bluuebunny/crossref_metadata_2025 huggingface dataset:
Age-Related Changes in Strength, Joint Laxity, and Walking Patterns: Are They Related to Knee Osteoarthritis?
Authors: Rudolph Katherine S , Schmitt Laura C , Lewek Michael D
Published: September 2007

Background and Purpose

Aging is associated with musculoskeletal changes and altered walking patterns. These changes are common in people with knee osteoarthritis (OA) and may precipitate the development of OA. We examined age-related changes in musculoskeletal structures and walking patterns to better understand the relationship between aging and knee OA.

Methods

Forty-four individuals without OA (15 younger, 15 middle-aged, 14 older adults) and 15 individuals with medial knee OA participated. Knee laxity, quadriceps femoris muscle strength (force-generating capacity), and gait were assessed.

Results

Medial laxity was greater in the OA group, but there were no differences between the middle-aged and older control groups. Quadriceps femoris strength was less in the older control group and in the OA group. During the stance phase of walking, the OA group demonstrated less knee flexion and greater knee adduction, but there were no differences in knee motion among the control groups. During walking, the older control group exhibited greater quadriceps femoris muscle activity and the OA group used greater muscle co-contraction.

Discussion and Conclusion

Although weaker, the older control group did not use truncated motion or higher co-contraction. The maintenance of movement patterns that were similar to the subjects in the young control group may have helped to prevent development of knee OA. Further investigation is warranted regarding age-related musculoskeletal changes and their influence on the development of knee OA.
Reference Group Data for the Functional Gait Assessment
Authors: Walker Martha L , Austin Alvis G , Banke Gina M , Foxx Suzanne R , Gaetano Lynn , Gardner Laurie A , McElhiney Jill , Morris Kisiah , Penn Liz
Published: September 2007

Background and Purpose

The Functional Gait Assessment (FGA) is a clinical tool for evaluating performance in walking. The purpose of this study was to determine age-referenced norms for performance on the FGA in community-living older adults.

Subjects

Subjects were 200 adults, ages 40 to 89 years, living independently.

Methods

Each subject completed the FGA one time and was scored simultaneously by 2 testers.

Results

The intraclass correlation coefficient for interrater reliability was .93. Mean scores for the FGA ranged from 29/30 for adults in their 40s to 21/30 for adults in their 80s.

Discussion and Conclusion

Patient performance on the FGA can be compared with age-referenced norms for expected performance. Further research is needed to determine the FGA’s usefulness in tracking clinical changes or predicting falls. The FGA is a reliable test for people without disease, and it is able to detect decreases in gait performance among typical older adults.
Automated live cell imaging of green fluorescent protein degradation in individual fibroblasts
Authors: Halter Michael , Tona Alex , Bhadriraju Kiran , Plant Anne L. , Elliott John T.
Published: September 2007

To accurately interpret the data from fluorescent proteins as reporters of gene activation within living cells, it is important to understand the kinetics of the degradation of the reporter proteins. We examined the degradation kinetics over a large number (>1,000) of single, living cells from a clonal population of NIH3T3 fibroblasts that were stably transfected with a destabilized, enhanced green fluorescent protein (eGFP) reporter driven by the tenascin‐C promoter. Data collection and quantification of the fluorescence protein within a statistically significant number of individual cells over long times (14 h) by automated microscopy was facilitated by culturing cells on micropatterned arrays that confined their migration and allowed them to be segmented using phase contrast images. To measure GFP degradation rates unambiguously, protein synthesis was inhibited with cycloheximide. Results from automated live cell microscopy and image analysis indicated a wide range of cell‐to‐cell variability in the GFP fluorescence within individual cells. Degradation for this reporter was analyzed as a first order rate process with a degradation half‐life of 2.8 h. We found that GFP degradation rates were independent of the initial intensity of GFP fluorescence within cells. This result indicates that higher GFP abundance in some cells is likely due to higher rates of gene expression, because it is not due to systematically lower rates of protein degradation. The approach described in this study will assist the quantification and understanding of gene activity within live cells using fluorescent protein reporters. Published 2007 Wiley‐Liss, Inc.
The stigma of public programs: Does a separate S‐CHIP program reduce it?
Authors: Ketsche Patricia , Adams E. Kathleen , Minyard Karen , Kellenberg Rebecca
Published: September 2007

Previous studies suggest access to and satisfaction with care may be different for enrollees in S‐CHIP and Medicaid, but it is unclear whether those differences are fully explained by socioeconomic characteristics of the enrollees. We analyze access and satisfaction of three groups of children: Medicaid enrolled, S‐CHIP enrolled, and children who are income eligible for Medicaid but carry a card similar to the state's S‐CHIP children's card. Both enrollees and providers may believe that these children are enrolled in S‐CHIP despite the fact that reimbursement is through the state's Medicaid system. Results indicate that the same network of providers treat, or are perceived by families to treat, the three groups differently. They support the notion that some of the differences in satisfaction between S‐CHIP and Medicaid enrollees are related to unmeasured characteristics (for example, income) of the families in the different programs, but that programmatic identity contributes substantially to differential care experience. © 2007 by the Association for Public Policy Analysis and Management
CLASSI: A classification model for the study of sequential processes and individual differences therein
Authors: Ceulemans Eva , Van Mechelen Iven
Published: September 2007

In psychological research, one often aims at explaining individual differences in S-R profiles, that is, individual differences in the responses (R) with which people react to specific stimuli (S). To this end, researchers often postulate an underlying sequential process, which boils down to the specification of a set of mediating variables (M) and the processes that link these mediating variables to the stimuli and responses under study. Obviously, a crucial task is to chart how the individual differences in the S-R profiles are caused by individual differences in the S-M link and/or by individual differences in the M-R link. In this paper we propose a new model, called CLASSI, which was explicitly designed for this task. In particular, the key principle of CLASSI consists of reducing the S, M, and R nodes of a sequential process to a few mutually exclusive types and inducing an S-M and an M-R person typology from the data, with the S-M person types being characterized in terms of if S type then M type rules and the M-R person types in terms of if M type then R type rules. As such, the S-M and M-R person types and their associated if–then rules represent the important individual differences in the S-M and M-R links of the sequential process under study. An algorithm to fit the CLASSI model is described and evaluated in a simulation study. An application of CLASSI to data from the behavioral domain of anger and sadness is discussed. Finally, we relate CLASSI to other methods and discuss possible extensions.
Bak Foong protects dopaminergic neurons against MPTP‐induced neurotoxicity by its anti‐apoptotic activity
Authors: Liu Bin , Xie Jun Xia , Tsang Lai Ling , Rowlands Dewi Kenneth , Ho Lok Sze , Gou Yu Lin , Chung Yiu Wa , Chan Hsiao Chang
Published: September 2007

Bak Foong pill (BFP) is a well‐known traditional Chinese medicine used for treatment of various gynaecological disorders. In addition, it exerts beneficial effects on other functional systems including the central nervous system. In the present study, we have investigated the possible neuroprotective action of BFP upon the nigrostriatal dopaminergic system by examining its effect on the expression patterns of tyrosine hydroxylase (TH) and dopamine transporter (DAT) in the 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahyrdropyridine (MPTP)‐induced Parkinson's disease (PD) mouse model. MPTP significantly decreased TH and DAT mRNA levels in the striatum and midbrain of both female and male C57BL/6 mice. However, with BFP pre‐treatment mice showed a reduced neurotoxicity, with TH and DAT mRNA levels either not affected by MPTP or affected to a lesser extent in the midbrain and striatum when compared to vehicle treated animals. Possible anti‐apoptotic activity of BFP was further studied in a dopamine‐secreting neuroendocrine cell line, PC12. In this assay, MPTP elevated the expression of a pro‐apoptotic gene, Bax, while this expression was reduced by BFP pre‐treatment. Flow cytometry results also revealed that the effect of MPTP‐induced apoptosis in PC12 cell lines was significantly reduced by BFP. The present results suggest that BFP is able to protect dopaminergic neurons from neurotoxin‐induced neuronal injury with anti‐apoptotic activity being one of the possible mechanisms.
Immunological aspects of human amniotic fluid cells: Implication for normal pregnancy
Authors: Yan Wei‐Hua , Lin Aifen , Chen Xue‐Jiao , Dai Mei‐Zhen , Xu Hui‐Hui , Chen Bao‐Guo , Gan Lin‐Hong , Shi Wei‐Wu
Published: September 2007

Amniotic fluid cells (AFCs) are routinely obtained and expanded in vitro for prenatal diagnosis; nevertheless current knowledge about their properties is limited. The detailed mechanisms underlying normal pregnancies are yet to be discovered. The goal of this study was to identify the immunological aspects of AFCs including cytokine production and human leukocyte antigen (HLA) expression, and to discuss its implication for pregnancy. Eighty‐six samples of AFCs were determined for HLA expression before and after culture. Cytokine production was measured with flow cytometry in AFC culture supernatants. Treatment of interferon (IFN)‐γ on induction of HLA‐DR expression in cultured AFCs was also investigated. Data indicated that both fresh and cultured AFCs express HLA‐I, HLA‐G, but not HLA‐DR, and the cultured AFCs predominately produce the cytokine interleukin (IL)‐6. Importantly, we observed that IFN‐γ could induce HLA‐DR expression on cultured AFCs in a dose‐dependent manner. Taken together, our results indicated that AFCs are functionally active cells and are significant in pregnancy.
Vitamin A treatment induces apoptosis through an oxidant‐dependent activation of the mitochondrial pathway
Authors: Klamt Fábio , Dal‐Pizzol Felipe , Gelain Daniel Pens , Dalmolin Rodrigo Siqueira , de Oliveira Birnfeld Ramatis , Bastiani Michele , Horn Fabiana , Moreira José Cláudio Fonseca
Published: September 2007

Even though retinoids are widely used as adjuvant in chemotherapeutic interventions to improve cancer cell death, their mechanism(s) of action involves multiple overlapping pathways that remain unclear. We have previously shown that vitamin A, the natural precursor of the retinoids, induces oxidative‐dependent cytochrome c release from isolated mitochondria, suggesting a putative mechanism for apoptosis activation. Using Sertoli cells in culture, we show that retinol causes mitochondrial‐dependent apoptosis, involving oxidative stress. Apoptosis was evaluated by nuclear morphology, DNA fragmentation, and caspase‐3/7 activity. Retinol induced oxidant‐ and time‐dependent imbalance of several mitochondrial parameters, cytochrome c release and caspase‐3/7 activation, leading cells to commit apoptosis. All parameters tested were attenuated or blocked by trolox co‐administration, suggesting that retinol induces apoptosis through oxidative damage, which mitochondria plays a pivotal role.
Early‐stage apoptosis is associated with DNA‐damage‐independent ATM phosphorylation and chromatin decondensation in NIH3T3 fibroblasts
Authors: Schou Kenneth Bødtker , Schneider Linda , Christensen Søren Tvorup , Hoffmann Else Kay
Published: September 2007

Chromatin condensation and degradation of DNA into internucleosomal DNA fragments are key hallmarks of apoptosis. The phosphorylation of protein kinase ataxia telangiectasia mutated (ATM) and histone H2A.X was recently shown to occur concurrently with apoptotic DNA fragmentation. We have used immunofluorescence microscopy, Western blot analysis and alkali comet assays to show that phosphorylation of ATM in NIH3T3 fibroblasts occurs prior to apoptotic DNA fragmentation, nuclease degradation and phosphorylation of histone H2A.X in cells treated with low levels of either staurosporine (STS) or tumor necrosis factor‐α mixed with cycloheximide (TNF‐α/CHX). In extension to previous findings, ATM phosphorylation was associated with chromatin decondensation, i.e., by loss of dense foci of constitutive heterochromatin. These results suggest that chromatin is decondensed and that ATM is activated independently of DNA damage signaling pathways during the very early stages of apoptosis.
Post‐conditioning exacerbates the MnSOD immune‐reactivity after experimental cerebral global ischemia and reperfusion in the rat brain hippocampus
Authors: Nemethova Miroslava , Danielisova Viera , Gottlieb Miroslav , Burda Jozef
Published: September 2007

This study monitored the effects of sub‐lethal ischemia (post‐conditioning) applied after a previous ischemic attack by way of the MnSOD immune‐reactivity examined in CA1 and dentate gyrus of the rat hippocampus. The experimental 10 min transient cerebral ischemia was followed by 2 days of reperfusion, the rats then underwent a second ischemia (4 or 6 min post‐conditioning). MnSOD immune‐reactivity was evaluated after 5 h, 1 and 2 days. Results obtained by computer microdensitometric image analysis indicated that 4 min of ischemic post‐conditioning caused higher MnSOD immune‐reactivity than 6 min. However, higher viability of CA1 neurons after stronger (6 min) post‐conditioning when production of MnSOD is lower, as well as differences between MnSOD in CA1 and dentate gyrus indicates another mechanism switching pro‐apoptotic destination of CA1 neurons to anti‐apoptotic.
Effect of nicotine and polyaromtic hydrocarbons on cerebral endothelial cells
Authors: Hutamekalin Pilaiwanwadee , Farkas Attila E. , Orbók Anna , Wilhelm Imola , Nagyőszi Péter , Veszelka Szilvia , Deli Mária A. , Buzás Krisztina , Hunyadi‐Gulyás Éva , Medzihradszky Katalin F. , Meksuriyen Duangdeun , Krizbai István A.
Published: September 2007

The present study was designed to investigate the effect of nicotine and polyaromatic hydrocarbon compounds on cerebral endothelial cells (CECs). Nicotine treatments from 15 min to 5 h did not cause any changes in the expression and localization of principal junctional proteins. One day of treatment with a relatively high concentration of nicotine induced a decrease in the expression of the tight junction protein ZO‐1, occludin, and the adherens junction protein, cadherin. Treatment with 3 × 10−5 M phenanthrene for 24 h caused a redistribution of occludin from the Triton X‐100 insoluble to the Triton X‐100 soluble fraction. Transendothelial electrical resistance was not significantly affected by 24 h treatments with nicotine, methylanthracene or phenanthrene. However, 24 h nicotine treatment increased transendothelial permeability in CECs exposed to oxidative stress. Both nicotine and phenanthrene were able to regulate the expression of a large number of proteins as revealed by 2D electrophoresis. Our experiments suggest that tobacco smoking may affect the junctional complex of CECs, and that this effect is enhanced by oxidative stress.
The Bax lnhibitor‐1 needs a functional electron transport chain for cell death suppression
Authors: Oshima Reiko , Yoshinaga Keiko , Ihara-Ohori Yuri , Fukuda Ryouichi , Ohta Akinori , Uchimiya Hirofumi , Kawai-Yamada Maki
Published: September 2007

Bax inhibitor‐1 (BI‐1) is an evolutionarily conserved cell death suppresser in animals, yeast, and plants. In this study, yeast strains carrying single‐gene deletions were screened for factors related to cell death suppression by Arabidopsis BI‐1 (AtBI‐1). Our screen identified mutants that failed to survive Bax‐induced lethality even with AtBI‐1 coexpression (Bax suppressor). The Δcox16 strain was isolated as a BI‐1‐inactive mutant; it was disrupted in a component of the mitochondrial cytochrome c oxidase. Other mutants defective in mitochondrial electron transport showed a similar phenotype. ATP levels were markedly decreased in all these mutants, suggesting that BI‐1 requires normal electron transport activity to suppress cell death in yeast.
Localization and regulation of mouse pantothenate kinase 2
Authors: Leonardi Roberta , Zhang Yong-Mei , Lykidis Athanasios , Rock Charles O. , Jackowski Suzanne
Published: September 2007

Coenzyme A (CoA) biosynthesis is initiated by pantothenate kinase (PanK) and CoA levels are controlled through differential expression and feedback regulation of PanK isoforms. PanK2 is a mitochondrial protein in humans, but comparative genomics revealed that acquisition of a mitochondrial targeting signal was limited to primates. Human and mouse PanK2 possessed similar biochemical properties, with inhibition by acetyl‐CoA and activation by palmitoylcarnitine. Mouse PanK2 localized in the cytosol, and the expression of PanK2 was higher in human brain compared to mouse brain. Differences in expression and subcellular localization should be considered in developing a mouse model for human PanK2 deficiency.
Clinical Rounds: Intrauterine Contraception: Current Evidence‐Based Recommendations
Authors: Kelly Elizabeth K. , Rudinsky Sarah W.
Published: September 2007

A 28‐year‐old nulliparous female presented to our family planning clinic for initiation of a new contraceptive method. Her past medical history was significant for chlamydial infection at age 20, which was successfully treated with antibiotics. Her family history was essentially unknown because she was adopted as an infant. She began menstruation at 12 years old, with regular periods occurring every 28 days, lasting between 4 and 5 days each. She had no history of pelvic inflammatory disease (PID), abnormal Pap smears, or known uterine abnormalities. She had her first sexual experience at age 17, and has had a total of six partners, two within the past year. She was not in a relationship at the time of the clinical encounter. She reported sexual partnership with men only. Her contraceptive history consisted of intermittent condom use from age 17 to age 20, followed by oral contraceptives with consistent condom use recently. She stated a desire for a nonhormonal contraceptive method. Upon questioning, she reported no desire to have children within the next 5 years. After discussing her contraceptive alternatives, she opted for a copper intrauterine device (IUD). She was tested for chlamydia and gonorrhea, and the results of both tests were negative. She returned to the clinic for IUD insertion the following week. At that time, she was advised that expulsion is the most likely cause of IUD failure, and is most common in the first 3 months of insertion, usually during menstruation.1 Instructions on how to check for the IUD and its threads were offered. She was instructed to assume the device had been expelled if she is unable to find the threads after menstruation, and that alternative contraception should be used until she is able to return to the clinic. Finally, she was informed of the signs and symptoms of pelvic infection and told to seek immediate medical care upon experiencing any of them, especially within the first 3 weeks following insertion.1 Upon returning to the clinic 4 weeks after insertion, she reported complete satisfaction with the method. She was reminded that menstrual abnormalities, including spotting or longer menstrual periods, are common in the first 3 to 6 months of use, but that any serious abnormalities in her bleeding pattern after 6 months should be reported.1
Clinical Rounds: Management of Occiput Posterior Position
Authors: Hart Jocelyn , Walker Amy
Published: September 2007

A 27‐year‐old, para 1 at 40 1/7 weeks' gestation presented to the labor and delivery unit in labor. Her prenatal course was uncomplicated, and her previous obstetric history included a vaginal delivery of a full‐term 7‐pound, 9‐ounce male infant. She described her first birth as being “straightforward.” It was 10 hours in length, and she received an epidural for analgesia. Upon this admission, she stated that she had been having regular, painful contractions for the past 10 hours. Her cervix was 1 cm dilated, 50% effaced, and the fetus was at −3 station. The membranes were intact. She was experiencing intensely painful contractions every 2 to 3 minutes, and reported severe back pain and exhaustion. Leopold's maneuvers revealed small parts on the left anterior side, and the fetal back was difficult to palpate, consistent with an occiput posterior (OP) position. Per hospital protocol, she was confined to bed rest and placed on continuous fetal and uterine monitoring. Five hours after admission, her membranes ruptured spontaneously with clear fluid. The fetus was then at −2 station, and her cervix had dilated to 4 cm and was 80% effaced. She reported increased pain and requested an epidural, hoping to get some rest. After the epidural was placed, her contractions became irregular (every 3–10 min), and as a result, oxytocin augmentation was started. Approximately 1 hour later, the external uterine monitor began failing to record contractions, and an intrauterine pressure catheter was placed. Ten hours after admission, and 4 hours after oxytocin was started, her cervix had dilated to 7 cm. Despite several epidural boluses, she continued to experience severe back pain, and a belly binder was applied as a relief measure. Throughout her labor, she stayed in bed with position changes that were limited to left lateral and right lateral. Cervical dilatation did not progress beyond 7 cm, and no fetal descent occurred over the next 4 hours, despite progressive oxytocin augmentation and an adequate contraction pattern based on Montevideo units. The midwife collaborated with the attending obstetrician and a cesarean section was recommended for failure to progress. A healthy baby boy who was noted to be in direct OP position was born via cesarean section with Apgar scores of 9/9. He weighed 8 pounds, 10 ounces.
Use of the Postpartum Depression Screening Scale in a Collaborative Obstetric Practice
Authors: Mancini Felicia , Carlson Cristina , Albers Leah
Published: September 2007

Postpartum depression is a clinical depressive episode that occurs in 13% to 20% of women after birth or miscarriage. This illness has potentially devastating consequences for both mother and infant, and is thought to be highly underreported and under‐diagnosed. Our study examined the use of the Postpartum Depression Screening Scale (PDSS) in a high‐volume collaborative obstetric and midwifery practice. The prevalence of women with a positive screen for major postpartum depression in our study was 16%, which is consistent with other studies. An additional 20% of the participants had symptoms that indicated a potential postpartum depression. Obstetric clinicians were willing to use the PDSS, and 15 of 20 clinicians actively participated in the study. Women who had a positive screen at 6 weeks after birth were more likely to have not completed a high school education, be unpartnered, be exclusively bottle feeding, and have a history of depression. Two variables were statistically significant predictors of screening positively with the PDSS following logistic regression: history of depression (risk ratio, 4.8; 95% confidence interval, 4.4–5.2) and exclusive bottle feeding (risk ratio, 2.0; 95% confidence interval, 1.6–2.4).
The Role of Litigation in Midwifery Practice in the United States: Results from a Nationwide Survey of Certified Nurse‐Midwives/Certified Midwives
Authors: McCool William F. , Guidera Mamie , Hakala Sarah , Delaney Erica J.
Published: September 2007

Professional liability litigation is playing an increasing role in the practice of women's health care in this country. Although the impact of litigation on obstetricians' practices has been widely documented, data on the effect of litigation on midwifery practice are scant. The authors conducted a nationwide Web‐based survey of American College of Nurse‐Midwives (ACNM) members about the experience of being involved in litigation. The survey was completed by 600 midwives (17.5% response rate). Of those midwives completing the survey, 152 (25.3%) had been named in a lawsuit at least once during their midwifery careers. The litigation cases had been resolved for 114 (75%) of these respondents at the time of the survey. Forty‐one (36%) reported being dropped from the case, even though the litigation continued without their involvement. Another 54 individuals (47.4%) were involved in cases that were settled before going to court, and an additional 10 cases (8.8%) were dropped without a settlement. Of the nine lawsuits (7.9%) that went to court, four favored the plaintiff (3.5%) and five (4.4%) favored the defendant. Future surveys are needed to better define the relationship between the practices of midwives and medical malpractice litigation.
Miscarriage Experiences of Lesbian Couples
Authors: Wojnar Danuta
Published: September 2007

This was a descriptive phenomenological study of 10 self‐identified lesbian couples who had experienced miscarriage in the context of a committed relationship. Analysis of individual and joint open‐ended interviews revealed that the experience of miscarriage for lesbian couples must be viewed from the perspective of the difficulties surrounding conception as well as the actual pregnancy loss. The overarching theme, “We are not in control,” captures the struggles lesbian couples faced in conceiving their pregnancies and the sense of loss that accompanied miscarrying. These experiences constituted two sub‐themes: “We work so hard to get a baby” and “It hurts so bad: The sorrow of miscarriage.” Our results indicate that the experience of miscarriage is compounded by the complexities of planning and achieving pregnancy. Practitioners need to be aware of the unique perspectives lesbian couples have on pregnancy and miscarriage and remain sensitive to their unique needs. Findings may serve as an intervention framework for nurse midwives and others caring for lesbian couples after miscarriage.
Certified Nurse Midwife‐Attended Births: Trends in Washington State, 1995–2004
Authors: Bussey Carie G. , Bell Janice F. , Lydon‐Rochelle Mona T.
Published: September 2007

Nationwide, the proportion of certified nurse‐midwife (CNM)‐attended births has increased steadily. We examined trends in CNM‐attended singleton spontaneous vaginal births between 1995 and 2004 in Washington State by site of birth, payer source, and hospital birth volume. CNMs were more likely than other providers to care for women at risk for adverse outcomes based on several sociodemographic indicators. The increased rate of CNM‐attended births occurred primarily in hospitals and among both Medicaid‐ and privately‐funded births. The rate of CNM‐attended births doubled in hospitals with high birth volumes. We recommend future research designed to understand these trends.
Comparing electronic structure predictions for the ground state dissociation of vinoxy radicals
Authors: Bennett Doran I. G. , Butler Laurie J. , Werner Hans-Joachim
Published: September 2007

This paper reports a series of electronic structure calculations performed on the dissociation pathways of the vinoxy radical (CH2CHO). We use coupled-cluster with single, double, and perturbative triple excitations (CCSD(T)), complete active space self-consistent field (CASSCF), multireference configuration interaction (MRCI), and MRCI with the Davidson correction (MRCI+Q) to calculate the barrier heights of the two unimolecular dissociation pathways of this radical. The effect of state averaging on the barrier heights is investigated at the CASSCF, MRCI, and MRCI+Q levels. The change in mixing angle along the reaction path is calculated as a measure of derivative coupling and found to be insufficient to suggest nonadiabatic recrossing. We also present a new analysis of previous experimental data on the unimolecular dissociation of ground state vinoxy. In particular, an error in the internal energy distribution of vinoxy radicals reported in a previous paper is corrected and a new analysis of the experimental sensitivity to the onset energy (barrier height) for the isomerization reaction is given. Combining these studies, a final “worst case” analysis of the product branching ratio is given and a statistical model using each of the calculated transition states is found to be unable to correctly reproduce the experimental data.
Tuning of electrical characteristics in networked carbon nanotube field-effect transistors using thiolated molecules
Authors: Lee Chun Wei , Zhang Keke , Tantang H. , Lohani Anup , Mhaisalkar S. G. , Li Lain-Jong , Nagahiro T. , Tamada K. , Chen Y.
Published: September 2007

The authors examine the effects of adsorption of four thiolated molecules (HS–C10H21, HS–C11H22OH, HS–C10H20COOH, and HS–C2H4C4F9) on the electrical characteristics of single-walled carbon nanotube network FETs (SNFETs). Work function of the electrodes was measured before and after molecule adsorption. Schottky barrier energy extraction for SNFETs was also performed and the results provide direct evidence that the device characteristics of SNFETs after SAM adsorption are altered primarily due to the change in energy-level alignment between the Au and SWNTs, which thus provides an effective methodology for the tuning and performance optimization of these devices in a controllable way.
Low-temperature synthesis of homogeneous nanocrystalline cubic silicon carbide films
Authors: Cheng Qijin , Xu S.
Published: September 2007

Silicon carbide films are fabricated by inductively coupled plasma chemical vapor deposition from feedstock gases silane and methane heavily diluted with hydrogen at a low substrate temperature of300 °C. Fourier transform infrared absorption spectroscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy analyses show that homogeneous nanocrystalline cubic silicon carbide (3C-SiC) films can be synthesized at an appropriate silane fraction X[100%×silane flow(SCCM)/silane+methane flow(SCCM)] in the gas mixture. The achievement of homogeneous nanocrystalline 3C-SiC films at a low substrate temperature of300 °C is a synergy of a low deposition pressure (22 mTorr), high inductive rf power (2000 W), heavy dilution of feedstock gases silane and methane with hydrogen, and appropriate silane fractions X (X≤33%) in the gas mixture employed in our experiments.
Growth and characterization of α-Fe2O3 nanowires
Authors: Srivastava Himanshu , Tiwari Pragya , Srivastava A. K. , Nandedkar R. V.
Published: September 2007

Hematite (α-Fe2O3) nanowires have been synthesized on a large surface area by thermal oxidation of iron foil in an ozone-rich environment. The effects of annealing time, temperature, and oxidizing environment on the growth of nanowires have been systematically studied. The samples were characterized using scanning electron microscope (SEM), transmission electron microscope (TEM), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS). It was found that annealing in ozone-rich environment for 2–4 h at 700 °C yielded the best results in terms of number density and diameter of nanowires. The average diameter of the nanowires was found to be 85 nm. It was found that nanowires are bicrystal in nature with a length around 4 μm, which grows uniquely along the [110] direction.
Testing universality of the quantum Hall effect by means of the Wheatstone bridge
Authors: Schopfer F. , Poirier W.
Published: September 2007

We report on a study concerning an on-chip quantum Hall effect (QHE) circuit made of two series arrays of two Hall bars set parallel to each other. This array, the design of which is based on the quadruple connection technique, can be studied either as an RK∕i resistance standard (RK is the von Klitzing constant, i is the Hall plateau index) or as a Wheatstone bridge. Metrological characterizations were carried out by varying the temperature, the magnetic field and the bias current. In particular, by measuring the unbalance current with a cryogenic current comparator, it has been possible to compare the four quantum resistances constituting the Wheatstone bridge with a relative uncertainty, never achieved so far, of 8 parts in 1011. This work shows not only the efficiency of the multiple connection technique but also the interest of a QHE Wheatstone bridge made of Hall bars of different natures to realize QHE universality tests with attainable accuracies as low as some parts in 1012. The verification of the QHE universality property with a relative uncertainty one order of magnitude lower than that of the previous universality tests should support, as recommended by the Comité International des Poids et Mesures, the redefinition of the Système International of units based on the fundamental constants of physics.
Absolute photoluminescence quantum efficiency measurement of light-emitting thin films
Authors: Johnson Aaron R. , Lee Shu-Jen , Klein Julien , Kanicki Jerzy
Published: September 2007

We developed an integrated monochromatic excitation light source integrating sphere based detection system to accurately characterize the absolute photoluminescence quantum efficiency of commonly used polymer light emitting films without using a reference sample. Our methodology is similar to the method reported by de Mello et al. [Adv. Mater. 9, 230 (1997)] In this Note, we show that the absolute photoluminescence quantum efficiency might only be measured when an appropriate calibration of the spectral variation of the measurement system is done. This calibration is especially important when employing a short excitation wavelength (<400nm) for common silicon-based detector.
Quantum singularities in space-times with spherical and cylindrical topological defects
Authors: Pitelli Paulo M. , Letelier Patricio S.
Published: September 2007

Exact solutions of Einstein equations with null Riemman-Christoffel curvature tensor everywhere, except on a hypersurface, are studied using quantum particles obeying the Klein-Gordon equation. We consider the particular cases when the curvature is represented by a Dirac delta function with support either on a sphere or on a cylinder (spherical and cylindrical shells). In particular, we analyze the necessity of extra boundary conditions on the shells.
Ti- and Sr-rich surfaces of SrTiO3 studied by grazing incidence x-ray diffraction
Authors: Fragneto A. , De Luca G. M. , Di Capua R. , Scotti di Uccio U. , Salluzzo M. , Torrelles X. , Lee Tien-Lin , Zegenhagen J.
Published: September 2007

The structure of SrTiO3 (100) (STO) single crystal surfaces has been investigated by grazing incidence x-ray diffraction. The authors found that chemically etched STO is composed ∼75% of an ideal TiO2 surface layer and ∼25% of SrO and it is very stable when annealed in ultrahigh vacuum or in O2 at high temperatures. A monolayer of SrO, epitaxially grown by pulsed laser deposition, is found to cover only a fraction of the TiO2 layers and exhibits a 2×2 reconstruction with strong structural changes after annealing in conditions typically used for the deposition of oxides.
Phonon-limited mobility in two-dimensional semiconductors with spin-orbit coupling
Authors: Chen Lei , Ma Zhongshui , Cao J. C. , Zhang T. Y. , Zhang Chao
Published: September 2007

The authors demonstrate that the Rashba spin-orbit interaction in low-dimensional semiconductors can enhance or reduce the electron-phonon scattering rate by as much as 25%. The underlying mechanism is that the electron-phonon scattering phase space for the upper (lower) Rashba band is significantly enhanced (suppressed) by the spin-orbit interaction. While the scattering time decreases for the upper level, the mobility of the level increases due to an additional term in the electron velocity.
Increased competition for antigen during priming negatively impacts the generation of memory CD4 T cells
Authors: Blair David A. , Lefrançois Leo
Published: September 2007

The factors involved in the differentiation of memory CD4 T cells from naïve precursors are poorly understood. We developed a system to examine the effect of increased competition for antigen by CD4 T cells on the generation of memory in response to infection with a recombinant vesicular stomatitis virus. Competition was initially regulated by increasing the precursor frequency of adoptively transferred naïve T cell antigen receptor transgenic CD4 T cells. Despite robust proliferation at high precursor frequencies, memory CD4 T cells did not develop, whereas decreasing the input number of naïve CD4 T cells promoted memory development after infection. The lack of memory development was linked to reduced blastogenesis and poor effector cell induction, but not to initial recruitment or proliferation of antigen-specific CD4 T cells. To prove that availability of antigen alone could regulate memory CD4 T cell development, we used treatment with an mAb specific for the epitope recognized by the transferred CD4 T cells. At high doses, this mAb effectively inhibited the antigen-specific CD4 T cell response. However, at a very low dose of mAb, primary CD4 T cell expansion was unaffected, although memory development was dramatically reduced. Moreover, the induction of effector function was concomitantly inhibited. Thus, competition for antigen during CD4 T cell priming is a major contributing factor to the development of the memory CD4 T cell pool.
High-resolution timing of cell cycle-regulated gene expression
Authors: Rowicka Maga , Kudlicki Andrzej , Tu Benjamin P. , Otwinowski Zbyszek
Published: September 2007

The eukaryotic cell division cycle depends on an intricate sequence of transcriptional events. Using an algorithm based on maximum-entropy deconvolution, and expression data from a highly synchronized yeast culture, we have timed the peaks of expression of transcriptionally regulated cell cycle genes to an accuracy of 2 min (≈1% of the cell cycle time). The set of 1,129 cell cycle-regulated genes was identified by a comprehensive analysis encompassing all available cell cycle yeast data sets. Our results reveal distinct subphases of the cell cycle undetectable by morphological observation, as well as the precise timeline of macromolecular complex assembly during key cell cycle events.
Coupling of dispersal and aggression facilitates the rapid range expansion of a passerine bird
Authors: Duckworth Renée A. , Badyaev Alexander V.
Published: September 2007

Behaviors can facilitate colonization of a novel environment, but the mechanisms underlying this process are poorly understood. On one hand, behavioral flexibility allows for an immediate response of colonizers to novel environments, which is critical to population establishment and persistence. On the other hand, integrated sets of behaviors that display limited flexibility can enhance invasion success by coupling behaviors with dispersal strategies that are especially important during natural range expansions. Direct observations of colonization events are required to determine the mechanisms underlying changes in behavior associated with colonization, but such observations are rare. Here, we studied changes in aggression on a large temporal and spatial scale across populations of two sister taxa of bluebirds (Sialia) to show that coupling of aggression and dispersal strongly facilitated the range expansion of western bluebirds across the northwestern United States over the last 30 years. We show that biased dispersal of highly aggressive males to the invasion front allowed western bluebirds to displace less aggressive mountain bluebirds. However, once mountain bluebirds were excluded, aggression of western bluebirds decreased rapidly across consecutive generations in concordance with local selection on highly heritable aggressive behavior. Further, the observed adaptive microevolution of aggression was accelerated by the link between dispersal propensity and aggression. Importantly, our results show that behavioral changes among populations were not caused by behavioral flexibility and instead strongly implicate adaptive integration of dispersal and aggression in facilitating the ongoing and rapid reciprocal range change of these species in North America.
Rice P1B-Type Heavy-Metal ATPase, OsHMA9, Is a Metal Efflux Protein
Authors: Lee Sichul , Kim Yu-Young , Lee Youngsook , An Gynheung
Published: September 2007

P1B-type heavy-metal ATPases (HMAs) are transmembrane metal-transporting proteins that play a key role in metal homeostasis. Despite their importance, very little is known about their functions in monocot species. We report the characterization of rice (Oryza sativa) OsHMA9, a member of the P1B-type ATPase family. Semiquantitative reverse transcription-polymerase chain reaction analyses of seedlings showed that OsHMA9 expression was induced by a high concentration of copper (Cu), zinc (Zn), and cadmium. We also determined, through promoter∷β-glucuronidase analysis, that the main expression was in the vascular bundles and anthers. The OsHMA9:green fluorescence protein fusion was localized to the plasma membrane. Heterologous expression of OsHMA9 partially rescued the Cu sensitivity of the Escherichia coli copA mutant, which is defective in Cu-transporting ATPases. It did not rescue the Zn sensitivity of the zntA mutant, which is defective in Zn-transporting ATPase. To further elucidate the functional roles of OsHMA9, we isolated two independent null alleles, oshma9-1 and oshma9-2, from the T-DNA insertion population. Mutant plants exhibited the phenotype of increased sensitivity to elevated levels of Cu, Zn, and lead. These results support a role for OsHMA9 in Cu, Zn, and lead efflux from the cells. This article is the first report on the functional characterization of a P1B-type metal efflux transporter in monocots.
Transcriptional Regulation of the Respiratory Genes in the CyanobacteriumSynechocystissp. PCC 6803 during the Early Response to Glucose Feeding
Authors: Lee Sanghyeob , Ryu Jee-Youn , Kim Soo Youn , Jeon Jae-Heung , Song Ji Young , Cho Hyung-Taeg , Choi Sang-Bong , Choi Doil , de Marsac Nicole Tandeau , Park Youn-Il
Published: September 2007

The coordinated expression of the genes involved in respiration in the photosynthetic cyanobacterium Synechocystis sp. PCC 6803 during the early period of glucose (Glc) treatment is poorly understood. When photoautotrophically grown cells were supplemented with 10 mm Glc in the light or after a dark adaptation period of 14 h, significant increases in the respiratory activity, as determined by NAD(P)H turnover, respiratory O2 uptake rate, and cytosolic alkalization, were observed. At the same time, the transcript levels of 18 genes coding for enzymes associated with respiration increased with differential induction kinetics; these genes were classified into three groups based on their half-rising times. Transcript levels of the four genes gpi, zwf, pdhB, and atpB started to increase along with a net increase in NAD(P)H, while the onset of net NAD(P)H consumption coincided with an increase in those of the genes tktA, ppc, pdhD, icd, ndhD2, ndbA, ctaD1, cydA, and atpE. In contrast, the expression of the atpI/G/D/A/C genes coding for ATP synthase subunits was the slowest among respiratory genes and their expression started to accumulate only after the establishment of cytosolic alkalization. These differential effects of Glc on the transcript levels of respiratory genes were not observed by inactivation of the genes encoding the Glc transporter or glucokinase. In addition, several Glc analogs could not mimic the effects of Glc. Our findings suggest that genes encoding some enzymes involved in central carbon metabolism and oxidative phosphorylation are coordinately regulated at the transcriptional level during the switch of nutritional mode.
Phytochrome Induces Rapid PIF5 Phosphorylation and Degradation in Response to Red-Light Activation
Authors: Shen Yu , Khanna Rajnish , Carle Christine M. , Quail Peter H.
Published: September 2007

The phytochrome (phy) family of sensory photoreceptors (phyA–phyE in Arabidopsis thaliana) induces changes in target-gene expression upon light-induced translocation to the nucleus, where certain members interact with selected members of the constitutively nuclear basic helix-loop-helix transcription factor family, such as PHYTOCHROME-INTERACTING FACTOR3 (PIF3). Previous evidence indicates that the binding of the photoactivated photoreceptor molecule to PIF3 induces rapid phosphorylation of the transcription factor in the cell prior to its degradation via the ubiqitin-proteosome system. To investigate whether this apparent primary signaling mechanism can be generalized to other phy-interacting partners, we have examined the molecular behavior of a second related phy-interacting member of the basic helix-loop-helix family, PIF5, during early deetiolation, immediately following initial exposure of dark-grown seedlings to light. The data show that red light induces very rapid phosphorylation and subsequent degradation (t  1/2 < 5 min) of PIF5 via the proteosome system upon irradiation. Photobiological and genetic evidence indicates that the photoactivated phy molecule acts within 60 s to induce this phosphorylation of PIF5, and that phyA and phyB redundantly dominate this process, with phyD playing an apparently minor role. Collectively, the data support the proposal that the rapid phy-induced phosphorylation of PIF3 and PIF5 may represent the biochemical mechanism of primary signal transfer from photoactivated photoreceptor to binding partner, and that phyA and phyB (and possibly phyD) may signal to multiple, shared partners utilizing this common mechanism.
Distinct Functions for the Two PsbP-Like Proteins PPL1 and PPL2 in the Chloroplast Thylakoid Lumen of Arabidopsis
Authors: Ishihara Seiko , Takabayashi Atsushi , Ido Kunio , Endo Tsuyoshi , Ifuku Kentaro , Sato Fumihiko
Published: September 2007

PsbP, an extrinsic subunit of photosystem II (PSII), is a nuclear-encoded protein that optimizes the water-splitting reaction in vivo. In addition to PsbP, higher plants have two nuclear-encoded genes for PsbP homologs (PsbP-like proteins [PPLs]) that show significant sequence similarity to a cyanobacterial PsbP homolog (cyanoP); however, the function of PPLs in higher plants has not yet been elucidated. In this study, we characterized Arabidopsis (Arabidopsis thaliana) mutants lacking either of two PPLs, PPL1 and PPL2. Phylogenetic analysis suggests that PPL1 would be an ortholog of cyanoP, and PPL2 and PsbP may have a paralogous relationship with PPL1. Analysis on mRNA expression profiles showed that PPL1 expressed under stress conditions and PPL2 coexpressed with the subunits of chloroplast NAD(P)H dehydrogenase (NDH) complex. Consistent with these suggestions, PSII activity in a ppl1 mutant was more sensitive to high-intensity light than wild type, and the recovery of photoinhibited PSII activity was delayed in ppl1 plants. Therefore, PPL1 is required for efficient repair of photodamaged PSII. Furthermore, the stoichiometric level and activity of the chloroplast NDH complex in thylakoids were severely decreased in a ppl2 mutant, demonstrating that PPL2 is a novel thylakoid lumenal factor required for accumulation of the chloroplast NDH complex. These results suggest that during endosymbiosis and subsequent gene transfer to the host nucleus, cyanoP from ancient cyanobacteria evolved into PPL1, PPL2, and PsbP, and each of them has a distinct role in photosynthetic electron transfer in Arabidopsis.