bluuebunny/crossref_metadata_2025 huggingface dataset:
Very strong nonlinear optical absorption in green GaInN/GaN multiple quantum well structures
Authors: Zhao W. , Zhu M. , Xia Y. , Li Y. , Senawiratne J. , You S. , Detchprohm T. , Wetzel C.
Published: April 2008

The efficiency of green GaInN/GaN light emitting diodes (LEDs) is known to drop under high current densities. To explore the reason, 535 nm emitting GaInN/GaN multiple quantum well (MQW) and GaN epilayers were characterized using Z‐scan techniques under comparable excitation conditions with a continuous wave laser. Two wavelengths, 514 nm and 488 nm, were selected right below and above the apparent optical absorption edge. At 514 nm, a very large nonlinear absorption coefficient β = 2.6 cm/W was obtained. This leads to a 20% absorption enhancement at a photon flux of 21 kW/cm2. We attribute this to nonlinear free‐carrier absorption. On the other hand, at 488 nm, a nonlinear saturable absorption with β = –1.7 cm/W was observed. This induced transparency indicates photon bleaching in the MQW. Apparently, free carrier dynamics strongly affects optical nonlinearity, while nonlinear absorption provides a small contribution to the limitations of current green LEDs. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical properties of InGaN grown by molecular beam epitaxy
Authors: Schaff William J. , Chen Xiaodong , Hao Dong , Matthews Kris , Richards Troy , Eastman Lester F. , Lu Hai , Cho Clara Ji‐Hyun , Cha Ho‐Young
Published: April 2008

The electrical properties of InGaN that is either undoped, or Mg doped, are compared to learn about the nature of p‐type conductivity. For In alloy fraction beyond 5% Hall measurements do not indicate p‐type polarity, even when Mg doping is employed. In contrast, hot probe measurements show that p‐polarity can be measured for the entire range of Mg‐doped In mole fractions. The conflicting polarity indications are primarily the result of surface electron accumulation. Parasitic surface electron conductivity can further be seen in p–n homojunctions at In fractions including 20% and 30%. This has an impact on structures such as solar cells. Temperature variable conductivity and PL from different layer structures provides further understanding of the nature of InGaN:Mg. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth and characterization of InN thin film by metal‐organic vapor phase epitaxy (MOVPE) on different buffers
Authors: Chang P. H. , Wei Y. Y. , Chen C. W. , Peng H. C. , Ling D. C. , Chen N. C. , Chang C. A.
Published: April 2008

Superconductivity and transport characteristics of high‐quality wurtzite‐structured In‐ and N‐polarity InN thin film on sapphire substrate by metal‐organic vapor phase epitaxy (MOVPE) were presented in this study. Single‐crystalline InN films with various n‐typed carrier concentrations (n = 1 ∼ 6 × 1019cm–3) resulting from nitrogen vacancy (VN) were obtained by changing buffer layers. Superconductivity phase transition at Tc,onset around 3.5 K are observed in both In‐ and N‐polarity InN. This strongly suggest that the superconduc‐ tivity originate in the In‐VN(and/or VN+)‐In chain in the a‐b plane of InN thin film. Our experimental results show that the nitrogen vacancy in a‐b plane of InN thin film must play important roles for the quasi‐2D superconducting network in InN system. Temperature ‐ dependent resistance broadening of InN at T < Tc,onset(K) under zero magnetic fields was observed and can be expressed by Kosterlitz‐Thouless transition. Details were discussed in this paper. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of GaN capping on performance of InAlN/AlN/GaN MOS‐HEMT with Al2O3 gate insulation grown by CVD
Authors: Pozzovivo G. , Kuzmik J. , Golka S. , Čičo K. , Fröhlich K. , Carlin J.‐F. , Gonschorek M. , Grandjean N. , Schrenk W. , Strasser G. , Pogany D.
Published: April 2008

We investigate InAlN/AlN/GaN‐based MOS‐HEMTs with and without a 20 Å‐GaN capping below an Al2O3‐insulator. An excellent reduction of the leakage current, up‐to 6 orders of magnitude, is observed in MOS‐HEMT structures compared to Schottky‐based‐HEMTs, both with GaN capping. In the case of uncapped samples the reduction in the leakage current is 3 orders of magnitude. The maximal transconductance value gm,max for the GaN‐capped‐MOS‐HEMT is about 10% higher than that for the conventional Schottky‐based‐HEMT, while in the case of uncapped devices gm,max is about the same for both Schottky and MOS‐HEMT. Similarly the maximal‐drain‐current in the GaN capped MOS‐HEMT is 950mA/mm, exhibiting an increase of 180mA/mm in comparison to the corresponding conventional Schottky‐based‐HEMT. Performance improvement of MOS structure can be explained by a mobility‐dependent carrier depletion effect. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High temperature sensing characteristics of a high performance Pd/AlGaN/GaN Schottky diode hydrogen sensor obtained by oxygen gettering
Authors: Akazawa M. , Hasegawa H.
Published: April 2008

High temperature sensing characteristics of a Pd/AlGaN/GaN Schottky diode hydrogen sensor were investigated. By applying an oxygen gettering process, the diode showed very small leakage currents even at elevated temperatures. On exposure to 10 Torr hydrogen in an air ambient (200 Torr), the diode showed a large current change of four orders of magnitude. The observed sensing behaviour could be fitted to a theory based on the sensing mechanism involving Schottky barrier height reduction due to interface dipole formation by atomic hydrogen. The diode showed much improved characteristics at 110 °C than at room temperature. This surprising result is explained in terms of the current transport mechanism. The diode showed much better sensing characteristics than those of GaAs and InP. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micro‐pixel light emitting diodes with wavelength‐tunable output
Authors: Ng W. N. , Leung C. H. , Lai P. T. , Choi H. W.
Published: April 2008

A novel design and implementation of a single‐chip wavelength tunable light emitting diode (LED) is introduced in this paper, with varying emission spectral characteristics ranging between 470 nm (blue) and 525 nm (green). The emission wavelength of green fluorescent microspheres (525 nm), acting as a colour conversion agent, is chosen to be efficiently excited by a GaN LED of 470 nm. It is selectively‐coated onto designated micrometer‐scaled pixels, which are interconnected via metal lines. As a result, the LED allows separate control of optical output either 470 nm, 525 nm or even a mixture of both wavelengths. Since the pixels are of micron‐scale which are non‐resolvable by the unaided human eye, the output appears optically mixed. This type of device, combining the application of micro‐light‐emitting diode and fluorescent microsphere technologies, offers a colour tunable output suitable for a wide range of applications including such as outdoor panel displays. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Impact of AlN interlayer on the transport properties of AlGaN/GaN heterostructures grown on silicon
Authors: Elhamri S. , Mitchel W. C. , Berney R. , Ahoujja M. , Roberts J. C. , Rajagopal P. , Cook J. W. , Piner E. L. , Linthicum K. J.
Published: April 2008

Hall and Shubnikov‐de Haas effects measurements were performed to identify the impact of inserting a 1nm AlN interlayer between AlGaN and GaN. The transport properties of this AlGaN/AlN/GaN structure were compared to the conventional structure (AlGaN/GaN). Our measurements indicate the AlN interlayer resulted in improved transport in the temperature range studied (300 K‐1.2 K). However, the impact of the AlN layer was found to be much more significant at low temperatures. The improvement is believed to be the result of reduced alloy scattering arising from a stronger confinement of the 2DEG. At 300 K the carrier density and mobility for the AlGaN/AlN/GaN structure were roughly 1.00 x 1013 cm–2 and 1937 cm2/Vs. Whereas those of the conventional structure were 8.57 x 1012 cm–2 and 1523 cm2/Vs. Shubnikov‐de Haas oscillations were observed in both samples at low T. This is an indication that a high quality 2DEG is present in each structure. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the electronic structures and spectroscopic properties of polyyne and its derivatives
Authors: Yao Shujuan , Zhou Chenggang , Wu Jinping , Li Jiaye , Han Bo , Cheng Hansong
Published: April 2008

We present a theoretical study on the electronic structure and spectroscopic properties of polyyne and its derivatives using periodic density functional theory study and semiempirical ZINDO/s methods. The electronic density of states were calculated, which indicates that polyyne behaves like a semiconductor and the insertion of aromatic groups into the polymer chain gives rise to significant metallic characters in the materials. The vibrational and UV–vis spectra of polyyne and its derivatives were simulated using a monomer or oligomer model. The effects of aromatic insertion into polyyne chain on their electronic and spectroscopic properties were discussed. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Impact of short‐term regulation on hyporheic water quality in a boreal river
Authors: Nyberg Lars , Calles Olle , Greenberg Larry
Published: April 2008

Water regulation may alter hydraulic head gradients with consequences for the exchange of water between the river and the hyporheic zone. The objective of this study was to investigate the effect of discharge on hyporheic water quality in a regulated Swedish boreal river during a 10‐day experimental period with a sequence of alternating high‐ and low‐flow episodes. A 250 m reach was instrumented with 28 piezometers placed at 150 and 300 mm below the river bed or below the mean groundwater level in the floodplain, and these piezometers were used to measure temperature, oxygen, electric conductivity and pH. High daily variation in air temperature during the first 3 days was transmitted vertically through the stream water into the hyporheic zone within hours. An oxygen saturation of 100% in the river water corresponded to 60–70% saturation at 150 mm depth and 30% at 300 mm depth. The hyporheic oxygen concentration at 150 mm depth decreased during the experimental period, falling into a range that is potentially harmful to incubating salmonid eggs. This was interpreted as a long‐term response to the overall regulation regime, rather than a response to short‐term water regulation during the experiment. Even though the effect of short‐term regulation on the quality of hyporheic water in the river bed was limited, there was a more pronounced effect on the quality of floodplain hyporheic water. Most of the driving forces for temporal variation of water quality in the river bed came vertically from the river water, rather than from the lateral exchange. Copyright © 2008 John Wiley & Sons, Ltd.
Influence of minor alloying elements on the initial stages of oxidation of austenitic stainless steel materials
Authors: Jussila P. , Lahtonen K. , Lampimäki M. , Hirsimäki M. , Valden M.
Published: April 2008

Surface oxidation of Fe‐19Cr‐17Ni, Fe‐19Cr‐18Ni‐1Al and TiC‐enriched Fe‐19Cr‐18Ni‐1Al alloys was investigated by photoelectron spectroscopy (PES). The experiments were conducted at 323 K in pure O2 (2.7 × 10−6 mbar). Composition and morphology of the nanoscale surface oxides were determined quantitatively by inelastic electron background analysis. Moreover, use of synchrotron radiation facilities were necessary to obtain improved sensitivity for studying minor alloying elements such as Al and Si. The results indicate oxygen‐induced segregation of Al, which significantly hinders the oxidation of the major alloying elements Fe and Cr. Ti remains in its inert carbide form. The relative concentration of Fe within the oxide layer was found to increase with the oxide‐layer thickness, indicating greater mobility of Fe relative to other alloying elements. Copyright © 2008 John Wiley & Sons, Ltd.
Information asymmetry and the dismissal of newly appointed CEOs: an empirical investigation
Authors: Zhang Yan
Published: April 2008

Why are some newly appointed CEOs (i.e., those with tenure of three years or less) dismissed while others are not? Drawing upon previous reseach on information asymmetry and adverse selection in CEO selection, I argue that the board of directors may make a poor selection at the time of CEO succession, and as a result, must dismiss the appointee after succession when better information about him/her is obtained. Therefore, the level of information asymmetry at the time of succession increases the likelihood of dismissal. With data on 204 newly appointed CEOs, the results of this study support this argument. After controlling for alternative explanations of CEO dismissal (e.g., firm performance and political factors), the results show that the likelihood of dismissal of newly appointed CEOs is higher in outside successions and/or if the succession follows the dismissal of the preceding CEO. Further, if at the time of succession, the firm's board has a nominating committee that is independent and/or on which outside directors have few external directorships, the likelihood of dismissal is lower. Contributions to the CEO dismissal/succession literature are discussed. Copyright © 2008 John Wiley & Sons, Ltd.
Scanning Probe Parallel Nanolithography with Multiprobe Cantilever Array Fabricated by Bulk Silicon Micromachining
Authors: Gandjar Hensy , Takagi Yuki , Matsuzuka Naoki , Isono Yoshitada
Published: April 2008

This work describes a scanning probe parallel nanolithography (SPNL) technique for high throughput in nanometric patterning on single‐crystal silicon (SCS) substrates. Two types of multiprobe cantilever arrays used for SPNL were fabricated by conventional micromachining. All the probes mounted on the free end of each cantilever were made of quasitrihedral pyramidal shape composed of (311) and (411) planes using the originally designed mask. Negative and positive types of nanolithography were performed on the basis of field‐enhanced anodization and self‐assembled monolayer mask techniques, respectively, and they succeeded in drawing a number of nanometric patterns of silicon dioxide (SiO2) on SCS substrates. After anisotropic wet etching of the SCS substrates using the SiO2 films as the mask material, we were also able to fabricate nanowires and nanogrooves. The effects of the applied voltage and scan time of cantilever arrays on wire and groove dimensions were systematically examined by atomic force microscopy (AFM) observations. An optimum condition for the parallel SPNL is proposed on the basis of this research. © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Defecation proctography and translabial ultrasound in the investigation of defecatory disorders
Authors: Perniola G. , Shek C. , Chong C. C. W. , Chew S. , Cartmill J. , Dietz H. P.
Published: April 2008

Objectives

Defecation proctography is the standard method used in the investigation of obstructed defecation. Translabial ultrasound has recently been shown to demonstrate rectocele, enterocele and rectal intussusception. We performed a comparative clinical study to determine agreement between the two methods.

Methods

Thirty‐seven women scheduled to undergo defecation proctography for obstructed defecation were recruited. Using both proctography and translabial ultrasound, we determined the anorectal angle, presence of a rectocele and rectocele depth, rectal intussusception and prolapse. Measurements were obtained by operators blinded to all other data. All patients rated discomfort on a scale of 0–10.

Results

Six women did not attend defecation proctography, leaving 31 cases for comparison. The mean age was 53 years. Patients rated discomfort at a median of 1 (range 0–10) for ultrasound and 7 (range 0–10) for defecation proctography (P < 0.001). Defecation proctography suggested rectocele and rectal intussusception/prolapse more frequently than did ultrasound. While the positive predictive value of ultrasound (considering defecation proctography to be the definitive test) was 0.82 for rectocele and 0.88 for intussusception/prolapse, negative predictive values were only 0.43 and 0.27, respectively. Cohen's kappa values were 0.26 and 0.09, respectively. There was poor agreement between ultrasound and defecation proctography measurements of anorectal angle and rectocele depth.

Conclusions

Translabial ultrasound can be used in the initial investigation of defecatory disorders. It is better tolerated than defecation proctography and also yields information on the lower urinary tract, pelvic organ prolapse and levator ani. Agreement between ultrasound and defecation proctography in the measurement of quantitative parameters was poor, but when intussusception or rectocele was diagnosed on ultrasound these results were highly predictive of findings on defecation proctography. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
Acinetobacter baumanniiInfections in a Surgical Intensive Care Unit: Predictors of Multi‐drug Resistance
Authors: Katsaragakis Stilianos , Markogiannakis Haridimos , Toutouzas Konstantinos G. , Drimousis Panagiotis , Larentzakis Andreas , Theodoraki Eleni‐Maria , Theodorou Dimitrios
Published: April 2008

Objectives

This study was designed to evaluateAcinetobacter baumanniiinfections incidence in our Surgical Intensive Care Unit, clinical features and outcome of these patients, and multi‐resistance incidence to identify predictors of such a resistance.

Methods

Prospective study of all patients with ICU‐acquiredAcinetobacter baumanniiinfection from June 1, 2003 to May 31, 2005. Patients with multi‐resistant infection, susceptible exclusively to colistin, were compared with those sustaining non‐multi‐drug resistant infection.

Results

Among 411 patients, 52 (12.6%) developed Acinetobacter infection. Their mean age was 66.3 ± 8.4 years and APACHE II 20.4 ± 7.3 (men: 51.9%). Infection sites were: bloodstream (46.2%), respiratory tract (32.7%), central venous catheter (11.5%), surgical site (7.7%), and urinary tract (1.9%). High multi‐resistance (44.2%), morbidity (63.4%), and mortality (44.2%) were identified. Colistin was the most effective antibiotic (100% susceptibility), whereas resistance against all other antibiotics was >60%. Previous septic shock (p= 0.04), previous adult respiratory distress syndrome (ARDS) (p= 0.01), number of previous antibiotics (p= 0.01), previous aminoglycoside use (p= 0.04), and reoperation (p= 0.01) were risk factors for multi‐resistance in univariate analysis. Morbidity in the multi‐resistant group was significantly higher than the non‐multi‐resistant group (82.6% vs. 48.2%,p= 0.02). Mortality in the multi‐resistant group also was higher; however, this difference did not marginally reach statistical significance (60.8% vs. 31.1%,p= 0.06). Multivariate analysis identified previous septic shock (p= 0.04; odds ratio (OR), 9.83; 95% confidence interval (CI), 1.003–96.29) and reoperation (p= 0.01; OR, 8.45; 95% CI, 1.52–46.85) as independent predictors of multi‐resistance.

Conclusion

Acinetobacter baumanniiinfections are frequent and associated with high morbidity, mortality, and multi‐resistance. Avoidance of unnecessary antibiotics is a high priority, and specific attention should be paid to patients with previous ARDS and, particularly, previous septic shock and reoperation. When such risk factors are identified, colistin may be the only appropriate treatment.
Breast Cancer in Chinese Women Younger than Age 40: Are They Different from Their Older Counterparts?
Authors: Kwong Ava , Cheung Polly , Chan Stephanie , Lau Silvia
Published: April 2008

Background

Breast cancer in young women is uncommon, but when it does occur it has been reported to have aggressive biological characteristics. The incidence of breast cancer peaks at age 40 in Hong Kong Chinese women, earlier than in Caucasians. This study is the first to report the tumor characteristics and management of breast cancer in Chinese women younger than age 40 and a comparison with their older counterparts.

Materials and methods

Demographic and clinicopathologic findings of 1,485 Chinese women with breast cancer seen during the period September 2003 to November 2006 were prospectively recorded, and comparisons were made between those who were under the age of 40 and those 40 years of age and older. These results were then compared with a reference population obtained from the Surveillance, Epidemiology and End Results (SEER) database between 2003 and 2004.

Results

17.6% of the women were younger than 40 years old, and age distribution was significantly different from women in the SEER database. The mean age at menarche was lower in women under age 40 (p < 0.0005), and age at first live birth was also higher (p = 0.017). The rate of first detection by screening mammography was significantly higher among women who were 40 of age and older (p = 0.002). Breast conservation surgery was more commonly performed in the younger age group of Chinese women, particularly when tumor size was less than 2 cm (p = 0.001). A significantly higher proportion of women under age 40 had breast reconstruction (p < 0.001). The majority of women presented with stage 0‐II disease, but in the Chinese groups the younger patients presented at a later stage (p = 0.04). Younger women had higher pathological grade and poorly differentiated tumors (p = 0.02), more nodal involvement (p = 0.024), and lymphovascular permeation involvement (p < 0.001). The majority of tumors were ER and PR positive in both groups, but younger women had a higher proportion of cerbB2‐positive tumors.

Conclusion

Chinese women present with breast cancer at an earlier age. Younger women present with more advanced disease and more aggressive tumor characteristics. More ethnic‐specific screening protocols and treatment decisions may benefit this group of patients.
Fat Utilization in Healthy Subjects Consuming Diacylglycerol Oil Diet: Dietary and Whole Body Fat Oxidation
Authors: Hibi Masanobu , Takase Hideto , Yasunaga Koichi , Yamaguchi Tohru , Harada Ushio , Katsuragi Yoshihisa , Tokimitsu Ichiro
Published: April 2008

Several studies in animals and humans have reported beneficial effects of diacylglycerol (DAG) on lipid and energy metabolism. We assessed the effect of DAG versus triacylglycerol (TAG) treatment on total energy expenditure (TEE), total fat oxidation (Fox) and respiratory quotient (RQ), and measured the oxidation rate of each oil using a respiratory chamber and the 13C‐stable isotope. Eleven healthy subjects participated in a double‐blind, randomized crossover study. Subjects consumed an energy maintenance diet consisting of 55% of total calories from carbohydrate, 15% from protein and 30% from fat during both the 3‐day pre‐chamber and 36‐h chamber period. Fifty percent of the fat was test oil, containing either DAG oil or TAG oil. The oxidation rate of ingested test oils was determined by monitoring 13CO2 excretion in the breath from 13C‐labeled diolein or 13C‐labeled triolein. There were no significant differences in TEE, RQ and total Fox between the DAG and TAG treatment in the overall analysis. In the subgroup analysis, DAG treatment decreased RQ significantly in subjects with a high fat ratio (HFR) compared to TAG treatment. In addition, ingested diolein oxidation in DAG treatment was significantly faster than triolein oxidation in TAG treatment in the HFR group. Enhanced fat utilization with DAG treatment and rapid oxidation of ingested DAG may, at least in part, explain the greater loss of body weight and body fat related to DAG consumption found in the weight‐loss studies.
Mitochondria, endoplasmic reticulum and actin filament behavior after PDT with chloroaluminum phthalocyanine liposomal in HeLa cells
Authors: Maftoum‐Costa Maíra , Naves Karina Teixeira , Oliveira Alexandre Lima , Tedesco Antonio Cláudio , da Silva Newton Soares , Pacheco‐Soares Cristina
Published: April 2008

Photodynamic therapy (PDT) for cancer is a therapeutic modality in the treatment of tumors in which visible light is used to activate a photosensitizer. Cell membranes have been identified as an important intracellular target for singlet oxygen produced during the photochemical pathway. This study analyzed the cytotoxicity in specific cellular targets of a photosensitizer used in PDT in vitro. The photosensitizing effects of chloroaluminum phthalocyanine liposomal were studied on the mitochondria, cytoskeleton and endoplasmic reticulum of HeLa cells. Cells were irradiated with a diode laser working at 670 nm, energy density of 4.5 J/cm2 and power density of 45 mW/cm2. Fluorescence microscopic analysis of the mitochondria showed changes in membrane potential. After PDT treatment, the cytoskeleton and endoplasmic reticulum presented basic alterations in distribution. The combined effect of AlPHCl liposomal and red light in the HeLa cell line induced photodamage to the mitochondria, endoplasmic reticulum and actin filaments in the cytoskeleton.
Hyaluronan involvement in the changes of mouse interpubic tissue during late pregnancy and post‐partum
Authors: Garcia Eduardo A. , Veridiano Adriano M. , Martins João R.M. , Nader Helena B. , Pinheiro M.C. , Joazeiro Paulo P. , Toledo Olga M.S.
Published: April 2008

The present work quantifies hyaluronan (HA) during the late pregnancy and post‐partum in order to provide a better understanding of the role of HA in the adaptations that occur in the pubic symphysis during this period. HA was quantified in situ (histochemically) and in interpubic tissue extracts by fluorimetric assay. Samples were taken from virgin mice and from pregnant animals at various stages of pregnancy: 12th‐18th days into pregnancy, the day of delivery (D19) and the 3rd and 5th day post‐partum. The quantitative fluorimetric analysis indicated a gradual increase of HA in the interpubic tissue throughout late pregnancy (2.4–14.6 μg/mg dry weight). This was followed by a decrease beginning on D19 (12.4 μg/mg), reaching close to virgin levels (2.2 μg/mg) on the 5th day post‐partum. The same optical density changes could be seen in the HA staining. Furthermore, the histochemical analysis demonstrated the presence of HA both in the extracellular matrix of the tissue and within its cells. Such results indicate that the extracellular presence of HA may contribute to the transformation of the symphysis into a flexible structure. In addition, HA's intracellular presence (until the 18th day of pregnancy) may contribute to cellular proliferation. Finally, during parturition and on the 5th day post‐partum, HA may contribute to the maintenance of the myofibroblastic phenotype of ligament cells, aiding the ligament involution after parturition.
Erythroid expansion and survival in response to acute anemia stress: The role of EPO receptor, GATA‐1, Bcl‐xL and caspase‐3
Authors: Aispuru Gualberto Rodrigo , Aguirre María Victoria , Aquino‐Esperanza José Andrés , Lettieri Carolina Noelia , Juaristi Julián Antonio , Brandan Nora Cristina
Published: April 2008

Erythropoietic stress occurs under conditions of tissular hypoxia, such as anemia. Functional relationships between erythroid bone marrow (BM) proliferation, differentiation, the expression of survival and apoptotic related proteins, as well as the features of the BM microenvironment upon acute anemic stress, are not fully elucidated. To achieve this aim, CF‐1 Swiss mice were injected with a single dose of 5‐fluorouracil (5‐FU, 150 mg/kg ip) and a multiparametric analysis was conducted for 20 days.

Apoptosis (TUNEL assay), BM architecture organization (scanning electronic microscopy), proliferation (DNA assay), differentiation (clonogenic cultures), expression of survival erythroid related proteins (EPO‐R, GATA‐1, Bcl‐xL) as well as the expression of apoptotic‐ related proteins (Bax, activated Caspase‐3) by Western blotting, were evaluated. Experimental data showed that apoptosis, arrest of cell proliferation and disruptions of BM architecture were maximal within the first period of acute stress (1–3 days). Bax and caspase‐3 overexpressions were also coincident during this acute period. Moreover, from day 5 upon drug challenge BM responds to acute stress through the EPO‐EPO‐R system, prompting expressions of GATA‐1 and Bcl‐xL. Erythroid proliferation rates and red‐cell‐committed progenitors enhanced in a coordinated way to restore the size and function of the red cell compartment. A second overexpression wave of active caspase‐3 was noticed during stress recovery.

Together, these results indicate that in response to acute stress a dramatic increase in CFU‐E (erythroid colony forming units) population is concomitant with upregulation of EPO‐R, GATA‐1 and Bcl‐xL in the BM erythroid compartment, and that these concurrent processes are crucial for acquiring proper erythroid cell functionality without delayed response to tissular hypoxia.
The vacuolar V1/V0‐ATPase is involved in the release of the HOPS subunit Vps41 from vacuoles, vacuole fragmentation and fusion
Authors: Takeda Kozue , Cabrera Margarita , Rohde Jan , Bausch Dirk , Jensen Ole N. , Ungermann Christian
Published: April 2008

At yeast vacuoles, phosphorylation of the HOPS subunit Vps41 depends on the Yck3 kinase. In a screen for mutants that mimic the yck3Δ phenotype, in which Vps41 accumulates in vacuolar dots, we observed that mutants in the V0‐part of the V0/V1‐ATPase, in particular in vma16Δ, also accumulate Vps41. This accumulation is not due to a phosphorylation defect, but to reduced release of Vps41 from vma16Δ vacuoles. One reason could be a connection to vacuole fission, which is blocked in V‐ATPase mutants. Vacuole fusion is not impaired between vacuoles lacking the V0‐subunits Vma16 or Vma6 and wild‐type vacuoles, whereas fusion between mutant vacuoles is reduced. Our data suggest a connection between vacuole biogenesis and membrane fusion.
The distributions and correlates of serum albumin levels in institutionalised individuals with intellectual and/or motor disabilities
Authors: Ohwada Hiroko , Nakayama Takeo
Published: April 2008

The serum albumin level is a widely accepted indicator of nutritional status in healthy adults and elderly individuals. However, there are few data regarding the distribution and correlates of serum albumin levels in individuals with intellectual and/or motor disabilities. We conducted a cross-sectional study at a public facility for individuals with intellectual and/or motor disabilities in Ibaraki prefecture, Japan. Health check-up data obtained in 2001 from 477 individuals with intellectual disability (286 males, average age 40·6 (sd 12·3) years; 191 females, average age 45·1 (sd 11·6) years) were retrospectively reviewed. With the exception of men with cerebral palsy, the serum albumin level was nearly normally distributed. The mean was 44 (sd 3·6) g/l for males and 44 (sd 3·6) g/l for females with intellectual disability, 43 (sd 3·2) g/l in males and 44 (sd 2·6) g/l for females with cerebral palsy, 41 (sd 2·7) g/l for males and 42 (sd 3·7) g/l for females with Down's syndrome, and 42 (sd 4·5) g/l for males and 41 (sd 3·2) g/l for females with severe motor and intellectual disabilities. Only six of 474 individuals (1·3 %) had a serum albumin ≤ 35 g/l. Low serum albumin was related to age, use of anticonvulsants and/or major tranquilisers, use of other medications, high C-reactive protein (CRP), high zinc sulfate turbidity test (ZTT), low serum Hb and low serum Fe among men; among women, high CRP and high ZTT were related to low serum albumin. The present study found an unexpectedly low incidence of low serum albumin among institutionalised individuals with intellectual and/or motor disabilities. Low serum albumin was associated with age, medications and inflammation in men, as well as inflammation in women.
Effects of lifelong intervention with an oligofructose-enriched inulin in rats on general health and lifespan
Authors: Rozan Pascale , Nejdi Amine , Hidalgo Sophie , Bisson Jean-François , Desor Didier , Messaoudi Michaël
Published: April 2008

Ageing is associated with changes in physiology and morphology; nutritional strategies to decrease morbidity and to prolong life are of high interest. The aim of the study was to investigate the effects of lifelong supplementation with an oligofructose-enriched inulin on morphological and biological markers and lifespan in male and female rats. Male and female rats, age 3 months, were randomised into two groups to receive either a diet with 10 % of an oligofructose-enriched inulin (Synergy1) or a standard diet (control) for 27 months. The rats were weighed every 2 weeks and their food intake was evaluated on four successive days every 4–6 weeks. Samples were taken at 12, 18 and 24 months of age. During the whole intervention period, male rats receiving Synergy1 (SYN1-M) displayed lower body weight, cholesterol and plasma triacylglycerolaemia compared with the controls (Cont-M). The survival rate at 24 months of age of SYN1-M rats was 35·3 % greater than that of Cont-M rats. In female rats, the Synergy1 supplementation (SYN1-F) group also reduced body weight, cholesterol and triacylglycerolaemia levels, but results were less consistent over the experiment. The survival rate at 24 months of age in SYN1-F rats was 33·3 % greater compared with that of the control (Cont-F) group. To conclude, lifelong intervention with Synergy1 improved biological markers during ageing and survival rate (lifespan) of rats.
Minimally invasive endoscopic techniques for treating large, benign processes of the nose, paranasal sinus, and pterygomaxillary and infratemporal fossae: solitary fibrous tumour
Authors: Jurado-Ramos A , Romero F Ropero , Baños E Cantillo , Molina J Salas
Published: April 2008

Objectives:

We report an extremely rare case of a large solitary fibroma of the paranasal sinus, which we treated by sinonasal endoscopic surgery. We describe its clinical and histopathological features, and we report the endoscopic technique used to deal with such a large sinonasal mass (penetrating the pterygomaxillary and infratemporal fossae); we also offer a brief survey of the literature.

Case report:

A woman presented with an approximately one-year history of nasal obstruction. Nasal endoscopy revealed an irregularly shaped, friable, reddish mass that occupied the whole of the right nasal fossa. Magnetic resonance imaging of the paranasal sinuses revealed a large mass that occupied the anterior and posterior ethmoids and the maxillary and sphenoid sinuses, displacing the septum and penetrating the pterygomaxillary fossa, having destroyed the lateral wall of the right nasal fossa. The tumour was resected by means of sinonasal endoscopic surgery; an endoscopic medial maxillectomy with extension to the pterygomaxillary and infratemporal regions was performed. Histological analysis confirmed the diagnosis of solitary fibrous tumour. During follow up, we performed regular nasal endoscopies, as well as computed tomography scans one and six months post-operatively.

Conclusions:

Endoscopic techniques are currently the approach of choice for the treatment of such tumours of the sinonasal cavity and pterygomaxillary and infratemporal regions. The size of the lesion did not contraindicate endoscopic sinonasal surgery as a curative treatment.
Xylometazoline hydrochloride 0.1 per cent versus physiological saline in nasal surgical aftercare: a randomised, single-blinded, comparative clinical trial
Authors: Humphreys M R , Grant D , McKean S A , Eng C Y , Townend J , Evans A S
Published: April 2008

Objectives:

A variety of topical preparations are used for symptomatic relief following nasal surgery. The aim of this study was to compare the effect of two commonly used products on patient symptom scores following nasal surgery.

Design:

Randomised, single-blinded, comparative clinical trial.

Setting:

A single, secondary otorhinolaryngology centre.

Participants:

One hundred and twenty patients undergoing septoplasty or functional endoscopic sinus surgery as an isolated procedure between November 2003 and January 2006. Patients undergoing additional nasal procedures were excluded, as were those requiring additional post-operative medications other than standardised analgesia.

Methods:

Following nasal surgery, patients were randomised to receive either xylometazoline hydrochloride 0.1 per cent nasal spray or a sterile physiological saline aerosol.

Main outcome measures:

Visual analogue scale symptom scores for nasal obstruction, rhinorrhoea, pain, loss of sense of smell and bleeding were assessed at day 10 post-operatively.

Results:

Post-operative symptom scores were compared between treatment groups. Overall, median pain scores were significantly higher in the xylometazoline group (p = 0.03, chi-square test). When analysed by procedure, median pain scores were significantly higher in septoplasty patients using xylometazoline (p = 0.019, chi-square test).

Conclusion:

There is no evidence to support the use of xylometazoline hydrochloride 0.1 per cent nasal spray over aerosolised physiological saline alone, following nasal surgery. Furthermore, there may be more pain associated with the post-operative use of xylometazoline.
POTBELLY SCULPTURE
Authors: Thompson Lauri McInnis , Valdez Fred
Published: April 2008

Prehistoric potbelly (boulder) sculpture has been of great interest for many decades. Most such sculptures occur in the highlands and piedmont of the Pacific Coast in Guatemala and El Salvador. The specific function and dating of the monuments has been of particular concern to researchers. This paper presents a summary of data in an attempt to place potbelly sculptures into recognizable stylistic groups that may in turn allow scholars to hypothesize their general function or functions. The excavation of a ceramic potbelly figure in northern Belize may provide hard evidence for the dating of certain potbelly styles and demonstrate the use of this style/manifestation in a mode beyond stone sculpture.
Evaluation of magma mixing and fractional crystallization using whole‐rock chemical analyses: Polytopic vector analyses
Authors: Vogel Thomas A. , Hidalgo Paulo J. , Patino Lina , Tefend Karen S. , Ehrlich Robert
Published: April 2008

Magma mixing and crystal fractionation are fundamental processes that lead to the diversity of magma compositions, but rarely are all of the major and trace element data on whole rocks used simultaneously in evaluating proposed models. Polytopic vector analysis (PVA) is an oblique factor analysis procedure designed specifically to evaluate mixing or unmixing (fractional crystallization) in geologic systems using all of the analytes (major and trace elements) simultaneously. It differs from other techniques in that it not only determines the number of end‐members and their compositions, but also partitions the relative proportions of the end‐members into each sample in the data array. These samples, expressed as proportions of end‐members, can be used as input in other multivariate analyses. The purpose of this paper is to use PVA to evaluate some examples of magma mixing and fractional crystallization and use these examples as templates for more complicated systems in order to show both the strengths and the weaknesses of the approach. Five well‐constrained examples illustrate how PVA can discriminate between these two processes and provide additional petrogenetic information. Using PVA, mixing between magma types can be easily distinguished from crystal fractionation. With fractional crystallization the end‐members, generated by PVA, are the initial and final liquids and the compositions where new phases join the crystallizing assemblage.
Formation and exhumation of ultra‐high‐pressure rocks during continental collision: Role of detachment in the subduction channel
Authors: Warren Clare J. , Beaumont Christopher , Jamieson Rebecca A.
Published: April 2008

UHP rocks commonly form and exhume during the transition from oceanic subduction to continental collision. Their exhumation in subduction channels depends on the balance between down‐channel shear traction and up‐channel buoyancy. Thermal‐mechanical upper‐mantle‐scale numerical models are used to investigate how variations in material properties of the subducting continental margin affect this balance. Changes in shear traction leading to crustal decoupling/detachment are investigated by varying the onset of strain weakening, thermal parameters, and convergence velocity. Variations in buoyancy force are investigated by modifying subducted material density and volume. The model results are interpreted in terms of the exhumation number E, which expresses the role of the pressure gradient, channel thickness, effective viscosity, and subduction velocity. Peak metamorphic conditions, exhumation velocity, and timing of exhumation are temporally and spatially variable and are sensitive to the evolution of E. The models reproduce natural PTt constraints and indicate that neither slab breakoff nor surface erosion is required for UHP exhumation.
Relation of substorm onset to Harang discontinuity
Authors: Weygand James M. , McPherron R. L. , Frey H. U. , Amm O. , Kauristie K. , Viljanen A. , Koistinen A.
Published: April 2008

In this study we investigate the relation of auroral substorm onset to the Harang discontinuity (HD). Various studies have reported that the substorm onset occurs poleward, equatorward, or within the HD. The motivation for the present study is to further investigate this relation with a much larger database. Using a database of over 3700 onsets determined from auroral images taken on the IMAGE spacecraft, we statistically examine the magnetic latitude location of the onset with respect to the location of the HD. The location of the discontinuity is determined with data from the IMAGE ground magnetometer network. We define the location of the HD as the transition from relatively strong eastward to relatively strong westward equivalent ionospheric currents at the latitude of the main nightside auroral electrojet flow. Our results show that the location of 75 onsets that occurred above the IMAGE ground array about 31% occurred within 6° of latitude of the HD observed during the growth phase of the substorm and 37% occur within 5° of latitude of the HD observed during the expansion phase. We also find that 23% of the onsets occur in association with vortices of ionospheric currents observed during the growth phase. The remaining 31% of the onsets do not appear to be associated with a HD or a vortex during the growth phase. Ten of the initial 75 onsets were identified as likely pseudo breakups and not fully developed substorms. Seven of the initial 75 onsets were probably poleward boundary intensifications (PBI). This study demonstrates that approximately 2/3 of the auroral substorm onsets do not occur within or near the HD identified in the growth phase. These results do not support the prediction made by Lyons et al. (2003) that substorm auroral onset should occur within the upward field aligned current in the Harang discontinuity.
Perpendicular scattering for electron beams by the electron/electron instability in solar electron bursts
Authors: Saito Shinji , Gary S. Peter
Published: April 2008

Energy dependence of electron pitch angle distributions in solar electron bursts is studied using both particle‐in‐cell simulations of the electron/electron instability and a time‐of‐flight model for streaming electrons. The simulations show that the electron/electron instability leads to a maximum of electron pitch angle width in electron kinetic energy. The energy where the maximum appears varies with electron beam parameters. The simulations further show that the maximum electron pitch angle width increases with increasing electron beam density. The time‐of‐flight effect which leads to positive slopes in electron velocity distributions implies that the probability of electron/electron instability growth in the solar wind depends on electron kinetic energy because of the presence of an electron halo distribution. It is concluded that the electron/electron instability induced by the time‐of‐flight effect is likely to yield a maximum electron pitch angle width near 1 keV.
Oxygen minimum zone in the North Atlantic south and east of the Cape Verde Islands
Authors: Stramma Lothar , Brandt Peter , Schafstall Jens , Schott Friedrich , Fischer Jürgen , Körtzinger Arne
Published: April 2008

The open‐ocean oxygen minimum zone (OMZ) south and east of the Cape Verde Islands is studied from CTD hydrography, ADCP velocities, Argo float trajectories, and historical data, with a focus on the zonal supply and drainage paths. The strongest oxygen minimum is located north of the North Equatorial Countercurrent (NECC) at about 400 to 500‐m depth just above the boundary between Central Water and Antarctic Intermediate Water (AAIW). It is shown that the NECC, the North Equatorial Undercurrent at 4 to 6°N, and a northern branch of the NECC at 8 to 10°N are the sources for oxygen‐rich water supplied to the OMZ in summer and fall. A weak eastward NECC at 200‐m depth also exists in winter and spring as derived from Argo floats drifting at shallow levels. Historical oxygen data from 200‐m depth confirm this seasonality showing high (low) oxygen content in summer and fall (spring) within the supply paths. Compared to the strong oxygen supply at 150 to 300‐m depth, the ventilation of the OMZ at 300 to 600‐m depth is weaker. Westward drainage of oxygen‐poor water takes place north of the Guinea Dome, i.e., north of 10°N, most pronounced at 400 to 600‐m depth. In July 2006 the total eastward transport of both NECC bands above σθ = 27.1 kg m−3 at 23°W was about 13 Sv (1 Sv = 106 m3 s−1). About half of this water volume circulates within the Guinea Dome or recirculates westward north of the Guinea Dome.
Oxygen tongues and zonal currents in the equatorial Atlantic
Authors: Brandt Peter , Hormann Verena , Bourlès Bernard , Fischer Jürgen , Schott Friedrich A. , Stramma Lothar , Dengler Marcus
Published: April 2008

Equatorial zonal currents and associated oxygen distributions are studied using shipboard hydrographic data, trajectories from isopycnic floats drifting at about 300 m depth, and velocity time series from the upper 1100 m obtained at two equatorial moorings located at 35°W and 23°W. Mean profiles of zonal velocity measured by moored acoustic Doppler current profilers yielded a westward flowing Equatorial Intermediate Current (EIC) below the Equatorial Undercurrent (EUC) at both locations. The EIC consists of two westward current cores at about 250 and 450 m. The upper core of the EIC deepens by about 30 m from 23°W, where it has a mean velocity of 6 ± 2 cm s−1, to 35°W, where the mean is 5 ± 3 cm s−1. The lower core of the EIC is about twice as strong with 12 ± 1 cm s−1 at 23°W and 9 ± 2 cm s−1 at 35°W. The flow below the EUC is characterized by substantial interannual variability. From May to December 2005 a strong, zonally coherent eastward jet occurred at 300 to 350 m depth, found to be an expression of shallow stacked jets superimposed on the mean EIC. Shipboard hydrographic observations in June–July 2006 revealed the existence of a high‐oxygen tongue that can be traced from 35°W to 10°W in the depth range of the eastward jet prevailing during the preceding year. On the basis of an advection‐diffusion balance, it is suggested that the oxygen decrease from 35°W to 10°W within the oxygen tongue is mainly balanced by lateral eddy diffusivity and oxygen consumption, with diapycnal turbulent diffusivity playing only a minor role.