3,203 research outputs found

    Thermal Infrared Observations of Asteroid (99942) Apophis with Herschel

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    The near-Earth asteroid (99942) Apophis is a potentially hazardous asteroid. We obtained far-infrared observations of this asteroid with the Herschel Space Observatory's PACS instrument at 70, 100, and 160 micron. These were taken at two epochs in January and March 2013 during a close Earth encounter. These first thermal measurements of Apophis were taken at similar phase angles before and after opposition. We performed a detailed thermophysical model analysis by using the spin and shape model recently derived from applying a 2-period Fourier series method to a large sample of well-calibrated photometric observations. We find that the tumbling asteroid Apophis has an elongated shape with a mean diameter of 375−10+14^{+14}_{-10} m (of an equal volume sphere) and a geometric V-band albedo of 0.30−0.06+0.05^{+0.05}_{-0.06}. We find a thermal inertia in the range 250-800 Jm−2^{-2}s−0.5^{-0.5}K−1^{-1} (best solution at 600 Jm−2^{-2}s−0.5^{-0.5}K−1^{-1}), which can be explained by a mixture of low conductivity fine regolith with larger rocks and boulders of high thermal inertia on the surface. The thermal inertia, and other similarities with (25143) Itokawa indicate that Apophis might also have a rubble-pile structure. If we combine the new size value with the assumption of an Itokawa-like density and porosity we estimate a mass between 4.4 and 6.2 1010^{10} kg which is more than 2-3 times larger than previous estimates. We expect that the newly derived properties will influence impact scenario studies and influence the long-term orbit predictions of Apophis.Comment: Accepted for publication in Astronomy & Astrophysics, 21 pages, 8 figures, 2 table

    The XMM-Newton Slew Survey

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    XMM-Newton, with the huge collecting area of its mirrors and the high quantum efficiency of its EPIC detectors, is the most sensitive X-ray observatory ever flown. This is strikingly evident during slew exposures, which, while yielding only at most 14 seconds of on-source exposure time, actually constitute a 2-10 keV survey ten times deeper than all other "all-sky" surveys. The current (April 2005) XMM archive contains 374 slew exposures which give a uniform coverage over around 10,000 square degrees (approx. 25% of the sky). Here we describe the results of pilot studies, the current status of the XMM-Newton Slew Survey, up-to-date results and our progress towards constructing a catalogue of slew detections in the full 0.2-12 keV energy band.Comment: 3 pages, 4 figures, XMM-Newton EPIC Consortium Meeting, Schloss Ringberg, Germany, April 2005, to appear in MPE Repor

    Chandra and optical/IR observations of CXOJ1415.2+3610, a massive, newly discovered galaxy cluster at z~1.5

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    (Abridged) We report the discovery of CXO J1415.2+3610, a distant (z~1.5) galaxy cluster serendipitously detected in a deep, high-resolution Chandra observation targeted to study the cluster WARP J1415.1+3612 at z=1.03. This is the highest-z cluster discovered with Chandra so far. Moreover, the total exposure time of 280 ks with ACIS-S provides the deepest X-ray observation currently achieved on a cluster at z>1.5. We perform an X-ray spectral fit of the extended emission of the intracluster medium (ICM) with XSPEC, and we detect at a 99.5% confidence level the rest frame 6.7-6.9 keV Iron K_\alpha line complex, from which we obtain z_X=1.46\pm0.025. The analysis of the z-3.6\mu m color-magnitude diagram shows a well defined sequence of red galaxies within 1' from the cluster X-ray emission peak with a color range [5 < z-3.6 \mu m < 6]. The photometric redshift obtained by spectral energy distribution (SED) fitting is z_phot=1.47\pm 0.25. After fixing the redshift to z=1.46, we perform the final spectral analysis and measure the average gas temperature with a 20% error, kT=5.8^{+1.2}_{-1.0} keV, and the Fe abundance Z_Fe = 1.3_{-0.5}^{+0.8}Z_\odot. We fit the background subtracted surface brightness with a single beta--model out to 35" and derive the deprojected electron density profile. The ICM mass is 1.09_{-0.2}^{+0.3}\times 10^{13} M_\odot within 300 kpc. The total mass is M_{2500}= 8.6_{-1.7}^{+2.1} \times 10 ^{13} M_\odot for R_{2500}=(220\pm 55) kpc. Extrapolating the profile at larger radii we find M_{500}= 2.1_{-0.5}^{+0.7} \times 10 ^{14} M_\odot for R_{500} = 510_{-50}^{+55}$ kpc. This analysis establishes CXOJ1415.2+3610 as one of the best characterized distant galaxy clusters based on X-ray data alone.Comment: 12 pages, 9 figures, A\&A in press, minor modifications in the tex

    Survivin at a glance

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    Survivin (also known as BIRC5) is an evolutionarily conserved eukaryotic protein that is essential for cell division and can inhibit cell death. Normally it is only expressed in actively proliferating cells, but is upregulated in most, if not all cancers; consequently, it has received significant attention as a potential oncotherapeutic target. In this Cell Science at a Glance article and accompanying poster, we summarise our knowledge of survivin 21 years on from its initial discovery. We describe the structure, expression and function of survivin, highlight its interactome and conclude by describing anti-survivin strategies being trialled

    A ring galaxy at z=1 lensed by the cluster Abell 370

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    We present a study of a very peculiar object found in the field of the cluster-lens Abell 370. This object displays, in HST imaging, a spectacular morphology comparable to nearby ring-galaxies. From spectroscopic observations at the CFHT, we measured a redshift of z=1.062z=1.062 based on the identification of [O ii] 3727 \AA and [Ne v] 3426 \AA emission lines. These emission lines are typical of starburst galaxies hosting a central active nucleus and are in good agreement with the assumption that this object is a ring-galaxy. This object is also detected with ISO in the LW2 and LW3 filters, and the mid Infra-Red (MIR) flux ratio favors a Seyfert 1 type. The shape of the ring is gravitationally distorted by the cluster-lens, and most particularly by a nearby cluster elliptical galaxy. Using the cluster mass model, we can compute its intrinsic shape. Requiring that the outer ring follows an ellipse we put constraints on the M/L ratio of the nearby galaxy and derive a magnification factor of 2.5 ±\pm 0.2. The absolute luminosities of the source are then $L_B = 1.3 \ 10^{12} L_{B \odot}and and \nuL L_\nu \simeq 4. 10^{10}L L_\odot$ in the mid-IR.Comment: 5 pages, 5 figures, uses aa.cls, accepted to A&A Letters. Minor changes, Figure 1 revisited and typos adde

    Extended sources in the XMM-Newton slew survey

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    The low background, good spatial resolution and great sensitivity of the EPIC-pn camera on XMM-Newton give useful limits for the detection of extended sources even during the short exposures made during slewing maneouvers. In this paper we attempt to illustrate the potential of the XMM-Newton slew survey as a tool for analysing flux-limited samples of clusters of galaxies and other sources of spatially extended X-ray emission.Comment: 2 pages, 4 figures, to appear in the proceedings of "The X-ray Universe 2005", San Lorenzo de El Escorial (Spain), 26-30 September 200

    The XMM-Newton Slew Survey: towards the XMMSL1 catalogue

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    The XMM-Newton satellite is the most sensitive X-ray observatory flown to date due to the great collecting area of its mirrors coupled with the high quantum efficiency of the EPIC detectors. It performs slewing manoeuvers between observation targets tracking almost circular orbits through the ecliptic poles due to the Sun constraint. Slews are made with the EPIC cameras open and the other instruments closed, operating with the observing mode set to the one of the previous pointed observation and the medium filter in place. Slew observations from the EPIC-pn camera in FF, eFF and LW modes provide data, resulting in a maximum of 15 seconds of on-source time. These data can be used to give a uniform survey of the X-ray sky, at great sensitivity in the hard band compared with other X-ray all-sky surveys.Comment: 2 pages, 2 figures, to appear in the proceedings of "The X-ray Universe 2005", San Lorenzo de El Escorial (Spain), 26-30 September 200

    Borderline personality disorder and dialectical behaviour therapy in an Australian private hospital setting: treatment response and BPD subtypes

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    &amp;nbsp;Borderline Personality Disorder (BPD) is a complex psychological disorder, often considered to be one of the most severe of all the personality disorders because of the impact the symptoms have on the life of the person with the diagnosis and on those around them. Characterised by highly unstable affective reactions to environmental or interpersonal events and stimuli, it is often difficult for both the person and their significant others to understand and predict these reactions, and thus formulate and implement effective response strategies. Borderline personality disorder characteristics often cause sufferers and families high levels of distress and treatment uses public and private resources extensively and expensively. The impact of this disorder is profound at both the individual and community domains. In particular, the high number of suicide and self harm behaviours associated with this diagnosis and the high levels of emotional distress experienced by both the sufferer and their family members causes immense distress (Beatson, Rao, &amp;amp; Watson, 2010; Kraus &amp;amp; Reynolds, 2001; Paris, 2008)

    The XMM-LSS survey: the Class 1 cluster sample over the extended 11 deg2^2 and its spatial distribution

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    This paper presents 52 X-ray bright galaxy clusters selected within the 11 deg2^2 XMM-LSS survey. 51 of them have spectroscopic redshifts (0.05<z<1.060.05<z<1.06), one is identified at zphot=1.9z_{\rm phot}=1.9, and all together make the high-purity "Class 1" (C1) cluster sample of the XMM-LSS, the highest density sample of X-ray selected clusters with a monitored selection function. Their X-ray fluxes, averaged gas temperatures (median TX=2T_X=2 keV), luminosities (median LX,500=5×1043L_{X,500}=5\times10^{43} ergs/s) and total mass estimates (median 5×1013h−1M⊙5\times10^{13} h^{-1} M_{\odot}) are measured, adapting to the specific signal-to-noise regime of XMM-LSS observations. The redshift distribution of clusters shows a deficit of sources when compared to the cosmological expectations, regardless of whether WMAP-9 or Planck-2013 CMB parameters are assumed. This lack of sources is particularly noticeable at 0.4≲z≲0.90.4 \lesssim z \lesssim 0.9. However, after quantifying uncertainties due to small number statistics and sample variance we are not able to put firm (i.e. >3σ>3 \sigma) constraints on the presence of a large void in the cluster distribution. We work out alternative hypotheses and demonstrate that a negative redshift evolution in the normalization of the LX−TXL_{X}-T_X relation (with respect to a self-similar evolution) is a plausible explanation for the observed deficit. We confirm this evolutionary trend by directly studying how C1 clusters populate the LX−TX−zL_{X}-T_X-z space, properly accounting for selection biases. We point out that a systematically evolving, unresolved, central component in clusters and groups (AGN contamination or cool core) can impact the classification as extended sources and be partly responsible for the observed redshift distribution.[abridged]Comment: 33 pages, 21 figures, 3 tables ; accepted for publication in MNRA

    Oligomers, organosulfates, and nitrooxy organosulfates in rainwater identified by ultra-high resolution electrospray ionization FT-ICR mass spectrometry

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    Wet deposition is an important removal mechanism for atmospheric organic matter, and a potentially important input for receiving ecosystems, yet less than 50% of rainwater organic matter is considered chemically characterized. Precipitation samples collected in New Jersey, USA, were analyzed by negative ion ultra-high resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Elemental compositions of 552 unique molecular species were determined in the mass range 50–500 Da in the rainwater. Four main groups of organic compounds were identified: compounds containing carbon, hydrogen, and oxygen (CHO) only, sulfur (S) containing CHOS compounds, nitrogen (N) containing CHON compounds, and S- and N- containing CHONS compounds. Organic acids commonly identified in precipitation were detected in the rainwater. Within the four main groups of compounds detected in the rainwater, oligomers, organosulfates, and nitrooxy-organosulfates were assigned based on elemental formula comparisons. The majority of the compounds identified are products of atmospheric reactions and are known contributors to secondary organic aerosol (SOA) formed from gas phase, aerosol phase, and in-cloud reactions in the atmosphere. It is suggested that the large uncharacterized component of SOA is the main contributor to the large uncharacterized component of rainwater organic matter
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