bluuebunny/crossref_metadata_2025 huggingface dataset:
Developing an asset threshold using the consensual approach: Results from Mashonaland West, Zimbabwe
Authors: Mtapuri Oliver
Published: July 2009

Although poverty lines have been constructed on the basis of an income threshold, this article defines a poverty line on the basis of an asset threshold using the consensual approach as postulated by Mack and Lansley. In this article, an asset threshold is defined using this approach, which is a European method in an African rural setting. The determination of the asset threshold—the Minimally Adequate Asset Level, which is context‐sensitive, fixed bundle of assets, is the major contribution of this article. This asset poverty line opens up possibilities for calculating asset‐based FGT measures as well as an asset‐gini‐coefficient. The article also shows that location matters in the perception of poverty as a consequence of differing lifestyles. Copyright © 2009 John Wiley & Sons, Ltd.
Automated zone‐sampling dilution by coupling sequential injection analysis to high‐throughput HPLC for the direct determination of gemfibrozil
Authors: Tzanavaras Paraskevas D. , Themelis Demetrius G. , Rigas Pantelis
Published: July 2009

A novel automated analytical scheme for the rapid determination of gemfibrozil in drug dissolution samples is reported. The procedure is based on direct coupling of a low pressure continuous flow technique such as sequential injection analysis (SI) to HPLC. SI performs automated dilution of the samples based on zone sampling and fills on‐line the loop of the high pressure injection valve. Rapid separation of the analyte from the samples' matrix can be achieved in less than 1.0 min, by using a short RP monolithic column (25×4.6 mm id) at a flow rate of 2 mL/min. The SI and HPLC parts of the setup operate independently: during HPLC separation the next sample is treated by SI. This way a maximum throughput of 60 samplesperhour is achieved allowing the complete analysis of a batch of six dissolution samples within 12–18 min based on the replicates. The proposed method was validated in terms of linearity, LOD and LOQ, precision, selectivity and accuracy. Its applicability was tested during quality control of four validation batches of a gemfibrozil‐containing formulation. The results were in good agreement with the HPLC method proposed by the US Pharmacopeia.
Highly cross‐linked polymeric capillary monoliths for the separation of low, medium, and high molecular weight analytes
Authors: Lubbad Said H. , Buchmeiser Michael R.
Published: June 2009

Highly rigid capillary monoliths with low swelling propensity were prepared within the confines of 200 μm ID fused silica capillaries via thermally induced free radical polymerization of tetrakis(4‐vinylbenzyl)silane (TVBS) in the presence of 1‐dodecanol and toluene. α,α′‐Azobisisobutyronitrile (AIBN) was used as initiator. The resulting monoliths were optimized for the separation of low, medium, and high molecular weight analytes. The microstructure and porosity of the monoliths prepared were studied by SEM and inverse size‐exclusion chromatography (ISEC). The porosity of the monolithic supports was tuned by varying the amount of initiator (i. e. AIBN) between 0.5 and 2 wt%. All monoliths were tested for a series of low molecular weight compounds including alkylbenzenes, amines, carboxylic acids, phenols, carbonyl compounds, and β‐blockers, as well as for the separation of medium molecular weight analytes such as peptides and high‐molecular weight analytes such as proteins. Due to the microporous structure, the novel monoliths displayed high efficiency and performance particularly in the separation of low molecular weight analytes. Relevant chromatographic parameters including permeability, swelling propensity, and height equivalents to theoretical plates were determined.
Effect of temperature during photopolymerization of capillary monolithic columns
Authors: Szumski Michal , Buszewski Boguslaw
Published: July 2009

Polymeric monolithic capillary columns were synthesized using butyl methacrylate (BMA), ethylene glycol dimethacrylate (EDMA), and 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) as monomers and 1,4‐butanediol, 1‐propanol, and water as a porogen mixture. The synthesis was performed over a wide temperature range from –15°C to +70°C using UV radiation to trigger the polymerization process initiated by benzoin methyl ether (BME). The columns exhibited different hydrodynamic properties (permeability) as well as efficiency. The most efficient and the most permeable columns were those polymerized at low temperatures (–15°C to +10°C). The columns photopolymerized at higher temperatures (T ⪈ 30°C) were completely useless because of low permeability or efficiency. The presented results indicate that temperature can be another factor which allows control of porosity during the preparation of monoliths by photopolymerization.
Layer‐by‐Layer Assembled Nanotubes as Biomimetic Nanoreactors for Calcium Carbonate Deposition
Authors: He Qiang , Möhwald Helmuth , Li Junbai
Published: June 2009

Enzyme‐loaded magnetic polyelectrolyte multilayer nanotubes prepared by layer‐by‐layer assembly combined with the porous template could be used as biomimetic nanoreactors. It is demonstrated that calcium carbonate can be biomimetically synthesized inside the cavities of the polyelectrolyte nanotubes by the catalysis of urease, and the size of the calcium carbonate precipitates was controlled by the cavity dimensions. The metastable structure of the calcium carbonate precipitates inside the nanotubes was protected by the outer shell of the polyelectrolyte multilayers. These features may allow polyelectrolyte nanotubes to be applied in the fields of nanomaterials synthesis, controlled release, and drug delivery.

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Synthesis and structure elucidation of three series of nitro‐2‐styrylchromones using 1D and 2D NMR spectroscopy
Authors: Barros Ana I. R. N. A. , Silva Artur M. S.
Published: July 2009

2‐Styrylchromones, although scarce in nature, constitute a group of oxygen heterocyclic compounds which have shown significant biological activities. New nitro‐2‐styrylchromones have been synthesised by the Baker–Venkataraman method, and the structure elucidation was accomplished using extensive 1D (1H, 13C) and 2D NMR spectroscopic studies (COSY, HSQC and HMBC experiments). Copyright © 2009 John Wiley & Sons, Ltd.
Adverse effects associated with persistent stimulation of Leydig cells with hCG in vitro
Authors: Aggarwal Archana , Misro Man M. , Maheshwari Ankur , Sehgal Neeta , Nandan Deoki
Published: July 2009

The detrimental effects of persistent stimulation with hCG were investigated in rat Leydig cells in vitro. Significant rise in lipid peroxidation and reactive oxygen species (ROS) with concomitant attenuation in the activities of antioxidant enzymes: superoxide dismutase, catalase, and glutathione‐S‐transferase was observed. Transcripts for catalase and superoxide dismutase were also depleted. Subsequent to each hCG challenge, the total antioxidant capacity in the target cells also declined significantly (P < 0.05). There was an increase in cell apoptosis (23%), which was associated with a rise in caspase‐3 activity, PARP cleavage, and Fas, FasL, caspase‐8 expression. While Bax and Caspase‐9 expression remained unchanged, Bcl‐2 demonstrated a marked decline. Taken together, the above data indicate that persistent hCG stimulation of Leydig cells induced adverse effects leading to oxidative stress and apoptosis which was channeled primarily through the extrinsic pathway. Mol. Reprod. Dev. 76: 1076–1083, 2009. © 2009 Wiley‐Liss, Inc.
A Padé family of iterations for the matrix sector function and the matrix pth root
Authors: Laszkiewicz Beata , Ziȩtak Krystyna
Published: July 2009

A family of iterations for the sector function based on the Padé table of a certain hypergeometric function is derived and investigated. This generalizes a result of Kenney and Laub for the sign function and yields a whole family of iterative methods for computing the matrix pth root.

It is proved that the iterations for the matrix sector function corresponding to the main diagonal of the Padé table preserve the structure of a group of automorphisms associated with a scalar product.

The regions of convergence of the Padé iterations for the matrix sector function are investigated theoretically and experimentally. Certain conjectures formulated on the regions of convergence have been verified in particular cases. Copyright © 2009 John Wiley & Sons, Ltd.
A preliminary study on multiscale ELLAM schemes for transient advection‐diffusion equations
Authors: Cheng Aijie , Wang Kaixin , Wang Hong
Published: July 2009

We study multiscale Eulerian–Lagrangian localized adjoint methods (MsELLAMs) for transient linear advection‐diffusion equations with oscillatory coefficients, which arise in mathematical models for describing flow and transport through heterogeneous porous media, composite material design, and other applications. Several MsELLAM schemes are presented and studied. Numerical experiments are presented to observe the numerical performance of these MsELLAM schemes. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2010
Incisor microwear textures of five bioarcheological groups
Authors: Krueger K. L. , Ungar P. S.
Published: July 2009

Dental microwear texture analysis has proven to be a valuable tool for inferring aspects of subsistence behaviour in human groups and diet in other mammals. Studies have to date been limited to molar teeth. Here we report on the first microwear texture analysis of incisors. Five bioarcheological groups were included in this analysis: Aleuts from various islands in the Bering Sea (n = 24), Arikara from the Mobridge site in South Dakota (n = 18), ethnic Chinese cannery workers from Kodiak Island (n = 16), a Late Woodland Bluff sample from Jersey County, Illinois (n = 18) and Puye Pueblo from Pajarito Plateau in New Mexico (n = 18). First, point clouds with 0.18 µm lateral spacing and 0.005 µm vertical resolution were obtained from maxillary central incisor labial surfaces using a white‐light confocal profiler. Four adjoining fields were sampled for a total area of 276 µm × 204 µm for each specimen. Surface data were then imported into scale‐sensitive fractal analysis software for texture characterisation. Results indicate significant variation among groups in anisotropy, fill volume and heterogeneity. These differences are likely related to differences in diet, degrees and types of non‐dietary incisor use, as well as exposure to abrasives. This study also suggests that texture variables most useful for characterising and comparing incisor microwear may differ from those most useful for distinguishing molar microwear patterns. Copyright © 2009 John Wiley & Sons, Ltd.
Polyamide‐6/high‐density polyethylene blend using recycled high‐density polyethylene as compatibilizer: Morphology, mechanical properties, and thermal stability
Authors: Vallim Márcio R. , Araujo Joyce R. , Spinacé Márcia A. Silva , De Paoli Marco‐A.
Published: July 2009

Blends of polyamide‐6 (PA6) or postindustry polyamide‐6 (piPA6) and high‐density polyethylene (HDPE) or recycled high‐density polyethylene (rHDPE) were processed in single and twin‐screw extruders. The use of rHDPE in the blends promotes a significant decrease of size domains and improvement in the mechanical properties. The thermal stability was also slightly improved compared with PA6 and HDPE blends. The Molau test exhibited a stable emulsion in formic acid, which can be attributed to the formation of an interfacial copolymer involving polar amino end groups of PA6 and the rHDPE, respectively. These results indicate that recycled polymers can be used in the production of polymer blends with improved properties. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers.
Low‐loss planar optical waveguides fabricated from polycarbonate
Authors: Chen Jian‐guo , Zhang Tong , Zhu Jin‐song , Zhang Xiao‐yang , Zhou Jing‐lun , Fan Jiang‐feng , Hu Guo‐hua
Published: July 2009

Low‐loss slab waveguides with air as overcladding based on a high glass transition temperature (Tg) polycarbonate were fabricated through spin‐coating. Optical absorption and thermo‐optic coefficient were investigated by spectrum analysis and prism coupler, respectively. Prism‐coupling and charge‐coupled device (CCD) camera imaging method were exploited together to evaluate the overall propagation loss of slab waveguides. The measured results of prism coupler were 0.282 dB/cm at 1310 nm and 0.197 dB/cm at 632.8 nm, whereas 0.07 dB/cm at 632.8 nm using CCD camera imaging method. Based on the same material, straight ridge waveguides and multimode interference couplers were fabricated through photolithograph and reactive ion etching, revealing smooth sides and excellent definition. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers.
Synthesis and characterization of LiBOB‐based PVdF/PVC‐TiO2 composite polymer electrolytes
Authors: Aravindan Vanchiappan , Vickraman Palanisamy
Published: July 2009

Synthesis and characterization of composite polymer electrolytes based on lithium bis(oxalato)borate (LiBOB) and a host matrix of nanoparticulate anatase dispersed in phase‐separated poly(vinylidenefluoride) (PVdF)‐poly(vinylchloride) (PVC) are described. Ethylene carbonate (EC) and diethyl carbonate (DEC) were used as plasticizers in the membranes, and nanoparticulate TiO2 (anatase) was used as the filler. The membranes were characterized by SEM, XRD, and a.c. impedance measurements. A membrane with 2.5 wt% filler exhibited a conductivity of 5.43 × 10−4 S.cm−1 at ambient temperature. Filler levels above 2.5 wt% increased the crystallinity of the membranes, rendering them less conducting. Activation energy and coherent length of the composite polymer electrolytes have also been calculated. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers.
Heterocyclic polyimides containing siloxane groups in the main chain
Authors: Damaceanu Mariana‐Dana , Bacosca Irina , Bruma Maria , Robison Jenifer , Rusanov Alexander
Published: July 2009

BACKGROUND: Among the polymers widely studied for applications in advanced techniques, aromatic polyimides have received considerable attention due to their outstanding thermal stability associated with good electrical and mechanical properties. However, these polymers are usually difficult to process, being insoluble and without a glass transition. To improve the processing characteristics of polyimides, modification of their structure is often achieved by the introduction of flexible linkages in the macromolecular chain or various substituents on the aromatic rings.

RESULTS: A series of polyimides and intermediate polyamidic acids were synthesized from aromatic oxadiazole‐diamines and a dianhydride containing a siloxane bridge (R2SiOSiR2). These polymers exhibit good solubility in certain organic solvents and can be cast into thin and very thin films from their solutions. They exhibit high thermal stability with decomposition being above 440 °C and relatively low glass transition temperatures in the range 160–190 °C. These polymers show strong photoluminescence in the blue spectral region.

CONCLUSION: The introduction of oxadiazole rings together with siloxane groups into the chains of aromatic polyimides gives highly thermostable polymers with remarkable solubility and film‐forming ability and that emit blue light, being attractive for applications in micro‐ and nanoelectronics and other related advanced fields. Copyright © 2009 Society of Chemical Industry
Adults matter: Protecting children from the negative impacts of bullying
Authors: Conners‐Burrow Nicola A. , Johnson Danya L. , Whiteside‐Mansell Leanne , McKelvey Lorraine , Gargus Regina A.
Published: July 2009

This study examines the degree to which support from parents and teachers buffers the level of depression for four groups of children involved in bullying (victim, bully, bully‐victims, or not involved children). Nine hundred and seventy‐seven 5th‐, 9th‐, and 11th‐grade students in the rural South completed questionnaires on bullying, social support, and depression. Children who were not involved in bullying reported less depression and more social support than children involved in bullying, and bully‐victims were the most at‐risk group. Furthermore, results indicate that in all four bully status groups, children reported fewer symptoms of depression when support from parents was high compared to when it was low. For all groups except victims, when parental support was low, support from teachers was associated with fewer symptoms of depression. When parental support was high, the impact of support from the teacher was not significant. © 2009 Wiley Periodicals, Inc.
Emotion, understanding, and social skills among boys at risk of attention deficit hyperactivity disorder
Authors: Kats‐Gold Inna , Priel Beatriz
Published: July 2009

There is growing interest in the role of emotional competence in middle school children's adjustment and functioning, yet many populations remain underresearched. Few studies have explored the emotional competence, especially emotion understanding, of children with, or at risk of, attention deficit hyperactivity disorder (ADHD), and even fewer have examined the role emotion understanding plays in these children's social skills. Our study investigates a profile of the emotion understanding capacities of Israeli boys at risk of ADHD and evaluates its association with their social skills. One hundred and fifty‐two boys (grades 4–6) were each assigned to an at‐risk (n = 66) or comparison (n = 86) group based on their scores on an ADHD symptoms questionnaire (Conners Rating System–Revised). The two groups were matched on age, socioeconomic status and class, and school environment. Group comparisons revealed that relative to their non–at‐risk counterparts, at‐risk boys demonstrated less mature emotion understanding. Finally, our findings indicate that poor emotion understanding plays a more notable role in the social functioning of at‐risk than non–at‐risk children. This study's contribution to the understanding and school treatment of children with ADHD emotional and social competencies is discussed. © 2009 Wiley Periodicals, Inc.
Deposition of Biodegradable Polycaprolactone Coatings Using an In‐line Atmospheric Pressure Plasma System
Authors: Tynan John , Ward Pat , Byrne Gerry , Dowling Denis. P.
Published: July 2009

Polycaprolactone (PCL) is a biodegradable and bioresorbable polymer with applications ranging from use in packaging to medical sutures. In this study, the use of an atmospheric pressure plasma to deposit plasma polymerised PCL (P‐PCL) coatings from a PCL diol precursor is evaluated. Fourier transform infrared spectroscopy demonstrated the retention of PCL functional groups in the deposited coating. Changes in coating surface energy were monitored with time after deposition using the contact angle technique. The rate of degradation of 500 nm thick P‐PCL coatings was assessed after immersion in a phosphate‐buffered saline (PBS) solution at 37 °C. It was observed that slower rates of P‐PCL coating degradation were obtained for coatings deposited at higher applied powers and lower precursor flow rates.
Or0504–Investigations on the Effect of Dielectric Barrier Discharge (DBD) Treatment as a Preconditioning Method for Low Temperature Silicon Wafer Bonding
Authors: Michel Benedikt , Eichler Marko , Klages Claus‐Peter
Published: July 2009

The individual effects of an atmospheric‐pressure dielectric barrier discharge (DBD) treatment in oxygen on the low temperature bonding behavior of native oxide covered silicon wafers are evaluated. The role of oxide porosity as well as the hindering influence of embedded water molecules are particularly emphasized. The need for maximization of surface silanol density is relativized. Reasons are given, why highly reactive groups and catalytic agents are not expected to have severe influence on the improvement of bond strengthening.
Reactive Plasma Jet High‐Rate Etching of SiC
Authors: Eichentopf Inga‐Maria , Böhm Georg , Meister Johannes , Arnold Thomas
Published: July 2009

The material removal of SiC utilizing a 2.45 GHz microwave‐driven plasma jet source in comparison with a 13.56 MHz RF excited plasma jet source at atmospheric pressure has been investigated. A coaxial nozzle with a central tube for helium, CF4 and O2 feeding the plasma and the outer ring‐shaped nozzle for N2 to shield the plasma jet from the surrounding air is applied. Additionally an O2 gas flow is provided and its effect on the etching rate is discussed for varied [CF4]/[O2] ratios. By optimizing the ratio of CF4 and O2 gas flow an improvement in etching rates and a change in surface roughness have been found. An increase of the etching rate with a decrease of the CF4 ratio has been detected for both jets. The etching rate of the microwave excited jet has been improved additionally by heating the SiC sample up to 350 °C.
Study of Shape and Distribution of TiO2 Nanorods Produced by Atmospheric Pressure Plasma
Authors: Aliofkhazraei Mahmood , Rouhaghdam Alireza Sabour , Ghobadi Ehsan , Mohsenian Ehsan
Published: July 2009

A new method in plasma surface engineering called pulsed plasma electrolytic deposition (PPED) was applied to copper substrates. Corrosion properties of the produced layers were evaluated via potentiodynamic polarization. Results indicated relations among treatment time as well as peak applied voltage, frequency, and duty cycle on average density of TiO2 nanorods significantly. Investigation of the corrosion characteristics showed that the magnitude of corrosion resistance strongly followed from the experimental parameters of applied treatment as well as the average density of TiO2 nanorods. The average density of TiO2 nanorods measurements was done via figure analysis with minimum possible errors.
RF‐Ionised Physical Vapour Deposition for Cu Thin Films: Deposition on Polymer Substrate
Authors: Guesmi Ismael , de Poucques Ludovic , Teule‐Gay Lionel , Bretagne Jean , Boisse‐Laporte Caroline
Published: July 2009

Ionised physical vapour deposition (IPVD), performed with a magnetron and a one‐loop radio frequency (RF) coil, was used to deposit copper thin films on polymer substrates in order to cover complex shapes. This process allows improving the films conformity and their resistivity by ionising the sputtered vapour. The coil coupling was adapted in order to optimise the process. The film resistivity is influenced by the RF power and the pressure. A substrate cleaning phase, required to obtain good film adhesion, was done using the RF coil. The influence of treatment parameters (pressure, RF power, duration) was studied on the adhesion. Optical emission and absorption spectroscopy were performed to identify and quantify neutral and ionic copper species in the plasma and furthermore to study the influence of the coil on the vapour properties.
Docetaxel down‐regulates the expression of androgen receptor and prostate‐specific antigen but not prostate‐specific membrane antigen in prostate cancer cell lines: Implications for PSA surrogacy
Authors: Kuroda Kenji , Liu He , Kim Sae , Guo Ming , Navarro Vincent , Bander Neil H.
Published: July 2009

BACKGROUND

Docetaxel (DOC) has potent anti‐tumor efficacy as a result of promoting microtubule assembly and microtubule bundling thereby impairing mitosis. Knowing that some anti‐microtubule agents affect the polarity of prostate‐specific membrane antigen (PSMA) expression and that androgen ablation can up‐regulate PSMA expression, we sought to determine any effect of DOC on PSMA expression in prostate cancer (PC) cell lines as a prelude to a clinical effort. As controls, we also looked at the expression of androgen receptor (AR) and prostate‐specific antigen (PSA).

METHODS

The effect of DOC on cell viability and PSMA, AR, and PSA expression was examined by flow cytometry and immunoblotting using LNCaP, CWR22Rv1, and MDA‐PCa‐2b cells. The effect of DOC on PSA levels of LNCaP and MDA‐PCa‐2b cells was also measured in conditioned media. The effect of DOC was also studied using LNCaP and MDA‐PCa‐2b cells that were transfected to over‐express AR.

RESULTS

PSMA levels were not affected by DOC treatment. Unexpectedly, we found DOC significantly down‐regulated both AR and PSA in a dose‐dependent manner in the cell lines studied. Over‐expression of AR partially abrogated the cytotoxic effects of DOC.

CONCLUSIONS

While DOC did not affect PSMA expression, it was unexpectedly found to down‐regulate AR and PSA. DOC‐induced down‐regulation of AR might be one of the anti‐tumor mechanisms active in PC. Down‐regulation of PSA may account for the significantly higher PSA response rates (45–50%) relative to measurable response rates (8–17%) reported in DOC PC trials and have implications for PSA surrogacy observations derived from DOC trials. Prostate 69: 1579–1585, 2009. © 2009 Wiley‐Liss, Inc.
Majorana zero modes in graphene with trigonal warping
Authors: Dóra Balázs , Gulácsi Miklós , Sodano Pasquale
Published: July 2009

We study the low energy properties of warped monolayer graphene, where the symmetry of the original honeycomb lattice reveals itself. The zero energy solutions are Majorana fermions, whose wave function, originating from the corresponding modified Dirac equation is spatially localized. Experimental consequences are discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The impact of soil moisture modifications on CBL characteristics in West Africa: A case‐study from the AMMA campaign
Authors: Kohler M. , Kalthoff N. , Kottmeier C.
Published: July 2009

Within the framework of the AMMA campaign in 2006, the response of surface properties to precipitation and their effect on the state of the convective boundary layer (CBL) and on convective instability were analysed. The observation periods covered the pre‐monsoon onset (SOP 1) and the mature monsoon phase (SOP 2) and were performed in southwest Burkina Faso. Precipitation caused a distinctive increase in the volumetric soil moisture content in the upper 20 cm of the soil. Coupled with the increase in soil moisture, a continuous decrease of surface and soil temperature with time was observed. Changes in surface temperature, albedo, and a higher availability of water affected the partitioning of the energy balance. Highest values of the Bowen ratio were found during SOP 1 when the surface was dry and vegetation sparse. In SOP 2, a higher vegetation cover made the albedo and Bowen ratio less sensitive to changes in soil moisture. Modifications of surface fluxes influenced the CBL conditions. The CBL height in SOP 1 was 1658 m and in SOP 2 877 m. The heat budget of the CBL was dominated by sensible heat flux convergence, whereas the moisture budget was controlled by both advection and latent heat flux convergence. It was confirmed by the measurements that the diurnal development of convective instability was dominated by the CBL evolution and controlled by changes in the mid‐ or upper troposphere to a minor degree only. Linear correlations were found between the near‐surface equivalent potential temperature and both convective available potential energy and convection index. Copyright © 2009 Royal Meteorological Society
Suitability of tetrahydofuran as a dopant and the comparison to other existing dopants in dopant‐assisted atmospheric pressure photoionization mass spectrometry in support of drug discovery
Authors: Cai Yanxuan , McConnell Oliver , Bach Alvin C.
Published: July 2009

In this paper, we investigated the suitability of tetrahydofuran (THF) as a dopant and compared it against other common dopants for atmospheric pressure photoionization mass spectrometry (APPI‐MS). In a systematic analysis of 37 drug standards and 100 Wyeth proprietary drug candidates, THF was found to increase ionization efficiency as high as 33‐fold when introduced through a syringe pump at a flow rate of 20 µL/min, and as high as 114‐fold when introduced through the mobile phase at 100 µL/min. As a dopant, THF is as effective as acetone, better than anisole, and slightly less effective than toluene for the majority of the test compounds. The increase in ionization efficiency by THF was found to be compound‐dependent. THF was more effective in facilitating the ionization of polar compounds than of non‐polar compounds. With THF, toluene and acetone as dopants, a single type of molecular ion ([M+H]+ or M+•) is produced for analyte molecules. However, anisole can cause the formation of an ion cluster for polar analytes. The cluster contains [M–2H+H]+, M+•, and [M+H]+ ions with varied ratios. This complexity may make interpretation of spectra difficult for unknown compounds when complimentary data are not available. Our findings indicate that THF is a suitable dopant in the daily usage for increasing ionization efficiency, especially when THF is used as the mobile phase or as an organic modifier in the mobile phase. Copyright © 2009 John Wiley & Sons, Ltd.
A test of comparative equilibration for determining non‐exchangeable stable hydrogen isotope values in complex organic materials
Authors: Kelly Jeffrey F. , Bridge Eli S. , Fudickar Adam M. , Wassenaar Leonard I.
Published: July 2009

Comparative equilibration has been proposed as a methodological approach for determining the hydrogen isotopic composition (δD) of non‐exchangeable hydrogen in complex organic materials, from feathers to blood and soils. This method depends on using homogenized standards that have been previously calibrated for their δD values of non‐exchangeable H, that are compositionally similar to unknown samples, and that span an appropriate isotopic range. Currently no certified organic reference materials with exchangeable H exist, and so isotope laboratories have been required to develop provisional internal calibration standards, such as the keratin standards currently used in animal migration studies. Unfortunately, the isotope ratios of some samples fall outside the range of keratin standards currently used for comparative equilibration. Here we tested a set of five homogenized keratin powders as well as feathers from Painted Buntings and Dark‐eyed Juncos to determine the effects of extrapolating comparative equilibration normalization equations outside the isotopic range of keratin standards. We found that (1) comparative equilibration gave precise results within the range of the calibration standards; (2) linear extrapolation of normalization equations produced accurate δD results to ∼40‰ outside the range of the keratins standards used (−187 to −108); and (3) for both homogenized keratin powders and heterogeneous unknown samples there was no difference in variance between samples within and outside the range of keratin standards. This suggested that comparative equilibration is a robust and practical method for determining the δD of complex organic matrices, although caution is required for samples that fall far outside the calibration range. Copyright © 2009 John Wiley & Sons, Ltd.
Energy‐resolved depth profiling of metal‐polymer interfaces using dynamic quadrupole secondary ion mass spectrometry
Authors: Téllez Helena , Vadillo José M. , Laserna J. Javier
Published: July 2009

Quadrupole secondary ion mass spectrometry (qSIMS) characterization of a metallized polypropylene film used in the manufacturing of capacitors has been performed. Ar+ primary ions were used to preserve the oxidation state of the surface. The sample exhibits an incomplete metallization that made it difficult to determine the exact location of the metal‐polymer interface due to the simultaneous contribution of ions with identical m/z values from the metallic and the polymer layers. Energy filtering by means of a 45° electrostatic analyzer allowed resolution of the metal‐polymer interface by selecting a suitable kinetic energy corresponding to the ions generated in the metallized layer but not from the polymer. Under these conditions, selective analyses of isobaric interferences such as 27Al+ and 27C2H or 43AlO+ and 43C3H have been successfully performed. Copyright © 2009 John Wiley & Sons, Ltd.
Searching forin silicopredicted metabolites and designer modifications of (cortico)steroids in urine by high‐resolution liquid chromatography/time‐of‐flight mass spectrometry
Authors: Peters Ruud J. B. , van Engelen Marcel C. , Touber Manja E. , Georgakopoulus Costas , Nielen Michel W. F.
Published: July 2009

Glucocorticosteroids are a restricted class of substances and appear on the ‘in‐competition’ prohibited list of the World Anti‐Doping Agency (WADA). Analysis of glucocorticosteroids is complicated since they show significant phase 1 and 2 metabolism in the human body and are excreted into urine in concentrations in the µg/L range. Full scan, high‐resolution time‐of‐flight mass spectrometry analysis generates information on all ionisable components in urine, including known and unknown metabolites of steroids and even designer modifications of anabolic steroids. However, evaluation of the data obtained can be difficult and time‐consuming because of the need to differentiate between endogenous components and compounds of interest. MetaboLynx™, a spectral and chromatographic search program, was modified for the determination ofin silicopredicted metabolites of glucocorticosteroids and designer modifications of anabolic steroids in human urine. Spiked urine samples were successfully screened for known components in a targeted approach and for unknown species in a non‐targeted approach using data filtering to limit potential false‐positives. A simplified combined approach of targeted and untargeted screening was used for the detection of metabolites and designer modifications of existing compounds. This approach proved successful and showed its strength in the detection of tetrahydrogestrinone (THG), a designer modification of gestrinone. THG was positively detected in a spiked urine sample and correctly identified as a twofold hydrogenation of gestrinone. The developed screening method can easily be adapted to specific needs and it is envisaged that a similar approach would be amendable to the discovery of metabolites or designer modifications of other compounds of interest. Copyright © 2009 John Wiley & Sons, Ltd.
Muscle and scale isotopic offset of three fish species in the Mediterranean Sea: Dentex dentex, Argyrosomus regius and Xyrichtys novacula
Authors: Blanco A. , Deudero S. , Box A.
Published: July 2009

Diet information of organisms was traditionally acquired by the use of lethal techniques (gut content or muscle δ13C and δ15N isotopic ratios). An increase in the number of isotopic ratio studies and the vulnerability of some species have led to increased use of non‐lethal methodologies for conservation purposes. In the present work we have compared the δ13C and δ15N isotopic signals of muscle and scales of three different fish species in order to test fish‐scale sampling as a non‐lethal technique in fish trophodynamics. A positive correlation was found between muscle and scales in Argyrosomus regius and Xyrichtys novacula, while Dentex dentex showed no correlation due to the small length range of this species. The isotopic offset (Δ13C and Δ15N) between muscle and scales was significantly different among species (analysis of variance (ANOVA), p < 0.001) with Tukey's post‐hoc HSD indicating a tissue offset difference (p < 0.001) for both stable isotopes in all species, except for Δ13C between A. regius and X. novacula and for Δ15N between D. dentex and X. novacula (p > 0.05). Mean δ13C and δ15N values between species showed significant differences (paired t‐test, p < 0.01) between muscle and scale with an enrichment for δ13C and a depletion for δ15N. Spatial differences were found in the Δ13C of X. novacula between the studied locations, while no differences were found for Δ15N, indicating that non‐geographical differences should be considered in the application of scales instead of muscle for 15N, while for 13C differences in the geographical isotopic offset should be considered. Copyright © 2009 John Wiley & Sons, Ltd.
Electrospray ionisation with selected reaction monitoring for the determination of Mn‐citrate, Fe‐citrate, Cu‐citrate and Zn‐citrate
Authors: Nischwitz Volker , Michalke Bernhard
Published: July 2009

Citrate complexes of Mn and Fe, and potentially those of Cu and Zn, are considered as important low molecular mass species in human serum and cerebrospinal fluid (CSF). For example, Mn is supposed to enter the brain under excess exposure as Mn‐citrate leading to neurotoxic effects. Mn‐citrate has been characterised in human CSF using chromatography and electrophoresis online with inductively coupled plasma mass spectrometry, but not yet with molecular mass spectrometry. Therefore, this study explores the potential of electrospray ionisation (ESI) with selected reaction monitoring (SRM) for the detection of metal‐citrate complexes, in particular Mn‐citrate. The collision‐induced dissociation of precursor ions with various metal:citrate stoichiometries was studied for Mn‐citrate, Fe‐citrate, Cu‐citrate and Zn‐citrate. High selectivity was achieved for Mn(II)‐citrate even in respect to Fe(III)‐citrate which forms isobaric precursor ions. The limit of detection for Mn‐citrate was estimated to be around 250 µg L−1 (referring to the total Mn content in the standard) using flow injection. The sensitivity was sufficient for the determination of Mn‐citrate in standard solutions and in an extract of an Mn‐citrate‐containing supplement. An improved ESI source design is expected to reduce the limits of detection significantly. The developed ESI‐SRM method has the potential to provide complementary data for the quality control of current separation methods for metal citrates using element‐selective detection, with application to biomedical samples and further matrices. Copyright © 2009 John Wiley & Sons, Ltd.
Analysing the isotopic life history of the alpine ungulates Capra ibex and Rupicapra rupicapra rupicapra through their horns
Authors: Barbosa Inês C. R. , Kley Maximiliane , Schäufele Rudi , Auerswald Karl , Schröder Wolf , Filli Flurin , Hertwig Stefan , Schnyder Hans
Published: July 2009

The horn of ungulate grazers offers a valuable isotopic record of their diet and environment. However, there have been no reports of the spatio‐temporal variation of the isotopic composition of horns. We investigated patterns of carbon (δ13C) and nitrogen (δ15N) isotopic composition along and perpendicular to the horn axis in Capra ibex and Rupicapra rupicapra rupicapra to assess the effects of animal age, within‐year (seasonal) and inter‐annual variation, natural contamination and sampling position on horn isotope composition. Horns of male C. ibex (n = 23) and R. r. rupicapra (n = 1) were sampled longitudinally on the front (only R. r. rupicapra) and back side and on the surface and sub‐surface. The sides of the R. r. rupicapra horn did not differ in δ13C. In both species, the horn surface had a 0.15‰ lower δ13C and a higher carbon‐to‐nitrogen (C/N) ratio than the sub‐surface. Washing the horn with water and organic solvents removed material that caused these differences. With age, the δ15N of C. ibex horns increased (+0.1‰ year−1), C/N ratio increased, and 13C discrimination relative to atmospheric CO2 (13Δ) increased slightly (+0.03‰ year−1). Geostatistical analysis of one C. ibex horn revealed systematic patterns of inter‐annual and seasonal 13C changes, but 15N changed only seasonally. The work demonstrates that isotopic signals in horns are influenced by natural contamination (δ13C), age effects (13Δ and δ15N), and seasonal (δ13C and δ15N) and inter‐annual variation (δ13C). The methods presented allow us to distinguish between these effects and thus allow the use of horns as isotopic archives of the ecology of these species and their habitat. Copyright © 2009 John Wiley & Sons, Ltd.
Comparison of inert supports in laser desorption/ionization mass spectrometry of peptides: pencil lead, porous silica gel, DIOS‐chip and NALDI™ target
Authors: Shenar Nawar , Cantel Sonia , Martinez Jean , Enjalbal Christine
Published: July 2009

In the search for alternative inert surfaces replacing silicon chips in Desorption/Ionization On porous Silicon (DIOS)‐like mass spectrometry analyses, nanostructured silicon‐based NALDI™ chips were evaluated in Laser Desorption/Ionization (LDI) of peptides. Comparisons were made using commercially available DIOS chips (MassPREP™‐DIOS‐target™), amorphous carbon powder from lead pencil and porous silica gel used for chromatographic purposes as reference supports. A set of synthetic model peptides presenting variable amino acid sequences of various lengths was analyzed under all conditions. The LDI responses of the four ‘matrix‐free’ techniques were compared, especially in terms of peptide detection sensitivity and overall experiment robustness. Copyright © 2009 John Wiley & Sons, Ltd.
In with the old, in with the new: capabilities, strategies, and performance among the Hollywood studios
Authors: Shamsie Jamal , Martin Xavier , Miller Danny
Published: July 2009

An increased focus on turbulent environments has led to a growing interest among researchers in the concept of dynamic capabilities. In this study, we approach dynamic capabilities in a framework of two complementary processes. On one hand, firms can build upon existing capabilities in products and markets in which they have experienced recent success; on the other hand, they can also intentionally focus on other products and markets in which they seek to build capabilities to address their lack of recent success. We examine these two processes within project‐based industries and identify replication and renewal as two types of strategies that firms use to add a dynamic component to their capabilities. We also theorize that the success of each of these strategies is tied to differentiation from rivals, and to firm‐level resource availability and industry‐level demand characteristics. We test these propositions by focusing on the film genres that were offered by the Hollywood studios over a thirty‐year period. Copyright © 2009 John Wiley & Sons, Ltd.
Reputations for toughness in patent enforcement: implications for knowledge spillovers via inventor mobility
Authors: Agarwal Rajshree , Ganco Martin , Ziedonis Rosemarie H.
Published: July 2009

‘Job hopping’ by engineers and scientists is widely heralded as an important channel for knowledge spillovers within industries. Far less is known, however, about the actions firms take to reduce the outward flow of knowledge through markets for skilled labor. This study investigates the efficacy of a lever that has received little research attention: corporate reputations for toughness in patent enforcement. Drawing on unique data on enforcement activity, intra‐industry inventor mobility, and patent citations in the U.S. semiconductor industry, we find that a firm's litigiousness significantly reduces spillovers otherwise anticipated from departures of employee inventors, particularly when the hiring organizations are entrepreneurial ventures. Surprisingly, the deterrent effects of patent enforcement are similar in magnitude for firms located in California, a state characterized by open norms for knowledge trading, and firms headquartered in other U.S. states. The study sheds new light on the strategic actions firms use to prevent rivals from capturing value from their investments in human capital and research and development. Copyright © 2009 John Wiley & Sons, Ltd.
Supporting valid interpretations of learning progression level diagnoses
Authors: Steedle Jeffrey T. , Shavelson Richard J.
Published: July 2009

Assessments associated with learning progressions are designed to provide diagnostic information about the level and nature of student understanding. Valid interpretations of such diagnoses are only possible when students consistently express the ideas associated with a single learning progression level. Latent class analysis was employed to evaluate whether patterns of expected responses to diagnostic multiple‐choice items afforded valid interpretations of learning progression level diagnoses. Results indicated that students with scientifically accurate understanding of the forces acting on an object with constant speed usually reasoned systematically across items, but many other students did not. Consequently, interpretations of learning progression level diagnoses on a proposed learning progression would often be invalid. Analyses of this sort would be useful in developing and validating future learning progressions. © 2009 Wiley Periodicals, Inc. J Res Sci Teach 46: 699–715, 2009
Experimental mathematics and computational statistics
Authors: Bailey David H. , Borwein Jonathan M.
Published: July 2009

The field of statistics has long been noted for techniques to detect patterns and regularities in numerical data. In this article, we explore connections between statistics and the emerging field of ‘experimental mathematics’. These include both applications of experimental mathematics in statistics as well as statistical methods applied to computational mathematics. Copyright © 2009 John Wiley & Sons, Inc.

This article is categorized under:

Applications of Computational Statistics > Computational Mathematics
Statistical and Applied Mathematical Sciences Institute
Authors: Berger James
Published: July 2009

The Statistical and Applied Mathematical Sciences Institute (SAMSI) is a national institute in the USA devoted to forging a synthesis of the statistical sciences and the applied mathematical sciences with disciplinary science to confront the very hardest and most important data and model‐driven scientific challenges. The vision of SAMSI is described herein, as well as the research programs that have been undertaken at SAMSI. Opportunities for becoming involved with SAMSI are also highlighted. Such opportunities exist for senior researchers, new researchers, postdoctoral fellows, graduate students, undergraduate students, and K‐12 teachers. Copyright © 2009 John Wiley & Sons, Inc.

This article is categorized under:

Applications of Computational Statistics > Organizations and Publications
Ridge regression
Authors: McDonald Gary C.
Published: July 2009

Ridge regression is a popular parameter estimation method used to address the collinearity problem frequently arising in multiple linear regression. The formulation of the ridge methodology is reviewed and properties of the ridge estimates capsulated. In particular, four rationales leading to a regression estimator of the ridge form are summarized. Algebraic properties of the ridge regression coefficients are given, which elucidate the behavior of a ridge trace for small values of the ridge parameter (i.e., close to the least squares solution) and for large values of the ridge parameter. Further properties involving coefficient sign changes and rates‐of‐change, as functions of the ridge parameter, are given for specific correlation structures among the independent variables. These results help relate the visual behavior of a ridge trace to the underlying structure of the data. Copyright © 2009 John Wiley & Sons, Inc.

This article is categorized under:

Statistical Models > Linear Models

Algorithms and Computational Methods > Least Squares
Algorithms for response adaptive sampling designs
Authors: Hardwick Janis , Stout Quentin F.
Published: July 2009

An experimental design is a formula or algorithm that specifies how resources are to be utilized throughout a study. The design is considered to be good or even optimal if it allows for sufficiently precise and accurate data analysis with the least output of resources such as time, money and experimental units. Most experimental designs use fixed sampling procedures in which the sample sizes and order of allocations to different study groups are known in advance. Copyright © 2009 John Wiley & Sons, Inc.

This article is categorized under:

Statistical and Graphical Methods of Data Analysis > Sampling