1,322 research outputs found
Azimuthal angle for boson-jet production in the back-to-back limit
We show for the first time that the azimuthal angle between a vector boson
and a jet, when using the Winner-Take-All recombination scheme, can be
predicted at high precision in the back-to-back limit in the transverse plane.
Specifically, we present a factorization theorem, and obtain numerical
predictions at next-to-next-to-leading logarithmic (NNLL) accuracy. To allow
for improved angular resolution, we provide results for track-based jet
reconstruction, which only requires minimal changes in the calculation. We also
find that linearly-polarized transverse momentum dependent (TMD) beam and jet
functions enter at next-to-leading order (NLO) in the factorization theorem,
originating from spin superpositions for one gluon, rather than the known case
of spin correlations between gluons. We validate the switch from calorimetry to
tracks using Pythia, and confirm the presence of linearly-polarized TMD
functions using MCFM.Comment: 6 pages, 4 figure
Computed tomography of the human developing anterior skull base
Abstract
The ossification of the anterior skull base, especially the lamina cribrosa, has been studied by computed tomography and histopathology. Sixteen human fetuses, (referred to our laboratory for pathological examination after spontaneous abortion between 18 and 32 weeks of gestation) and three infants, (1, 2 and 6 years of age, respectively) were examined. The cartilaginous preformation of the anterior skull base creates a ‘pseudo-defect’ on CT in the coronal plane, even with ultra thin sections and high resolution CT. By the age of 6 years of life this ‘artefact’ is no longer, as the present ossification of the lamina cribrosa is, by that time, complete
Visual objects approaching the body modulate subsequent somatosensory processing at 4 months of age
Abstract We asked whether, in the first year of life, the infant brain can support the dynamic crossmodal interactions between vision and somatosensation that are required to represent peripersonal space. Infants aged 4 (n = 20, 9 female) and 8 (n = 20, 10 female) months were presented with a visual object that moved towards their body or receded away from it. This was presented in the bottom half of the screen and not fixated upon by the infants, who were instead focusing on an attention getter at the top of the screen. The visual moving object then disappeared and was followed by a vibrotactile stimulus occurring later in time and in a different location in space (on their hands). The 4-month-olds’ somatosensory evoked potentials (SEPs) were enhanced when tactile stimuli were preceded by unattended approaching visual motion, demonstrating that the dynamic visual-somatosensory cortical interactions underpinning representations of the body and peripersonal space begin early in the first year of life. Within the 8-month-olds’ sample, SEPs were increasingly enhanced by (unexpected) tactile stimuli following receding visual motion as age in days increased, demonstrating changes in the neural underpinnings of the representations of peripersonal space across the first year of life
Acute intoxications among humans and animals. National Poisons Information Centre. Annual Report, 2005-2006
Het Nationaal Vergiftigingen Informatie Centrum (NVIC) ontving in 2005 36.375 en in 2006 37.088 informatieverzoeken over acute intoxicaties van mensen en dieren. Deze informatievragen betroffen circa 50.000 blootstellingen aan lichaamsvreemde stoffen per jaar. Ruim de helft van deze intoxicaties betrof overdoseringen met geneesmiddelen. Het aantal vergiftigingen met pijnstillers die zonder recept verkrijgbaar zijn, zoals paracetamol en ibuprofen, is in 2005 en 2006 weer toegenomen. Daarnaast is bij volwassenen het aantal meldingen over melatonine de afgelopen jaren sterk gestegen, van 3 in 2001 naar 76 in 2006. Een relatief nieuw verschijnsel waar het NVIC in 2006 over geraadpleegd werd, waren de zogenaamde crofty-bommen: doe-het-zelfbommen gemaakt met gootsteenontstopper. Bij ontploffing van crofty-bommen en aanraking met de vloeistof, kunnen ernstige chemische letsels ontstaan aan huid en ogen. Het aantal meldingen over drugs is voor het eerst in jaren afgenomen, van 1.383 in 2005 naar 1.146 in 2006. Het aantal meldingen over amfetamine-intoxicaties is sinds 2005 echter sterk gestegen, van 31 in 2004 naar 114 in 2005 en 97 in 2006. Het aantal vergiftigingen met efedra is na 2004 met 57% afgenomen. De wetswijziging in 2004, waardoor efedra-bevattende producten uitsluitend nog als geneesmiddel mogen worden verhandeld, is hier mogelijk de oorzaak van. Nadat in november 2006 Alexander Litvinenko in Londen werd vergiftigd met radioactief polonium-210, heeft het Rijksinstituut voor Volksgezondheid en Milieu (RIVM) urinemonsters geanalyseerd van 11 mogelijk blootgestelde Nederlanders. Het NVIC heeft daarbij een actieve rol gespeeld in de opsporing van de betreffende Nederlanders en de medische beoordeling van de resultaten. Het persbericht over het RIVM onderzoek heeft veel media-aandacht getrokken, waardoor het NVIC 73 maal is geconsulteerd over het poloniumincident.In 2005 the National Poisons Information Centre (NVIC) received 36,375 enquiries and in 2006, 37,088, all on acute intoxications of humans and animals. These enquiries concerned about 50,000 exposures to chemical substances per year. More than half of these intoxications were due to a medication overdose. The number of intoxications due to over-the-counter painkillers, such as paracetamol and ibuprofen, increased again in 2005 and in 2006. In addition, the number of consultations on melatonin exposure in adults increased sharply the last few years, from 3 in 2001 to 76 in 2006. A relatively new phenomenon calling for NVIC consultation in 2006 were the so-called crofty bombs (do-it-yourself bombs made from caustic soda). Explosion of a crofty bomb and contact with the liquid can result in serious chemical injuries to skin and eyes. For the first time in years, the number of consultations on drugs decreased, from 1,383 in 2005 to 1,146 in 2006. However, the number of enquiries about intoxications with amphetamines increased sharply compared to 2004, from 31 in 2004 to 114 in 2005 and 97 in 2006. After 2004, the number of intoxications with ephedra decreased by 57%. The amendment of the law in 2004, stating that ephedra-containing products could, with immediate effect, only be marketed as medicinal products, may have induced this decrease. Following the poisoning of Alexander Litvinenko in London with radioactive polonium-210 in November 2006, the National Institute for Public Health and the Environment (RIVM) analysed urine samples from 11 Dutch citizens who had possibly been exposed. The NVIC played an active role here in tracing the people concerned and in the medical evaluation of the results. The press release on the RIVM study attracted considerable attention from the media, resulting in 73 enquiries to the NVIC for information on the polonium incident.Directie Publieke Gezondhei
Optical Discovery of Probable Stellar Tidal Disruption Flares
Using archival Sloan Digital Sky Survey (SDSS) multi-epoch imaging data (Stripe 82), we have searched for the tidal disruption of stars by supermassive black holes in non-active galaxies. Two candidate tidal disruption events (TDEs) are identified. The TDE flares have optical blackbody temperatures of 2 × 10^4 K and observed peak luminosities of M_g = –18.3 and –20.4 (νL_ν = 5 × 10^(42), 4 × 10^(43) erg s^(–1), in the rest frame); their cooling rates are very low, qualitatively consistent with expectations for tidal disruption flares. The properties of the TDE candidates are examined using (1) SDSS imaging to compare them to other flares observed in the search, (2) UV emission measured by GALEX, and (3) spectra of the hosts and of one of the flares. Our pipeline excludes optically identifiable AGN hosts, and our variability monitoring over nine years provides strong evidence that these are not flares in hidden AGNs. The spectra and color evolution of the flares are unlike any SN observed to date, their strong late-time UV emission is particularly distinctive, and they are nuclear at high resolution arguing against these being first cases of a previously unobserved class of SNe or more extreme examples of known SN types. Taken together, the observed properties are difficult to reconcile with an SN or an AGN-flare explanation, although an entirely new process specific to the inner few hundred parsecs of non-active galaxies cannot be excluded. Based on our observed rate, we infer that hundreds or thousands of TDEs will be present in current and next-generation optical synoptic surveys. Using the approach outlined here, a TDE candidate sample with O(1) purity can be selected using geometric resolution and host and flare color alone, demonstrating that a campaign to create a large sample of TDEs, with immediate and detailed multi-wavelength follow-up, is feasible. A by-product of this work is quantification of the power spectrum of extreme flares in AGNs
Mitosene-DNA adducts. Characterization of two major DNA monoadducts formed by 1,10-bis(acetoxy)-7-methoxymitosene upon reductive activation
Reductive activation of racemic 1,10-bis(acetoxy)-7-methoxymitosene WV15 in the presence of DNA, followed by enzymatic digestion and HPLC analysis, revealed the formation of various DNA adducts. Reduction is a necessary event for adduct formation to occur. This reductive activation was performed under hypoxic conditions in various ways: (1) chemically, using a 2-fold excess of sodium dithionite (Na2S2O4), (2) enzymatically using NADH-cytochrome c reductase, (3) electrochemically on a mercury pool working electrode, and (4) catalytically, using a H2/PtO2 system. Five different mitosene−DNA adducts were detected. These adducts were also present when poly(dG-dC) was used instead of DNA, but were absent with poly(dA-dT). All were shown to be adducts of guanine. Reduction of 1,10-dihydroxymitosene WV14 in the presence of DNA did not result in detectable adduct formation, demonstrating the importance of good leaving groups for efficient adduct formation by these mitosenes. Finally, two of the adducts were isolated and their structures elucidated, using mass spectrometry, 1H NMR and circular dichroism (CD). The structures were assigned as the diastereoisomers N2-(1‘ ‘-n-hydroxymitosen-10‘ ‘-yl), 2‘-deoxyguanosine (n = α or β). These type of adducts, in which the mitosene C-10 is covalently bonded to the N-2 of a guanosylic group, are different from the well-known mitomycin C 2‘-deoxyguanosine monoadducts, that is linked via the mitomycin C C-1 position, demonstrating that the order of reactivity of the C-1 and C-10 in these mitosenes is reversed, as compared to mitomycin C. The 7-methoxy substituent of WV15 is a likely factor causing this switch. Evidence is presented that the 7-substituent of mitosenes also influences their DNA alkylation site. Adducts 4 and 5 represent the first isolated and structurally characterized covalent adducts of DNA and a synthetic mitosene
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