bluuebunny/crossref_metadata_2025 huggingface dataset:
A new assessment in North Atlantic waters of the relationship between DMS concentration and the upper mixed layer solar radiation dose
Authors: Belviso S. , Caniaux G.
Published: March 2009

The results of the POMME experiment, conducted in the northeast Atlantic Ocean in 2001, were used to explore whether dimethylsulfide (DMS) concentrations are linked to epipelagic ecosystem exposure to solar radiation as proposed by Vallina and Simó (2007). According to the seasonal variations in the DMS‐to‐dimethylsulfoniopropionate (DMSP) ratio, we found that the summer surface water concentration of DMS was, on average, threefold higher than expected from the abundance of DMSP. This is in agreement with previous observations and confirms that seasonal changes in the trophic regime, from mesotrophy in winter and spring to oligotrophy in summer, are accompanied by a relative enhancement of DMS over DMSP. However, contrary to the observations carried out at Hydrostation S in the northwest Atlantic Ocean, no strong relationship between DMS and the solar radiation dose (SRD) exists in the northeast Atlantic Ocean. From a series of sensitivity tests, where different combinations of the three parameters that drive the SRD were investigated (i.e., the solar irradiance, the law of its attenuation in the sea, and the mixed layer depth), we found that the SRD accounted for only 19% to 24% of the variance associated with monthly surface DMS concentrations. Additionally, the slope of the relationship between DMS and SRD was particularly sensitive to the choice of the irradiance attenuation law. Overall, we find that the DMS versus SRD relationship is much less significant in the northeast Atlantic Ocean than in the Sargasso Sea. In addition, we suggest a large impact of algal community structure on summer DMS concentrations in the mesotrophic coastal waters of the Mediterranean Sea. Therefore, we question the consistency between DMS versus SRD relationships at local, basin, and global scales and propose that empirical relationships relating DMS to SRD be applied with caution.
Increased dissolved terrestrial input to the coastal ocean during the last deglaciation
Authors: Klinkhammer G. P. , Mix A. C. , Haley B. A.
Published: March 2009

Here we present the first downcore results for a new paleoproxy, the Mn/Ca ratio of foraminiferal calcite, applied to sediment accumulated in the extreme Eastern Tropical North Pacific (ETNP) over the last 30,000 years. The Mn/Ca results are compared to oxygen isotopes and sea surface temperature calculated from Mg/Ca. We determined metal ratios using flow‐through time‐resolved analysis to minimize the effects of secondary mineralization. The foraminiferal species used for this study calcify at different depths. Core top ratios of these variant species change in proportion to the concentration of dissolved manganese in the water column at the depth of calcification. Since terrestrial input and oxidation reduction reactions control the levels of dissolved Mn in the oceans today, it therefore should be possible to use the Mn/Ca ratios of foraminifera as a proxy for these processes in the past. Mn/Ca of a mixed‐layer species (G. ruber) suggest that dissolved terrestrial input to the surface waters of the ETNP during the last glacial maximum was lower than today but began to increase with initial sea level rise and reached a maximum at 15 ka B.P. before coming down to present‐day levels at the end of sea level rise in the mid‐Holocene (7–5 ka). Ratios of a deeper calcifying species (N. dutertrei) mimic those of G. ruber over this same time period, consistent with shoaling of the 18°C thermocline. Mn/Ca of a benthic species (U. peregrina) does not show a maximum at 15 ka, suggesting that Mn was efficiently remineralized in the water column during deglaciation. Assuming that the period from the last glacial until the mid‐Holocene was a time of increased productivity, as elevated Mn might imply, the oxygen minimum zone (OMZ) was at least as well developed during deglaciation as it is today. Expansion of the OMZ may have contributed to the Mn/Ca trends we observe through time.
Temporal evolution of the equatorial thermocline associated with the 1991–2006 ENSO
Authors: Masuda Shuhei , Awaji Toshiyuki , Toyoda Takahiro , Shikama Yasutaka , Ishikawa Yoichi
Published: March 2009

An oceanic reanalysis data set for the period 1991–2006 has been used to investigate the temporal evolution of the thermocline depth during El Niño–Southern Oscillation (ENSO) cycles. We have examined the dynamical behavior of the thermocline depth in the central eastern equatorial basin by carrying out a detailed investigation into the water mass budget in a selected region lying east of the equatorial Pacific. The result shows that the time change in thermocline depth (i.e., the speed of the local vertical motion) caused by the meridional movement of warm water is consistent with the recharge‐oscillator theory. On the other hand, the time change associated with Bjerknes feedback via zonal mass movement seems to be linked to the development of the El Niño as often suggested by previous observational studies. The speed of the local vertical motion estimated from the meridional mass transport is negatively correlated with that estimated from the zonal mass transport and lags in time by three months. This relationship stems from the fact that rapid adjustments to changes in the surface zonal pressure gradient are observed in the equatorial basin, whereas delayed adjustments through the propagation of baroclinic Rossby waves take place in the central eastern equatorial basin. This time‐lagged relationship introduces a phase shift in the temporal evolution of the thermocline depth. The implications of these results for a better understanding and more accurate prediction of the ENSO time evolution are discussed.
Geographic variability of nitrate deposition and preservation over the Greenland Ice Sheet
Authors: Burkhart John F. , Bales Roger C. , McConnell Joseph R. , Hutterli Manuel A. , Frey Markus M.
Published: March 2009

An analysis of 96 snow pit and ice cores distributed over the Greenland ice sheet is used to determine the main drivers of variability in the preserved records of nitrate concentration. The data set provides samples from spatially distributed locations, allowing us to investigate the effect of snow accumulation rate, temperature, and sublimation on nitrate concentration. The mean ice sheet concentration in the dry snow zone (2000 ≥ mean annual sea level (masl)) is 132 ng g−1, ranging between 47 and 265 ng g−1 with a standard deviation of ±37 ng g−1. Nitrate flux varies between 1.1 and 14.7 μg cm−2 a−1 with a mean of 4 ± 2 μg cm−2 a−1. Large‐scale spatial variability exists as a result of accumulation gradients, with concentration 5% greater in the northern plateau, yet flux over the northern plateau is 30% lower than the dry snow zone as a whole. While spatially, flux appears to be more dependent on accumulation, preservation of flux shows increasing dependence on concentration with increasing accumulation. The relationship between concentration and accumulation is nonlinear, showing less dependence in the low‐accumulation regions versus high‐accumulation regions. Accumulation alone is insufficient to account for the observed variability in nitrate flux in the low‐accumulation regions, and evidence supports the need for additional components to a transfer function model for nitrate that includes photochemistry, temperature, and sublimation. Spatial variability across the ice sheet is nonuniform, and changes in nitrate concentration have occurred in some regions at a greater rate than others. While the data support that overall the ice sheet acts as an archive of paleoatmospheric concentration despite the effects of postdepositional processing, one needs to consider spatial variables to properly account for trends and variability in the records. This is tested by evaluating past spatial relationships and yields the result that the significant geographic shifts with respect to reactive N concentrations have occurred over the ice sheet in the past century.
Concentric gravity waves in the mesosphere generated by deep convective plumes in the lower atmosphere near Fort Collins, Colorado
Authors: Yue Jia , Vadas Sharon L. , She Chiao‐Yao , Nakamura Takuji , Reising Steven C. , Liu Han‐Li , Stamus Pete , Krueger David A. , Lyons Walter , Li Tao
Published: March 2009

Gravity waves in the mesopause region (80–105 km) may induce perturbations in OH Meinal Band emissions at ∼87 km. These perturbations can be observed by ground‐based OH airglow imagers. In this paper, we present observations of concentric gravity waves (CGW) by the all‐sky OH imager at Yucca Ridge Field Station (40.7°N, 104.9°W) near Fort Collins, Colorado. We find that expanding rings of concentric gravity waves were observed on 9 out of 723 clear nights from 2003 to 2008. In particular, on 11 May 2004, concentric rings were observed for ∼1.5 h, with nearly perfect circular rings entirely in the field of view during the first 30 min. The centers of the concentric rings occurred at the geographic locations of two strong convective plumes which were active in the troposphere ∼1 h earlier. We measured the horizontal wavelengths and periods of these gravity waves as functions of both radius and time. These results agreed reasonably well with the internal Boussinesq gravity wave dispersion relation with an assumed zero background wind. Similarly, for the other 8 cases, strong convective plumes occurred prior to the CGW observations near the apparent center of each of the arcs or rings. For the 7 out of the 9 cases, radiosonde data were available up to z = 30–35 km. These data showed that the wind speeds from the tropopause to ∼30–35 km were smaller than ∼20–30 m/s. Because 8 of the 9 cases occurred when the total horizontal mean winds were weak and because the horizontal winds below ∼87 km were less than ∼20 m/s on 11 May 2004 (according to radiosonde and TIME‐GCM model data), we postulate that weak background horizontal winds are likely a necessary condition for gravity waves excited from convective overshooting to be observed as concentric arcs or rings in the OH layer.
Importance of carbon‐nitrogen interactions and ozone on ecosystem hydrology during the 21st century
Authors: Felzer Benjamin S. , Cronin Timothy W. , Melillo Jerry M. , Kicklighter David W. , Schlosser C. Adam
Published: March 2009

There is evidence that increasing CO2 concentrations have reduced evapotranspiration and increased runoff through reductions in stomatal conductance during the twentieth century. While this process will continue to counteract increased evapotranspiration associated with future warming, it is highly dependent upon concurrent changes in photosynthesis, especially due to CO2 fertilization, nitrogen limitation, and ozone exposure. A new version of the Terrestrial Ecosystem Model (TEM‐Hydro) was developed to examine the effects of carbon and nitrogen on the water cycle. We used two climate models (NCAR CCSM3 and DOE PCM) and two emissions scenarios (SRES B1 and A2) to examine the effects of climate, elevated CO2, nitrogen limitation, and ozone exposure on the hydrological cycle in the eastern United States. While the direction of future runoff changes is largely dependent upon predicted precipitation changes, the effects of elevated CO2 on ecosystem function (stomatal closure and CO2 fertilization) increase runoff by 3–7%, as compared to the effects of climate alone. Consideration of nitrogen limitation and ozone damage on photosynthesis increases runoff by a further 6–11%. Failure to consider the effects of the interactions among nitrogen, ozone, and elevated CO2 may lead to significant regional underestimates of future runoff.
Patterns and magnitude of deep sea carbonate dissolution during Eocene Thermal Maximum 2 and H2, Walvis Ridge, southeastern Atlantic Ocean
Authors: Stap Lucy , Sluijs Appy , Thomas Ellen , Lourens Lucas
Published: March 2009

Eocene Thermal Maximum 2 (ETM2 or H1; ∼53.7 Ma) represents a short‐lived warming episode, associated with the injection of a large mass of 13C‐depleted carbon into the ocean‐atmosphere system. The mass of injected carbon, the extent of deep sea dissolution, and the amount of warming during ETM2 appear to be approximately half of those documented for the Paleocene‐Eocene thermal maximum (PETM, ∼55.5 Ma), but the pattern of lysocline migration during ETM2 has not yet been documented sufficiently to decipher potential differences in carbon sources and sequestration mechanisms. We present high‐resolution carbonate dissolution and bulk stable isotope records across ETM2 and the successive H2 event (∼53.6 Ma) on a common age model for four sites along the Walvis Ridge depth transect (1500 to 3600 m paleowater depth) to assess lysocline evolution. The onset of ETM2 is characterized by multiple, depth‐dependent transitions of carbonate dissolution (up to ∼96% of the total flux), associated with rapid depletions in bulk carbonate carbon (up to ∼1–1.5‰) and oxygen (up to ∼0.7–1.5‰) isotope values. H2 shows a ∼0.7‰ negative carbon isotope excursion, with a coeval decrease in δ18O of ∼0.5‰ and ∼80% of carbonate dissolution. During ETM2, the lysocline recovered within ∼30 ka. We attribute this rapid recovery to terrestrial CaCO3 neutralization through enhanced chemical weathering of carbonates in soils and rocks. According to theory, carbonate dissolution was lower after recovery than prior to ETM2, indicating carbonate ion oversaturation and a deeper position of the lysocline. Spectral analysis indicates that the changes in carbonate dissolution and δ13C values were precession paced, implying that weathering feedbacks and short‐term perturbations in the carbon cycle were important in determining early Eocene background and hyperthermal ocean [CO32−] conditions.
Biochemical characterization of GSK1070916, a potent and selective inhibitor of Aurora B and Aurora C kinases with an extremely long residence time1
Authors: Anderson Kelly , Lai Zhihong , Mcdonald Octerloney B. , Stuart J. Darren , Nartey Eldridge N. , Hardwicke Mary Ann , Newlander Ken , Dhanak Dashyant , Adams Jerry , Patrick Denis , Copeland Robert A. , Tummino Peter J. , Yang Jingsong
Published: March 2009

The Aurora kinases AurA, B and C are serine/threonine protein kinases that play essential roles in mitosis and cytokinesis. Among them, AurB is required for maintaining proper chromosome alignment, separation and segregation during mitosis, and regulating a number of critical processes involved in cytokinesis. AurB overexpression has been observed in a variety of cancer cell lines, and inhibition of AurB has been shown to induce tumour regression in mouse xenograft models. In the present study we report the enzymatic characterization of a potent and selective AurB/AurC inhibitor. GSK1070916 is a reversible and ATP-competitive inhibitor of the AurB–INCENP (inner centromere protein) enzyme. It selectively inhibits AurB–INCENP (Ki*=0.38±0.29 nM) and AurC–INCENP (Ki*=1.5±0.4 nM) over AurA–TPX2 (target protein for Xenopus kinesin-like protein 2) (Ki=490±60 nM). Inhibition of AurB–INCENP and AurC–INCENP is time-dependent, with an enzyme-inhibitor dissociation half-life of >480 min and 270±28 min respectively. The extremely slow rate of dissociation from the AurB and AurC enzymes distinguishes GSK1070916 from two other Aurora inhibitors in the clinic, AZD1152 and VX-680 (also known as MK-0457).
Sympatho-vagal responses in patients with sleep and typical vasovagal syncope
Authors: Jardine David L. , Krediet C. T. Paul , Cortelli Pietro , Frampton Christopher M. , Wieling Wouter
Published: March 2009

Sleep syncope is a recently described form of vasovagal syncope that interrupts sleep. The pathophysiology of this condition is uncertain but a ‘central’ non-baroreflex-mediated trigger has been suggested. In the present study, we tested the hypothesis that patients with sleep syncope have abnormal sympatho-vagal responses to non-baroreflex, but normal responses to baroreflex stimuli. We collected historical data from SS patients (patients with vasovagal syncope with sleep syncope; n=16) and NSS patients (patients with vasovagal syncope without sleep syncope; n=35), including demography, and triggers and symptoms during syncope. MBP (mean blood pressure), HR (heart rate) and MSNA (muscle sympathetic nerve activity) in SS patients were compared with NSS patients and matched controls (n=16) during HG (handgrip), CPTs (cold pressor tests), HUT (head-up tilting) and tilt-induced pre-syncope. Patients and controls were of similar age and gender distribution [SS patients, age 46.0±4 years (69% female); NSS patients, 47.3±4 years (63% female); controls, 43.7±5 years (69% female)]. Compared with NSS patients, SS patients reported more fainting episodes: (i) triggered by phobias (75 compared with 37%; P=0.001); (ii) while in the horizontal position (44 compared with 6%; P=0.001); and (iii) associated with abdominal symptoms (69 compared with 9%; P=0.001). Compared with controls, the MBP response to HG was attenuated in SS patients (P=0.016), and MSNA (burst frequency and incidence) responses to CPT were attenuated in both syncope groups (SS, P=0.011 and 0.003 respectively; NSS, P=0.021 and 0.049 respectively). MSNA responses to HUT did not differ. For both non-baroreflex and baroreflex responses, there were no differences in any of the MSNA indices between the syncope groups. Patients with vasovagal syncope, with or without sleep syncope, have very similar sympatho-vagal responses to both non-baroreflex and baroreflex stimuli. This is consistent with sleep syncope being a subform of vasovagal syncope. Attenuation of sympathetic responses to non-baroreflex pathways may be important in the mechanism of vasovagal syncope.
Ethical Service Delivery to Culturally and Linguistically Diverse Populations: A Specific Focus on Gay, Lesbian, Bisexual, and Transgender Populations
Authors: Masiongale Tedd
Published: March 2009

Purpose: Shifting demographics amid a growing population have given rise to a culturally and linguistically diverse client base. Professionals' recognition and understanding of effective service delivery with individuals from culturally and linguistically diverse groups is improving. Cultural competence is emerging as a necessary skill set for practitioners to deliver clinically competent services with diverse communities including the gay, lesbian, bisexual, and transgender (GLBT) population.

Method: Current literature and Internet sources were used to gather demographic information analyze policy documents related to ethical service delivery and explore current trends and recommendations for appropriate service delivery with a specific focus on the GLBT population.

Results and Conclusions: The demographic makeup of the U.S. population is rapidly changing. Professionals, especially those outside urban areas, are only beginning to understand and adapt their clinical practices to adequately serve the GLBT population. Despite some resistance to change and political maneuvering, which could be construed to contradict ethical service delivery, professionals are realizing that ethical service delivery that embraces a recognition of their own culture and that of the individuals they serve results in greater functional outcomes.
Creative, Convergent, and Social: Prospects for Mobile Computing
Authors: Wareham Jonathan D , Busquets Xavier , Austin Robert D
Published: March 2009

This paper highlights the over-arching themes salient in the rapidly converging mobile computing industry. Increasingly, the developers of mobile devices and services are looking toward exploratory, non-determinist or, user-driven development methodologies in an effort to cultivate products that consumers will consistently pay for. These include Design Thinking, Living Labs, and other forms of ethnography that embrace serendipity, playfulness, error, and other human responses that have previously rested outside the orthodoxy of technology design. Secondly, the mobile device is likely the world's foremost social computer. Mobile vendors seeking to foster the production, propagation, and consumption of content on mobile devices are increasingly viewing the challenge as a complex social phenomenon, not a merely a well-defined technology problem. Research illustrating these themes is presented.
“Quarantine Matters!”: Quotidian Relationships around Quarantine in Australia's Northern Borderlands
Authors: Muller Samantha , Power Emma R , Suchet-Pearson Sandra , Wright Sarah , Lloyd Kate
Published: March 2009

This paper investigates practices of border formation through an analysis of Australia's quarantine processes. We use the work of the Australian Quarantine and Inspection Service (AQIS), through the Northern Australia Quarantine Strategy (NAQS), to interrogate the ways in which borders are made and remade in daily life. By exploring quotidian practices of quarantine we argue that borders are the sites of complex and fluid relationships that are constantly being renegotiated as multiple active agents cohabit, contest, belong, and exclude. We find that quarantine borders are constantly being (re)made by forces outside NAQS's control, including through the practices of Yolngu Indigenous land-management staff and rangers, individual local residents, and diverse non-humans. Borders are revealed as active spaces produced in multiple locations at multiple scales. They are underpinned by diverse ontologies and are always more-than-human. This challenges the overly simplified view evoked within AQIS's public awareness material and the prevailing national discourse of defence, invasion, and fear. Through attention to quotidian practices of border making, different ways of understanding borderland geographies emerge.
Thinking like a trader selectively reduces individuals' loss aversion
Authors: Sokol-Hessner Peter , Hsu Ming , Curley Nina G. , Delgado Mauricio R. , Camerer Colin F. , Phelps Elizabeth A.
Published: March 2009

Research on emotion regulation has focused upon observers' ability to regulate their emotional reaction to stimuli such as affective pictures, but many other aspects of our affective experience are also potentially amenable to intentional cognitive regulation. In the domain of decision-making, recent work has demonstrated a role for emotions in choice, although such work has generally remained agnostic about the specific role of emotion. Combining psychologically-derived cognitive strategies, physiological measurements of arousal, and an economic model of behavior, this study examined changes in choices (specifically, loss aversion) and physiological correlates of behavior as the result of an intentional cognitive regulation strategy. Participants were on average more aroused per dollar to losses relative to gains, as measured with skin conductance response, and the difference in arousal to losses versus gains correlated with behavioral loss aversion across subjects. These results suggest a specific role for arousal responses in loss aversion. Most importantly, the intentional cognitive regulation strategy, which emphasized “perspective-taking,” uniquely reduced both behavioral loss aversion and arousal to losses relative to gains, largely by influencing arousal to losses. Our results confirm previous research demonstrating loss aversion while providing new evidence characterizing individual differences and arousal correlates and illustrating the effectiveness of intentional regulation strategies in reducing loss aversion both behaviorally and physiologically.
miR-375
maintains normal pancreatic α- and β-cell mass
Authors: Poy Matthew N. , Hausser Jean , Trajkovski Mirko , Braun Matthias , Collins Stephan , Rorsman Patrik , Zavolan Mihaela , Stoffel Markus
Published: March 2009

Altered growth and development of the endocrine pancreas is a frequent cause of the hyperglycemia associated with diabetes. Here we show that microRNA-375 (
miR-375
), which is highly expressed in pancreatic islets, is required for normal glucose homeostasis. Mice lacking
miR-375
(
375KO
) are hyperglycemic, exhibit increased total pancreatic α-cell numbers, fasting and fed plasma glucagon levels, and increased gluconeogenesis and hepatic glucose output. Furthermore, pancreatic β-cell mass is decreased in
375KO
mice as a result of impaired proliferation. In contrast, pancreatic islets of obese mice (
ob
/
ob
), a model of increased β-cell mass, exhibit increased expression of
miR-375
. Genetic deletion of
miR-375
from these animals (
375
/
ob
) profoundly diminished the proliferative capacity of the endocrine pancreas and resulted in a severely diabetic state. Bioinformatic analysis of transcript data from
375KO
islets revealed that
miR-375
regulates a cluster of genes controlling cellular growth and proliferation. These data provide evidence that
miR-375
is essential for normal glucose homeostasis, α- and β-cell turnover, and adaptive β-cell expansion in response to increasing insulin demand in insulin resistance.
EZH2 is a mediator of EWS/FLI1 driven tumor growth and metastasis blocking endothelial and neuro-ectodermal differentiation
Authors: Richter Günther H. S. , Plehm Stephanie , Fasan Annette , Rössler Sabine , Unland Rebekka , Bennani-Baiti Idriss M. , Hotfilder Marc , Löwel Diana , von Luettichau Irene , Mossbrugger Ilona , Quintanilla-Martinez Leticia , Kovar Heinrich , Staege Martin S. , Müller-Tidow Carsten , Burdach Stefan
Published: March 2009

Ewing tumors (ET) are highly malignant, localized in bone or soft tissue, and are molecularly defined by ews/ets translocations. DNA microarray analysis revealed a relationship of ET to both endothelium and fetal neural crest. We identified expression of histone methyltransferase enhancer of Zeste,Drosophila, Homolog 2 (EZH2) to be increased in ET. Suppressive activity of EZH2 maintains stemness in normal and malignant cells. Here, we found EWS/FLI1 bound to the EZH2 promoter in vivo, and induced EZH2 expression in ET and mesenchymal stem cells. Down-regulation of EZH2 by RNA interference in ET suppressed oncogenic transformation by inhibiting clonogenicity in vitro. Similarly, tumor development and metastasis was suppressed in immunodeficient Rag2−/−γC−/−mice. EZH2-mediated gene silencing was shown to be dependent on histone deacetylase (HDAC) activity. Subsequent microarray analysis of EZH2 knock down, HDAC-inhibitor treatment and confirmation in independent assays revealed an undifferentiated phenotype maintained by EZH2 in ET. EZH2 regulated stemness genes such as nerve growth factor receptor (NGFR), as well as genes involved in neuroectodermal and endothelial differentiation (EMP1, EPHB2, GFAP, and GAP43). These data suggest that EZH2 might have a central role in ET pathology by shaping the oncogenicity and stem cell phenotype of this tumor.
Enrichment of the amino acid
l
-isovaline by aqueous alteration on CI and CM meteorite parent bodies
Authors: Glavin Daniel P. , Dworkin Jason P.
Published: March 2009

The distribution and enantiomeric composition of the 5-carbon (C
5
) amino acids found in CI-, CM-, and CR-type carbonaceous meteorites were investigated by using liquid chromatography fluorescence detection/TOF-MS coupled with
o
-phthaldialdehyde/
N
-acetyl-
l
-cysteine derivatization. A large
l
-enantiomeric excess (ee) of the α-methyl amino acid isovaline was found in the CM meteorite Murchison (
l
ee
= 18.5 ± 2.6%) and the CI meteorite Orgueil (
l
ee
= 15.2 ± 4.0%). The measured value for Murchison is the largest enantiomeric excess in any meteorite reported to date, and the Orgueil measurement of an isovaline excess has not been reported previously for this or any CI meteorite. The
l
-isovaline enrichments in these two carbonaceous meteorites cannot be the result of interference from other C
5
amino acid isomers present in the samples, analytical biases, or terrestrial amino acid contamination. We observed no
l
-isovaline enrichment for the most primitive unaltered Antarctic CR meteorites EET 92042 and QUE 99177. These results are inconsistent with UV circularly polarized light as the primary mechanism for
l
-isovaline enrichment and indicate that amplification of a small initial isovaline asymmetry in Murchison and Orgueil occurred during an extended aqueous alteration phase on the meteorite parent bodies. The large asymmetry in isovaline and other α-dialkyl amino acids found in altered CI and CM meteorites suggests that amino acids delivered by asteroids, comets, and their fragments would have biased the Earth's prebiotic organic inventory with left-handed molecules before the origin of life.
Impaired recollection but spared familiarity in patients with extended hippocampal system damage revealed by 3 convergent methods
Authors: Vann Seralynne D. , Tsivilis Dimitris , Denby Christine E. , Quamme Joel R. , Yonelinas Andrew P. , Aggleton John P. , Montaldi Daniela , Mayes Andrew R.
Published: March 2009

To understand recognition memory, the detection of stimulus repetition, it first is necessary to resolve the debate between 2 fundamentally different models of recognition. Contemporary single-process models assume that recognition memory relies solely on the neural system required for the recall of prior events. Dual-process models assume that recognition comprises 2 independent forms of memory: one supports recall, and the other detects repeated stimuli by signaling their familiarity, the feeling of previous occurrence without the recall of any associated information. These 2 models were contrasted in patients who had undergone surgical removal of a colloid cyst, a condition associated with memory loss when accompanied by fornix and/or mammillary body atrophy. Comparisons were made between 2 groups of 9 patients that differed only with respect to the extent of mammillary body atrophy. Only the more atrophied group was impaired on tests of recall, but both groups showed normal recognition levels on a task that equates recall and recognition performance in normal participants. To explore the nature of this spared recognition, we estimated recall-based recognition and familiarity-based recognition using 3 distinct methods: self-report, receiver operating characteristics, and structural equation modeling. All 3 methods showed impaired recall-based recognition accompanied by intact familiarity in the most atrophied group, as predicted only by dual-process models. When structural equation modeling was applied to all 62 colloid cyst patients, the recall/familiarity dual-process model best explained the patients' memory pattern. The convergent evidence that mammillary body atrophy impairs recall but spares familiarity-based recognition appears irreconcilable with single-process models.
Prostaglandin mediates IL-23/IL-17-induced neutrophil migration in inflammation by inhibiting IL-12 and IFNγ production
Authors: Lemos Henrique P. , Grespan Renata , Vieira Silvio M. , Cunha Thiago M. , Verri Waldiceu A. , Fernandes Karla S. S. , Souto Fabricio O. , McInnes Iain B. , Ferreira Sergio H. , Liew Foo Y. , Cunha Fernando Q.
Published: March 2009

IL-23/IL-17-induced neutrophil recruitment plays a pivotal role in rheumatoid arthritis (RA). However, the mechanism of the neutrophil recruitment is obscure. Here we report that prostaglandin enhances the IL-23/IL-17-induced neutrophil migration in a murine model of RA by inhibiting IL-12 and IFN γ production. Methylated BSA (mBSA) and IL-23-induced neutrophil migration was inhibited by anti-IL-23 and anti-IL-17 antibodies, COX inhibitors, IL-12, or IFNγ but was enhanced by prostaglandin E2(PGE2). IL-23-induced IL-17 production was increased by PGE2and suppressed by COX-inhibition or IL-12. Furthermore, COX inhibition failed to reduce IL-23-induced neutrophil migration in IL-12- or IFNγ-deficient mice. IL-17-induced neutrophil migration was not affected by COX inhibitors, IL-12, or IFNγ but was inhibited by MK886 (a leukotriene synthesis inhibitor), anti-TNFα, anti-CXCL1, and anti-CXCL5 antibodies and by repertaxin (a CXCR1/2 antagonist). These treatments all inhibited mBSA- or IL-23-induced neutrophil migration. IL-17 induced neutrophil chemotaxis through a CXC chemokines-dependent pathway. Our results suggest that prostaglandin plays an important role in IL-23-induced neutrophil migration in arthritis by enhancing IL-17 synthesis and by inhibiting IL-12 and IFNγ production. We thus provide a mechanism for the pathogenic role of the IL-23/IL-17 axis in RA and also suggest an additional mechanism of action for nonsteroidal anti-inflammatory drugs.
Natural images dominate in binocular rivalry
Authors: Baker Daniel H. , Graf Erich W.
Published: March 2009

Ecological approaches to perception have demonstrated that information encoding by the visual system is informed by the natural environment, both in terms of simple image attributes like luminance and contrast, and more complex relationships corresponding to Gestalt principles of perceptual organization. Here, we ask if this optimization biases perception of visual inputs that are perceptually bistable. Using the binocular rivalry paradigm, we designed stimuli that varied in either their spatiotemporal amplitude spectra or their phase spectra. We found that noise stimuli with “natural” amplitude spectra (i.e., amplitude content proportional to 1/
f
, where
f
is spatial or temporal frequency) dominate over those with any other systematic spectral slope, along both spatial and temporal dimensions. This could not be explained by perceived contrast measurements, and occurred even though all stimuli had equal energy. Calculating the effective contrast following attenuation by a model contrast sensitivity function suggested that the strong contrast dependency of rivalry provides the mechanism by which binocular vision is optimized for viewing natural images. We also compared rivalry between natural and phase-scrambled images and found a strong preference for natural phase spectra that could not be accounted for by observer biases in a control task. We propose that this phase specificity relates to contour information, and arises either from the activity of V1 complex cells, or from later visual areas, consistent with recent neuroimaging and single-cell work. Our findings demonstrate that human vision integrates information across space, time, and phase to select the input most likely to hold behavioral relevance.
Solution to the problem of the poor cyclic fatigue resistance of bulk metallic glasses
Authors: Launey Maximilien E. , Hofmann Douglas C. , Johnson William L. , Ritchie Robert O.
Published: March 2009

The recent development of metallic glass-matrix composites represents a particular milestone in engineering materials for structural applications owing to their remarkable combination of strength and toughness. However, metallic glasses are highly susceptible to cyclic fatigue damage, and previous attempts to solve this problem have been largely disappointing. Here, we propose and demonstrate a microstructural design strategy to overcome this limitation by matching the microstructural length scales (of the second phase) to mechanical crack-length scales. Specifically, semisolid processing is used to optimize the volume fraction, morphology, and size of second-phase dendrites to confine any initial deformation (shear banding) to the glassy regions separating dendrite arms having length scales of ≈2 μm, i.e., to less than the critical crack size for failure. Confinement of the damage to such interdendritic regions results in enhancement of fatigue lifetimes and increases the fatigue limit by an order of magnitude, making these “designed” composites as resistant to fatigue damage as high-strength steels and aluminum alloys. These design strategies can be universally applied to any other metallic glass systems.
Stance, Navigation, and Reader Response in Expository Hypertext
Authors: McEneaney John E. , Li Ledong , Allen Kris , Guzniczak Lizabeth
Published: March 2009

This article reports on two studies investigating reader stance, navigation, and response in expository hypertext. Subjects in the studies included 69 and 147 adult readers prompted to adopt either an efferent or aesthetic stance when reading a 36-node expository hypertext. Reading was followed by recall and essay writing tasks. Results of the studies indicate that prompts can be designed to induce readers to adopt more efferent or aesthetic stances. Main effects for stance on navigation and the essay response measures were found. Aesthetic readers were found to attain higher levels of understanding and tended to rely more heavily on a built-in reading path that was part of the hypertext interface. Graphic analyses revealed wide variability in the navigational strategies of readers, with distinctive visual patterns that appeared to be related to reader stance. Exploratory analyses examining data collapsed across both studies suggest node size may play a role in navigation and response and may interact with reader stance. The studies suggest that navigation has an important role in online literacy transactions and that usability of online materials may be enhanced by accounting for reader variables such as stance in the design of interface elements.
Defining advantage and athletic performance: The case of Oscar Pistorius
Authors: Jones Carwyn , Wilson Cassie
Published: March 2009

Olympic style games were first held for athletes with disabilities in Rome in 1960. Today the Paralympic Games (parallel Olympics) feature competition for athletes from six disability groups, including amputee, visually impaired, and spinal cord injury. Olympic hosts, both summer and winter, are now contractually obliged to organize the Paralympics in the same venue. The size and popularity of the games have grown exponentially since their inception, but they remain largely separate from the Olympics themselves. Recently, a very successful Paralympic athlete from South Africa, Oscar Pistorius, made it clear that despite his double below‐the‐knee amputation he wanted to compete in his event (400 m) at the Olympics. Initially, however, Oscar Pistorius was prohibited from competing at any International Amateur Athletics Federation (IAAF) competition on grounds of fairness. On the basis of biomechanical and physiological evidence, the IAAF argued that his highly specialized prosthetic limbs gave him an advantage and were therefore in contravention of Rule 144.2. This rule forbids the use of any technical device (such as prosthetic limbs) that provides the user with an advantage over another athlete not using such a device. This decision was subsequently overturned by the Court of Arbitration for Sport following an appeal by Pistorius. Using this case as an example, the aim of this paper is to highlight the empirical and ethical difficulties associated with the application of the principle of fairness in sport. In particular, we discuss both the complexity of identifying the nature and size of athletic advantage and the basis for determining its validity. Moreover, we explore how similar difficulties arise when attempting to establish criteria for “relevant athletic performance”. We argue that reasonable rules and norms for competition are not simply inferred from the principle of fairness. Such rules and norms should result from careful judgements informed by scientific, conceptual, and ethical evidence, and be guided by the standards of excellence that best characterize the sport in question.
Sem1 is a functional component of the nuclear pore complex–associated messenger RNA export machinery
Authors: Faza Marius Boulos , Kemmler Stefan , Jimeno Sonia , González-Aguilera Cristina , Aguilera Andrés , Hurt Ed , Panse Vikram Govind
Published: March 2009

The evolutionarily conserved protein Sem1/Dss1 is a subunit of the regulatory particle (RP) of the proteasome, and, in mammalian cells, binds the tumor suppressor protein BRCA2. Here, we describe a new function for yeast Sem1. We show that sem1 mutants are impaired in messenger RNA (mRNA) export and transcription elongation, and induce strong transcription-associated hyper-recombination phenotypes. Importantly, Sem1, independent of the RP, is functionally linked to the mRNA export pathway. Biochemical analyses revealed that, in addition to the RP, Sem1 coenriches with components of two other multisubunit complexes: the nuclear pore complex (NPC)-associated TREX-2 complex that is required for transcription-coupled mRNA export, and the COP9 signalosome, which is involved in deneddylation. Notably, targeting of Thp1, a TREX-2 component, to the NPC is perturbed in a sem1 mutant. These findings reveal an unexpected nonproteasomal function of Sem1 in mRNA export and in prevention of transcription-associated genome instability. Thus, Sem1 is a versatile protein that might stabilize multiple protein complexes involved in diverse pathways.
Normally occurring NKG2D+CD4+ T cells are immunosuppressive and inversely correlated with disease activity in juvenile-onset lupus
Authors: Dai Zhenpeng , Turtle Cameron J. , Booth Garrett C. , Riddell Stanley R. , Gooley Theodore A. , Stevens Anne M. , Spies Thomas , Groh Veronika
Published: March 2009

The NKG2D receptor stimulates natural killer cell and T cell responses upon engagement of ligands associated with malignancies and certain autoimmune diseases. However, conditions of persistent NKG2D ligand expression can lead to immunosuppression. In cancer patients, tumor expression and shedding of the MHC class I–related chain A (MICA) ligand of NKG2D drives proliferative expansions of NKG2D+CD4+ T cells that produce interleukin-10 (IL-10) and transforming growth factor-β, as well as Fas ligand, which inhibits bystander T cell proliferation in vitro. Here, we show that increased frequencies of functionally equivalent NKG2D+CD4+ T cells are inversely correlated with disease activity in juvenile-onset systemic lupus erythematosus (SLE), suggesting that these T cells may have regulatory effects. The NKG2D+CD4+ T cells correspond to a normally occurring small CD4 T cell subset that is autoreactive, primed to produce IL-10, and clearly distinct from proinflammatory and cytolytic CD4 T cells with cytokine-induced NKG2D expression that occur in rheumatoid arthritis and Crohn's disease. As classical regulatory T cell functions are typically impaired in SLE, it may be clinically significant that the immunosuppressive NKG2D+CD4+ T cells appear functionally uncompromised in this disease.
Thymic progenitor homing and lymphocyte homeostasis are linked via S1P-controlled expression of thymic P-selectin/CCL25
Authors: Gossens Klaus , Naus Silvia , Corbel Stephane Y. , Lin Shujun , Rossi Fabio M.V. , Kast Jürgen , Ziltener Hermann J.
Published: March 2009

Thymic T cell progenitor (TCP) importation is a periodic, gated event that is dependent on the expression of functional P-selectin ligands on TCPs. Occupancy of intrathymic TCP niches is believed to negatively regulate TCP importation, but the nature of this feedback mechanism is not yet resolved. We show that P-selectin and CCL25 are periodically expressed in the thymus and are essential parts of the thymic gate-keeping mechanism. Periodicity of thymic TCP receptivity and the size of the earliest intrathymic TCP pool were dependent on the presence of functional P-selectin ligand on TCPs. Furthermore, we show that the numbers of peripheral blood lymphocytes directly affected thymic P-selectin expression and TCP receptivity. We identified sphingosine-1-phosphate (S1P) as one feedback signal that could mediate influence of the peripheral lymphocyte pool on thymic TCP receptivity. Our findings suggest a model whereby thymic TCP importation is controlled by both early thymic niche occupancy and the peripheral lymphocyte pool via S1P.
Clifton E. Barry, III: TB's strategic opponent
Authors: Maxmen Amy
Published: March 2009

Leaping from the periodic table to the petri dish, from clinical studies to policy, Clif Barry battles the obstacles involved in eradicating tuberculosis (TB) from multiple fronts.
INTERSTELLAR EXPOSURE AGES OF LARGE PRESOLAR SiC GRAINS FROM THE MURCHISON METEORITE
Authors: Gyngard Frank , Amari Sachiko , Zinner Ernst , Ott Ulrich
Published: March 2009

We report the Li isotopic compositions of nine large, greater than 5 μm, presolar SiC grains from the Murchison (CM) meteorite. Most of the SiC grains analyzed are isotopically similar in C and Si and morphologically distinct from other presolar SiC grains. Their 7Li/6Li ratios range from ∼9.3 to the solar value (∼12). The 6Li enrichments observed in the grains can only arise from galactic cosmic ray spallation off C atoms during travel through the interstellar medium (ISM) and before incorporation into the meteorite parent body. Using appropriate production rates, we calculate recoil-loss-corrected individual exposure ages of eight grains with 6Li excesses that range from 40 Myr to about 1 Gyr. The long exposure ages (>500 Myr) are consistent with calculations of grain survival lifetimes in the ISM, while the shorter ages (<100 Myr) of two grains are more consistent with previous cosmogenic noble gas studies. Although the sample size is only eight grains, there appears to be little evidence for clustering of exposure ages and no obvious correlation between exposure age and grain size.
Momentum transport in electron-dominated NSTX spherical torus plasmas
Authors: Kaye S.M. , Solomon W. , Bell R.E. , LeBlanc B.P. , Levinton F. , Menard J. , Rewoldt G. , Sabbagh S. , Wang W. , Yuh H.
Published: March 2009

The National Spherical Torus Experiment (NSTX) operates between 0.35 and 0.55 T, which, when coupled to up to 7 MW of neutral beam injection, leads to central rotation velocities in excess of 300 km s−1 and E × B shearing rates up to 1 MHz. This level of E × B shear can be up to a factor of five greater than typical linear growth rates of long-wavelength ion (e.g. ITG) modes, at least partially suppressing these instabilities. Evidence for this turbulence suppression is that the inferred diffusive ion thermal flux in NSTX H-modes is often at the neoclassical level, and thus these plasmas operate in an electron-dominated transport regime. Analysis of experiments using n = 3 magnetic fields to change plasma rotation indicate that local rotation shear influences local transport coefficients, most notably the ion thermal diffusivity, in a manner consistent with suppression of the low-k turbulence by this rotation shear. The value of the effective momentum diffusivity, as inferred from steady-state momentum balance, is found to be larger than the neoclassical value. Results of perturbative experiments indicate inward pinch velocities of up to 40 m s−1 and perturbative momentum diffusivities of up to 4 m2 s−1, which are larger by a factor of several than those values inferred from steady-state analysis. The inferred pinch velocity values are consistent with values based on theories in which low-k turbulence drives the inward momentum pinch. Thus, in NSTX while the neoclassical ion energy transport effects can be relatively high and dominate the ion energy transport, the neoclassical momentum transport effects are near zero, meaning that transport of momentum is dominated by any low-k turbulence that exists.
On the onset of type I edge localized modes
Authors: G.Y. Antar  , S.I. Krasheninnikov  , P.B. Snyder  , R.A. Moyer  , R. Pugno  , D.S. Gray
Published: March 2009

The affiliation of the first author should be corrected to read G.Y. Antar, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA, Present address: American University of Beirut, Riad El-Solh, Beirut 1107 2020, Lebanon.

The following Acknowledgment should be added: This work was supported in part by the US Department of Energy under DE-FG02-04ER54758 and DE-FC02-04ER54698.