bluuebunny/crossref_metadata_2025 huggingface dataset:
The Impact of Institutional Grant Aid on College Choice
Authors: Hurwitz Michael
Published: May 2012

In this study, I exploit exogenous differences in institutional policies regarding the treatment of home equity in grant aid allocation to estimate a causal impact of institutional grant aid on college choice. Because institutional grant aid is typically not awarded randomly, the college-estimated home equity value serves as an instrumental variable from which the causal relationship between institutional grant aid and college choice is identified. An additional $1,000 in institutional grant aid awarded by the typical sampled college increases the probability that the typical accepted student will choose that college by 1.66 percentage points. I also find that choice elasticity varies by student socioeconomic status, with the lowest income students nearly three times more sensitive to institutional grant aid than high-income students.
Improving Mantel–Haenszel DIF Estimation Through Bayesian Updating
Authors: Zwick Rebecca , Ye Lei , Isham Steven
Published: May 2012

This study demonstrates how the stability of Mantel–Haenszel (MH) DIF (differential item functioning) methods can be improved by integrating information across multiple test administrations using Bayesian updating (BU). The authors conducted a simulation that showed that this approach, which is based on earlier work by Zwick, Thayer, and Lewis, can yield more accurate DIF estimation and improve the detection of DIF items, even when compared to other approaches that aggregate data across administrations. The authors also applied the method to data from several college-level tests. The BU approach provides a natural way to accumulate all known DIF information about each test item while mitigating the undesirable bias toward zero that affected the performance of two previous Bayesian DIF methods.
Brain surgery in patients with liver cirrhosis
Authors: Chen Ching-Chang , Hsu Peng-Wei , Lee Shih-Tseng , Chang Chen-Nen , Wei Kuo-Chen , Wu Chieh-Tsai , Hsu Yung-Hsin , Lin Tzu-Kang , Lee Sai-Cheung , Huang Yin-Cheng
Published: May 2012

Object

Liver cirrhosis was identified as an independent predictor of poor outcomes in patients suffering trauma and in those undergoing major surgeries. The aim of this study was to report the authors' experiences treating patients with cirrhosis who undergo brain surgeries.

Methods

Between 2004 and 2009, 121 consecutive patients with cirrhosis underwent 144 brain procedures. Patients were categorized as Child-Turcotte-Pugh (referred to as “Child”) Class A, B, or C. The patient profiles, including the severity of cirrhosis, reason for surgery, complications, and prognosis factors, were analyzed.

Results

In this retrospective study, the overall surgical complication rate for patients with cirrhosis was 52.1% and the mortality rate was 24.3%. For patients with acute traumatic brain injury (TBI), the complication, rebleeding, and mortality rates reached 84.4%, 68.8%, and 37.5%, respectively. Surgery for TBI was a significant risk factor for postoperative complications (p = 0.0002) and postoperative hemorrhage (p < 0.0001). Otherwise, according to the Child classification, the complication rate increased in a stepwise fashion from 38.7% to 60% to 84.2%, the rebleeding rate from 29.3% to 48.0% to 63.2%, and the mortality rate from 5.3% to 38% to 63.2% for Child A, B, and C, respectively. The Child classification was associated with higher risk of complications—Child B vs A OR 2.84 (95% CI 1.28–6.29), Child C vs A OR 5.39 (95% CI 1.32–22.02). It was also associated with risk of death—Child C vs A OR 30.43 (95% CI 7.71–120.02), Child B vs A OR 10.88 (95% CI 3.42–34.63).

Conclusions

Liver cirrhosis is a poor comorbidity factor for brain surgery. The authors' results suggest that the Child classification used independently is a poor prognostic factor; in addition, grave outcomes were observed in patients with TBI.
Multivariate analysis of C-5 palsy incidence after cervical posterior fusion with instrumentation
Authors: Nakashima Hiroaki , Imagama Shiro , Yukawa Yasutsugu , Kanemura Tokumi , Kamiya Mitsuhiro , Yanase Makoto , Ito Keigo , Machino Masaaki , Yoshida Go , Ishikawa Yoshimoto , Matsuyama Yukihiro , Hamajima Nobuyuki , Ishiguro Naoki , Kato Fumihiko
Published: May 2012

Object

Postoperative C-5 palsy is a significant complication resulting from cervical decompression procedures. Moreover, when cervical degenerative diseases are treated with a combination of decompression and posterior instrumented fusion, patients are at increased risk for C-5 palsy. However, the clinical and radiological features of this condition remain unclear. Therefore, the purpose of this study was to clarify the risk factors for developing postoperative C-5 palsy.

Methods

Eighty-four patients (mean age 60.1 years) who had undergone posterior instrumented fusion using cervical pedicle screws to treat nontraumatic lesions were independently reviewed. The authors analyzed the medical records of some of these patients who developed postoperative C-5 palsy, paying particular attention to their plain radiographs, MRI studies, and CT scans. Risk factors for postoperative C-5 palsy were assessed using multivariate logistic regression analysis. The cutoff values for the pre- and postoperative width of the intervertebral foramen (C4–5) were determined by receiver operating characteristic curve analysis.

Results

Ten (11.9%) of 84 patients developed postoperative C-5 palsy. Seven patients recovered fully from the neurological complications. The pre- and postoperative C4–5 angles showed significant kyphosis in the C-5 palsy group. The pre- and postoperative diameters of the C4–5 foramen on the palsy side were significantly smaller than those on the opposite side in the C-5 palsy group and those bilaterally in the non–C5 palsy group. Risk factors identified by multivariate logistic regression analysis were as follows: 1) ossification of the posterior longitudinal ligament (relative risk [RR] 7.22 [95% CI 1.03–50.55]); 2) posterior shift of the spinal cord (C4–5) (RR 1.73 [95% CI 1.00–2.98]); and 3) postoperative width of the C-5 intervertebral foramen (RR 0.33 [95% CI 0.14–0.79]). The cutoff values of the pre- and postoperative widths of the C-5 intervertebral foramen for C-5 palsy were 2.2 and 2.3 mm, respectively.

Conclusions

Patients with preoperative foraminal stenosis, posterior shift of the spinal cord, and additional iatrogenic foraminal stenosis due to cervical alignment correction were more likely to develop postoperative C-5 palsy after posterior instrumentation with fusion. Prophylactic foraminotomy at C4–5 might be useful when preoperative foraminal stenosis is present on CT. Furthermore, it might be useful for treating postoperative C-5 palsy. To prevent excessive posterior shift of the spinal cord, the authors recommend that appropriate kyphosis reduction should be considered carefully.
Potential advantage of student-run clinics for diversifying a medical school class
Authors: Gu Chris N. , McElroy Jane A. , Corcoran Blake C.
Published: May 2012

The purpose of this study was to evaluate the influence of a student-run clinic on the diversification of a medical student class. We distributed a two-page, 20-item, paper survey to students of the University of Missouri School of Medicine (MU SOM) class of 2015 in July of 2011. The survey gathered information on general demographics, opinions on the importance of medical education opportunities, and opinions on the importance of medical school characteristics in applying to and attending MU SOM. A total of 104 students responded to the survey. A majority of the students identified the MedZou Community Health Clinic, a student-run, free health clinic affiliated with MU SOM, and simulated-patient encounters as important educational experiences (81% and 94%, respectively). More than half of the self-identified non-white??students reported MedZou as an important factor in their choice to apply to (60%; 95% confidence interval [CI], 32 to 88) and attend (71%; 95% CI, 44 to 98) MU SOM, over half of the females reported MedZou as important in their choice to apply (59%; 95% CI, 43 to 76) and attend (57%; 95% CI, 40 to 74), and over half of non-Missouri residents reported MedZou as important in their choice to apply (64%; 95% CI, 36 to 93) and attend (71%; 95% CI, 44 to 98). According to the above results, it can be said that students clearly value both MedZou and simulated-patient encounters as important educational experiences. Women, minorities, and non-Missouri residents value MedZou more highly than their peers who are First Year Medical Students who are Missouri residents, suggesting that MedZou may provide a promising opportunity to advance diversity within MU SOM. These results highlight the need for additional research to further explore MedZou?占퐏 potential to enhance the recruitment of a diverse medical student class.
Early Silurian (Aeronian) East Point Coral Patch Reefs of Anticosti Island, Eastern Canada: First Reef Recovery from the Ordovician/Silurian Mass Extinction in Eastern Laurentia
Authors: Copper Paul , Jin Jisuo
Published: May 2012

An extensive late Aeronian patch reef swarm outcrops for 60–70 km on Anticosti Island, eastern Canada, located in the inner to mid-shelf area of a prominent tropical carbonate platform of southeastern Laurentia, at 20°–25° S paleolatitude of the southern typhoon belt. This complex, described here for the first time, includes more than 100 patch reefs, up to 60–80 m in diameter and 10 m high. Reefs are exposed three-dimensionally on present-day tidal flats, as well as inland along roads and rivers. Down the gentle 1°–2° paleoslope, the reefs grade into coral-sponge biostromes, and westerly they grade into inter-reef or deeper ‘crinoidal meadow’ facies. The reef builders were dominantly tabulate and rugose corals, with lesser stromatoporoids. Other components include crinoids, brachiopods, green algae (especially paleoporellids), and encrusting cyanobacteria: reefs display some of the earliest known symbiotic intergrowths of corals and stromatoporoids. Reefs were variably built on a base of crinoidal grainstones, meadows of baffling tabulate corals, brachiopod shells, or chlorophytes. These reefs mark an early phase of reef recovery after a prominent reef gap of 5–6 million years following the Ordovician/Silurian mass extinction events. The reefs feature a maximal diversity of calcifying cyanobacteria, corals and stromatoporoids, but low diversity of brachiopods, nautiloids and crinoids. Following the North American Stratigraphic Code, we define herein the Menier Formation, encompassing the lower two members of the existing Jupiter Formation.
Road Dust Lead (Pb) in Two Neighborhoods of Urban Atlanta, (GA, USA)
Authors: Deocampo Daniel M. , Reed Phillip Jack , Kalenuik Alexander P.
Published: May 2012

Road dust continues to be a major potential reservoir of Pb in the urban environment, and an important potential component of child Pb exposure. This study presents ICP-AES analyses of metals in 72 samples of road dust ( < 250 µm) collected in the urban core of Atlanta, Georgia. In the Downtown area, median Pb concentrations are ~63 mg/kg Pb, with high values of 278 mg/kg. For comparison, median Pb values in a nearby residential neighborhood (also in the urban core) were ~93 mg/kg, with a high of 972 mg/kg. Geospatial variability is high, with significant variation observed over tens to hundreds of meters. Spearman Rank Correlation tests suggest that Pb and other metals (Cu, Ni, V, Zn) are associated with iron and manganese oxide phases in the residential area, as reported in other cities. However, Pb in the Downtown area is not correlated with the others, suggesting a difference in source or transport history. Given these complexities and the expected differences between road dust and soil Pb, future efforts to assess exposure risk should therefore be based on spatially distributed sampling at very high spatial resolution.
Phytochemical and Biological Studies of Agave attenuata
Authors: Rizwan Komal , Zubair Muhammad , Rasool Nasir , Riaz Muhammad , Zia-Ul-Haq Muhammad , De Feo Vincenzo
Published: May 2012

The present study was conducted to examine various biological activities of a methanol extract of Agave attenuata leaves. GC-MS analysis of the n-hexane fraction from the extract revealed the presence of 31 compounds, with mono-2-ethylhexyl phthalate (11.37%), 1,2-benzenedicarboxylic acid (6.33%), n-docosane (6.30%) and eicosane (6.02%) as the major components. The leaves contained appreciable levels of total phenolic contents (10.541–39.35 GAE, mg/100 g) and total flavonoid contents (43.35–304.8 CE, mg/100 g). The extract and some of its fractions showed moderate antimicrobial effects. Leaves extract and fractions also exhibited a good antioxidant potential when measured by DPPH radical scavenging activity and inhibition of lipid peroxidation assays. The hemolytic effect of the plant was found to be in a range of 1.01%–2.64%. From the present study it is concluded that this plant could be used as a source of natural antioxidants and functional food nutraceutical applications.
The Quiescent Cellular State is Arf/p53-Dependent and Associated with H2AX Downregulation and Genome Stability
Authors: Yoshioka Ken-ichi , Atsumi Yuko , Fukuda Hirokazu , Masutani Mitsuko , Teraoka Hirobumi
Published: May 2012

Cancer is a disease associated with genomic instability and mutations. Excluding some tumors with specific chromosomal translocations, most cancers that develop at an advanced age are characterized by either chromosomal or microsatellite instability. However, it is still unclear how genomic instability and mutations are generated during the process of cellular transformation and how the development of genomic instability contributes to cellular transformation. Recent studies of cellular regulation and tetraploidy development have provided insights into the factors triggering cellular transformation and the regulatory mechanisms that protect chromosomes from genomic instability.
Growth Promotion of Yunnan Pine Early Seedlings in Response to Foliar Application of IAA and IBA
Authors: Xu Yulan , Zhang Yuemin , Li Yunfei , Li Genqian , Liu Daiyi , Zhao Minchong , Cai Nianhui
Published: May 2012

A field experiment was conducted using a 3 × 3 orthogonal regression design to explore the growth promotion of one-year-old Yunnan pine seedlings (Pinus yunnanensis Franch.) in response to foliar application of IAA (indole-3-acetic acid) at rates of 0, 200 and 400 mg·L−1 and IBA (indole-3-butyric acid) at rates of 0, 200 and 400 mg·L−1 in order to promote the growth during the seedlings’ early stage. The experiment was conducted at the Lufeng Village Forest Farm of Yiliang County in Kunming, Yunnan, China. The results showed that IAA and IBA were effective in growth promotion of Yunnan pine seedlings. The response of both growth increment and biomass accumulation to the concentration of IAA and IBA can be modeled using a bivariate surface response, and each growth index had a peak value. Growth indexes increased with the increase of the dosage of photohormones before reaching a peak value, and then decreased. The different growth indexes had various responses to the concentrations and ratio of IAA and IBA. The foliar application of IAA in combination with IBA showed the largest improvement on the biomass of the needles, followed by stems and roots. The higher ratio of IAA promoted stem diameter growth, root system development and biomass accumulation in the needles, while a higher ratio of IBA contributed to height growth and biomass accumulation in the stem. Based on the auxin effect equations on the different growth indexes and surface response, the optimum concentrations and the (IAA:IBA) ratios can be obtained. The optimum concentrations of IAA and IBA were 167 and 186, 310 and 217, 193 and 159, 191 and 221, and 206 and 186 mg·L−1, with corresponding ratios of 1:1.11, 1:0.70, 1:0.82, 1:1.15 and 1:0.90, respectively, at the maximum seedling height and collar diameter growth as well as biomass accumulation at the root, stem and needle. The above growth indexes were 22.00%, 79.80%, 48.65%, 82.20% and 107.00% higher than the control treatment.
In-Line Phase-Contrast X-ray Imaging and Tomography for Materials Science
Authors: Mayo Sheridan C. , Stevenson Andrew W. , Wilkins Stephen W.
Published: May 2012

X-ray phase-contrast imaging and tomography make use of the refraction of X-rays by the sample in image formation. This provides considerable additional information in the image compared to conventional X-ray imaging methods, which rely solely on X-ray absorption by the sample. Phase-contrast imaging highlights edges and internal boundaries of a sample and is thus complementary to absorption contrast, which is more sensitive to the bulk of the sample. Phase-contrast can also be used to image low-density materials, which do not absorb X-rays sufficiently to form a conventional X-ray image. In the context of materials science, X-ray phase-contrast imaging and tomography have particular value in the 2D and 3D characterization of low-density materials, the detection of cracks and voids and the analysis of composites and multiphase materials where the different components have similar X-ray attenuation coefficients. Here we review the use of phase-contrast imaging and tomography for a wide variety of materials science characterization problems using both synchrotron and laboratory sources and further demonstrate the particular benefits of phase contrast in the laboratory setting with a series of case studies.
Diversity of Nonribosomal Peptide Synthetase Genes in the Microbial Metagenomes of Marine Sponges
Authors: Pimentel-Elardo Sheila Marie , Grozdanov Lubomir , Proksch Sebastian , Hentschel Ute
Published: May 2012

Genomic mining revealed one major nonribosomal peptide synthetase (NRPS) phylogenetic cluster in 12 marine sponge species, one ascidian, an actinobacterial isolate and seawater. Phylogenetic analysis predicts its taxonomic affiliation to the actinomycetes and hydroxy-phenyl-glycine as a likely substrate. Additionally, a phylogenetically distinct NRPS gene cluster was discovered in the microbial metagenome of the sponge Aplysina aerophoba, which shows highest similarities to NRPS genes that were previously assigned, by ways of single cell genomics, to a Chloroflexi sponge symbiont. Genomic mining studies such as the one presented here for NRPS genes, contribute to on-going efforts to characterize the genomic potential of sponge-associated microbiota for secondary metabolite biosynthesis.
Synthesis of Chalcones with Anticancer Activities
Authors: Syam Suvitha , Abdelwahab Siddig Ibrahim , Al-Mamary Mohammed Ali , Mohan Syam
Published: May 2012

Several chalcones were synthesized and their in vitro cytotoxicity against various human cell lines, including human breast adenocarcinoma cell line MCF-7, human lung adenocarcinoma cell line A549, human prostate cancer cell line PC3, human adenocarcinoma cell line HT-29 (colorectal cancer) and human normal liver cell line WRL-68 was evaluated. Most of the compounds being active cytotoxic agents, four of them with minimal IC50 values were chosen and studied in detail with MCF-7 cells. The compounds 1, 5, 23, and 25 were capable in eliciting apoptosis in MCF-7 cells as shown by multiparameter cytotoxicity assay and caspase-3/7, -8, and -9 activities (p < 0.05). The ROS level showed 1.3-fold increase (p < 0.05) at the low concentrations used and thus it was concluded that the compounds increased the ROS level eventually leading to apoptosis in MCF-7 cells through intrinsic as well as extrinsic pathways.
Scutellaria baicalensis Alleviates Cantharidin-Induced Rat Hemorrhagic Cystitis through Inhibition of Cyclooxygenase-2 Overexpression
Authors: Huan Steven Kuan-Hua , Wang Kun-Teng , Yeh Shauh-Der , Lee Chia-Jung , Lin Li-Chun , Liu Der-Zen , Wang Ching-Chiung
Published: May 2012

Cantharidin, an active component in mylabris, is used in traditional Chinese medicine (TCM) to treat scabies and hepatoma, but accompanied by hemorrhagic cystitis. Evidence shows that cantharidin induces human bladder carcinoma cell death through COX-2 overexpression in vitro. In TCM, Scutellaria baicalensis is usually used to cure mylabris-induced hematuria. This work was undertaken to determine the mechanisms of cantharidin-induced rat hemorrhagic cystitis and explore the uroprotective effect of S. baicalensis. In vitro results showed cantharidin could induce cytotoxicity through prostaglandin (PG)E2 overproduction of T24 cells. Boiling-water extract of S. baicalensis (SB-WE) could significantly inhibit PGE2 production and COX-2 expression in lipo-polysaccharide-induced RAW 264.7 cells, indicating obvious anti-inflammatory abilities. In vivo results indicated that cantharidin caused rat hemorrhagic cystitis with hematuria via c-Fos and COX-2 overexpression. SB-WE was given orally to cantharidin-treated rats, whereby hematuria level, elevated PGE2 and COX-2 protein overexpression were significantly and dose-dependently inhibited by SB-WE. The anti-inflammatory components of SB-WE are baicalin and wogonin, whose contents were 200.95 ± 2.00 and 31.93 ± 0.26 μg/mg, respectively. In conclusion, cantharidin induces rat cystitis through c-Fos and COX-2 over-expression and S. baicalensis can prevent the resulting hematuria because of its anti-inflammatory effects.
Chemistry of Fullerene Epoxides: Synthesis, Structure, and Nucleophilic Substitution-Addition Reactivity
Authors: Tajima Yusuke , Takeshi Kazumasa , Shigemitsu Yasuo , Numata Youhei
Published: May 2012

Fullerene epoxides, C60On, having epoxide groups directly attached to the fullerene cage, constitute an interesting class of fullerene derivatives. In particular, the chemical transformations of fullerene epoxides are expected to play an important role in the development of functionalized fullerenes. This is because such transformations can readily afford a variety of mono- or polyfunctionalized fullerene derivatives while conserving the epoxy ring arrangement on the fullerene surface, as seen in representative regioisomeric fullerene polyepoxides. The first part of this review addresses the synthesis and structural characterization of fullerene epoxides. The formation of fullerene epoxides through different oxidation reactions is then explored. Adequate characterization of the isolated fullerene epoxides was achieved by concerted use of NMR and LC-MS techniques. The second part of this review addresses the substitution of fullerene epoxides in the presence of a Lewis acid catalyst. Most major substitution products have been isolated as pure compounds and their structures established through spectroscopic methods. The correlation between the structure of the substitution product and the oxygenation pattern of the starting materials allows elucidation of the mechanistic features of this transformation. This approach promises to lead to rigorous regioselective production of various fullerene derivatives for a wide range of applications.
Vitamin D and Musculoskeletal Status in Nova Scotian Women Who Wear Concealing Clothing
Authors: Ojah Rani C. I. , Welch Jo M.
Published: May 2012

Bone and muscle weakness due to vitamin D deficiency is common among Muslim women who reside in sunny, equatorial countries. The purpose of this study was to determine if living in a northern maritime location additionally disadvantages women who wear concealing clothes. A cross-sectional matched pair design was used to compare women who habitually wore concealing clothing with women who dressed according to western norms. Each premenopausal hijab-wearing woman (n = 11) was matched by age, height, weight and skin tone with a western-dressed woman. Subjects were tested by hand grip dynamometry to assess muscular strength and by quantitative ultrasound at the calcaneus to assess bone status. Nutritional intake was obtained by 24 h recall. Serum 25-hydroxyvitamin D (s-25(OH)D) status was determined in seven matched pairs. The hijab group had lower s-25(OH)D than women who wore western clothes (40 ± 28 vs. 81 ± 32 nmol/L, p = 0.01). Grip strength in the right hand was lower in the hijab-wearing women (p = 0.05) but this appeared to be due to less participation in intense exercise. Bone status did not differ between groups (p = 0.9). Dietary intake of vitamin D was lower in the hijab-wearers (316 ± 353 vs. 601 ± 341 IU/day, p = 0.001). This pilot study suggests that women living in a northern maritime location appear to be at risk for vitamin D insufficiency and therefore should consider taking vitamin D supplements.
Enhancing Positioning Accuracy in Urban Terrain by Fusing Data from a GPS Receiver, Inertial Sensors, Stereo-Camera and Digital Maps for Pedestrian Navigation
Authors: Baranski Przemyslaw , Strumillo Pawel
Published: May 2012

The paper presents an algorithm for estimating a pedestrian location in an urban environment. The algorithm is based on the particle filter and uses different data sources: a GPS receiver, inertial sensors, probability maps and a stereo camera. Inertial sensors are used to estimate a relative displacement of a pedestrian. A gyroscope estimates a change in the heading direction. An accelerometer is used to count a pedestrian’s steps and their lengths. The so-called probability maps help to limit GPS inaccuracy by imposing constraints on pedestrian kinematics, e.g., it is assumed that a pedestrian cannot cross buildings, fences etc. This limits position inaccuracy to ca. 10 m. Incorporation of depth estimates derived from a stereo camera that are compared to the 3D model of an environment has enabled further reduction of positioning errors. As a result, for 90% of the time, the algorithm is able to estimate a pedestrian location with an error smaller than 2 m, compared to an error of 6.5 m for a navigation based solely on GPS.
Prediction of Gap Asymmetry in Differential Micro Accelerometers
Authors: Zhou Wu , Li Baili , Peng Bei , Su Wei , He Xiaoping
Published: May 2012

Gap asymmetry in differential capacitors is the primary source of the zero bias output of force-balanced micro accelerometers. It is also used to evaluate the applicability of differential structures in MEMS manufacturing. Therefore, determining the asymmetry level has considerable significance for the design of MEMS devices. This paper proposes an experimental-theoretical method for predicting gap asymmetry in differential sensing capacitors of micro accelerometers. The method involves three processes: first, bi-directional measurement, which can sharply reduce the influence of the feedback circuit on bias output, is proposed. Experiments are then carried out on a centrifuge to obtain the input and output data of an accelerometer. Second, the analytical input-output relationship of the accelerometer with gap asymmetry and circuit error is theoretically derived. Finally, the prediction methodology combines the measurement results and analytical derivation to identify the asymmetric error of 30 accelerometers fabricated by DRIE. Results indicate that the level of asymmetry induced by fabrication uncertainty is about ±5 × 10−2, and that the absolute error is about ±0.2 µm under a 4 µm gap.
Optical Oxygen Micro- and Nanosensors for Plant Applications
Authors: Ast Cindy , Schmälzlin Elmar , Löhmannsröben Hans-Gerd , Van Dongen Joost T.
Published: May 2012

Pioneered by Clark’s microelectrode more than half a century ago, there has been substantial interest in developing new, miniaturized optical methods to detect molecular oxygen inside cells. While extensively used for animal tissue measurements, applications of intracellular optical oxygen biosensors are still scarce in plant science. A critical aspect is the strong autofluorescence of the green plant tissue that interferes with optical signals of commonly used oxygen probes. A recently developed dual-frequency phase modulation technique can overcome this limitation, offering new perspectives for plant research. This review gives an overview on the latest optical sensing techniques and methods based on phosphorescence quenching in diverse tissues and discusses the potential pitfalls for applications in plants. The most promising oxygen sensitive probes are reviewed plus different oxygen sensing structures ranging from micro-optodes to soluble nanoparticles. Moreover, the applicability of using heterologously expressed oxygen binding proteins and fluorescent proteins to determine changes in the cellular oxygen concentration are discussed as potential non-invasive cellular oxygen reporters.
Electrochemical Determination of Pentachlorophenol in Water on a Multi-Wall Carbon Nanotubes-Epoxy Composite Electrode
Authors: Remes Adriana , Pop Aniela , Manea Florica , Baciu Anamaria , Picken Stephen J. , Schoonman Joop
Published: May 2012

The aim of this study was the preparation, characterization, and application of a multi-wall carbon nanotubes-epoxy composite electrode (MWCNT-EP) with 25%, wt. MWCNTs loading for the voltammetric/amperometric determination of pentachlorophenol (PCP) in aqueous solutions. The structural and morphological aspects of the MWCNT-EP composite electrode were examined by scanning electron microscopy. The electrical properties were characterized by direct-current conductivity measurements in relation with the percolation threshold. The electrochemical behavior of PCP at the MWCNT-EP composite electrode was investigated using cyclic voltammetry in 0.1 M Na2SO4 supporting electrolyte in order to establish the parameters for amperometric/voltammetric determination of PCP. The linear dependence of current vs. PCP concentrations was reached in a wide concentration range from 0.2 to 12 μM PCP using cyclic voltammetry, differential-pulsed voltammetry, square-wave voltammetry, chronoamperometry, and multiple-pulsed amperometry techniques. The best electroanalytical performances of this composite electrode were achieved using a pre-concentration/square-wave voltammetric technique and also multiple-pulsed amperometry techniques envisaging the practical applications. The ease of preparation, high sensitivity, and stability of this composite electrode should open novel avenues and applications for fabricating robust sensors for detection of many important species.
Wood-Pellet Heating in Norway: Early Adopters’ Satisfaction and Problems That Have Been Experienced
Authors: Skjevrak Geir , Sopha Bertha Maya
Published: May 2012

Given the vital role of early adopters during the early stage of wood-pellet heating development, this study aims to explore the factors that explain the overall satisfaction among the early adopters of this type of heating as well as the problems experienced with wood-pellet heating in Norway. Ordinal regression was used to analyze empirical data which was collected from a mail survey in autumn 2008. The response rate of 45% was composed of 669 early adopters of wood-pellet heating. Findings show that both economic factor (i.e., cost) and technical factors (i.e., pellet stove performance) have played a significant role in early adopters’ overall satisfaction with wood-pellet heating. The most common problems experienced are igniter failure in the pellet stove, lack of committed and competent suppliers/vendors, more time and effort than expected during maintenance, and fines from pellets both during handling and combustion.
Synthesis and characterization of a novel carboxyl group containing (co)polyimide with sulfur in the polymer backbone
Authors: Mrsevic Miroslav , Düsselberg David , Staudt Claudia
Published: May 2012

Soluble functional (co)polyimides are of great interest in the area of separation processes or optical applications, due to their excellent mechanical-, thermal- and optical properties, their superior processability and the ability to adapt their properties to a wide range of special applications. Therefore, two series of novel (co)polyimides containing fluorinated sulfur- and carboxylic acid groups consisting of 4,4′-(hexafluoroisopropylidene)di(phthalic anhydride) (6FDA), 3,5-diaminobenzoic acid (DABA), 4,4′-diaminodiphenylsulfide (4,4′-SDA) and 3,3′-diaminodiphenylsulfone (3,3′-DDS) were synthesized in a two-step polycondensation reaction. The synthesized copolymers were characterized by using NMR, FTIR, GPC, and DSC. Furthermore, with regard to processing and potential applications, the thermal stability, solubility in common organic solvents, moisture uptake, and transparency were investigated. Compared to commercially available transparent polymers, i.e., polymethylmethacrylate and cycloolefin polymers, the sulfur (co)polyimides containing carboxyl groups showed much higher glass-transition temperatures, comparably low moisture uptake and high transmission at the sodium D-line. Furthermore, good solubility in commonly used organic solvents makes them very attractive as high-performance coating materials.
OPTIMIZATION-BASED SEARCH FOR NORDSIECK METHODS OF HIGH ORDER WITH QUADRATIC STABILITY POLYNOMIALS
Authors: Cardone Angelamaria , Jackiewicz Zdzislaw , Mittelmann Hans
Published: May 2012

We describe the search for explicit general linear methods in Nordsieck form for which the stability function has only two nonzero roots. This search is based on state-of-the-art optimization software. Examples of methods found in this way are given for order p = 5, p = 6, and p = 7.
SIMILARITY SOLUTIONS FOR STRONG SHOCKS IN A NON-IDEAL GAS
Authors: Arora Rajan , Tomar Amit , Singh Ved Pal
Published: May 2012

A group theoretic method is used to obtain an entire class of similarity solutions to the problem of shocks propagating through a non-ideal gas and to characterize analytically the state dependent form of the medium ahead for which the problem is invariant and admits similarity solutions. Different cases of possible solutions, known in the literature, with a power law, exponential or logarithmic shock paths are recovered as special cases depending on the arbitrary constants occurring in the expression for the generators of the transformation. Particular case of collapse of imploding cylindrically and spherically symmetric shock in a medium in which initial density obeys power law is worked out in detail. Numerical calculations have been performed to obtain the similarity exponents and the profiles of the flow variables behind the shock, and comparison is made with the known results.
Les précurseurs des voyageurs et représentants de commerce parmi les hommes d'affaires toscans de la Renaissance (fin XIVe-début XVIe siècle)
Authors: Orlandi Angela
Published: May 2012

Résumé On peut trouver des contrats régissant les activités analogues à celles de voyageur de commerce ou d’agent commercial dans les livres de compte et la correspondance des marchands toscans de la fin du Moyen Âge. Par exemple, dans les dernières années du XIV e siècle, Tucci di Gennaio, qui était employé par le comptoir des Datini à Valence, travaillait de façon analogue à un voyageur de commerce dans le territoire espagnol du Maestrazgo : avec toute liberté de négocier, il achetait de la laine lorsqu’il rencontrait les bergers de cette région. Il recevait un fixe plus une commission et une indemnité de séjour incluant le logement et les repas. Au début du XVI e siècle, le marchand florentin Bernardo dei Bardi effectuait des voyages de Florence à Constantinople à la manière d’un commis voyageur : il n’était pas employé par ses donneurs d’ordres et ne recevait d’eux qu’une commission fondée sur les transactions réalisées. Contrairement à la plupart des représentants de commerce actuels, il travaillait pour plusieurs clients, ayant un certain degré de liberté pour fixer le prix des biens qui lui étaient confiés pour être vendus au cours de son voyage et dans les villes du Bosphore.
Les représentants des « marchands-magasiniers » et le rôle de leurs voyages dans l'organisation régionale du commerce lorrain au XVIIIe siècle (années 1720-années 1770)
Authors: Villain Julien
Published: May 2012

Résumé Malgré la relative facilité des communications par lettre ou par route, les grossistes lorrains du XVIII e siècle envoyaient fréquemment leurs commis en « tournée » auprès de leurs clients de la province, pour en récupérer acomptes et commandes. Les petites foires locales ou régionales étaient pour ce faire des moments privilégiés. C’était toutefois lors de la préparation des grandes foires de Champagne ou de Francfort, où les grossistes lorrains s’approvisionnaient massivement, que les voyages des commis étaient les plus nombreux. Ces derniers se voyaient toutefois confier des missions plus occasionnelles, de recouvrement des créances auprès des mauvais payeurs, notamment.
Les commis voyageurs lyonnais au XVIIIe siècle
Authors: Bayard Françoise
Published: May 2012

Résumé Les débats importants auxquels a donné lieu, ces dernières années, le rôle de la confiance et des réseaux marchands dans la pratique du commerce à distance dans l’Europe préindustrielle amènent à évoquer sous un angle nouveau la question du voyage d’affaires, plus souvent évoquée, jusqu’alors, comme une étape dans la formation du jeune négociant que comme un moyen, pour des négociants établis, d’élargir ou de consolider leurs réseaux de correspondants. C’est pourtant bien pour remplir de telles fonctions que nombre de négociants prenaient la route ou faisaient voyager, en leur nom, des agents, ce que montre le cas de Jean-Joseph Leydet, un commis marseillais qui voyagea pour le compte de son employeur, la firme Collique et Cie, au début du XIX e siècle. Grâce à la riche correspondance de Jean-Joseph Leydet et aux documents divers qui ont été conservés au consulat de France à la suite de son décès à Cadix en 1804, il nous est possible de reconstituer les dernières missions qu’il accomplit à Gênes et à Cadix et d’apporter des informations inédites sur les tâches commerciales qu’assumaient de tels agents (recouvrement, gestion de contentieux, espionnage), leur condition sociale et professionnelle – tant au sein des firmes qui les emploient que de la société de leur temps – et les aspects matériels de leurs déplacements. Il devient dès lors possible de mieux envisager quelles étaient les fonctions réelles du voyage d’affaires et de saisir ce qui le rendait, dans certains cas, incontournable.
L'expérimentation d'une nouvelle pratique commerciale : la maison Moët d'Épernay et ses commis voyageurs (1790-1815)
Authors: Musset Benoît
Published: May 2012

Résumé À partir des années 1760-1780, les négociants en vins de Champagne entreprennent des voyages de prospection dans l’Est de l’Europe, afin d’y placer leurs vins, déjà connus dans la région, en plus grandes quantités. Dans les années 1790, toutes les maisons importantes disposent d’un ou plusieurs voyageurs, en particulier en Allemagne. La maison Moët d’Epernay participe à ce mouvement avec Charles Küssel, embauché en 1789. Jean-Rémy Moët, jeune dirigeant de la maison, découvre alors la difficulté d’utiliser un voyageur à distance : autonomie trop grande, défense variable de ses intérêts, rivalités personnelles. Après cette première expérience, achevée en 1795, Moët se repose sur une famille allemande, les Geiger, dont quatre membres ont voyagé pour lui de 1796 à 1814, tissant un réseau plus solide dans l’intérieur de l’Allemagne, poussant même, contre sa volonté, en Russie, à Vienne et en Angleterre. Malgré cet appui, la couverture de plusieurs dizaines de villes allemandes a été, jusqu’en 1815, un défi très imparfaitement surmonté. Les difficultés de la tournée allemande, l’irrégularité des commandes sous l’effet des guerres, les recouvrements difficiles de créances sans parler des fatigues du voyage entraînèrent un turn-over très important. À l’inverse, Henri-Jacob et Frédéric Geiger se sédentarisaient à Vienne et Saint-Pétersbourg, s’imposant davantage comme des agents, délaissant le statut de commis voyageur. Moët cédait dans un premier temps, les ventes se soutenant, mais rappelait furieusement ses voyageurs à leurs devoirs, sans succès, rompant finalement avec l’un en 1810, et avec l’autre en 1813. Cependant c’est lui-même qui installait un agent à Londres, Martell, tout en conservant officiellement le statut de voyageur. Le négociant restait, à la sortie d’une période troublée, dans une phase d’indécision quant à la structure commerciale de sa maison à l’exportation, tout en ayant acquis une grande expérience pendant 25 ans dans l’emploi des commis voyageurs.
Représentations champenoises d'un commis voyageur performant. L'exemple d'Henry Jacob Geiger, premier des commis voyageurs de la maison Jean-Rémy Moët
Authors: Perron Fabrice
Published: May 2012

Résumé Pratique en plein essor depuis la seconde moitié du XVIII e siècle, le recours aux commis voyageurs par les négociants champenois est un facteur essentiel du développement commercial du champagne. Rigoureusement sélectionnés, en fonction de besoins, préférences et contraintes inégalement affirmés, ces commis voyageurs doivent faire preuve de savoirs et de savoir-être. Embauchés le plus souvent à la mission, ils exercent un rôle triple en étant à la fois agents d’information, agents de recouvrement et prospecteurs de marché. Enfin, certains se distinguent par des responsabilités grandissantes au sein des maisons.
Vers la professionnalisation. Les agents de commerce et les commis voyageurs à Trieste au XIXe siècle
Authors: Andreozzi Daniele
Published: May 2012

Résumé Dans le cadre des mutations politiques et économiques qui ont affecté Trieste, principal port de l’empire des Habsbourg sur la Méditerranée, des tensions propres à cet empire et des changements impliquant les moyens de transport, les techniques commerciales et l’économie dans son ensemble, la professionnalisation des agents commerciaux à Trieste a été le fruit d’un processus de différenciation à la fois verticale et horizontale par rapport aux autres employés de commerce. Dans le même temps, les relations entre propriétaires et agents ont changé : des visions différentes des avantages concurrentiels se sont affrontées et chacune était porteuse de résultats complexes. Toute cette évolution a été aussi un élément important des stratégies mises en œuvre par les élites de Trieste dans leur lutte pour la suprématie tant au niveau local qu’au niveau des multiples enjeux de l’empire.
Entre salariat et indépendance : le statut hybride du représentant de commerce en France de la fin du XIXe siècle au milieu du XXe siècle
Authors: Barrière Jean-Paul
Published: May 2012

Résumé Le commis voyageur, représentant et/ou voyageur de commerce, devenu VRP (voyageur-représentant-placier), longtemps décrié en France, acquiert entre le dernier tiers du XIX e siècle et le milieu du XX e siècle, après d’autres pays européens, mais différemment, un statut plus rigoureusement défini que dans les Codes civils ou de Commerce existants, tout en conservant ses ambiguïtés fonctionnelles et sa polysémie. Le « VRP » s’inscrit dans la dialectique de la professionnalisation et du contrôle national à l’œuvre dans maints métiers « libéraux » au cours du premier tiers du XX e siècle en France, mais il s’en distingue par l’hybridation de son statut – lié d’un côté au développement du salariat (le commis ou voyageur est un employé) et de l’autre à l’alignement international et à la marge de décision que supposent ses missions (le « représentant », souvent multicartes, est travailleur indépendant et se rapproche de l’agent commercial) : meilleure identification (carte d’identité professionnelle délivrée par l’employeur après la loi de 1921 obligeant les représentants à intégrer le registre du commerce créé en 1919), formation (premières écoles spécifiques fin XIX e siècle), défense corporative (des amicales aux syndicats d’employés ou de représentants « libres »), expression propre (journaux et revues professionnels)... Ainsi, la loi française du 18 juillet 1937 sur le statut légal des VRP, consacrant une évolution de plusieurs décennies, leur confère la protection salariale due à l’employé (ainsi le non assujettissement à la patente, l’intégration au Code du Travail contre les renvois abusifs, le recours aux prud’hommes ou les accidents du travail), alors que sa mise en œuvre, réglementaire ou judiciaire (jurisprudence), tout comme les modes de rémunération et le contexte européen (Belgique 1922, Suisse 1930, Luxembourg 1934, Italie 1938...), l’infléchissent dans le sens de l’indépendance. En fait comme en droit, cette profession participe d’une régulation accrue des échanges internationaux à la fin du XIX e siècle qui suppose une reconnaissance des « cartes de légitimation » à l’étranger dans un cadre bi- ou multilatéral (convention douanière de Genève 1923), à défaut d’une véritable carte de VRP internationale. L’étude des VRP est un des moyens de définir le salariat par ses marges, grâce aux sources législatives et juridiques nationales, aux archives professionnelles (Chambres de Commerce de Lille et de Marseille) et syndicales.
Salesmen in comparative perspective
Authors: Friedman Walter A.
Published: May 2012

Résumé Cet article dresse le bilan de 20 années de recherches historiques sur les commis voyageurs puis, à partir des apports de ce numéro d’ Entreprises et Histoire sur l’Europe, présente des pistes de recherche pour une histoire comparée des vendeurs.
Procédure de constitution d’un corpus attesté d’articles de recherche scientifique en vue d’une étude contrastive
Authors: Bachschmidt Patrick
Published: May 2012

Pour pouvoir se livrer à une étude contrastive à partir d’un corpus qui soit véritablement représentatif de la discipline concernée, il nous paraît nécessaire de se référer à trente articles de recherche par langue étudiée, couvrant une période de six ans. Les auteurs de ces articles auront été tirés au hasard sur une liste officielle de professeurs des universités spécialistes du domaine ; étant donné que cette population est supérieure à cent vingt individus (assimilable à l’infini), dans chaque groupe linguistique, l’on peut appliquer la loi de Gauss dont le tableau indique que le nombre d’échantillons doit être égal à trente. Il suffit ensuite de consulter la base de données PASCAL (couvrant la quasi-totalité des domaines scientifiques) pour sélectionner un article par auteur en fonction de la qualité scientifique du support médiatique, déterminée par un panel de spécialistes du domaine à partir d’une liste de référence de revues et journaux spécialisés. Cependant, cette procédure ne saurait se passer de quelques précautions d’ordre linguistique et soulève quelques problèmes d’ordre culturel.
Identification of mercury emissions from forest fires, lakes, regional and local sources using measurements in Milwaukee and an inverse method
Authors: de Foy B. , Wiedinmyer C. , Schauer J. J.
Published: May 2012

Abstract. Gaseous elemental mercury is a global pollutant that can lead to serious health concerns via deposition to the biosphere and bio-accumulation in the food chain. Hourly measurements between June 2004 and May 2005 in an urban site (Milwaukee, WI) show elevated levels of mercury in the atmosphere with numerous short-lived peaks as well as longer-lived episodes. The measurements are analyzed with an inverse model to obtain information about mercury emissions. The model is based on high resolution meteorological simulations (WRF), hourly back-trajectories (WRF-FLEXPART) and forward grid simulations (CAMx). The hybrid formulation combining back-trajectories and grid simulations is used to identify potential source regions as well as the impacts of forest fires and lake surface emissions. Uncertainty bounds are estimated using a bootstrap method on the inversions. Comparison with the US Environmental Protection Agency's National Emission Inventory (NEI) and Toxic Release Inventory (TRI) shows that emissions from coal-fired power plants are properly characterized, but emissions from local urban sources, waste incineration and metal processing could be significantly under-estimated. Emissions from the lake surface and from forest fires were found to have significant impacts on mercury levels in Milwaukee, and to be underestimated by a factor of two or more.