bluuebunny/crossref_metadata_2025 huggingface dataset:
Dissecting the insecticide‐resistance‐ associated cytochrome P450 gene Cyp6g1
Authors: McCart Caroline , ffrench‐Constant Richard H
Published: March 2008

BACKGROUND: The cytochrome P450 gene Cyp6g1 is overtranscribed in all field isolates of DDT‐resistant Drosophila melanogaster (Meigen) and confers a fitness advantage when inherited via the female. Overtranscription is associated with the insertion of an Accord transposable element into the 5′ end of the resistance allele. Here the authors attempt to dissect the transcription of the P450 gene in order to understand why resistance confers an advantage rather than the expected cost.

RESULTS: Using a transgenic UAS:GAL4 reporter, the authors document the overexpression patterns of green fluorescent protein (GFP) in the fat body, midgut and Malpighian tubules driven by flies carrying the resistant 5′ construct. Knockout of Cyp6g1 via RNAi decreases both the level of Cyp6g1 transcript and the metabolism of the artificial substrate MROD (methyl ether resorufin, Sigma M1544). RNAi does not, however, significantly increase the susceptibility of susceptible flies to DDT. Finally, quantification of Cyp6g1 RNA in embryos laid by resistant females indicates that they pass on more Cyp6g1 RNA to their progeny than their susceptible counterparts.

CONCLUSION: These results help explain why the eggs and larvae of resistant females enjoy a fitness benefit rather than a cost, and suggest that the provisioning of Cyp6g1 RNA to embryos provides a direct, but uncharacterised, fitness benefit. Copyright © 2008 Society of Chemical Industry
Unusual pentagon and hexagon geometry of three isomers (no 1, 20, and 23) of fullerene C84
Authors: Khamatgalimov Ayrat R. , Luzhetskii Andrey V. , Kovalenko Valeri I.
Published: March 2008

Three isomers 23 (D2d), 1 (D2), and 20 (Td) of fullerene C84 have been investigated by PM3, HF/6‐31G*, and DFT methods with B3LYP functional at the 6‐31G and 6‐31G* levels. In this article we reveal for the first time that some distortion of hexagon (pentagon), measured as its maximal dihedral angles, caused by local molecular strains may serve as a new criterion of stability of fullerenes with closed shell. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Natural bond orbital‐based energy density analysis for correlated methods: Second‐order Møller–Plesset perturbation and coupled‐cluster singles and doubles
Authors: Imamura Yutaka , Baba Takeshi , Nakai Hiromi
Published: March 2008

Natural bond orbital‐based energy density analysis (NBO‐EDA), which split energies into atomic and bonding contributions, is proposed for correlated methods such as coupled‐cluster singles and doubles (CCSD) and second‐order Møller–Plesset (MP2) perturbation. Applying NBO‐EDA for CCSD and MP2 to ethylene and the Diels–Alder reaction, we are successful in obtaining useful knowledge regarding electron correlation of π‐ and σ‐type orbitals, and clarifying the difference of the reaction barriers and heat of reaction calculated by CCSD and MP2. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Correlation between the sensorial perception and the descriptive instrumental analysis of the tackiness of silicone elastomers
Authors: Mith Setha , Carpentier Luc , Monteil Guy
Published: March 2008

One of the objectives of sensorial metrology devices aims to substitute or to reproduce the operating of human organs with a high accuracy. The advantage of such a device is to get rid of the subjective nature of human perceptions. Thus, a probe tack test device has been developed in order to reproduce human tactile exploration, especially the perception of tackiness (or stickiness). Such a device enables, indeed, to study and to quantify mechanically the tackiness of silicone elastomers. However, tackiness can also be considered with a qualitative approach by a touch test. The resulting sensorial analysis requires the achievement of tactile experiments. The descriptive instrumental analysis and the sensorial analysis enable to establish a correlation on the phenomena of adhesion between two different ways of studying tackiness. This report shows that the sensorial perception of tackiness is not necessarily related to the “tack” force but also depends on other characteristics of tackiness, such as the energy of adhesion or the “tack” distance, which represent respectively the energy required to separate the punch from the sample and the distance between the moment when the force is negative and the moment when the probe is completely separated from the sample. Copyright © 2008 John Wiley & Sons, Ltd.
Dynamic regression hazards models for relative survival
Authors: Cortese Giuliana , Scheike Thomas H.
Published: March 2008

A natural way of modelling relative survival through regression analysis is to assume an additive form between the expected population hazard and the excess hazard due to the presence of an additional cause of mortality. Within this context, the existing approaches in the parametric, semiparametric and non‐parametric setting are compared and discussed. We study the additive excess hazards models, where the excess hazard is on additive form. This makes it possible to assess the importance of time‐varying effects for regression models in the relative survival framework. We show how recent developments can be used to make inferential statements about the non‐parametric version of the model. This makes it possible to test the key hypothesis that an excess risk effect is time varying in contrast to being constant over time. In case some covariate effects are constant, we show how the semiparametric additive risk model can be considered in the excess risk setting, providing a better and more useful summary of the data. Estimators have explicit form and inference based on a resampling scheme is presented for both the non‐parametric and semiparametric models. We also describe a new suggestion for goodness of fit of relative survival models, which consists on statistical and graphical tests based on cumulative martingale residuals. This is illustrated on the semiparametric model with proportional excess hazards. We analyze data from the TRACE study using different approaches and show the need for more flexible models in relative survival. Copyright © 2008 John Wiley & Sons, Ltd.
Expanding the repertoire of plasmids for PCR‐mediated epitope tagging in yeast
Authors: Moqtaderi Zarmik , Struhl Kevin
Published: March 2008

Epitope tagging of yeast proteins provides a convenient means of tracking proteins of interest in Western blots and immunoprecipitation experiments without the need to raise and test specific antibodies. We have constructed four plasmids for use as templates in PCR‐based epitope tagging in the yeast Saccharomyces cerevisiae. These plasmids expand the range of epitopes available in a tag–URA3–tag context to include the FLAG, HSV, V5 and VSV‐G epitopes. The cloning strategy used would be easily applicable to the construction of a similar tag–URA3–tag molecule for essentially any desired epitope. Oligonucleotides designed for PCR from one plasmid may be used interchangeably with any of the other template molecules to allow tagging with different epitopes without the need for new primer synthesis. We have tagged Tfc6 with each of the triple epitope tags and assessed the efficiency of these epitopes for chromatin immunoprecipitation (ChIP). For all the tagged alleles, ChIP occupancy signals are easily detectable at known Tfc6 target genes. These new tags provide additional options in experimental schemes requiring multiple tagged proteins. Copyright © 2008 John Wiley & Sons, Ltd.
Effects of high hydrostatic pressure on the growth and β‐carotene production of Rhodotorula glutinis
Authors: Wang Sui‐Lou , Chen De‐Jing , Deng Bai‐Wan , Wu Xiao‐Zong
Published: March 2008

The effects of high hydrostatic pressure (HHP) on the biomass and β‐carotene biosynthesis of Rhodotorula glutinis R68 were studied. After treatment with five repeated cycles at 300 MPa for 15 min, the barotolerant mutant PR68 was obtained. After 72 h of culture, the biomass of mutant PR68 was 21.6 g/l, decreased by 8.5% compared to the parental strain R68, but its β‐carotene production reached 19.4 mg/l, increased by 52.8% compared to the parental strain R68. The result of restriction fragment length polymorphism (RFLP) analysis suggested that mutant strain PR68 was likely to change in nucleic acid level, and thus enhanced β‐carotene production in this strain as a result of gene mutation induced by HHP treatment. Copyright © 2008 John Wiley & Sons, Ltd.
Appraisal of Hepatic Resection in the Treatment of Hepatocellular Carcinoma with Severe Thrombocytopenia
Authors: Sugimachi Keishi , Ikeda Yasuharu , Tomikawa Morimasa , Taketomi Akinobu , Tsukamoto Shuichi , Kawasaki Katsumi , Yamamura Shinji , Korenaga Daisuke , Maehara Yoshihiko , Takenaka Kenji
Published: March 2008

Background

Hepatic resection for hepatocellular carcinoma (HCC) patients with liver cirrhosis and severe hypersplenic thrombocytopenia is risky and controversial.

Methods

From 1989 to 2005, 341 patients underwent hepatic resection for HCC in our hospital. Of these, 15 patients were concomitant with severe thrombocytopenia (platelet count, ≤5 × 104/mm3), and their clinical outcomes were retrospectively reviewed.

Results

Among the 15 patients, 11 underwent hepatectomy alone and 4 underwent concomitant splenectomy. The mean preoperative platelet count was 4.2 ± 0.8 × 104/mm3 (range, 1.9–5 x 104/mm3). The surgical procedures performed were partial resection in five patients, subsegmentectomy in three, and segmentectomy in seven. A blood transfusion was required for 11 of 15 patients, and 8 of these received a platelet‐rich plasma transfusion. With the exception of one patient who suffered from postoperative liver failure, all the patients had an uneventful postoperative course. The 3‐year cumulative survival rate of these patients was comparable to those without thrombocytopenia.

Conclusions

Severe thrombocytopenia alone is not a contraindication for hepatectomy in patients with HCC associated with liver cirrhosis. For these patients, hepatic resection—hepatectomy alone or concomitant splenectomy—should be considered as a treatment option.
Expression of Parafibromin in Distant Metastatic Parathyroid Tumors in Patients with Advanced Secondary Hyperparathyroidism Due to Chronic Kidney Disease
Authors: Tominaga Yoshihiro , Tsuzuki Toyonori , Matsuoka Susumu , Uno Nobuaki , Sato Tetsuhiko , Shimabukuro Syuichi , Goto Norihiko , Nagasaka Takaharu , Uchida Kazuharu
Published: March 2008

Background

Recently, somatic inactivating mutations in HRPT2 have been reported in the majority of sporadic parathyroid carcinoma in primary hyperparathyroidism (HPT). Parafibromin is a tumor suppressor protein encoded by HRPT2, and loss of nuclear expression of parafibromin was found in approximately 70% of the carcinoma. In secondary HPT due to chronic kidney disease (CKD), parathyroid carcinoma is very rare and whether HRPT2 plays a role in the carcinogenesis in these cases is not clear. We evaluated the expression of parafibromin in hemodialysis patients with distant metastatic parathyroid tumors.

Methods

Between June 1973 and December 2006, 2,142 patients underwent parathyroidectomy (PTx) for secondary HPT in our department. We encountered five (0.23%) patients with distant metastatic parathyroid tumors. We evaluated the immunohistochemistry for parafibromin in eight primary parathyroid glands removed from the neck at the initial operation and/or at reoperation and seven distant metastatic tumors resected at reoperation.

Results

In only one lung metastatic parathyroid tumor, negative staining for parafibromin was detected. In the other three lung, two regional node, and one chest wall metastatic parathyroid tumor, parafibromin was strongly stained in the nuclei of the parathyroid cells. Among eight primary glands, except for one with weakly positive staining, the expression of parafibromin was detected diffusely and strongly.

Conclusion

We conclude that the inactivating mutations and/or allelic loss of the HRPT2 gene may not play a major role in parathyroid carcinogenesis in secondary HPT due to CKD, but in these cases cancer development may be associated with a heterogeneous genetic disorder.
Long‐term Follow‐up of Local Rectal Cancer Surgery by Transanal Endoscopic Microsurgery
Authors: Serra‐Aracil Xavier , Vallverdú Helena , Bombardó‐Junca Jordi , Pericay‐Pijaume Carles , Urgellés‐Bosch Joan , Navarro‐Soto Salvador
Published: March 2008

Background

In 1997 we launched a prospective program of transanal endoscopic microsurgery (TEM) for the treatment of rectal cancer.

Methods

Suitability for TEM was based on endorectal ultrasound results, classified as follows: (I) benign tumors; (II) adenocarcinomas uT0 and uT1 with uN0; (III) adenocarcinomas uT2‐ uN0, low histological grade with intention to cure; and (IV) advanced stage adenocarcinomas with palliative care

Results

Transanal endoscopic microsurgery was performed in 218 patients: 122 adenomas, and 96 adenocarcinomas: group II–72, group III–19, and group IV–5. Follow‐up was >24 months (median 59 months) in 61 patients. Nine were lost to follow‐up, and so 52 patients were studied: group II–38, group III–11, and group IV–3. The Kaplan‐Meier probability of nonrecurrence of adenocarcinoma by group was 93% in tumors in situ (Tis) and T1; and 77.8% in T2. The Kaplan‐Meier probability of survival by group was 100% in Tis and T1 and 82% in T2.

Conclusions

Rates of recurrence and long‐term survival in Tis and T1 adenocarcinomas treated with TEM are similar to those in previously published reports using conventional surgery. Further studies are required in T2 adenocarcinomas to determine a definitive strategy.
Continuous Follow‐up of Surgical Site Infections for 30 Days After Colorectal Surgery
Authors: Kobayashi Minako , Mohri Yasuhiko , Inoue Yasuhiro , Okita Yoshiki , Miki Chikao , Kusunoki Masato
Published: March 2008

Background

Surgical site infection (SSI) prolongs hospital stay, increases medical costs, and occasionally leads to mortality. Our goal was to clarify the differences in SSI incidence between our own data and the National Nosocomial Infections Surveillance (NNIS) data.

Methods

From January 2003 to December 2006, we prospectively collected surveillance data from patients who were undergoing elective colorectal resection at the Mie University Graduate School of Medicine.

Results

Three hundred fifty‐five elective colorectal resections (144 colon surgeries, 211 rectal surgeries) were included. The median patient age was 57.4 years. SSIs were identified in 60 patients. Cumulative SSI incidence was 16.9%. The average SSI onset was 8.7 days (range = 3–20 days) after operation. Nineteen patients (19/30:31.7%) developed SSI within 6 days of the operation. The incidence of SSI occurring within 6 days after the operation was 5.4%.

Conclusion

Seventeen percent of SSIs occurred despite the use of perioperative management according to the CDC guidelines. We reported a much higher SSI incidence than that in the NNIS data. However, the SSI incidence within 6 days of surgery was similar to that of the NNIS data. The difference in SSI incidence between our data and that of the NNIS range may result from the different strict surveillance periods.
Chronic, but not acute, tricyclic antidepressant treatment alleviates neuropathic allodynia after sciatic nerve cuffing in mice
Authors: Benbouzid Malika , Choucair‐Jaafar Nada , Yalcin Ipek , Waltisperger Elisabeth , Muller André , Freund‐Mercier Marie José , Barrot Michel
Published: March 2008

Antidepressant drugs act mainly by blocking the noradrenaline and/or serotonin uptake sites and require a chronic treatment. Tricyclic antidepressants are among the first line treatments clinically recommended against neuropathic pain. As observed against depression, a chronic treatment is required for a therapeutic effect. However, both in depression‐related and pain‐related research in rodents, it is difficult to design models that reproduce the clinical conditions and are sensitive to chronic but not to acute treatment by antidepressant drugs. In this study, we used a murine neuropathic pain model induced by the unilateral insertion of a polyethylene cuff around the main branch of the sciatic nerve. This model induced a long‐lasting ipsilateral mechanical allodynia. We evidenced that chronic, but not acute, treatment with the tricyclic antidepressants nortriptyline or amitriptyline suppressed the cuff‐induced mechanical allodynia. On the contrary, fluoxetine, a selective serotonin reuptake inhibitor, remained ineffective. To understand which mechanism is recruited downstream in order to alleviate the allodynia, we tested the opioid receptor antagonist naloxone, the delta‐opioid receptor antagonist naltrindole and the kappa‐opioid receptor antagonist nor‐BNI. We show that the therapeutic effect of notriptyline implicates the endogenous opioid system, in particular the delta‐ and the kappa‐opioid receptors. For comparison, we tested the anticonvulsant gabapentin and showed that it alleviates neuropathic allodynia after 3 days of treatment. Naloxone had no effect on gabapentin therapeutic benefit, showing that antidepressants and anticonvulsants alleviate neuropathic allodynia through independent mechanisms. Our work provides a clinically relevant model to understand the mechanism by which chronic antidepressant treatment can alleviate neuropathic pain.
An urokinase receptor antagonist that inhibits cell migration by blocking the formyl peptide receptor
Authors: Bifulco Katia , Longanesi-Cattani Immacolata , Gargiulo Lucia , Maglio Ornella , Cataldi Mauro , De Rosa Mario , Stoppelli Maria Patrizia , Pavone Vincenzo , Carriero Maria Vincenza
Published: March 2008

Urokinase receptor (uPAR) plays a key role in physiological and pathological processes sustained by an altered cell migration. We have developed peptides carrying amino acid substitutions along the Ser88‐Arg‐Ser‐Arg‐Tyr92 (SRSRY) uPAR chemotactic sequence. The peptide pyro glutamic acid (pGlu)‐Arg‐Glu‐Arg‐Tyr‐NH2 (pERERY‐NH2) shares the same binding site with SRSRY and competes with N‐formyl‐Met‐Leu‐Phe (fMLF) for binding to the G‐protein‐coupled N‐formyl‐peptide receptor (FPR). pERERY‐NH2 is a dose‐dependent inhibitor of both SRSRY‐ and fMLF‐directed cell migration, and prevents agonist‐induced FPR internalization and fMLF‐dependent ERK1/2 phosphorylation. pERERY‐NH2 is a new and potent uPAR inhibitor which may suggest the generation of new pharmacological treatments for pathological conditions involving increased cell migration.
Cyclooxygenase‐2 induction by adiponectin is regulated by a sphingosine kinase‐1 dependent mechanism in cardiac myocytes
Authors: Ikeda Yasumasa , Ohashi Koji , Shibata Rei , Pimentel David R. , Kihara Shinji , Ouchi Noriyuki , Walsh Kenneth
Published: March 2008

The adipose‐derived plasma protein, adiponectin (APN), has various protective effects on cardiovascular diseases. In this study, we show that endogenous APN is required for full cyclooxygenase‐2 (COX‐2) induction by ischemia‐reperfusion injury in the heart in vivo. In rat neonatal cardiac myocytes, APN‐induced COX‐2 expression was reduced by treatment with a sphingosine kinase‐1 (SphK‐1) inhibitor or siRNA targeting SphK‐1. Treatment with a sphingosine‐1‐phosphate (S1P) receptor antagonist also diminished COX‐2 expression in response to APN stimulation. These findings suggest that APN is a physiological regulator of COX‐2 signaling in the heart and that this regulation occurs in part via a SphK‐1–S1P receptor dependent mechanism in cardiac myocytes.
ON THE FUNDAMENTAL REGIONS OF A FIXED POINT FREE CONSERVATIVE HÉNON MAP
Authors: BESSA MÁRIO , ROCHA JORGE
Published: March 2008

It is well known that an orientation-preserving homeomorphism of the plane without fixed points has trivial dynamics; that is, its non-wandering set is empty and all the orbits diverge to infinity. However, orbits can diverge to infinity in many different ways (or not) giving rise to fundamental regions of divergence. Such a map is topologically equivalent to a plane translation if and only if it has only one fundamental region. We consider the conservative, orientation-preserving and fixed point free Hénon map and prove that it has only one fundamental region of divergence. Actually, we prove that there exists an area-preserving homeomorphism of the plane that conjugates this Hénon map to a translation.
Topological entropy and partially hyperbolic diffeomorphisms
Authors: HUA YONGXIA , SAGHIN RADU , XIA ZHIHONG
Published: March 2008

We consider partially hyperbolic diffeomorphisms on compact manifolds. We define the notion of the unstable and stable foliations stably carrying some unique non-trivial homologies. Under this topological assumption, we prove the following two results: if the center foliation is one-dimensional, then the topological entropy is locally a constant; and if the center foliation is two-dimensional, then the topological entropy is continuous on the set of all $C^{\infty }$ diffeomorphisms. The proof uses a topological invariant we introduced, Yomdin’s theorem on upper semi-continuity, Katok’s theorem on lower semi-continuity for two-dimensional systems, and a refined Pesin–Ruelle inequality we proved for partially hyperbolic diffeomorphisms.
GET LOST: ON THE INTERSECTION OF ENVIRONMENTAL AND INTELLECTUAL HISTORY
Authors: SCHULTEN SUSAN
Published: March 2008

I finished The Humboldt Current at noon on a glorious spring day in northern California. Sachs concludes with a call to follow the work of Alexander von Humboldt: get lost in nature, allow it to overtake you even in everyday life. So I set off from my in-laws' home in the hills of the East Bay, and made my way to the local park nestled at the top of a ridge. Just as I have for the last ten years, I passed a sign that read “No Trespassing”—a message reinforced with barbed wire. Emboldened by Sachs and the spirit of Humboldt, I defied the sign, slipped the fence, and followed a footpath to the most spectacular views of the Bay I have ever experienced. Each bend rewarded me with verdant hillsides, wildflowers, and canyons. How could I have gone so many years without taking this path?
VICTORIAN PIETY PRACTICED
Authors: O'BRIEN MICHAEL
Published: March 2008

For some time, there has been reason for imagining that we live in neo-Victorian times. We are awash in restless evangelicals, profligate of stern and apocalyptic advice. We have had praying leaders who imagine that foreigners, usually with beards, require reform and invasion. Celts threaten secession and the Union is extolled. There is much talk of families, education, and the anxieties of class. Our novels grow long and vexed, and even have plots. Historians seek the common reader and write meandering narratives, full of metaphor, which may be purchased at railway stations.
Toward Development of Artificial Viruses for Gene Therapy: A Comparative Evaluation of Viral and Non‐viral Transfection
Authors: Douglas Kimberly L.
Published: March 2008

Problems related to the safety and efficacy of gene therapies have checked the enthusiasm once surrounding this field, though it remains a promising approach for the treatment of numerous diseases. Despite the high transfection efficiencies attainable using viral vectors, manufacturing difficulties, safety concerns, and limitations related to targeting and plasmid size have prompted considerable research into the development of non‐viral vectors. Non‐viral vectors demonstrate low toxicity, low immunogenicity, and ease of manufacture. However, they have not yet achieved the transfection efficiencies displayed by viruses. The inability to explain or predict transfection efficiencies results, in part, from insufficient understanding of the intracellular processes involved in gene delivery. Increasingly, research has been undertaken to probe the processes involved in overcoming the major obstacles to vector‐mediated transfection: (1) internalization, (2) intracellular trafficking, (3) escape to the cytosol, (4) nuclear translocation, and (5) gene transcription/expression. This paper reviews and compares the pathways and techniques involved in successful viral and non‐viral transfection. In addition, this review provides evidence that non‐viral vector development has been pursued successfully thus far, producing systems capable of evading almost all major obstacles to transfection. Evaluating the abilities of non‐viral and viral vectors to overcome specific cellular barriers reveals that the greatest advantage of viral vectors may be related to viral DNA, which is transcribed considerably more efficiently than plasmid DNA. Further study in this area should enable the development of non‐viral vectors that transfect as efficiently as viral vectors.
Impact of the Three Gorges Dam water storage on the Yangtze River outflow into the East China Sea
Authors: Yan Xiao‐Hai , Jo Young‐Heon , Jiang Lide , Wan Zhenwen , Liu W. Timothy , Li Yan , Zhan Jiemin , Du Tao
Published: March 2008

The role of the Three Gorges Dam Water Storage (TGDWS) in changing salinity in the East China Sea (ECS) near the Yangtze River Estuary (YRE) was investigated using a multi‐sensor remote sensing technique, namely the salt steric height anomaly, calculated from Sea Surface Height Anomaly (SSHA) and Sea Surface Temperature (SST) data. The patterns of the salt steric height anomaly near the YRE agreed well with the in situ Sea Surface Salinity (SSS) measurements. In order to examine the changes in stability in the mixed layer near the YRE due to TGDWS, the time series of the steric height anomaly ratio (Rs′) between heat and salt at three locations were estimated. The Rs′ was strongly associated with a coastal upwelling in the ECS, because the reduced freshwater outflow gives rise to changes of both mixed layer depth and surface current patterns off the YRE.
A crystalline‐to‐crystalline phase transition in Ca(OH)2 at 8 GPa and room temperature
Authors: Catalli K. , Shim S.‐H. , Prakapenka V. B.
Published: March 2008

X‐ray diffraction and Raman spectroscopy measurements reveal that Ca(OH)2‐portlandite transforms to a crystalline phase with an ordered OH sublattice between 8 and 14 GPa at room temperature under quasi‐hydrostatic stress conditions in an Ar pressure medium. The amorphization previously reported at 11 GPa under no pressure medium was not observed up to 26 GPa. The width and separation of the fluorescence peaks from the ruby chips embedded in Ca(OH)2 without a medium suggest that deviatoric stress is responsible for the previously observed amorphization. Our study demonstrates that the behavior of hydrous phases in the subducting slab could be sensitive to local deviatoric stresses. Together with similar reports on quartz, our observation on Ca(OH)2 indicates that deviatoric stress is an important factor to consider for P‐induced amorphization reported in a wide range of materials.
Current broadening as a mechanism for anticyclogenesis at the Northwest Corner of the North Atlantic Current
Authors: Woityra William , Rossby T.
Published: March 2008

The warm North Atlantic Current, flowing north just east of the Grand Banks, makes an abrupt turn to the east near 51°N. As the waters flow through this region, known as the Northwest Corner, the current broadens and weakens, effectively splitting into two zonal yet variable flows forming what is generally known as the Subpolar Front. The Northwest Corner also has the curious property that it expands and expels anticyclonic vortices on a quasi‐regular basis, approximately every 2‐1/2 months. Using an energy budget approach we show that this anticyclogenesis can be accounted for in terms of a kinetic energy convergence due to the broadening of the flow as it passes through the region. The principal export route for the newly formed eddies appears to be density‐driven subduction, i.e. sinking, driven by severe heat‐loss due to the exposed position of these warm waters in the southern Labrador Sea.
Solar cycle warming at the Earth's surface in NCEP and ERA‐40 data: A linear discriminant analysis
Authors: Tung Ka Kit , Camp Charles D.
Published: March 2008

The total solar irradiance (TSI) has been measured by orbiting satellites since 1978 to vary on an 11‐year cycle by about 0.08%. Because of previous controversies on the reality of solar cycle response at the surface, in this work we discuss the robustness of the solar response with respect to analysis methods, data sets and periods used. Furthermore we concentrate on the globally coherent signal. Two reanalysis data sets are used: one is from National Centers for Environmental Prediction and National Center for Atmospheric Research (NCEP for short) and the other is the European Centre for Medium‐Range Weather Forecasts (ECMWF)'s most recent reanalysis denoted by ERA‐40. Three analysis methods are considered, with increasing sophistication. Within each data set the analysis results are consistent with each other (i.e., each within the other's error bars), with the method of linear discriminant analysis (LDA) yielding the smallest error bar and the unfiltered global mean data yielding the largest error bar in the temperature amplitude. All three methods and both data sets are able to demonstrate that the 11‐year signal is statistically significant and attributable (i.e., related) to the solar cycle. We deduce the spatial surface pattern over the globe which best distinguishes the solar maximum years from the solar minimum years using the LDA method. The resulting warming pattern shows clearly the polar amplification of warming and the preference for continents over oceans. We propose that the magnitude of the surface warming is consistent with direct solar radiative forcing if positive feedback processes such as ice albedo, water vapor/lapse rate and cloud feedbacks, similar to some of those studied for the greenhouse warming problem, are incorporated. It does not appear to be necessary to invoke some previously proposed exotic indirect mechanisms for an explanation of the observed solar signal.
Sediment entrainment to the lee of roughness elements: Effects of vortical structures
Authors: Sutton S. L. F. , McKenna Neuman C.
Published: March 2008

This paper investigates the role of vortical structures shed by a roughness element, particularly the paired counterrotating vortices found in the element's wake, in the initiation of sand transport under conditions of both fluid and impact entrainment. Patterns of particle entrainment by fluid stress only were observed in wind tunnel studies employing narrow spanwise strips of sediment (277 μm mean diameter), which minimized dislodgement by particles transported from upwind. Composite images of the erosional patterns clearly illustrate regions of the bed where shear stress is above, equal to, and below fluid threshold in the vicinity of the roughness elements. The results clearly show that elevated shear stress allows entrainment to occur in the vicinity of the horseshoe and paired counterrotating vortices at wind speeds otherwise insufficient for entrainment on a smooth bed. Impact entrainment was observed using the same methodology, with a supply of saltators introduced to the airstream through an upwind particle feed. The grain‐borne momentum of the saltation cloud greatly reduced the influence of the vortices on the rate of entrainment. However, the vortices were seen to influence the proportion of grains entering the different modes of transport (saltation, reptation, and traction). The obstruction of the saltator's trajectory by the roughness elements allowed sand tails to form to their lee under saltation, as compared to the clean air experiments in which the sand tails did not form.
Surface water productivity and paleoceanographic implications in the Cenozoic Arctic Ocean
Authors: Knies Jochen , Mann Ute , Popp Brian N. , Stein Ruediger , Brumsack Hans‐Jürgen
Published: March 2008

Study of bulk nitrogen contents and isotopic composition in Arctic Ocean sequences (Integrated Ocean Drilling Program Expedition 302) over the past 60 Ma revealed changes in the export flux and sources of sedimentary nitrogen. The paleoproductivity calculated from the fraction of organic nitrogen to total nitrogen is distinctly lower (<20 g C m−2 a−1) during the ice‐covered Neogene compared to the ice‐free, warm, and biologically active early Paleogene (∼50–100 g C m−2 a−1). Nitrogen isotope measurements from late Paleocene to early Eocene sediments provide evidence for a stepwise stratification and nutrient depletion in surface water masses. Cyanobacterial nitrogen fixation appeared to be the main source of nutrient N in the Arctic Ocean during the early‐middle Eocene characterized by conditions of strong oxygen depletion, high nutrient N losses, and high organic carbon accumulation rates. We speculate that biological CO2 sequestration in the Arctic Ocean and enhanced organic carbon burial rates may have contributed to lower atmospheric CO2 subsequent to the early Eocene climate optimum.
Evidence for a widespread climatic anomaly at around 9.2 ka before present
Authors: Fleitmann Dominik , Mudelsee Manfred , Burns Stephen J. , Bradley Raymond S. , Kramers Jan , Matter Albert
Published: March 2008

The 8.2 ka event was triggered by a meltwater pulse (MWP) into the North Atlantic and resultant reduction of the thermohaline circulation (THC). This event was preceded by a series of at least 14 MWPs; their impact on early Holocene climate has remained almost unknown. A set of high‐quality paleoclimate records from across the Northern Hemisphere shows evidence for a widespread and significant climatic anomaly at ∼9.2 ka B.P. This event has climatic anomaly patterns very similar to the 8.2 ka B.P. event, cooling occurred at high latitudes and midlatitudes and drying took place in the northern tropics, and is concurrent with an MWP of considerable volume (∼8100 km3). As the 9.2 ka MWP occurs at a time of enhanced baseline freshwater flow into the North Atlantic, this MWP may have been, despite its relatively small volume, sufficient to weaken THC and to induce the observed climate anomaly pattern.
New Global Hydrography Derived From Spaceborne Elevation Data
Authors: Lehner Bernhard , Verdin Kristine , Jarvis Andy
Published: March 2008

To study the Earth system and to better understand the implications of global environmental change, there is a growing need for large‐scale hydrographic data sets that serve as prerequisites in a variety of analyses and applications, ranging from regional watershed and freshwater conservation planning to global hydrological, climate, biogeochemical, and land surface modeling. Yet while countless hydrographic maps exist for well‐known river basins and individual nations, there is a lack of seamless high‐quality data on large scales such as continents or the entire globe. Data for many large international basins are patchy, and remote areas are often poorly mapped.

In response to these limitations, a team of scientists has developed data and created maps of the world's rivers that provide the research community with more reliable information about where streams and watersheds occur on the Earth's surface and how water drains the landscape. The new product, known as HydroSHEDS (Hydrological Data and Maps Based on Shuttle Elevation Derivatives at Multiple Scales), provides this information at a resolution and quality unachieved by previous global data sets, such as HYDRO1k [U.S. Geological Survey (USGS), 2000].
Forest Disturbance and North American Carbon Flux
Authors: Goward Samuel N. , Masek Jeffrey G. , Cohen Warren , Moisen Gretchen , Collatz G. James , Healey Sean , Houghton R. A. , Huang Chengquan , Kennedy Robert , Law Beverly , Powell Scott , Turner David , Wulder Michael A.
Published: March 2008

North America's forests are thought to be a significant sink for atmospheric carbon. Currently, the rate of sequestration by forests on the continent has been estimated at 0.23 petagrams of carbon per year, though the uncertainty about this estimate is nearly 50%. This offsets about 13% of the fossil fuel emissions from the continent [Pacala et al., 2007]. However, the high level of uncertainty in this estimate and the scientific community's limited ability to predict the future direction of the forest carbon flux reflect a lack of detailed knowledge about the effects of forest disturbance and recovery across the continent.

The North American Carbon Program (NACP), an interagency initiative to better understand the distribution, origin, and fate of North American sources and sinks of carbon, has highlighted forest disturbance as a critical factor constraining carbon dynamics [Wofsy and Harris, 2002]. National forest inventory programs in Canada, the United States, and Mexico provide important information, but they lack the needed spatial and temporal detail to support annual estimation of carbon fluxes across the continent. To help with this, the NACP recommends that scientists use detailed remote sensing of the land surface to characterize disturbance.
The Role of Femininity and Averageness of Voice Pitch in Aesthetic Judgments of Women's Voices
Authors: Feinberg David R , DeBruine Lisa M , Jones Benedict C , Perrett David I
Published: March 2008

Although averageness is preferred in auditory stimuli (eg music) and non-face objects (eg wristwatches), exaggerated feminine characteristics are preferred to averageness in female faces. To establish whether or not men prefer femininity in female voices to average characteristics, we conducted a correlational study (study 1) to assess the relationship between voice pitch and attractiveness ratings. We found a positive linear relationship between voice pitch and attractiveness ratings. In study 2 we manipulated pitch in women's voices with low (lower than average), average, and high (higher than average) starting pitches and gauged men's preferences. Men preferred women's voices with raised pitch for all levels of starting pitch. These findings suggest that men prefer high voice pitch to average voice pitch in women's voices.
Large Manual Pointing Errors, but Accurate Verbal Reports, for Indications of Target Azimuth
Authors: Philbeck John , Sargent Jesse , Arthur Joeanna , Dopkins Steve
Published: March 2008

Many tasks have been used to probe human directional knowledge, but relatively little is known about the comparative merits of different means of indicating target azimuth. Few studies have compared action-based versus non-action-based judgments for targets encircling the observer. This comparison promises to illuminate not only the perception of azimuths in the front and rear hemispaces, but also the frames of reference underlying various azimuth judgments, and ultimately their neural underpinnings. We compared a response in which participants aimed a pointer at a nearby target, with verbal azimuth estimates. Target locations were distributed between 20° and 340°. Non-visual pointing responses exhibited large constant errors (up to −32°) that tended to increase with target eccentricity. Pointing with eyes open also showed large errors (up to −21°). In striking contrast, verbal reports were highly accurate, with constant errors rarely exceeding ±5°. Under our testing conditions, these results are not likely to stem from differences in perception-based versus action-based responses, but instead reflect the frames of reference underlying the pointing and verbal responses. When participants used the pointer to match the egocentric target azimuth rather than the exocentric target azimuth relative to the pointer, errors were reduced.
Manipulation of the mechanical properties of a virus by protein engineering
Authors: Carrasco Carolina , Castellanos Milagros , de Pablo Pedro J. , Mateu Mauricio G.
Published: March 2008

In a previous study, we showed that the DNA molecule within a spherical virus (the minute virus of mice) plays an architectural role by anisotropically increasing the mechanical stiffness of the virus. A finite element model predicted that this mechanical reinforcement is a consequence of the interaction between crystallographically visible, short DNA patches and the inner capsid wall. We have now tested this model by using protein engineering. Selected amino acid side chains have been truncated to specifically remove major interactions between the capsid and the visible DNA patches, and the effect of the mutations on the stiffness of virus particles has been measured using atomic force microscopy. The mutations do not affect the stiffness of the empty capsid; however, they significantly reduce the difference in stiffness between the DNA-filled virion and the empty capsid. The results (
i
) reveal that intermolecular interactions between individual chemical groups contribute to the mechanical properties of a supramolecular assembly and (
ii
) identify specific protein–DNA interactions as the origin of the anisotropic increase in the rigidity of a virus. This study also demonstrates that it is possible to control the mechanical properties of a protein nanoparticle by the rational application of protein engineering based on a mechanical model.
Experience is required for the maintenance and refinement of FM sweep selectivity in the developing auditory cortex
Authors: Razak Khaleel A. , Richardson Marlin D. , Fuzessery Zoltan M.
Published: March 2008

Frequency modulated (FM) sweeps are common components of vocalizations, including human speech. How developmental experience shapes neuronal selectivity for these important signals is not well understood. Here, we show that altered developmental experience with FM sweeps used in echolocation by the pallid bat leads to either a loss of sideband inhibition or millisecond delays in the timing of inhibitory inputs, both of which lead to a reduction in rate and direction selectivity in auditory cortex. FM rate selectivity develops in an experience-independent manner, but requires experience for subsequent maintenance. Direction selectivity depends on experience for both development and maintenance. Rate and direction selectivity are affected by experience over different time periods during development. Altered inhibition may be a general mechanism of experience-dependent plasticity of selectivity for vocalizations.
Bardet–Biedl syndrome proteins are required for the localization of G protein-coupled receptors to primary cilia
Authors: Berbari Nicolas F. , Lewis Jacqueline S. , Bishop Georgia A. , Askwith Candice C. , Mykytyn Kirk
Published: March 2008

Primary cilia are ubiquitous cellular appendages that provide important yet not well understood sensory and signaling functions. Ciliary dysfunction underlies numerous human genetic disorders. However, the precise defects in cilia function and the basis of disease pathophysiology remain unclear. Here, we report that the proteins disrupted in the human ciliary disorder Bardet–Biedl syndrome (BBS) are required for the localization of G protein-coupled receptors to primary cilia on central neurons. We demonstrate a lack of ciliary localization of somatostatin receptor type 3 (Sstr3) and melanin-concentrating hormone receptor 1 (Mchr1) in neurons from mice lacking the
Bbs2
or
Bbs4
gene. Because Mchr1 is involved in the regulation of feeding behavior and BBS is associated with hyperphagia-induced obesity, our results suggest that altered signaling caused by mislocalization of ciliary signaling proteins underlies the BBS phenotypes. Our results also provide a potential molecular mechanism to link cilia defects with obesity.
P-Rex2 regulates Purkinje cell dendrite morphology and motor coordination
Authors: Donald Sarah , Humby Trevor , Fyfe Ian , Segonds-Pichon Anne , Walker Simon A. , Andrews Simon R. , Coadwell W. John , Emson Piers , Wilkinson Lawrence S. , Welch Heidi C. E.
Published: March 2008

The small GTPase Rac controls cell morphology, gene expression, and reactive oxygen species formation. Manipulations of Rac activity levels in the cerebellum result in motor coordination defects, but activators of Rac in the cerebellum are unknown. P-Rex family guanine-nucleotide exchange factors activate Rac. We show here that, whereas P-Rex1 expression within the brain is widespread, P-Rex2 is specifically expressed in the Purkinje neurons of the cerebellum. We have generated P-Rex2
−/−
and P-Rex1
−/−
/P-Rex2
−/−
mice, analyzed their Purkinje cell morphology, and assessed their motor functions in behavior tests. The main dendrite is thinned in Purkinje cells of P-Rex2
−/−
pups and dendrite structure appears disordered in Purkinje cells of adult P-Rex2
−/−
and P-Rex1
−/−
/P-Rex2
−/−
mice. P-Rex2
−/−
mice show a mild motor coordination defect that progressively worsens with age and is more pronounced in females than in males. P-Rex1
−/−
/P-Rex2
−/−
mice are ataxic, with reduced basic motor activity and abnormal posture and gait, as well as impaired motor coordination even at a young age. We conclude that P-Rex1 and P-Rex2 are important regulators of Purkinje cell morphology and cerebellar function.
Human embryonic stem cell microenvironment suppresses the tumorigenic phenotype of aggressive cancer cells
Authors: Postovit Lynne-Marie , Margaryan Naira V. , Seftor Elisabeth A. , Kirschmann Dawn A. , Lipavsky Alina , Wheaton William W. , Abbott Daniel E. , Seftor Richard E. B. , Hendrix Mary J. C.
Published: March 2008

Embryonic stem cells sustain a microenvironment that facilitates a balance of self-renewal and differentiation. Aggressive cancer cells, expressing a multipotent, embryonic cell-like phenotype, engage in a dynamic reciprocity with a microenvironment that promotes plasticity and tumorigenicity. However, the cancer-associated milieu lacks the appropriate regulatory mechanisms to maintain a normal cellular phenotype. Previous work from our laboratory reported that aggressive melanoma and breast carcinoma express the embryonic morphogen Nodal, which is essential for human embryonic stem cell (hESC) pluripotency. Based on the aberrant expression of this embryonic plasticity gene by tumor cells, this current study tested whether these cells could respond to regulatory cues controlling the Nodal signaling pathway, which might be sequestered within the microenvironment of hESCs, resulting in the suppression of the tumorigenic phenotype. Specifically, we discovered that metastatic tumor cells do not express the inhibitor to Nodal, Lefty, allowing them to overexpress this embryonic morphogen in an unregulated manner. However, exposure of the tumor cells to a hESC microenvironment (containing Lefty) leads to a dramatic down-regulation in their Nodal expression concomitant with a reduction in clonogenicity and tumorigenesis accompanied by an increase in apoptosis. Furthermore, this ability to suppress the tumorigenic phenotype is directly associated with the secretion of Lefty, exclusive to hESCs, because it is not detected in other stem cell types, normal cell types, or trophoblasts. The tumor-suppressive effects of the hESC microenvironment, by neutralizing the expression of Nodal in aggressive tumor cells, provide previously unexplored therapeutic modalities for cancer treatment.
Funny Turns in Small Children
Authors: van Dorp Francoise , Simon Chantal
Published: March 2008

Small children are often brought to the GP by their parents because they have had a funny turn. The GP must make a decision on the cause of the child's funny turn and appropriate action to take. This article presents a strategy which a GP in training can use to deal with such situations and describes the major conditions which form the differential diagnosis.
Neonatal Bloodspot Screening
Authors: Simon Chantal
Published: March 2008

Neonatal bloodspot screening involves taking a small blood sample obtained by pricking a baby's heel. The blood is placed on special filter paper (formerly called the Guthrie card) and sent for analysis. The test is offered to all newborn babies in the UK and is usually carried out by the midwife when the baby is 5–8 days old. It is part of the national child health promotion programme. This article introduces the neonatal bloodspot screening test and describes the features of the important diseases that are currently screened for.