–wind speed approach significantly over‐estimate the submicron mass flux. Both the whitecap–wind speed component and the differential whitecap–aerosol productivity component of the source flux function contribute toward the over‐estimation.
Decadal‐ to centennial‐scale tropical Atlantic climate variability across a Dansgaard‐Oeschger cycle
Authors: Hertzberg J. E. , Black D. E. , Peterson L. C. , Thunell R. C. , Haug G. H.
Published: August 2012

The patterns and forcing mechanisms of climate variability on decadal to centennial time scales represent a major void in our current understanding of Earth's climate system. Furthermore, the response of the low latitudes to abrupt climate change is also not well understood, as most high‐resolution paleoclimate studies are from midlatitudes and high latitudes. This study explores the tropical Atlantic response to a Dansgaard‐Oeschger cycle (Interstadial 12) using ultra‐high resolution (∼2–3 years) foraminiferal census data from Cariaco Basin sediments. The interpretation of the abundance records for the onset of Interstadial 12 is complicated by the competing effects of rising sea level on Ekman‐induced upwelling within the Cariaco Basin and migrating Intertropical Convergence Zone–associated variations in trade wind location and fluvial nutrient delivery to the basin. The foraminiferal abundance records for the latter part of the interstadial suggest a southerly shift in the average annual position of the Intertropical Convergence Zone that acted to enhance upwelling and productivity within the Cariaco Basin. Sea level eventually reached a critical point in the transition back to stadial conditions that led to upwelling of nutrient‐depleted waters and a decline in productivity within the basin. Spectral analyses of theGlobigerina bulloidesabsolute abundance records reveal significant variability ranging from subdecadal‐ to centennial‐scale. Atlantic multidecadal‐scale climate variability is only evident in the warmest interval of Interstadial 12, suggesting that variability on this scale may only operate during warm climate periods, something that has significant implications for modern and near‐future climate variability.
Estimation of higher‐order ionospheric errors in GNSS positioning using a realistic 3‐D electron density model
Authors: Kashcheyev A. , Nava B. , Radicella S. M.
Published: August 2012

The accuracy of the positioning systems such as GPS, GLONASS or Galileo is heavily affected by the presence of the ionosphere. Ionosphere‐free dual‐frequency algorithms used for positioning applications remove most of the ionospheric error but do not take into account its higher‐order terms. In addition, the raypaths and total electron content (TEC) are assumed to be the same for both frequencies. This leads to centimeter‐level range errors that can cause millimeter‐level errors in positioning. In this paper an accurate estimation of the higher‐order ionospheric errors based on a realistic 3‐D electron density model is presented. A numerical homing‐in ray‐tracing algorithm is implemented to rigorously calculate satellite to receiver ray trajectories. The numerical simulations performed showed that higher‐order ionospheric residual range errors may reach several centimeters (up to 5 cm) at low and middle latitudes; however, at high latitudes they hardly exceed several millimeters (up to 1 cm).
Uncertainty in flood forecasting: A distributed modeling approach in a sparse data catchment
Authors: Mendoza Pablo A. , McPhee James , Vargas Ximena
Published: August 2012

Data scarcity has traditionally precluded the application of advanced hydrologic techniques in developing countries. In this paper, we evaluate the performance of a flood forecasting scheme in a sparsely monitored catchment based on distributed hydrologic modeling, discharge assimilation, and numerical weather predictions with explicit validation uncertainty analysis. For the hydrologic component of our framework, we apply TopNet to the Cautin River basin, located in southern Chile, using a fully distributed a priori parameterization based on both literature‐suggested values and data gathered during field campaigns. Results obtained from this step indicate that the incremental effort spent in measuring directly a set of model parameters was insufficient to represent adequately the most relevant hydrologic processes related to spatiotemporal runoff patterns. Subsequent uncertainty validation performed over a six month ensemble simulation shows that streamflow uncertainty is better represented during flood events, due to both the increase of state perturbation introduced by rainfall and the flood‐oriented calibration strategy adopted here. Results from different assimilation configurations suggest that the upper part of the basin is the major source of uncertainty in hydrologic process representation and hint at the usefulness of interpreting assimilation results in terms of model input and parameterization inadequacy. Furthermore, in this case study the violation of Markovian state properties by the Ensemble Kalman filter did affect the numerical results, showing that an explicit treatment of the time delay between the generation of surface runoff and the arrival at the basin outlet is required in the assimilation scheme. Peak flow forecasting results demonstrate that there is a major problem with the Weather Research and Forecasting model outputs, which systematically overestimate precipitation over the catchment. A final analysis performed for a large flooding event that occurred in July 2006 shows that, in the absence of bias introduced by an incorrect model calibration, the updating of both model states and meteorological forecasts contributes to a better representation of streamflow uncertainty and to better hydrologic forecasts.
Understanding the impact of dam‐triggered land use/land cover change on the modification of extreme precipitation
Authors: Woldemichael Abel T. , Hossain Faisal , Pielke Roger , Beltrán‐Przekurat Adriana
Published: August 2012

Two specific questions are addressed in this study regarding dams (artificial reservoirs). (1) Can a dam (artificial reservoir) and the land use/land cover (LULC) changes triggered by it physically alter extreme precipitation? The term extreme precipitation (EP) is used as a way of representing the model‐derived upper bound of precipitation that pertains to the engineering definition of the standard probable maximum precipitation (PMP) used in design of dams. (2) Among the commonly experienced LULC changes due to dams, which type of change leads to the most detectable alteration of extreme precipitation? The American River Basin (ARW) and the Folsom dam were selected as a study region. Four scenarios of LULC change (comprising also various reservoir surface areas) were analyzed in a step by step fashion to elucidate the scenario leading to most significant impact on EP. The Regional Atmospheric Modeling System (RAMS, version 6.0) was used to analyze the impact of these LULC scenarios in two modes. In the first mode (called normal), the probable precipitation pattern due to each LULC scenario was identified. The second mode (called moisture‐maximized), the PMP pattern represented from a 100% relative humidity profile was generated as an indicator of extreme precipitation (EP). For the particular case of ARW and Folsom dam, irrigation was found as having the most detectable impact on EP (a 5% increase in 72 h total for the normal mode and a 3% increase for the moisture‐maximized mode) in and around the ARW watershed. Doubling the reservoir size, on the other hand, brought only a small change in EP. Our RAMS‐simulated results demonstrate that LULC changes driven by surrounding landscape alteration resulting from the dams can, in fact, alter the local to regional hydrometeorology as well as extreme precipitation. There is a strong possibility of a positive feedback mechanism initiated by irrigated landscapes located upwind of orographic rain producing watersheds that are impounded by large dams.
Climatic and geomorphic controls on the erosion of terrestrial biomass from subtropical mountain forest
Authors: Hilton Robert G. , Galy Albert , Hovius Niels , Kao Shuh‐Ji , Horng Ming‐Jame , Chen Hongey
Published: August 2012

Erosion of particulate organic carbon (POC) occurs at very high rates in mountain river catchments, yet the proportion derived recently from atmospheric CO2 in the terrestrial biosphere (POCnon‐fossil) remains poorly constrained. Here we examine the transport of POCnon‐fossil in mountain rivers of Taiwan and its climatic and geomorphic controls. In 11 catchments we have combined previous geochemical quantification of POC source (accounting for fossil POC from bedrock), with measurements of water discharge (Qw) and suspended sediment concentration over 2 years. In these catchments, POCnon‐fossil concentration (mg L−1) was positively correlated with Qw, with enhanced loads at high flow attributed to rainfall driven supply of POCnon‐fossil from forested hillslopes. This climatic control on POCnon‐fossil transport was moderated by catchment geomorphology: the gradient of a linear relation of POCnon‐fossil concentration and Qw increased as the proportion of steep hillslopes (>35°) in the catchment increased. The data suggest enhanced supply of POCnon‐fossil by erosion processes which act most efficiently on the steepest sections of forest. Across Taiwan, POCnon‐fossil yield was correlated with suspended sediment yield, with a mean of 21 ± 10 tC km−2 yr−1. At this rate, export of POCnon‐fossil imparts an upper bound on the time available for biospheric growth, of ∼800 yr. Over longer time periods, POCnon‐fossil transferred with large amounts of clastic sediment can contribute to sequestration of atmospheric CO2 if buried in marine sediments. Our results show that this carbon transfer should be enhanced in a wetter and stormier climate, and the rates moderated on geological timescales by the regional tectonic setting.
Sediment mixing in the tropical Pacific and radiolarian stratigraphy
Authors: Moore Ted C. , Mayer Larry A. , Lyle Mitchell
Published: August 2012

The reworking of older radiolarian microfossils into near‐surface sediments of the tropical Pacific has long been the source of confusion for the development of radiolarian stratigraphy and of puzzlement over the mechanism(s) that could effect such pervasive reworking. Widespread dissolution “pits” in the sediments of the tropical Pacific are believed to be associated with hydrothermal circulation cells in the older oceanic crust and are here linked to processes which expose older sections and inject older non‐carbonate material into near‐bottom waters. Discharging waters of these circulation cells tend to dissolve carbonate in near‐surface sediments; thus, only the non‐carbonate material (including radiolarians) is preserved and reworked into younger sediments. Results from the study of two sites in the tropical Pacific indicate that reworked older, stratigraphically important radiolarians are less than 2% of the total radiolarian assemblage. This constitutes a minimum estimate of the amount of reworked, non‐carbonate material in the younger sediments. The oldest reworked radiolarians are no more than 10 m.y. younger than the underlying basement, and radiolarians from the entire older section above that level can be found in the reworked material. A time series of the flux of reworked material at one site is not constant but instead has varied by a factor of 3 to 4 over the past 2.5 m.y. During times when the flux of reworked material is particularly low, the proportion of older, more robust radiolarians is larger.
Observation system simulation experiments for a global wind observing sounder
Authors: Riishojgaard Lars Peter , Ma Zaizhong , Masutani Michiko , Woollen John S. , Emmitt George D. , Wood Sidney A. , Greco Steven
Published: August 2012

Observing System Simulation Experiments (OSSEs) are a powerful tool used to assess the potential impact on numerical weather prediction skill of planned or hypothetical future observing systems. Over the past several years an international Joint OSSE collaboration has emerged centered on the use of NASA's and NOAA's data assimilation systems. A Nature Run provided by the European Centre for Medium Range Weather Forecasts (ECMWF) has undergone extensive validation, and a set of simulated reference observations have been subjected to a set of calibration experiments. One of the first candidate observing systems assessed by this system is a wind lidar based on the Global Wind Observing Sounder (GWOS) concept developed by NASA in response to the National Research Council (NRC) Decadal Survey. A set of 45‐day assimilation and forecast experiments has been set up and executed. The experiments were done using the NCEP operational forecast system, and the results show that wind lidar observations are likely to provide a significant increase in forecast skill even when used in a modern, radiance‐based assimilation system.
The role of velocity‐neutral creep on the modulation of tectonic tremor activity by periodic loading
Authors: Ader Thomas J. , Ampuero Jean‐Paul , Avouac Jean‐Philippe
Published: August 2012

Slow slip events and associated non‐volcanic tremors are sensitive to oscillatory stress perturbations, such as those induced by tides or seismic surface waves. Slow slip events and tremors are thought to occur near the seismic‐aseismic transition regions of active faults, where the differencea − b = ∂μ/∂lnVbetween the sensitivity of friction to slip rate and fault state, which characterizes the stability of slip, can be arbitrarily small. We investigate the response of a velocity‐strengthening fault region to oscillatory loads through analytical approximations and spring‐slider simulations. We find that fault areas that are near velocity‐neutral at steady‐state, i.e., ∂μ / ∂lnV ≈ 0, are highly sensitive to cyclic loads: oscillatory stress perturbations in a certain range of periods induce large transient slip velocities. These aseismic transients can in turn trigger tremor activity with enhanced oscillatory modulation. In this sensitive regime, a harmonic Coulomb stress perturbation of amplitude ΔS causes a slip rate perturbation varying as eΔS/(a−b)σ, where σ is the effective normal stress. This result is in agreement with observations of the relationship between tremor rate and amplitude of stress perturbations for tremors triggered by passing seismic waves. Our model of tremor modulation mediated by transient creep does not require extremely high pore fluid pressure and provides a framework to interpret the sensitivity and phase of tidally modulated tremors observed in Parkfield and Shikoku in terms of spatial variations of friction parameters and background slip rate.
Uncertainties in the evolution of stratospheric ozone and implications for recent temperature changes in the tropical lower stratosphere
Authors: Solomon Susan , Young Paul J. , Hassler Birgit
Published: August 2012

Observations from satellites and balloons suggest that ozone abundances have decreased in the tropical lower stratosphere since the late 1970s, but this long‐term change is occurring in a region of large interannual variability. Three different ozone databases provide regression fits to the ozone observations, and are available for use in model studies of the influence of ozone changes on stratospheric and tropospheric temperatures. Differences between these ozone databases suggest that the estimated decreases of tropical lower stratospheric ozone in recent decades are uncertain by about a factor of two to three. The uncertainties in ozone decreases lead to similar uncertainties in cooling of the tropical lower stratosphere, a key area of focus in climate change studies.
Whitecaps in deep water
Authors: Plant William J.
Published: August 2012

Whitecaps in deep water are located near maximum slopes of the interference pattern of dominant wind waves and the most probable breaking waves are those waves that travel with the speed of the component of the interference pattern in the wind direction. These breaking waves are in the wavelength range 1 to 12 m, much shorter than typical dominant waves. The patterns of large steepness caused by interfering dominant waves move at speeds less than the group speed of the dominant wave unless the wave spectrum is narrow in both wavenumber and azimuth. For spectra with wavenumber and azimuth angle spreads representative of those observed on the ocean, the velocity of propagation of the pattern of steep waves in the wind direction is the same as the speed at the maximum of Phillips Λ(c) function, the speed of the peak of HH Doppler spectra, and the speed measured by acoustic event tracking.
Statistical analysis of SC‐associated geosynchronous magnetic field perturbations
Authors: Park J.‐S. , Kim K.‐H. , Lee D.‐H. , Araki T. , Lee E. , Jin H.
Published: August 2012

Kokubun (1983) reported the local time variation of normalized amplitude of sudden commencement (SC) with a strong day‐night asymmetry (i.e., maximum amplitude near noon and minimum amplitude near midnight) at geosynchronous orbit with 81 SC events. Further careful inspection of Kokubun's local time distribution reveals that the normalized SC amplitudes in the prenoon sector (MLT = 9–12) are larger than those in the postnoon sector (MLT = 12–15). That is, there is a morning‐afternoon asymmetry in the normalized SC amplitudes. Until now, however, there are no studies on this SC‐associated morning‐afternoon asymmetry at geosynchronous orbit. Motivated by this previous observation, we investigate a large data set (422 SC events in total) of geosynchronous SC observations and confirm that the geosynchronous SC amplitudes normalized to SYM‐H are larger in the morning sector than in the afternoon sector. This morning‐asymmetry is probably caused by the enhancement of partial ring current, which is located in the premidnight sector, due to solar wind dynamic pressure increase. We also examine seasonal variations of the normalized SC amplitude and find that the SC‐associated geosynchronous magnetic field perturbations are dependent on seasons of the year. This may be due to the location of the magnetopause current and cross‐tail current enhanced during the SC interval with respect to geosynchronous spacecraft position.
Characteristics of precipitating energetic ions/electrons associated with the wave‐particle interaction in the plasmaspheric plume
Authors: Yuan Zhigang , Xiong Ying , Wang Dedong , Li Ming , Deng Xiaohua , Yahnin A. G. , Raita T. , Wang Jingfang
Published: August 2012

In this paper, we present characteristics of precipitating energetic ions/electrons associated with the wave‐particle interaction in the plasmaspheric plume during the geomagnetic storm on July 18, 2005 with observations of the NOAA15 NOAA16, IMAGE satellites and Finnish network of search coil magnetometers. Conjugate observations of the NOAA15 satellite and the Finnish network of search coil magnetometers have demonstrated that a sharp enhancement of the precipitating ion flux is a result of ring current (RC) ions scattered into the loss cone by EMIC waves. Those precipitating RC ions lead to a detached subauroral proton arc observed by the IMAGE FUV. In addition, with observations of NOAA15 and NOAA16, the peak of precipitating electron flux was equatorward to that of precipitating proton flux, which is in agreement with the region separation of ELF hiss and EMIC waves observed by the Cluster C1 in the Yuan et al. (2012) companion paper. In combination with the result of the companion paper, we demonstrate the link between the wave activities (ELF hiss, EMIC waves) in plasmaspheric plumes and energetic ion/electron precipitation at ionospheric altitudes. Therefore, it is an important characteristic of the plasmaspheric plumes‐RC‐ionosphere interaction during a geomagnetic storm that the precipitation of energetic protons is latitudinally separated from that of energetic electrons.