bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interannual to decadal changes in extreme fire weather event frequencies across the southwestern United States
Authors: Crimmins Michael A. 
Published: June 2010

AbstractLow‐frequency changes (decades to years) in precipitation related to the El Niño‐Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) are known to influence wildfire variability across the southwest United States. Little work has been done to identify whether daily fire weather variability, also important to wildfire activity, is influenced by these same climatic phenomena. This study identifies the synoptic climatological conditions associated with extreme fire weather events in the Southwest and constructs an extreme fire weather frequency data set for the period of 1958–2003 using a logistic regression technique. Interannual changes in extreme fire weather day frequencies are not linearly correlated with either ENSO or PDO, but do show significant deviations from expected values when grouped by PDO phase (positive or negative) and further subgrouped by ENSO state (La Niña, El Niño or neutral). A higher number of extreme fire weather days occur during the negative phase of the PDO, especially when accompanied by a La Niña event. Copyright © 2010 Royal Meteorological Society
Extreme precipitation of the Waikato region, New Zealand
Authors: Dravitzki Stacey , McGregor James 
Published: June 2010

AbstractThis study investigates the relationship between regional precipitation and large‐scale climate variations. The Waikato is an economically important region of New Zealand that is dependant on a reliable source of precipitation for agriculture and hydroelectric power generation, but is also prone to flooding. Previous long‐term precipitation studies have represented this region by a single rain gauge. This study has incorporated more data from more rain gauges and extended the analysis period to 107 years, 1900–2007.The meteorological causes of extreme precipitation events within the region were examined. This identified that heavy precipitation is associated with periods of increased baroclinicity that produces a rapid sequence of mid‐latitude cyclones or the presence of a blocking high to the east of New Zealand.A regionally representative time series was used to compare known climate variations to the occurrence and magnitude of extreme precipitation events. Since 1900 there have been no significant variations in the total annual precipitation nor in the occurrence or magnitude of extreme precipitation events, indicating that the precipitation resource in this region is dependable. Events were also uncorrelated to the large‐scale Interdecadal Pacific Oscillation, El Niño–Southern Oscillation and Southern Annular Mode indicating that the seasonal probability of extreme precipitation is independent of these circulations. Copyright © 2010 Royal Meteorological Society
Identification and classification of organic and inorganic components of particulate matter via Raman spectroscopy and chemometric approaches
Authors: Schumacher Wilm , Kühnert Michael , Rösch Petra , Popp Jürgen 
Published: June 2010

AbstractIn this paper, a novel method for developing a tree‐like classifier which differentiates between organic and inorganic particulate matter by means of Raman spectroscopy is introduced. The algorithm is fully automatic and optimises itself without any human interaction. This method uses a tree‐like structure to classify Raman spectra as a decision tree. On every knot of this tree, the optimal classifier is automatically obtained, tested and trained. The optimal classifier is an artificial neural network, linear discriminant analysis or a support vector machine, where different kernels are possible. The support vector machine is optimised by the simulated annealing method to achieve the best possible classifier. After the training, a hold‐out experiment with two completely independent sets of Raman spectra was tried to show the abilities of this method for real‐world application. Copyright © 2010 John Wiley & Sons, Ltd.
Determination of fluoroquinolone antibiotics in wastewater using ultra high‐performance liquid chromatography with mass spectrometry and fluorescence detection
Authors: Seifrtová Marcela , Aufartová Jana , Vytlačilová Jitka , Pena Angelina , Solich Petr , Nováková Lucie 
Published: June 2010

AbstractA new ultra HPLC (UHPLC) method using both MS and fluorescence detection (FD) was developed for the determination of five fluoroquinolones in wastewaters. Systematic method development approach was compared with a conventional one. During the systematic approach, a possibility of automatic switching among four independent analytical columns of different chemistries has been used. Acidic as well as basic pH using ACN and methanol as organic modifiers was tested. The best separation of fluoroquinolones was obtained on phenyl analytical column at pH 10.5, which is a completely novel approach for separation of fluoroquinolones. Further, a new SPE procedure was developed for the sample preparation using basic pH as well. The sensitivity and selectivity of FD and MS detection were compared. FD at basic pH 10.5 demonstrated lower sensitivity than at acidic pH, which is conventionally performed. At basic pH, UHPLC‐MS/MS was found about two orders of magnitude more sensitive than FD. Both methods were validated and subsequently UHPLC‐FD method was used for the evaluation of stability of fluoroquinolones. UHPLC‐MS/MS method was used for the analysis of wastewater samples. Norfloxacin and ciprofloxacin were detected in samples of influent and effluent from wastewater treatment plant. Ofloxacin was detected only in influent from wastewater treatment plant.
Compensating for variation in 1JCH coupling constants in HSQC spectra acquired on small organic molecules
Authors: Howe Peter W. A. 
Published: June 2010

AbstractThe HSQC sequence provides a sensitive way of determining the 13C chemical shift of protonated carbons. It uses INEPT elements for magnetization transfer, which can only be optimized for one value of 1JCH, but small organic molecules contain a wide range of 1JCH values. One popular method of compensating for 1JCH variation is to incorporate adiabatic pulses into the INEPT elements. This article shows that this method fails for a significant subset of functional groups. It also shows that the effects of this failure can be reduced by avoiding refocusing delays and by using a J‐compensated excitation element. Copyright © 2010 John Wiley & Sons, Ltd.
P1‐conservative solution interpolation on unstructured triangular meshes
Authors: Alauzet F. , Mehrenberger M. 
Published: June 2010

AbstractThis paper presents an interpolation operator on unstructured triangular meshes that verifies the properties of mass conservation, P1‐exactness (order 2), and maximum principle. This operator is important for the resolution of the conservation laws in computational fluid dynamics by means of mesh adaptation methods as the conservation properties are not verified throughout the computation. Indeed, the mass preservation can be crucial for the simulation accuracy. The conservation properties are achieved by local mesh intersection and quadrature formulae. Derivatives reconstruction are used to obtain an order 2 method. Algorithmically, our goal is to design a method that is robust and efficient. The robustness is mandatory to apply the operator to highly anisotropic meshes. The efficiency will permit the extension of the method to dimension 3. Several numerical examples are presented to illustrate the efficiency of the approach. Copyright © 2010 John Wiley & Sons, Ltd.
Proposing a way forward: A review of standardisation in the use of age categories and ageing techniques in osteological analysis (2004–2009)
Authors: Falys C. G. , Lewis M. E. 
Published: June 2010

AbstractThis study assesses the current state of adult skeletal age‐at‐death estimation in biological anthropology through analysis of data published in recent research articles from three major anthropological and archaeological journals (2004–2009). The most commonly used adult ageing methods, age of ‘adulthood’, age ranges and the maximum age reported for ‘mature’ adults were compared. The results showed a wide range of variability in the age at which individuals were determined to be adult (from 14 to 25 years), uneven age ranges, a lack of standardisation in the use of descriptive age categories and the inappropriate application of some ageing methods for the sample being examined. Such discrepancies make comparisons between skeletal samples difficult, while the inappropriate use of some techniques make the resultant age estimations unreliable. At a time when national and even global comparisons of past health are becoming prominent, standardisation in the terminology and age categories used to define adults within each sample is fundamental. It is hoped that this research will prompt discussions in the osteological community (both nationally and internationally) about what defines an ‘adult’, how to standardise the age ranges that we use and how individuals should be assigned to each age category. Skeletal markers have been proposed to help physically identify ‘adult’ individuals. Copyright © 2010 John Wiley & Sons, Ltd.
DFT studies on the cascade rearrangement reactions of the cubylcarbinyl radical
Authors: Zhang Qing‐Li , Chen Bo‐Zhen 
Published: June 2010

AbstractDFT (U)B3LYP calculations with the 6‐311 + G** basis set were carried out to investigate the mechanisms of cascade rearrangement reactions (involving eight reaction channels) of the cubylcarbinyl radical (radical 1). The rate constant for each reaction step was calculated on the basis of the conventional transition state theory. The reaction channel from radical 1 to the 4‐(4‐methylenecyclobut‐2‐enyl) radical is preferred kinetically, while the reaction channel from radical 1 to the 1‐homocubyl radical is unfavorable. The mechanism of the conversion from radical 1 to the tricyclic dienes radical, which is experimentally uncertain, is predicted to be a stepwise process with the methylenesecocubyl radical as an intermediate instead of a concerted reaction. The energy barrier and rate constant of the initial reaction step are evaluated to be 2.8 kcal/mol and 3.0 × 1010 s−1, respectively, in excellent agreement with the corresponding experimental values. Copyright © 2010 John Wiley & Sons, Ltd.
Temperature‐dependent structural changes in intrinsically disordered proteins: Formation of α‒helices or loss of polyproline II?
Authors: Kjaergaard Magnus , Nørholm Ann‒Beth , Hendus‒Altenburger Ruth , Pedersen Stine F. , Poulsen Flemming M. , Kragelund Birthe B. 
Published: June 2010

AbstractStructural characterization of intrinsically disordered proteins (IDPs) is mandatory for deciphering their potential unique physical and biological properties. A large number of circular dichroism (CD) studies have demonstrated that a structural change takes place in IDPs with increasing temperature, which most likely reflects formation of transient α‒helices or loss of polyproline II (PPII) content. Using three IDPs, ACTR, NHE1, and Spd1, we show that the temperature‐induced structural change is common among IDPs and is accompanied by a contraction of the conformational ensemble. This phenomenon was explored at residue resolution by multidimensional NMR spectroscopy. Intrinsic chemical shift referencing allowed us to identify regions of transiently formed helices and their temperature‐dependent changes in helicity. All helical regions were found to lose rather than gain helical structures with increasing temperature, and accordingly these were not responsible for the change in the CD spectra. In contrast, the nonhelical regions exhibited a general temperature‐dependent structural change that was independent of long‐range interactions. The temperature‐dependent CD spectroscopic signature of IDPs that has been amply documented can be rationalized to represent redistribution of the statistical coil involving a general loss of PPII conformations.
Michael Elliott's billion dollar crystals and other discoveries in insecticide chemistry
Authors: Casida John E 
Published: June 2010

AbstractThe crowning achievement for Michael Elliott came in 1973 when his most outstanding candidate insecticide from 25 years of research crystallized from hexane solution. The stereochemically pure crystalline compound was the most potent synthetic insecticide ever made until that time, and it was highly selective for insects compared with mammals. It was given the name deltamethrin. Sequential stereospecific crystallization to isolate the most potent epimer and base‐catalyzed racemization of the remaining less active isomer could be used to produce deltamethrin efficiently on a large scale; it became the billion dollar crystals. Elliott's discoveries at Rothamsted in England with Norman Janes and David Pulman of resmethrin, permethrin, cypermethrin and ultimately deltamethrin provided crop protection and malaria control for millions of people. Michael also laid the background for lipophilic amide, dithiane and other insecticides and nerve probes that are not involved in pyrethroid cross‐resistance. Some aspects of these investigations were best conducted at Berkeley, where Michael studied pyrethrins in 1969, synthetic pyrethroids in 1974 and alternative insecticides in 1986–1988. This review considers Michael's seminal discoveries in insecticide chemistry, with emphasis on his Berkeley years. Copyright © 2010 Society of Chemical Industry
Testing insecticide resistance management strategies: mosaic versus rotations
Authors: Zhao Jian‐Zhou , Collins Hilda L , Shelton Anthony M 
Published: June 2010

AbstractBACKGROUND: Developing scientifically valid, economically acceptable insecticide resistance management (IRM) programs is critical for sustainable insect management. The diamondback moth, Plutella xylostella (L.), has demonstrated an ability to develop resistance to many different classes of insecticides, including proteins produced by the bacterium Bacillus thuringiensis Berliner (Bt). Recently it has developed resistance to the novel compounds spinosad and indoxacarb. In greenhouse cage experiments, a laboratory‐selected population of P. xylostella resistant to spinosad, indoxacarb and Bt was used to compare population growth and resistance evolution if these three insecticides were rotated or used in a mosaic fashion.RESULTS: The average population density through nine generations was lowest in the treatment in which the insecticide was rotated every generation (R‐1) (x̄ = 20.7 ± 3.20) compared with the treatment in which the insecticide was rotated every third generation (R‐3) (x̄ = 41.4 ± 17.6) or where the insecticides were applied as a mosaic (M) (x̄ = 41.8 ± 6.53). After nine generations, the survival of resistant individuals increased for each insecticide (7.2–73.5%) compared with the population without selection (CK) (0.73–3.1%). Survival on spinosad was significantly lower (23.7%) in the single‐generation rotation than for the other two treatments, both of which exceeded 72%. The calculated survival on all three insecticides treated simultaneously, according to the survival on each insecticide, was 0.26, 0.81 and 1.6% for R‐1, R‐3 and M treatments respectively.CONCLUSION: Results of both population density and resistance development indicated that insecticide rotation every generation was better for IRM than if the insecticide was rotated every third generation or if the three insecticides were applied as a mosaic. Copyright © 2010 Society of Chemical Industry
Benzhydrylamine linker grafting: a strategy for the improved synthesis of C‐terminal peptide amides
Authors: Alewood Dianne , Hopping Gene , Brust Andreas , Reid Robert C. , Alewood Paul F. 
Published: June 2010

AbstractThe standard p‐MBHA resin used during Boc‐chemistry synthesis of peptides carrying C‐terminal carboxamides is compromised by batch‐to‐batch variations in its performance. This can cause artificially ‘difficult’ couplings during peptide chain assembly, which may ultimately lead to failed syntheses given the inability to achieve acceptable coupling yields. To overcome these problems, we have developed a new approach by grafting a functionalized benzhydrylamine linker onto well‐characterized and well‐performing PAM resins. We combine optimized Boc‐chemistry, high‐performing PAM resins and new benzhydrylamine‐based linkers to achieve improved syntheses of peptide amides. Here we present the synthesis of two new benzhydrylamine linkers and their attachment to selected PAM resins. This novel solid support was evaluated through the synthesis of selected ‘difficult’ conotoxins and monitoring the coupling efficiency using quantitative ninhydrin assay. The results show a superior performance of the novel linker solid support compared to the standard p‐MBHA resins routinely used. In summary, we describe an alternative linker‐resin system that allows improved access to C‐terminal amide peptides employing Boc/Bzl chemistry. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.
Optical and structural properties of m ‐plane GaN substrates grown by ammonothermal method and GaN epilayers grown on these substrates
Authors: Kudrawiec R. , Rudziński M. , Kucharski R. , Zając M. , Doradziński R. , Sierzputowski L. P. , Garczyński J. , Serafińczuk J. , Strupiński W. , Misiewicz J. , Dwiliński R. 
Published: June 2010

Abstractm ‐plane oriented GaN substrates of size 6 x 8 mm have been obtained by ammonothermal method and used to growing GaN epilayers by metalorganic chemical vapor deposition. The structural and optical properties have been determined for both m ‐plane GaN substrates and GaN epilayers deposited on these substrates. Excellent structural quality of m ‐plane GaN substrates has been confirmed by very narrow XRD peaks (the full‐width‐half‐maximum for the symmetrical (10.0) and asymmetrical (20.1) peaks are 16 and 19 arcsec, respectively) and the low concentration of threading dislocation density (∼ 104 cm‐2). In addition, these substrates exhibit quite good optical quality: the energy gap‐related transition is clearly observed at room temperature in photoluminescence and contactless electroreflectance spectra. The optical quality becomes excellent for GaN epilayers deposited on these substrates. In low temperature reflectance spectra very narrow intrinsic exciton lines which are very sensitive to the optical selection rules typical for the hexagonal symmetry were observed. In low temperature photoluminescence spectra a strong bound exciton line, relatively strong FXA and FXB lines and no emission band around 3.42 eV, which could be associated with the stacking faults, were observed. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
(Ga,In)P emitter composition effect on the performance of (Ga,In)P/GaAsSb/InP DHBTs grown by MOCVD
Authors: Zeng Yuping , Lövblom Rickard , Ostinelli Olivier , Bolognesi C. R. 
Published: June 2010

Abstract(Ga,In)P/GaAsSb DHBTs with different emitter sizes were fabricated with the standard triple‐mesa process on wafers with GaInP [Ga] emitter contents of 0, 0.15, 0.24 in the emitter. The effect of the gallium content on the DC and RF characteristics of the DHBTs was studied. It was found that gain increases as the Ga mole fraction increases. This is due to a reduced surface recombination current and intrinsic recombination current with increasing [Ga]. 0.45 × 9.5 μm2 devices with a Ga content of 0.24 show the highest cut‐off frequency of 387 GHz. This is attributed to the reducing barrier at the E/B interface, which eases the injection of electrons from the emitter into the GaAsSb base. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical anisotropy of two‐photon absorption in GaAs/AlGaAs quantum wells measured by photoluminescence
Authors: Morita Ken , Niki Nobuyoshi , Kada Tkahiro , Isu Tosiro 
Published: June 2010

AbstractPhotoluminescence (PL) as a consequence of a two‐photon absorption excitation was measured in a GaAs/AlGaAs (001) multiple quantum well (MQW) at room temperature and an optical anisotropy of the two‐photon absorption was investigated by PL intensity depending on the polarization direction of the normal‐incidence excitation light. The anisotropic behavior with a four‐fold rotation symmetry was observed in the polarization dependence. Strength of the two‐photon absorption reaches its maximum when the excitation light is polarized to the [110] and [1$ \bar 1 $0] directions. It was found that the anisotropic behavior becomes more significant as the excitation energy approaches near the two‐photon absorption edge. The anisotropy parameter |σ| determined by the theoretical fitting curve reaches ∼ 2 at the two‐photon absorption edge, which was about 4 times larger than that of the bulk GaAs (|σ| ∼ 0.5). (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Monolithic electro‐optically modulated vertical cavity surface emitting laser with 10 Gb/s open‐eye operation
Authors: Germann T. D. , Strittmatter A. , Mutig A. , Nadtochiy A. M. , Lott J. A. , Blokhin S. A. , Karachinsky L. Ya. , Shchukin V. A. , Ledentsov N. N. , Pohl U. W. , Bimberg D. 
Published: June 2010

AbstractA vertical‐cavity surface‐emitting laser with a monolithically integrated electro‐optical modulator (EOM VCSEL) is fabricated using metal‐organic vapor phase epitaxy. 3 dB extinction ratio of the modulator at a very low power consumption and open‐eye operation of the EOM VCSEL at 10 Gb/s is demonstrated. The modulation of the 845 nm output is temperature‐stable up to 85 °C. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth and characterization of AlGaN/GaN/AlGaN field effect transistors
Authors: Chen Z. , Pei Y. , Chu R. , Newman S. , Brown D. , Chung R. , Keller S. , DenBaars S. P. , Nakamura S. , Mishra U. K. 
Published: June 2010

AbstractField effect transistors (FETs) on both GaN and AlGaN buffers were grown and compared. Development of high quality AlGaN is the key to obtain high performance AlGaN buffer FETs. An optimized Al0.04Ga0.96N layer on SiC substrate had (002) and (201) X‐ray rocking curves with full wide at half maximum (FWHM) of 140 and 450 arc sec, respectively, indicates the comparable crystal quality of AlGaN to that of a typical GaN layer. X‐ray reciprocal space mapping and ω –2θ scans showed that the AlGaN barriers grown on GaN and Al0.04Ga0.96N buffers had different Al compositions and thickness, which was attributed to the compositional pulling effect. At room temperature, the AlGaN buffer FET had a sheet carrier concentration and electron mobility of 8.3×1012 cm‐2 and 1750 cm2/Vs, respectively. AlGaN/GaN/AlGaN FETs demonstrated a status‐of‐the‐art power added efficiency (PAE) of 53.5%, and a status‐of‐the‐art power gain of 13.4 dB at a drain bias of 20 V at 30 GHz. This device also exhibited lower output conductance and better pinch‐off due to the improved electron confinement resulting from the increase in the effective buffer energy height. The device results imply that AlGaN buffer FETs are promising devices for highly scaled transistors in RF applications in the Ka‐ band and beyond. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Infrared single photon avalanche detectors
Authors: Campbell Joe C. , Hu Chong 
Published: June 2010

AbstractThere are a number of mature and emerging applications that require the ultimate in sensitivity, i.e., single photon detection. A promising candidate is the single photon avalanche diode (SPAD). Its performance is measured in terms single photon detection efficiency, dark count probability (dark count rate), operating temperature, spectral response, jitter, and afterpulsing. Quenching circuits for SPADs have also become active areas of research. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)