bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intensity Distribution near the Focus of a Large Aperture Optical System
Authors: Maruyama S. 
Published: March 2014

A general expression for the light disturbance near the focus of a large aperture optical system is obtained from the Kirchhoff integration. On reversal of the sign of the aberration function, the light intensity at a point symmetrical to an original point about an axis (y-axis), perpendicular to the meridian plane and passing through the Gaussian image point, is the same as that of the original one. The intensity distribution on the y-axis is expressed in a form,

I=I(γ_1^cγ_3^d…,γ_2^eγ_4^f…),
c+d+…=even, e+f+…=even,

where γ1, γ3,… are comatic aberration terms and γ2, γ4,… are astigmatic terms. This equation holds at the Gaussian image point, too. Aberrations of the same type, comatic or astigmatic, must be corrected one another in order to minimize the decrement of the intensity at the Gaussian image point.
A study of the active controlled useful load parachute systems in terms of subsystem design, test and methods
Authors: MERCAN Ümit , İNALHAN Gökhan 
Published: March 2014

Abstract

Taking into account the geograhy and the geostrategic location of Turkey, it has become a necessity to perform tasks which are time sensitive such as natural disaster, search and rescue and airlift of ammunition and supplies to operation zones by using unmanned parachute systems. Turkish Air Force (TURAF) Headquarters, in response to this necessity, has claimed its place in the race of possesing new generation unmanned systems and devices which are suitable for developing technology and other improvements of the era in the fields of aviation and space sciences. Within this scope, TURAF closely follows the active controlled useful load-carrying system technology which can be operated in two different options, remote controlled and autonomous, and aims to possess this technology by producing it using local means and sources.

Across the World, the system actively used for this purpose are known as Guided Precision Aerial Delivery Systems (GPADS). GPADS technology, which has not been used in Turkey yet, has been studied in detail with this thesis. In this context, a description of the concepts regarding the system TURAF needs has been made, and the technical specifications that the system on draft requires have been put forward. At the end of the study, it has been concluded that the system can be produced domestically with the cooparation of institutions and organizations in Turkey, and that the ram air canopy which produces the best flight performance results should be used during the design phase provided that the compulsory military standarts are met.
Calcium carbonate dissolution in the upper 1000 m of the eastern North Atlantic
Authors: Barrett Pamela M. , Resing Joseph A. , Buck Nathaniel J. , Feely Richard A. , Bullister John L. , Buck Clifton S. , Landing William M. 
Published: March 2014

AbstractRecent analyses suggest that considerable CaCO3 dissolution may occur in the upper water column of the ocean (< 1500 m). This study uses the distribution of particulate calcium from high‐resolution suspended matter sampling along the Climate Variability and Predictability/CO2 Repeat Hydrography A16N transect in 2003 to estimate CaCO3 dissolution in the top 1000 m of the North Atlantic. Dissolution rates were also approximated using changes in total alkalinity measurements along isopycnal surfaces. Water masses were found to be undersaturated with respect to aragonite at intermediate depths (400–1000 m) in the eastern tropical North Atlantic. The CaCO3 dissolution rate in this region is estimated to be 0.9 mmol CaCO3 m−2 d−1, indicating this region is a hotspot for upper water column CaCO3 dissolution compared to the Atlantic basin as a whole. Dissolution rates calculated from particulate calcium distributions outside of this region were significantly lower (0.2 mmol CaCO3 m−2 d−1) and are comparable to previous estimates of CaCO3 dissolution flux for the Atlantic Ocean. The magnitude of upper water column dissolution rates compared to measured surface ocean CaCO3 standing stocks suggests that biologically mediated CaCO3 dissolution may be occurring in the top 1000 m of the Atlantic.
Air‐sea CO2 fluxes in the California Current: Impacts of model resolution and coastal topography
Authors: Fiechter Jerome , Curchitser Enrique N. , Edwards Christopher A. , Chai Fei , Goebel Nicole L. , Chavez Francisco P. 
Published: March 2014

AbstractThe present study uses a suite of coupled physical‐biogeochemical model simulations at 1/3°, 1/10°, and 1/30° to assess the impact of horizontal resolution on air‐sea CO2 fluxes in the California Current System (CCS), a relevant issue for downscaling between coarser resolution global climate models and higher resolution regional models. The results demonstrate that horizontal resolution is important to reproduce the sharp transition between near‐shore outgassing and offshore absorption, as well as to resolve regions of enhanced near‐shore outgassing in the lee of capes. The width of the outgassing region is overestimated when horizontal resolution is not eddy resolving (i.e., 1/3°) but becomes more dependent on shelf topography for eddy‐resolving simulations (i.e., 1/10° and 1/30°). Enhanced near‐shore outgassing is associated with a local increase in wind‐driven upwelling in the lee of capes (i.e., expansion fans), meaning that sufficient horizontal resolution is needed both in the ocean circulation model and in the wind field forcing the model. From a global carbon budget perspective, the model indicates that biological production generates sufficient absorption within a few hundred kilometers of the coast to offset near‐shore outgassing, which is consistent with the notion that midlatitude eastern boundary current upwelling systems act both as a sink and source for atmospheric CO2. Based on the 1/30° solution, the CCS between 35 and 45 N and out to 600 km offshore is a net carbon sink of approximately 6 TgC yr−1, with the 1/10° solution underestimating this value by less than 10% and the 1/3° solution by a factor of 3.
Ecological processes dominate the 13C land disequilibrium in a Rocky Mountain subalpine forest
Authors: Bowling D. R. , Ballantyne A. P. , Miller J. B. , Burns S. P. , Conway T. J. , Menzer O. , Stephens B. B. , Vaughn B. H. 
Published: March 2014

AbstractFossil fuel combustion has increased atmospheric CO2 by ≈ 115 µmol mol−1 since 1750 and decreased its carbon isotope composition (δ13C) by 1.7–2‰ (the 13C Suess effect). Because carbon is stored in the terrestrial biosphere for decades and longer, the δ13C of CO2 released by terrestrial ecosystems is expected to differ from the δ13C of CO2 assimilated by land plants during photosynthesis. This isotopic difference between land‐atmosphere respiration (δR) and photosynthetic assimilation (δA) fluxes gives rise to the 13C land disequilibrium (D). Contemporary understanding suggests that over annual and longer time scales, D is determined primarily by the Suess effect, and thus, D is generally positive (δR > δA). A 7 year record of biosphere‐atmosphere carbon exchange was used to evaluate the seasonality of δA and δR, and the 13C land disequilibrium, in a subalpine conifer forest. A novel isotopic mixing model was employed to determine the δ13C of net land‐atmosphere exchange during day and night and combined with tower‐based flux observations to assess δA and δR. The disequilibrium varied seasonally and when flux‐weighted was opposite in sign than expected from the Suess effect (D = −0.75 ± 0.21‰ or −0.88 ± 0.10‰ depending on method). Seasonality in D appeared to be driven by photosynthetic discrimination (Δcanopy) responding to environmental factors. Possible explanations for negative D include (1) changes in Δcanopy over decades as CO2 and temperature have risen, and/or (2) post‐photosynthetic fractionation processes leading to sequestration of isotopically enriched carbon in long‐lived pools like wood and soil.
Unraveling the dynamics that scale cross‐shore headland relief on rocky coastlines: 2. Model predictions and initial tests
Authors: Limber Patrick W. , Murray A. Brad 
Published: March 2014

AbstractWe explore the behavior of a theoretical model of cross‐shore headland relief caused by alongshore differences in lithology and rock strength on rocky coastlines. Results address the question of why some rocky coasts exhibit frequent headland and embayment sequences while others evolve to a flat, smooth, and sandy configuration. Main model predictions are that cross‐shore headland amplitude is inversely proportional to beach sediment supply and the strength of wave energy convergence and divergence along the headland and bay, and proportional to the alongshore embayment length (or distance between headlands) and the difference between headland and bay rock strength. The coastline's initial physical properties (sea cliff height, composition, etc.) largely determine whether headlands will be persistent or transient landscape features. Model timescales over which the headland and bay reach steady state amplitude, or disappear to a flat coastline, range from 120 to 175,000 years depending on how close the initial amplitude is to steady state. In many cases, the coastline must evolve over several sea level highstands in order to reach equilibrium. A characteristic timescale (independent of initial conditions) shows that the coastline evolves most rapidly when: wave focusing is stronger; sea cliff rock is weaker or retreats faster in a given wave climate; the sea cliff retreat rate decreases rapidly as a function of beach width (i.e., the beach is very effective at dampening wave energy); and the coastline is sediment rich. Comparisons to nature suggest that our model is qualitatively capturing general rocky coastline dynamics and that modeled headland amplitudes are consistent with observed amplitudes.
Role of extreme snowfall events in interannual variability of snowfall accumulation in the western United States
Authors: Lute A. C. , Abatzoglou J. T. 
Published: March 2014

AbstractWater resources in the western United States are contingent on interannual variations in snowpack. Interannual snowpack variability has been attributed to large‐scale climate patterns including the El Niño‐Southern Oscillation (ENSO), however, the contribution of snowfall frequency and extreme snowfall events to this variability are less well quantified. Long‐term records from Snowpack Telemetry and Cooperative Observer Program stations in the 11 western states were used to investigate these relationships by considering the number of snowfall days and snowfall water equivalent (SFE) of extreme snowfall events. The top decile of snowfall events contributed 20–38% of annual SFE, depending on the region. An average of 65% and 69% of the interannual variability in annual SFE was explained by snowfall days and SFE of top decile snowfall events, respectively, with extreme events being a more significant predictor at most stations. The latitudinal dipole in SFE during ENSO phases results from changes in snowfall frequency and extreme events. In the Pacific Northwest, above normal SFE during La Niña winters was a product of both larger contributions from extremes and more snowfall days, while below normal SFE during El Niño winters was primarily associated with a substantial reduction in extremes. Conversely, annual SFE during ENSO phases in the mountains of Arizona was more closely linked to fluctuations in snowfall days than extremes. Results indicate the importance of extreme snowfall events in shaping interannual variability in water resources and suggest that improved predictive ability may inform better water resource management now and in the coming decades.
Dual role of salt marsh retreat: Long‐term loss and short‐term resilience
Authors: Mariotti G. , Carr J. 
Published: March 2014

AbstractTwo major causes of salt marsh loss are vertical drowning, when sediment accumulation on the platform cannot keep vertical pace with sea level rise, and horizontal retreat, associated with wave‐induced marsh boundary erosion. Despite these processes having been extensively documented and modeled, it is unclear which loss modality dominates given a set of environmental parameters. A three‐point dynamic model was developed to predict marsh loss as a function of sea level rise, allochthonous sediment supply, wind regime, tidal range, and marsh bank and mudflat erodability. Marsh horizontal and vertical evolutions were found to respond in opposing ways to wave‐induced erosion processes. Marsh horizontal retreat was triggered by large mudflats, strong winds, high erodability of marsh bank and mudflat, whereas the opposite conditions acted to reduce the sediment supply to the marsh platform, promoting marsh loss to drowning. With low and moderate rates of sea level rise (∼5 mm/yr), retreat was found to be a more likely marsh loss modality than drowning. However, conditions associated with marsh retreat also increase the system resilience by transferring sediment on the marsh platform and preventing drowning. Our results suggest the use of a modular strategy for short‐term marsh management: selectively protect extensive salt marsh regions by maintaining healthy vegetation on the platform, while allowing other areas to retreat, leveraging the natural resilience embedded in the lateral loss of marsh extent.
A robust output error identifier for continuous‐time systems
Authors: Wang Lei , Ortega Romeo , Su Hongye , Liu Zhitao , Liu Xiangbin 
Published: March 2014

SummaryThis paper shows that the adaptive output error identifier for linear time‐invariant continuous‐time systems proposed by Bestser and Zeheb is robustvis‐à‐visfinite energy measurement noise. More precisely, it is proven that the map from the noise to the estimation error is–stable—provided a tuning parameter is chosen sufficiently large. A procedure to determine the required minimal value of this parameter is also given. If the noise is exponentially vanishing, asymptotic convergence to zero of the prediction error is achieved. Instrumental for the establishment of the results is a suitable decomposition of the error system equations that allows us to strengthen—tostrict—the well‐known passivity property of the identifier. The estimator neither requires fast adaptation, a dead‐zone, nor the knowledge of an upperbound on the noise magnitude, which is an essential requirement to prove stability of standard output error identifiers. To robustify the estimator with respect to non‐square integrable (but bounded) noises, a prediction error‐dependent leakage term is added in the integral adaptation.–stability of the modified scheme is established under a technical assumption. A simulated example, which is unstable for the equation error identifier and the output error identifier of Bestser and Zeheb, is used to illustrate the noise insensitivity property of the new scheme. Copyright © 2014 John Wiley & Sons, Ltd.
Mehrdimensionales De‐novo‐Moleküldesign durch adaptive Fragmentauswahl
Authors: Reutlinger Michael , Rodrigues Tiago , Schneider Petra , Schneider Gisbert 
Published: March 2014

AbstractWir präsentieren die Entwicklung und Anwendung eines computergestützten Verfahrens für das De‐novo‐Design von bioaktiven niedermolekularen Substanzen mit gewünschten Bindungsprofilen. Der Ansatz überträgt das aus der Natur inspirierte Konzept der Ameisenkolonie‐Optimierung auf die Auswahl von kombinatorischen Synthesebausteinen. Basierend auf öffentlich zugänglichen Struktur‐Aktivitäts‐Daten haben wir ein quantitatives Polypharmakologie‐Vorhersagemodell für 640 humane Wirkstofftargets entwickelt. Am Beispiel der reduktiven Aminierung zeigen wir den Entwurf von sowohl selektiven als auch Multi‐Target‐modulierenden Dopamin‐D4‐Antagonisten sowie Sigma‐1‐Rezeptor‐selektiven Liganden mit genau vorausgesagten Affinitäten. Die nanomolaren Potenzen der erzielten Treffer, ihre hohe Ligandeneffizienz und eine Erfolgsquote von 90 % zeigen, dass die computerbasierte Moleküldesignmethode für die schnelle Entwicklung fokussierter kombinatorische Substanzbibliotheken geeignet ist.
Stimuli‐Responsive Theragrippers for Chemomechanical Controlled Release
Authors: Malachowski Kate , Breger Joyce , Kwag Hye Rin , Wang Martha O. , Fisher John P. , Selaru Florin M. , Gracias David H. 
Published: March 2014

AbstractWe report on a therapeutic approach using thermo‐responsive multi‐fingered drug eluting devices. These therapeutic grippers referred to as theragrippers are shaped using photolithographic patterning and are composed of rigid poly(propylene fumarate) segments and stimuli‐responsive poly(N‐isopropylacrylamide‐co‐acrylic acid) hinges. They close above 32 °C allowing them to spontaneously grip onto tissue when introduced from a cold state into the body. Due to porosity in the grippers, theragrippers could also be loaded with fluorescent dyes and commercial drugs such as mesalamine and doxorubicin, which eluted from the grippers for up to seven days with first order release kinetics. In an in vitro model, theragrippers enhanced delivery of doxorubicin as compared to a control patch. We also released theragrippers into a live pig and visualized release of dye in the stomach. The design of such tissue gripping drug delivery devices offers an effective strategy for sustained release of drugs with immediate applicability in the gastrointestinal tract.
Diastereoselective Carbocyclization of 1,6‐Heptadienes Triggered by Rhodium‐Catalyzed Activation of an Olefinic CH Bond
Authors: Aïssa Christophe , Ho Kelvin Y. T. , Tetlow Daniel J. , Pin‐Nó María 
Published: March 2014

AbstractThe use of α,ω‐dienes as functionalization reagents for olefinic carbon–hydrogen bonds has been rarely studied. Reported herein is the rhodium(I)‐catalyzed rearrangement of prochiral 1,6‐heptadienes into [2,2,1]‐cycloheptane derivatives with concomitant creation of at least three stereogenic centers and complete diastereocontrol. Deuterium‐labeling studies and the isolation of a key intermediate are consistent with a group‐directed CH bond activation, followed by two consecutive migratory insertions, with only the latter step being diastereoselective.
Short Stereoselective Synthesis of the Phytophthora Universal Mating Hormone α1 Using Lithiation/Borylation Reactions
Authors: Pulis Alexander P. , Fackler Philipp , Aggarwal Varinder K. 
Published: March 2014

AbstractThe universal mating hormone α 1 of the virulent plant pathogen Phytophthora has been synthesized in 12 steps and 28 % overall yield. Key CC bond‐forming steps involved the use of two lithiation/borylation reactions to couple together enantioenriched building blocks, one of which also set up the stereochemistry of the tertiary alcohol at C11. Detailed analysis showed that the diastereomeric purity of the target molecule was >91 %, the highest obtained to date.
Collagen‐immobilized poly(ethylene terephthalate)‐g‐poly(vinyl alcohol) fibers prepared by electron‐beam co‐irradiation
Authors: Dai Guoliang , Xiao Hong , Zhu Shifeng , Shi Meiwu 
Published: March 2014

ABSTRACTVinyl acetate was grafted onto poly(ethylene terephthalate) (PET) fibers under electron‐beam co‐irradiation. Then, the grafted products were hydrolyzed under HCl solution to obtain PET‐g‐poly(vinyl alcohol) (PVA) fibers. Afterward, to impart superior hydrophilicity and skin care, collagen was immobilized onto PET‐g‐PVA fibers with glutaraldehyde. The modified fabric was characterized in terms of moisture regain, wettability, and evaporation rate [Ev (%/h)]. The degree of alcoholysis of the grafting product was more than 90% in a 10% HCl solution at 100°C for 4 h, and its moisture regain was 1.4%. The modified PET fabric with collagen showed a shorter drip diffusion time and a higher wicking height than the unmodified PET and PET‐g‐PVA fabric before and after multiple washings. The evaporation ratio and Ev of the collagen‐immobilized PET fibers were far below those of the virgin PET fibers. The chemical structure, surface morphology, and element content of the product were characterized by attenuated total reflectance–Fourier transform infrared spectroscopy, scanning electron microscopy, and X‐ray photoelectron spectroscopy. This further certified that the collagen‐immobilized PET‐g‐PVA fiber was successfully prepared by the previous procedure. Furthermore, the PET–PVA–collagen fabric was capable of withstanding multiple washing cycles. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40597.
Investigating the structure and water permeation of membranes modified with natural and synthetic additives using tensile, porosity, and glass transition temperature studies
Authors: Vilakati Gcina Doctor , Hoek Eric M. V. , Mamba Bhekie Brilliance 
Published: March 2014

ABSTRACTThis article reports the results of a study on the effect of using different additives (lignin, polyethylene glycol [PEG], and polyvinyl pyrrolidone [PVP]) to fabricate ultrafiltration polysulfone (PSf) membranes. The main focus of this study was on the difference in permeation properties brought about by the absence or presence of a fabric when fabricating the membranes. Differential scanning calorimetry was used to characterize the thermal properties and was also used to predict the other membrane properties. An Instron machine was used to evaluate the mechanical properties. The bulk porosity of lignin and PVP‐modified membranes was observed to be higher than that of the membranes modified with PEG. There was a strong negative correlation between the bulk porosity and the glass transition temperature irrespective of the additive used. Membranes cast on a fabric showed higher flux compared with membranes cast on glass. There was a strong positive correlation between the bulk porosity and the observed permeability regardless of whether the membrane was cast on a nonwoven fabric or on a glass plate. Pore‐size distribution results showed that lignin and PVP‐modified membranes had a narrow pore‐size distribution ranging between 10 and 25 nm when compared with PEG‐modified membranes with a pore‐size distribution ranging between 2.5 and 20 nm. These results indicate that thermal, bulk porosity, and mechanical properties can be used to probe the membrane structure. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40616.
Morphological evolution and properties of thermoplastic vulcanizate/organoclay nanocomposites
Authors: Li Chaoqun , Jiang Zhiwei , Tang Tao 
Published: March 2014

ABSTRACTNanocomposites composed of organoclay and thermoplastic vulcanizates (TPVs) based on uncompatibilized or compatibilized polypropylene (PP)/ethylene–propylene–diene rubber (EPDM) blends were prepared in this study. The morphology of the nanocomposites was studied with wide‐angle X‐ray diffraction and transmission electron microscopy, which suggested that the addition of the compatibilizer played a key role in determining the morphology of the composites because of their interaction with the clay surface. Scanning electron microscopy study indicated the changes in the morphology of the rubber particles. Dynamic mechanical analysis was also applied to the analysis of these phenomena. Moreover, for nanocomposites with uncompatibilized PP/EPDM blends as the matrix, the samples showed tensile enhancement compared with neat TPV. Although the addition of the compatibilizer changed tensile properties of the composites in a rather different trend, the tensile modulus increased dramatically when the compatibilizer was added. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40618.