julilili42/papers huggingface dataset:
Synthesis and Structural Characterization of 9-Azido-9-Borafluorene: Monomer and Cyclotrimer of a Borole Azide
2010-04-16

The reaction of 2,2'-dilithiobiphenyl, generated from 2,2'-dibromobiphenyl and n-BuLi, with BCl(3) using n-hexane as solvent provides a high-yielding, simple preparative route to 9-chloro-9-borafluorene 1a. This in turn can be reacted with trimethylsilyl azide to yield 9-azido-9-borafluorene 2. Compound 2 exists as a cyclic trimer in the solid state, but in dichloromethane solution the monomer can coexist with the trimer. Azide 2 is rather unstable both in the solid state and in solution, and it transforms with trace amounts of water and oxygen to the 1,3,5-tris(2-biphenylyl)cyclotriboroxane that was characterized by X-ray diffraction analysis. Addition of pyridine and t-butyl pyridine to azide 2 afford the corresponding pyridine adducts. Compound 1a as well as the Lewis base adducts of 2 have been characterized by multinuclear NMR spectroscopy, and the structures were confirmed by X-ray diffraction analysis. The structural features of azide 2 and the strong Lewis acidity of its boron center have also been investigated by computational chemistry techniques at the MP2 level of theory.
A Procedure for Measuring Latencies in Brain–Computer Interfaces
2010-04-16

Brain-computer interface (BCI) systems must process neural signals with consistent timing in order to support adequate system performance. Thus, it is important to have the capability to determine whether a particular BCI configuration (i.e., hardware and software) provides adequate timing performance for a particular experiment. This report presents a method of measuring and quantifying different aspects of system timing in several typical BCI experiments across a range of settings, and presents comprehensive measures of expected overall system latency for each experimental configuration.
Gender expression and group size: a test in a hermaphroditic and a gonochoric congeneric species of Ophryotrocha (Polychaeta)
2010-04-16

SUMMARY Hermaphroditism and gonochorism are two contrasting forms of sexuality. Hermaphroditic species are generally seen as species adapted to conditions of low density, stabilized by poor mate search efficiency and high costs of searching. They can adjust allocation of reproductive resources to each sex function in response to current social conditions, making reproduction more efficient, at least in principle. By contrast, gonochorism (separate sexes) is advantageous when mates are frequent, making it ineffective to maintain two sex functions in a single individual. This, however, also rules out the need for a flexible response to mating opportunities as known for hermaphrodites. In the hermaphroditic marine polychaete worm Ophryotrocha diadema we showed earlier that group size is assessed through a chemical cue. In this study we verified the accuracy of the response to gradients of the chemical cue used to assess group size by O. diadema by checking reduction in egg production as the group of partners increases, as expected according to sex allocation theory. Furthermore we compared the effect of such a gradient with a similar gradient in a closely related gonochoric species (O. labronica). Here sex allocation adjustment is not predicted, thus an adaptive change in egg production in response to group-size cues is not expected. In fact, our results show that the group-size effect only occurs in O. diadema and not in O. labronica. Moreover, our study provides evidence of high perceptual abilities of chemical cues in O. diadema, suggesting that perceiving social cues and adjusting sex allocation appropriately are special properties of hermaphrodites.
Paraffin Tissue Microarrays Constructed With a Cutting Board and Cutting Board Arrayer
2010-04-17

Paraffin tissue microarrays (PTMAs) are blocks of paraffin containing up to 1300 paraffin tissue core biopsies (PTCBs). Normally, these PTCBs are punched from routine paraffin tissue blocks, which contain tissues of differing thicknesses. Therefore, the PTCBs are of different lengths. In consequence, the sections of the deeper portions of the PTMA do not contain all of the desired PTCBs. To overcome this drawback, cutting boards were constructed from panels of plastic with a thickness of 4 mm. Holes were drilled into the plastic and filled completely with at least one PTCB per hole. After being trimmed to a uniform length of 4 mm, these PTCBs were pushed from the cutting board into corresponding holes in a recipient block by means of a plate with steel pins. Up to 1000 sections per PTMA were cut without any significant loss of PTCBs, thereby increasing the efficacy of the PTMA technique.
A HECT E3 ubiquitin ligase negatively regulates Arabidopsis leaf senescence through degradation of the transcription factor WRKY53
2010-04-19

Summary WRKY transcription factors play a central role in controlling leaf senescence in Arabidopsis. One important member, WRKY53, is tightly regulated by various mechanisms, and is a convergence node between senescence and pathogen responses. Using WRKY53 in a yeast two‐hybrid screen, we isolated the HECT domain E3 ubiquitin ligase UPL5. In contrast to mammals, Arabidopsis contains only seven HECT E3 ubiquitin ligases, whose targets and functions are largely unknown. In yeast cells, UPL5 interacts with WRKY53 via its leucine zipper domain, and this interaction was confirmed in the cytoplasm of plant cells by a bimolecular fluorescence complementation assay. UPL5 was able to use the WRKY53 protein as a substrate for polyubiquitination in an in vitro system, and induction of UPL5 expression by an ethanol‐inducible system in upl5 plants led to degradation of the WRKY53 protein. Expression of both genes is regulated antagonistically in response to hydrogen peroxide, jasmonic acid and plant development. Two T‐DNA insertion lines ( upl5‐1 and upl5‐2 ) showed the same senescence phenotype as WRKY53 over‐expressers. Over‐expression of WRKY53 in the upl5 background enhanced the accelerated senescence phenotype of WRKY53 over‐expressers. Therefore, we conclude that UPL5 regulates leaf senescence in Arabidopsis through degradation of WRKY53 and ensures that senescence is executed in the correct time frame.
Intermediate uveitis and arthralgia as early symptoms in Whipple's disease
2010-04-19

A 56-year-old man presented at our clinic for a second opinion regarding a diagnosis of bilateral intermediate uveitis that had resisted treatment with local and systemic corticoids for three years. The patient had recurrent episodes of red eyes and blurred vision, predominantly in the right eye. All previous diagnostic tests were unrevealing. His medical history included arthralgia, which is not normally related to intermediate uveitis, and cataract surgery on the right eye several years earlier. No history of intestinal disorders, weight loss, or fever was reported. At our first examination visual acuity was 10/100 in the right eye and 10/20 in the left eye. Many white fluffy aggregates were present in the anterior chamber (Fig. 1) and vitreous body of the right eye, along with macular edema; however, there were no signs of retinal vasculitis. The left eye showed only mild inflammation. Chest radiography showed no signs of sarcoidosis or tuberculosis. Magnetic resonance imaging of the brain was unremarkable. Under suspicion of prolonged low-grade endophthalmitis, a diagnostic vitrectomy with lentectomy was performed, and white precipitates were collected for further analysis. Surprisingly, PCR analysis of these samples revealed Tropheryma whipplei DNA, leading to the diagnosis of ocular Whipple's disease (WD). The patient then underwent a duodenal biopsy, which showed macrophages with periodic acid–Schiff-positive staining (Fig. 2). PCR analysis of this biopsy specimen and of blood samples confirmed the diagnosis of WD. Systemic antibiotic therapy was started with ceftriaxone 2 g daily for 2 weeks, followed by systemic oral application of trimethoprim/sulfamethoxazole for one year.Fig. 2.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Ocular WD can exhibit a broad diversity of inflammatory ocular signs and should therefore always be included in the differential diagnosis of anterior, intermediate, or posterior uveitis. Although anterior and posterior uveitis are frequently associated with arthralgia or arthritis, for intermediate uveitis this is a very unusual combination. Thus intermediate uveitis presenting after or together with arthralgia should lead to the differential diagnosis of WD. Importantly, Lyme disease and, if gastrointestinal signs are present, inflammatory bowel disease with migratory polyarthropathy, have to be excluded. Early detection of WD is crucial for preventing irreversible neurological damage or even a fatal outcome. Although ocular involvement in WD is very rare, arthralgia is a common early sign; clinicians should be aware that both can precede intestinal symptoms and the neurological manifestations of WD. We declare that we have no conflicts of interest.
Genetic Basis of Monogenic Forms of Parkinson Disease
2010-04-19

Abstract There has been a plethora of genetic findings in Parkinson's disease (PD) during the last decade, and mutations in an increasing number of genes are found to cause monogenic forms of this disorder. To date, we know of 15 gene loci (PARK1–15) causing either autosomal dominantly or autosomal recessively inherited forms of PD. Proteins encoded by PD‐associated genes play important roles in different cellular functions and partially interact with each other suggesting that they share common pathways that lead to neuronal degeneration. At least some of these genes may also play a direct role in the aetiology of sporadic PD, and therefore it seems likely that the cellular pathways identified in familial variants of the disorder also elucidate the molecular pathogenesis in the sporadic form. Recently, these genetic findings have begun to impact clinical practice. Here, we highlight these genetic advances, and discuss their importance for clinical practice. Key Concepts: Since both, monogenic and sporadic forms of PD, tend to share many overlapping features that include, most importantly, parkinsonism with nigrostriatal dopaminergic degeneration genetic findings imply common pathogenic mechanisms and may provide new insights in the specific molecular pathways underlying PD. Since α‐synuclein was found to be the major component of Lewy bodies in familial and sporadic cases aggregation of this protein is thought to be a crucial step in dopaminergic neurodegeneration in both, SNCA ‐linked as well as sporadic PD. LRRK2 represents the most frequent form of autosomal dominantly inherited late‐onset PD offering the possibility to study the development of the disease in a sizeable population. Presumption is rising that parkin , PINK1 and DJ‐1 which are associated with autosomal recessive forms of PD may act in a common pathway and that mutations within one of these genes imply ‘loss‐of‐function mechanism’ leading to cell death underlying mitochondrial and proteasomal dysfunction. Longitudinal studies in presymptomatic mutation carriers may reveal pre‐motor changes by clinical, biochemical or imaging methods, indicating the very early phases of neurodegeneration. Therefore, further research in this population exploring neuroprotective or preventive measures are most promising to yield first results.
Two‐stage first‐trimester screening for trisomy 21 by ultrasound assessment and biochemical testing
2010-04-20

Abstract Objectives This study was carried out to examine the performance of a contingent policy in first‐trimester screening for trisomy 21, in which the estimated risk was first derived by a combination of maternal age, fetal nuchal translucency (NT) thickness, presence/absence of the nasal bone, blood flow in the ductus venosus or flow across the tricuspid valve, and biochemical testing was carried out only in those who were found to have an intermediate risk. We also examined the performance of a policy in which the estimated risk was first derived by a combination of maternal age and biochemical testing, and ultrasound examination was carried out only in those with an intermediate risk. Methods The data for this study were derived from prospective screening for trisomy 21 in singleton pregnancies, using, as markers, a combination of maternal age, fetal NT thickness and maternal‐serum free β‐human chorionic gonadotropin (β‐hCG) and pregnancy‐associated plasma protein‐A (PAPP‐A), in a one‐stop clinic for first‐trimester assessment of risk at 11 + 0 to 13 + 6 weeks of gestation. Assessment of the fetal nasal bone, ductus venosus flow and tricuspid flow were also routinely performed by appropriately trained sonographers. The performance of different screening policies was examined. Results The study population consisted of 19 614 pregnancies with a normal karyotype or delivery of a phenotypically normal baby (euploid group) and 122 cases of trisomy 21. The best performance was achieved by a contingent policy in which first‐stage screening was based on maternal age, fetal NT thickness and either tricuspid valve or ductus venosus blood flow, followed by biochemical testing only those with an intermediate risk, of 1 in 51 to 1 in 1000 (which constituted about 20% of the total). The performance of contingent screening in which first‐stage testing relies on biochemistry was poorer than when first‐stage screening was performed by ultrasound examination because, in order to achieve the same detection rate, the false‐positive rate was twice as high. Conclusion Effective first‐trimester screening for trisomy 21 can be achieved by a contingent policy in which first‐stage testing is based on ultrasound examination and second‐stage biochemical testing is carried out in only 20% of the patients. Copyright © 2010 ISUOG. Published by John Wiley &amp; Sons, Ltd.
Severity of Staphylococcus aureus Infection of the Skin Is Associated with Inducibility of Human β-Defensin 3 but Not Human β-Defensin 2
2010-04-20

ABSTRACT Gram-positive bacteria are the predominant cause of skin infections. Antimicrobial peptides (AMPs) are believed to be of major importance in skin's innate defense against these pathogens. This study aimed at providing clinical evidence for the contribution of AMP inducibility to determining the severity of Gram-positive skin infection. Using real-time PCR, we determined the induction of human β-defensin 2 (HBD-2), HBD-3, and RNase 7 by comparing healthy and lesional mRNA levels in 32 patients with Gram-positive skin infection. We then examined whether AMP induction differed by disease severity, as measured by number of recurrences and need for surgical drainage in patients with Staphylococcus aureus -positive lesions. We found that HBD-2 and -3, but not RNase 7, mRNA expression was highly induced by Gram-positive bacterial infection in otherwise healthy skin. Less induction of HBD-3, but not HBD-2, was associated with more-severe S. aureus skin infection: HBD-3 mRNA levels were 11.4 times lower in patients with more than 6 recurrences ( P = 0.01) and 8.8 times lower in patients reporting surgical drainage ( P = 0.01) than in the respective baseline groups. This suggests that inducibility of HBD-3 influences the severity of Gram-positive skin infection in vivo . The physiological function of HBD-2 induction in this context remains unclear.
Functional Impairment of Human Myeloid Dendritic Cells during Schistosoma haematobium Infection
2010-04-20

Chronic Schistosoma infection is often characterized by a state of T cell hyporesponsiveness of the host. Suppression of dendritic cell (DC) function could be one of the mechanisms underlying this phenomenon, since Schistosoma antigens are potent modulators of dendritic cell function in vitro. Yet, it remains to be established whether DC function is modulated during chronic human Schistosoma infection in vivo. To address this question, the effect of Schistosoma haematobium infection on the function of human blood DC was evaluated. We found that plasmacytoid (pDC) and myeloid DC (mDC) from infected subjects were present at lower frequencies in peripheral blood and that mDC displayed lower expression levels of HLA-DR compared to those from uninfected individuals. Furthermore, mDC from infected subjects, but not pDC, were found to have a reduced capacity to respond to TLR ligands, as determined by MAPK signaling, cytokine production and expression of maturation markers. Moreover, the T cell activating capacity of TLR-matured mDC from infected subjects was lower, likely as a result of reduced HLA-DR expression. Collectively these data show that S. haematobium infection is associated with functional impairment of human DC function in vivo and provide new insights into the underlying mechanisms of T cell hyporesponsiveness during chronic schistosomiasis.
Open‐shop unions and product market competition
2010-04-20

Abstract Evidence on the effect of product market competition on unionized wages is mixed. In this paper we show theoretically that the result may reflect genuine heterogeneity in the response of union wages to product market conditions. For low levels of unionization, union bargaining power may actually be enhanced by market competition, as firms have more to lose when there is a strike. Using recent data from the UK, we explore interactions between the level of industry competition and unionization, and find supporting evidence for this hypothesis.
Do rotating dust stars exist in general relativity?
2010-04-20

Abstract\\nIf rotating dust stars would exist in general relativity, they would represent examples of an improbable complete balance between the attractive quasi-Newtonian force (gravitoelectricity) and the repulsive gravitomagnetism. However, nonexistence proofs are available hitherto only for some dust " stars " extending to infinity, and for isolated dust stars of a very restricted class. By analyzing the lines of constant generalized Newtonian potential U in the interior and exterior of a large class of (hypothetical) stationary and axisymmetrically rotating dust stars in general relativity , we find that the existence of such stars can be disproved as soon as minima of the potential U in the exterior vacuum region can be excluded. We present some ideas how this minimum-problem could be attacked, and we summarize the present knowledge about Newtonian and Einsteinian rotating dust systems.
2-(4-Fluorophenyl)-N-{4-[6-(4-fluorophenyl)-2,3-dihydroimidazo[2,1-b][1,3]thiazol-5-yl]pyridin-2-yl}acetamide
2010-04-20

In the crystal structure of the title compound, C(24)H(18)F(2)N(4)OS, the imidazole system makes dihedral angles of 34.3 (1) and 43.9 (1)°, respectively, with the directly attached 4-fluoro-phenyl and pyridine rings. The crystal structure is stabilized by inter-molecular N-H⋯N hydrogen bonding and by an intra-molecular C-H⋯O hydrogen inter-action. The F atom of the 2-(4-fluoro-phen-yl) group is disordered over two positions with site-occupancy factors of 0.75 and 0.25.
Non-archimedean canonical measures on abelian varieties
2010-04-21

Abstract For a closed d -dimensional subvariety X of an abelian variety A and a canonically metrized line bundle L on A , Chambert-Loir has introduced measures c 1 ( L ∣ X ) ∧ d on the Berkovich analytic space associated to A with respect to the discrete valuation of the ground field. In this paper, we give an explicit description of these canonical measures in terms of convex geometry. We use a generalization of the tropicalization related to the Raynaud extension of A and Mumford’s construction. The results have applications to the equidistribution of small points.
Variable accretion as a mechanism for brightness variations in T Tauri S
2010-04-21

\\n Context. The southern “infrared companion” of T Tau is known to show strong photometric variations of several magnitudes on timescales of years, as well as more modest 1 mag variations on timescales as short as one week. The physical mechanism driving these variations is debated, intrinsic luminosity variations due to a variable accretion rate were initially proposed, but later challenged in favor of apparent fluctuations due to time-variable foreground extinction.\\n Aims. We seek to investigate the nature of the observed photometric variability. Based on simple geometric arguments and basic physics laws, a minimum variability timescale can be derived for which variable extinction is a viable mechanism. Because this timescale increases rapidly with wavelength, observations at long wavelengths provide the strongest constraints.\\n Methods. We used VISIR at the VLT to image the T Tau system at two epochs in February 2008, separated by 3.94 days. In addition we compiled an extensive set of near- and mid-infrared photometric data from the literature, supplemented by a number of previously unpublished measurements, and constructed light curves for the various system components. We constructed a 2D radiative transfer model for the disk of T Tau Sa, consisting of a passively irradiated dusty outer part and a central, actively accreting component.\\n Results. Our VISIR data reveal a +26 ± 2% change in the T Tau S/T Tau N flux ratio at 12.8 μm within four days, which can be attributed to a brightening of T Tau Sa. Variable extinction can be excluded as a viable mechanism for the observed flux variation based on the short timescale and the long observing wavelength. We show that also the high long-term photometric variability and its associated color–magnitude behavior can be plausibly explained with variable accretion. However, variable extinction is also a viable mechanism for the long-term variability, and a combination of both mechanisms may be required to explain the collective photometric variability of Sa.\\n Conclusions. We conclude that the observed short-term variability is caused by a variable accretion luminosity in T Tau Sa, which leads to substantial fluctuations in the irradiation of the disk surface and thus induces rapid variations in the disk surface temperature and IR brightness. Both variable accretion and variable foreground extinction can plausibly explain the long-term color and brightness variations. We suggest that the periods of high and variable brightness of Sa that we witnessed in the early and late 1990s were due to enhanced accretion induced by the periastron passage of Sb, which gravitationally perturbed the Sa disk.\\n
Convergent finite element discretization of the multi-fluid nonstationary incompressible magnetohydrodynamics equations
2010-04-21

We propose a convergent implicit stabilized finite element discretization of the nonstationary incompressible magnetohydrodynamics equations with variable density, viscosity, and electric conductivity. The discretization satisfies a discrete energy law, and a discrete maximum principle for the positive density, and iterates converge to weak solutions of the limiting problem for vanishing discretization parameters. A simple fixed point scheme, together with an appropriate stopping criterion is proposed, which decouples the computation of density, velocity, and magnetic field, and inherits the above properties, provided a mild mesh constraint holds. Computational studies are provided.