bluuebunny/crossref_metadata_2025_split huggingface dataset:
The consequences of a local approach in statistical models of convection on its large‐scale coherence
Authors: Tan Jackson , Jakob Christian , Lane Todd P. 
Published: January 2015

AbstractOrganized tropical convection is a crucial mechanism in the climate system, but its representation in climate models through parametrization schemes has numerous shortcomings. One of these shortcomings is that they are deterministic despite the statistical nature of the relationship they are representing. Several attempts at devising a stochastic parametrization scheme have been made, many of which assume a local approach, that is, one in which the convection in a grid box is determined without consideration of the previous time steps and the surrounding boxes. This study seeks to explore the effect of this assumption on the coherence of convection using cloud regimes, which represent various modes of tropical convection. First, we analyze the coherence of observed convection beyond the typical size of a model grid box and time step. Then, we evaluate the consequences of the local assumption on this coherence in simple statistical models. Cloud regimes in the real world show high degrees of coherence, manifesting in their lifetimes, areas, and inter‐regime relationships. However, in a local statistical model, they are too small, too short‐lived, and have incorrect relationships between each other. This can be improved by incorporating time memory and spatial dependence in the modeling. Our results imply that a local approach to a statistical representation of convection is not viable, and a statistical model must account for nonlocal influence in order to have large‐scale convective coherence that more closely resembles the real world.
Holocene peatland initiation in the Greater Everglades
Authors: Dekker Stefan C. , de Boer Hugo J. , Dermody Brian J. , Wagner‐Cremer Friederike , Wassen Martin J. , Eppinga Maarten B. 
Published: January 2015

AbstractThe mechanisms involved in the initiation and development of the Greater Everglades peatland ecosystems remain a topic of discussion. In this study, we first present an overview of basal ages of peat deposits in South Florida, which shows two major episodes of peatland initiation between 7.0–4.5 kyr and 3.5–2.0 kyr. Our analysis of regional climate proxy data sets led to three alternative hypotheses that may explain the timing and duration of these two peatland initiation episodes: (1) decreased drainage due to relative sea level (RSL) rise during the Holocene, (2) gradual increase in precipitation throughout the Holocene, and (3) a combination of increasing precipitation, rising RSL, and oscillations in the climate system. We test whether these three hypotheses can explain the pattern of initiation and development of the Greater Everglades peatlands using models that simulate the nonlinear processes involved in peat production and decomposition. The model results suggest that RSL rise could explain the onset of peatland initiation and imply that the climate was wet enough for peat development also during the early Holocene. The first two hypothesized mechanisms in combination with climate oscillations may explain the onset of peat accumulation at 8.2 kyr B.P. The two‐phased character of peatland initiation maybe explained by the spatial distribution of local drainage conditions. As peatland development is highly nonlinear, our model uncovers a mechanistic way how peats can suddenly shift from a dry high equilibrium to a wet low equilibrium resulting in lake formation as observed in paleoecological studies in the Greater Everglades.
Holocene shifts of the southern westerlies across the South Atlantic
Authors: Voigt Ines , Chiessi Cristiano M. , Prange Matthias , Mulitza Stefan , Groeneveld Jeroen , Varma Vidya , Henrich Ruediger 
Published: January 2015

AbstractThe southern westerly winds (SWW) exert a crucial influence over the world ocean and climate. Nevertheless, a comprehensive understanding of the Holocene temporal and spatial evolution of the SWW remains a significant challenge due to the sparsity of high‐resolution marine archives and appropriate SWW proxies. Here we present a north‐south transect of high‐resolution planktonic foraminiferal oxygen isotope records from the western South Atlantic. Our proxy records reveal Holocene migrations of the Brazil‐Malvinas Confluence (BMC), a highly sensitive feature for changes in the position and strength of the northern portion of the SWW. Through the tight coupling of the BMC position to the large‐scale wind field, the records allow a quantitative reconstruction of Holocene latitudinal displacements of the SWW across the South Atlantic. Our data reveal a gradual poleward movement of the SWW by about 1–1.5° from the early to the mid‐Holocene. Afterward, variability in the SWW is dominated by millennial scale displacements on the order of 1° in latitude with no recognizable longer‐term trend. These findings are confronted with results from a state‐of‐the‐art transient Holocene climate simulation using a comprehensive coupled atmosphere‐ocean general circulation model. Proxy‐inferred and modeled SWW shifts compare qualitatively, but the model underestimates both orbitally forced multimillennial and internal millennial SWW variability by almost an order of magnitude. The underestimated natural variability implies a substantial uncertainty in model projections of future SWW shifts.
Environmental and biological controls on size‐specific δ13C and δ18O in recent planktonic foraminifera
Authors: Ezard Thomas H. G. , Edgar Kirsty M. , Hull Pincelli M. 
Published: January 2015

AbstractAs living organisms, planktonic foraminifera are not passive tracers of the environment. Their test geochemistry—arguably the single most important resource for paleoceanographic research—reflects the combined signal of environmental, biological, and preservational processes. For most species, comparisons of test stable isotopic composition within and among taxa provide the primary means for disentangling the relative influences of these different processes. Here we test the foundations of our paleoceanographic interpretations with the first quantitative comparison of the determinants of carbon and oxygen isotopic variation across multiple ocean basins, studies, and species by re‐analyzing size‐specific data collated from the literature. We find clear evidence of species‐specific biological effects (i.e., vital effects), as the intercepts of size‐specific carbon and oxygen isotopic compositions differ significantly among species. Trends in body size and isotopic composition, particularly in dinoflagellate bearing taxa, suggest that much of the size‐dependent isotopic variation observed in death assemblages (i.e., core tops and sediments) relates to factors influencing the maximum size obtained by adults rather than ontogeny. The presence and type of photosymbiont hosted (dinoflagellate, chrysophyte, or none) were a major factor affecting species‐ and size‐specific δ18O values. In contrast, size‐related trends in δ13C values were driven by depth habitat (mixed layer, thermocline, subthermocline), symbiont ecology and whether the assemblage was alive or dead when sampled. On this broad geographic and oceanographic scale, ocean basin and biome had a significant effect on δ18O and δ13C values . Our analysis and its model‐averaged predictions provide a quantitative basis for interpreting size‐specific isotopic variation in 22 species of modern macroperforate planktonic foraminifera. We conclude by highlighting existing data gaps and outstanding questions of the relative influence of environmental, preservational, and biological processes on variation in the test geochemistry of planktonic foraminifera.
Functional connectivity changes in the language network during stroke recovery
Authors: Nair Veena A. , Young Brittany M. , La Christian , Reiter Peter , Nadkarni Tanvi N. , Song Jie , Vergun Svyatoslav , Addepally Naga Saranya , Mylavarapu Krishna , Swartz Jennifer L. , Jensen Matthew B. , Chacon Marcus R. , Sattin Justin A. , Prabhakaran Vivek 
Published: January 2015

AbstractObjectiveSeveral neuroimaging studies have examined language reorganization in stroke patients with aphasia. However, few studies have examined language reorganization in stroke patients without aphasia. Here, we investigated functional connectivity (FC) changes after stroke in the language network using resting‐state fMRI and performance on a verbal fluency (VF) task in patients without clinically documented language deficits.MethodsEarly‐stage ischemic stroke patients (N = 26) (average 5 days from onset), 14 of whom were tested at a later stage (average 4.5 months from onset), 26 age‐matched healthy control subjects (HCs), and 12 patients with cerebrovascular risk factors (patients at risk, PR) participated in this study. We examined FC of the language network with 23 seed regions based on a previous study. We evaluated patients' behavioral performance on a VF task and correlation between brain resting‐state FC (rsFC) and behavior.ResultsCompared to HCs, early stroke patients showed significantly decreased rsFC in the language network but no difference with respect to PR. Early stroke patients showed significant differences in performance on the VF task compared to HCs but not PR. Late‐stage patients compared to HCs and PR showed no differences in brain rsFC in the language network and significantly stronger connections compared to early‐stage patients. Behavioral differences persisted in the late stage compared to HCs. Change in specific connection strengths correlated with changes in behavior from early to late stage.ConclusionsThese results show decreased rsFC in the language network and verbal fluency deficits in early stroke patients without clinically documented language deficits.
An Efficient Method for the Production of Terminal Alkynes from 1,1‐Dibromo‐1‐alkenes and its Application in the Total Synthesis of Natural Product Dihydroxerulin
Authors: Liu Shihui , Chen Xiaobei , Hu Yanwei , Yuan Laiqi , Chen Shaohua , Wu Ping , Wang Wei , Zhang Shilei , Zhang Wei 
Published: January 2015

AbstractAn efficient method of preparing various terminal alkynes from 1,1‐dibromo‐1‐alkenes by using TBAF (tetra‐n‐butylammonium fluoride) as a base and triphenylphosphane as a reductant was developed. This method is strong base and low/high temperatures free, and can tolerate a broad range of substrates. These advantages were well demonstrated by the application of this method to the total synthesis of polyene natural product dihydroxerulin.magnified image
Bifunctional Amine‐Squaramides: Powerful Hydrogen‐Bonding Organocatalysts for Asymmetric Domino/Cascade Reactions
Authors: Chauhan Pankaj , Mahajan Suruchi , Kaya Uğur , Hack Daniel , Enders Dieter 
Published: January 2015

AbstractOrganocatalytic domino/cascade reactions provide a convenient method for the construction of complex molecular structures bearing multiple stereocenters in a highly stereoselective fashion. Among various organocatalysts, bifunctional squaramides have emerged as powerful hydrogen‐bonding catalysts for promoting a wide array of useful asymmetric organocascade sequences. Higher activity and ease of preparation make these catalysts excellent alternatives for thiourea‐based organocatalysts. This review highlights the advances in the rapidly growing field of amine‐squaramide‐catalyzed domino/cascade reactions and their mode of action.magnified image
Künstliche Photosynthese für die Produktion von nachhaltigen Kraftstoffen und chemischen Produkten
Authors: Kim Dohyung , Sakimoto Kelsey K. , Hong Dachao , Yang Peidong 
Published: January 2015

AbstractAngesichts der Unvereinbarkeit eines zunehmenden Verbrauchs von Kraftstoffen und chemischen Produkten und einer nur endlichen Menge an Ressourcen versuchen wir Möglichkeiten zu finden, wie wir unsere Gesellschaft auf Dauer nachhaltig gestalten können. Die künstliche Photosynthese nutzt das Sonnenlicht, um reichlich vorhandene Ressourcen in hochwertige Chemikalien umzuwandeln. Deshalb gilt sie als die aussichtsreichste Methode. Hier werden Entwicklungen und neueste Fortschritte sowie noch bestehende Herausforderungen für ihre Schlüsselprozesse, die photoelektrochemische Wasserspaltung und die elektrochemische CO2‐Reduktion, beschrieben. Ein Überblick über die Fortschritte in der Katalyse, um den erneuerbaren Wasserstoff als Grundstoff für die Produktion von Chemikalien einzusetzen, soll verdeutlichen, welche Rolle die künstliche Photosynthese in einer nachhaltigen Chemie spielen wird.
Artificial Photosynthesis for Sustainable Fuel and Chemical Production
Authors: Kim Dohyung , Sakimoto Kelsey K. , Hong Dachao , Yang Peidong 
Published: January 2015

AbstractThe apparent incongruity between the increasing consumption of fuels and chemicals and the finite amount of resources has led us to seek means to maintain the sustainability of our society. Artificial photosynthesis, which utilizes sunlight to create high‐value chemicals from abundant resources, is considered as the most promising and viable method. This Minireview describes the progress and challenges in the field of artificial photosynthesis in terms of its key components: developments in photoelectrochemical water splitting and recent progress in electrochemical CO2 reduction. Advances in catalysis, concerning the use of renewable hydrogen as a feedstock for major chemical production, are outlined to shed light on the ultimate role of artificial photosynthesis in achieving sustainable chemistry.
The conservation implications of spatial and temporal variability in the diurnal use of Bahamian tidal mangrove creeks by transient predatory fishes
Authors: Harborne Alastair R. , Talwar Brendan , Brooks Edward J. 
Published: January 2015

Abstract

Mangrove creeks have a range of functional roles in tropical seascapes, but their use as feeding and refuge areas for commercially and ecologically important transient predators is poorly understood.
This study used video cameras to investigate the diurnal use of three Bahamian mangrove creeks by transient predators during a 2‐month period. More than 500 fishes from 10 species were recorded, including elasmobranchs, reef‐associated fishes, and nearshore specialists. A multivariate analysis indicated that movement of the transient predator assemblage was not significantly linked to any abiotic variable and did not vary among creeks.
Generalized linear mixed‐effects models of the four most abundant transient predators demonstrated species‐specific variations in creek use. Sightings of Caranx ruber and Negaprion brevirostris varied significantly among the three creeks. Furthermore, C. ruber was seen most frequently close to high tide, while N. brevirostris was seen more frequently with increasing time since sunrise and during higher tidal ranges. Sphyraena barracuda and Tylosurus crocodilus were seen most frequently just after low tide. All three creeks appear to be functionally important for transient predators, but these species exhibit considerable spatio‐temporal variability in how they use this habitat.
Mangrove creeks are threatened by a range of anthropogenic stressors, and are frequently a target of conservation initiatives. The species‐specific spatial variability in creek use demonstrates that simply including representative creeks in marine protected areas could exclude functionally important areas. Furthermore, development that alters tidal cycles in creeks is likely to have significant impacts on transient predators, and underscores the need for restoration and conservation of hydrological flow.
Copyright © 2015 John Wiley & Sons, Ltd.
Niche specialization and functional traits regulate the rarity of charophytes in the Nordic countries
Authors: Baastrup‐Spohr Lars , Iversen Lars Lønsmann , Borum Jens , Sand‐Jensen Kaj 
Published: January 2015

Abstract

Charophytes are benthic macroalgae that live in fresh and brackish waters. Given the historic deterioration of their habitats and their competitive inferiority relative to tall rooted plants under eutrophic conditions, it is hypothesized that charophytes are among the most threatened autotrophs. Also, it is expected that charophytes with generalist niches and functional traits, such as tolerance of a broad salinity range and large height, should thrive owing to available habitats and stronger competitive ability.
These hypotheses were tested comparing the rarity of charophytes in the Nordic countries with other autotrophs and analysing the relationship to species niche specialization and functional traits. A value on a rarity–commonness scale was assigned to each species based on their Red List status. Niche specialization was evaluated by the Outlying Mean Index using a large Danish dataset while traits were derived from the literature.
Supporting the hypotheses, 50–87% of charophyte species were Red Listed, which is much greater than for vascular aquatic (30–35%) and terrestrial plants (18–28%). Commonness of charophytes decreased significantly with niche specialization in separate analyses of brackish and freshwater sites. For brackish water species, the most influential parameter determining species distribution was salinity while for freshwater species, alkalinity, lake size and chlorophyll concentration played a major role. Four functional traits: shoot height, salinity tolerance, bulbil production and flexible life cycle duration were significantly positively related to commonness.
In conclusion, charophytes contain a larger fraction of threatened species compared with other groups of autotrophs. The few common charophytes are generalists tolerant of a wide range of conditions, while specialists often have short stature, restricted life cycle variability and are rare in the disturbed contemporary landscape. It is thus a conservation priority to delineate accurately the environmental conditions preferred by the threatened species and protect or restore proper habitats.
Copyright © 2015 John Wiley & Sons, Ltd.
Racial/Ethnic Variation in All‐Cause Mortality Among United States Medicaid Recipients With Systemic Lupus Erythematosus: A Hispanic and Asian Paradox
Authors: Gómez‐Puerta José A. , Barbhaiya Medha , Guan Hongshu , Feldman Candace H. , Alarcón Graciela S. , Costenbader Karen H. 
Published: January 2015

ObjectiveThe incidence of systemic lupus erythematosus (SLE) is disproportionately high in nonwhite patients compared with white patients. However, variation in mortality according to race/ethnicity has not been well studied. The aim of this study was to examine all‐cause mortality according to race/ethnicity among SLE patients enrolled in Medicaid.MethodsWe used Medicaid Analytic eXtract data, with billing claims from 47 US states and Washington, DC, to identify individuals ages 18–65 years who were enrolled in Medicaid for ≥3 months in 2000–2006. Individuals were classified as having SLE if they had ≥3 visits ≥30 days apart with an International Classification of Diseases, Ninth Revision (ICD‐9) code for SLE (710.0). Among the individuals with SLE, those with lupus nephritis (LN) were identified by the presence of ≥2 ICD‐9 claims for glomerulonephritis, proteinuria, or renal failure. We calculated mortality rates per 1,000 person‐years, with 95% confidence intervals (95% CIs), according to race/ethnicity. Multivariable Cox proportional hazards regression models were used to estimate mortality risks, adjusting for age, sex, demographics, and comorbidities.ResultsAmong 42,221 prevalent cases of SLE, 8,191 prevalent cases of LN were identified. Blacks represented 40.1%, whites 38.4%, and Hispanics 15.3%. Overall SLE mortality rates per 1,000 person‐years were highest among Native American (27.52), white (20.17), and black (24.13) patients and were lower among Hispanic (7.12) or Asian (5.18) patients. After multivariable adjustment, Hispanic and Asian patients had lower mortality risks (hazard ratio [HR] 0.48 [95% CI 0.40–0.59] and 0.59 [95% CI 0.40–0.86], respectively) compared with whites. Conversely, the risk of death was significantly higher among Native American (HR 1.40 [95% CI 1.04–1.90]) and black (HR 1.21 [95% CI 1.10–1.33]) patients compared with white patients. Among patients with LN, mortality risks were lower in Hispanic and Asian patients compared with white patients.ConclusionAfter accounting for demographic and clinical factors, mortality among Asian and Hispanic Medicaid patients with SLE was lower than that among black, white, or Native American patients.
Electrochemical and Structural Study of Layered P2‐Type Na2/3Ni1/3Mn2/3O2 as Cathode Material for Sodium‐Ion Battery
Authors: Wen Yanfen , Wang Bei , Zeng Guang , Nogita Kazuhiro , Ye Delai , Wang Lianzhou 
Published: January 2015

AbstractP2‐type Na2/3Ni1/3Mn2/3O2 was synthesized by a controlled co‐precipitation method followed by a high‐temperature solid‐state reaction and was used as a cathode material for a sodium‐ion battery (SIB). The electrochemical behavior of this layered material was studied and an initial discharge capacity of 151.8 mA h g−1 was achieved in the voltage range of 1.5–3.75 V versus Na+/Na. The retained discharge capacity was found to be 123.5 mA h g−1 after charging/discharging 50 cycles, approximately 81.4 % of the initial discharge capacity. In situ X‐ray diffraction analysis was used to investigate the sodium insertion and extraction mechanism and clearly revealed the reversible structural changes of the P2‐Na2/3Ni1/3Mn2/3O2 and no emergence of the O2‐Ni1/3Mn2/3O2 phase during the cycling test, which is important for designing stable and high‐performance SIB cathode materials.
Unravelling the Quenching Mechanisms of a Luminescent RuII Probe for CuII
Authors: Santos André Ribeiro , Escudero Daniel , González Leticia , Orellana Guillermo 
Published: January 2015

AbstractWe have investigated the photophysical and photochemical features of a luminescent heteroleptic RuII‐polypyridyl probe and of its corresponding RuII‐CuII dinuclear complex formed upon the analyte binding through extensive density functional theory (DFT) and time‐dependent DFT (TD‐DFT) calculations. The molecular probe contains the tailored imidazo[4,5‐f]‐1,10‐phenanthroline (IIP) ligand for simultaneously binding the RuII core and the target metal ion in aqueous solution. We have rationalized the static photoluminescence quenching observed upon the CuII coordination, on the grounds of distinct excited state deactivation mechanisms which are absent in the free RuII complex probe. Additionally, the emission quenching found upon increasing the solution pH has also been investigated. When coordinated IIP deprotonates, the nature of the lowest excited state of its complex changes from 3MLCT to 3LLCT/3IL. The strong base‐induced emission quenching can be understood in terms of both the energy‐gap law, since the 3LLCT/3IL states lie at a significantly lower energy than the 3MLCT state increasing the contribution of non‐radiative mechanisms, and the expected slower radiative rates from such 3LLCT/3IL states. After CuII binding, the lowest triplet excited state is similar to the analyte‐free probe in both energy and electronic nature. However, Cu‐centered non‐radiative excited states, populated after photoinduced electron transfer and intersystem crossing processes, are responsible for the population drainage of the emissive state.
Stabilization of Fractional‐Order Linear Systems with State and Input Delay
Authors: Ammour Amar Si , Djennoune Said , Aggoune Woihida , Bettayeb Maamar 
Published: January 2015

AbstractThis paper describes a variable structure control for fractional‐order systems with delay in both the input and state variables. The proposed method includes a fractional‐order state predictor to eliminate the input delay. The resulting state‐delay system is controlled through a sliding mode approach where the controller uses a sliding surface defined by fractional order integral. Then, the proposed control law ensures that the state trajectories reach the sliding surface in finite time. Based on recent results of Lyapunov stability theory for fractional‐order systems, the stability of the closed loop is studied. Finally, an illustrative example is given to show the interest of the proposed approach.