Results for "Jes K. Jørgensen"

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Externally heated protostellar cores in the Ophiuchus star-forming regionNov 21 2016Nov 22 2016We present APEX 218 GHz observations of molecular emission in a complete sample of embedded protostars in the Ophiuchus star-forming region. To study the physical properties of the cores, we calculate H$_2$CO and c-C$_3$H$_2$ rotational temperatures, ... More
The Star Formation Rate of Molecular CloudsDec 18 2013We review recent advances in the analytical and numerical modeling of the star formation rate in molecular clouds and discuss the available observational constraints. We focus on molecular clouds as the fundamental star formation sites, rather than on ... More
Imaging the water snowline in a protostellar envelope with H$^{13}$CO$^+$Jan 08 2018Snowlines are key ingredients for planet formation. Providing observational constraints on the locations of the major snowlines is therefore crucial for fully connecting planet compositions to their formation mechanism. Unfortunately, the most important ... More
The ALMA-PILS survey: The sulphur connection between protostars and comets: IRAS 16293-2422 B and 67P/Churyumov-GerasimenkoFeb 08 2018The evolutionary past of our Solar System can be pieced together by comparing analogous low-mass protostars with remnants of our Protosolar Nebula - comets. Sulphur-bearing molecules may be unique tracers of the joint evolution of the volatile and refractory ... More
The chemical connection between 67P/C-G and IRAS 16293-2422Feb 08 2018The chemical evolution of a star- and planet-forming system begins in the prestellar phase and proceeds across the subsequent evolutionary phases. The chemical trail from cores to protoplanetary disks to planetary embryos can be studied by comparing distant ... More
Interplay between chemistry and dynamics in embedded protostellar disksSep 25 2013A fundamental part of the study of star formation is to place young stellar objects in an evolutionary sequence. Establishing a robust evolutionary classification scheme allows us not only to understand how the Sun was born but also to predict what kind ... More
Embedded Protostars in the Dust, Ice, and Gas In Time (DIGIT) Key Program: Continuum SEDs, and an Inventory of Characteristic Far-Infrared Lines from PACS SpectroscopyApr 27 2013May 09 2013We present 50-210 um spectral scans of 30 Class 0/I protostellar sources, obtained with Herschel-PACS, and 0.5-1000 um SEDs, as part of the Dust, Ice, and Gas in Time (DIGIT) Key Program. Some sources exhibit up to 75 H2O lines ranging in excitation energy ... More
Large-scale numerical simulations of star formation put to the test: Comparing synthetic images and actual observations for statistical samples of protostarsOct 27 2015Dec 14 2015(abridged) Context: Both observations and simulations of embedded protostars have progressed rapidly in recent years. Bringing them together is an important step in advancing our knowledge about the earliest phases of star formation. Aims: To compare ... More
The kinematics of NGC1333-IRAS2A - a true Class 0 protostarMay 28 2009Low-mass star formation is described by gravitational collapse of dense cores of gas and dust. At some point during the collapse, a disk is formed around the protostar and the disk will spin up and grow in size as the core contracts because of angular ... More
Subarcsecond resolution observations of warm water towards three deeply embedded low-mass protostarsMar 22 2012Water is present during all stages of star formation: as ice in the cold outer parts of protostellar envelopes and dense inner regions of circumstellar disks, and as gas in the envelopes close to the protostars, in the upper layers of circumstellar disks ... More
Warm water deuterium fractionation in IRAS 16293-2422 - The high-resolution ALMA and SMA viewNov 28 2012Measuring the water deuterium fractionation in the inner warm regions of low-mass protostars has so far been hampered by poor angular resolution obtainable with single-dish ground- and space-based telescopes. Observations of water isotopologues using ... More
Protostellar accretion traced with chemistry: Comparing synthetic C18O maps of embedded protostars to real observationsDec 01 2015Dec 19 2015Context: Understanding how protostars accrete their mass is a central question of star formation. One aspect of this is trying to understand whether the time evolution of accretion rates in deeply embedded objects is best characterised by a smooth decline ... More
Probing strange stars and color superconductivity by r-mode instabilities in millisecond pulsarsDec 20 1999Jun 06 2000R-mode instabilities in rapidly rotating quark matter stars (strange stars) lead to specific signatures in the evolution of pulsars with periods below 2.5 msec, and may explain the apparent lack of very rapid pulsars. Existing data seem consistent with ... More
Reply to Comment [arXiv:0809.2310] on Universal Charge-Radius Relation for Subatomic and Astrophysical Compact Objects [arXiv:0804.2140, PRL100 (2008) 151102]Oct 14 2008A reply to arXiv:0809.2310, "Comment on Universal Charge-Radius Relation for Subatomic and Astrophysical Compact Objects" [arXiv:0804.2140,PRL100(2008)151102]
Is Her X-1 a strange star?Jan 23 1996The possible identification of Her X-1 with a strange star (Li et al. 1995) is shown to be incorrect.
Strangelet propagation and cosmic ray fluxNov 18 2004Feb 03 2005The galactic propagation of cosmic ray strangelets is described and the resulting flux is calculated for a wide range of parameters as a prerequisite for strangelet searches in lunar soil and with an Earth orbiting magnetic spectrometer, AMS-02. While ... More
Color-flavor locked strangeletsAug 03 2001Oct 08 2001Finite lumps of color-flavor locked strange quark matter (CFL-strangelets) are significantly more stable than strangelets without color-flavor locking for wide ranges of parameters, increasing the likelihood of strangelet metastability, or even absolute ... More
How to identify a Strange StarJun 02 1998Contrary to young neutron stars, young strange stars are not subject to the r-mode instability which slows rapidly rotating, hot neutron stars to rotation periods near 10 ms via gravitational wave emission. Young millisecond pulsars are therefore likely ... More
Misaligned Disks in the Binary Protostar IRS 43Oct 12 2016Recent high angular resolution ($\sim$0.2") ALMA observations of the 1.1 mm continuum and of HCO+ J=3-2 and HCN J=3-2 gas towards the binary protostar IRS 43 reveal multiple Keplerian disks which are significantly misaligned ($\gt$ 60$^\circ$), both in ... More
Tentative detection of ethylene glycol toward W51/e2 and G34.3+0.2Jul 13 2015How complex organic - and potentially prebiotic - molecules are formed in regions of low- and high-mass star-formation remains a central question in astrochemistry. In particular, with just a few sources studied in detail, it is unclear what role environment ... More
Probing the effects of external irradiation on low-mass protostars through unbiased line surveysSep 08 2015Sep 29 2015(abridged) Context: The envelopes of molecular gas around embedded low-mass protostars show different chemistries, which can be used to trace their formation history and physical conditions. The excitation of some molecular species can also be used to ... More
Externally heated protostellar cores in the Ophiuchus star-forming regionNov 21 2016We present APEX 218 GHz observations of molecular emission in a complete sample of embedded protostars in the Ophiuchus star-forming region. To study the physical properties of the cores, we calculate H$_2$CO and c-C$_3$H$_2$ rotational temperatures, ... More
Complex Molecules in the L1157 Molecular OutflowMay 16 2008We report the detection of complex organic molecules in the young protostellar outflow L1157. We identify lines from HCOOCH3, CH3CN, HCOOH and C2H5OH at the position of the B1 shock in the blueshifted lobe, making it the first time that complex species ... More
Detection of glycolaldehyde towards the solar-type protostar NGC1333 IRAS2AFeb 03 2015Glycolaldehyde is a key molecule in the formation of biologically relevant molecules such as ribose. We report its detection with the Plateau de Bure interferometer towards the Class 0 young stellar object NGC1333 IRAS2A, which is only the second solar-type ... More
Misaligned Disks in the Binary Protostar IRS 43Oct 12 2016Oct 14 2016Recent high angular resolution ($\sim$0.2") ALMA observations of the 1.1 mm continuum and of HCO+ J=3-2 and HCN J=3-2 gas towards the binary protostar IRS 43 reveal multiple Keplerian disks which are significantly misaligned ($\gt$ 60$^\circ$), both in ... More
c2d Spitzer IRS spectra of embedded low-mass young stars: gas-phase emission linesMay 17 2010A survey of mid-IR gas-phase emission lines of H2, H2O and various atoms toward a sample of 43 embedded low-mass young stars in nearby star-forming regions is presented. The sources are selected from the Spitzer "Cores to Disks" (c2d) legacy program. ... More
An Unbiased Spectral Line Survey toward R CrA IRS7B in the 345 GHz Window with ASTEOct 10 2011We have conducted a spectral line survey in the 332 - 364 GHz region with the ASTE 10 m telescope toward R CrA IRS7B, a low-mass protostar in the Class 0 or Class 0/I transitional stage. We have also performed some supplementary observations in the 450 ... More
Classifying the embedded young stellar population in Perseus and Taurus & the LOMASS databaseNov 10 2015Context. The classification of young stellar objects (YSOs) is typically done using the infrared spectral slope or bolometric temperature, but either can result in contamination of samples. More accurate methods to determine the evolutionary stage of ... More
Compactly generated homotopy categoriesSep 11 2006Over an associative ring we consider a class $\mathbb{X}$ of left modules which is closed under set-indexed coproducts and direct summands. We investigate when the triangulated homotopy category $\mathsf{K}(\mathbb{X})$ is compactly generated, and give ... More
Free energy of bubbles and droplets in the quark-hadron phase transitionJul 07 1998Aug 02 1999Using the MIT bag model, we calculate the free energy of droplets of quark-gluon plasma in a bulk hadronic medium, and of hadronic bubbles in a bulk quark-gluon plasma, under the assumption of vanishing chemical potentials. We investigate the validity ... More
Neutrino decoupling in the early UniverseJun 02 1995A calculation of neutrino decoupling in the early Universe, including full Fermi-Dirac statistics and electron mass dependence in the weak reaction rates, is presented. We find that after decoupling, the electron neutrinos contribute 0.83\% more to the ... More
A Cosmological Three Level Neutrino LaserFeb 14 1997We present a calculation of a neutrino decay scenario in the early Universe. The specific decay is \nu_{2} \to \nu_{1} + \phi, where \phi is a boson. If there is a neutrino mass hierarchy, m_{\nu_{e}} < m_{\nu_{\mu}} < m_{\nu_{\tau}}, we show that it ... More
Viewpoint: Opportunities and challenges of two-dimensional magnetic van der Waals materials: magnetic graphene?Apr 29 2016There has been a huge increase of interests in two-dimensional van der Waals materials over the past ten years or so with the conspicuous absence of one particular class of materials: magnetic van der Waals systems. In this Viewpoint, we point it out ... More
Gaps below strange star crustsDec 06 2005The gap caused by a strong electric field between the quark surface and nuclear crust of a strange star is studied in an improved model including gravity and pressure as well as electrostatic forces. The transition from gap to crust is followed in detail. ... More
Does the quark-gluon plasma contain stable hadronic bubbles?Mar 17 2000We calculate the thermodynamic potential of bubbles of hadrons embedded in quark-gluon plasma, and of droplets of quark-gluon plasma embedded in hadron phase. This is a generalization of our previous results to the case of non-zero chemical potentials. ... More
Nucleosynthesis and the mass of the tau neutrinoMar 01 1996The primordial abundance of long-lived heavy Majorana neutrinos is calculated from the full Boltzmann equation. Inclusion of scattering reactions drastically change the predicted abundance of a heavy neutrino species. This loosens the well known mass ... More
The Earliest Stages of Star and Planet Formation: Core Collapse, and the Formation of Disks and OutflowsJan 10 2014(Abridged) In this review we focus on the observations and theory of the formation of early disks and outflows, and their connections with the first phases of planet formation. Large rotationally supported circumstellar disks, although common around more ... More
Detection of Infall in the Protostar B335 with ALMAOct 12 2015Observations of the isolated globule B335 with ALMA have yielded absorption features against the continuum that are redshifted from the systemic velocity in both HCN and HCO$^+$ lines. These features provide unambiguous evidence for infall toward a central ... More
BREN: Body Reflection Essence-Neuter Model for Separation of Reflection ComponentsAug 25 2015We propose a novel reflection color model consisting of body essence and (mixed) neuter, and present an effective method for separating dichromatic reflection components using a single image. Body essence is an entity invariant to interface reflection, ... More
Mixed dark matter with low-mass bosonsJan 24 1996We calculate the linear power spectrum for a range of mixed dark matter (MDM) models assuming a massive (few eV) boson, $\phi$, instead of a neutrino as the hot component. We consider both the case where the hot dark matter (HDM) particle is a boson and ... More
STRANGELETS AT NON-ZERO TEMPERATUREJan 17 1995A description of strange quark matter at finite temperature is given, with emphasis on the inclusion of finite size effects. For massless quarks all thermodynamic quantities can be evaluated analytically, while the case of massive quarks must be treated ... More
Nucleation of quark matter bubbles in neutron starsJan 03 1994The thermal nucleation of quark matter bubbles inside neutron stars is examined for various temperatures which the star may realistically encounter during its lifetime. It is found that for a bag constant less than a critical value, a very large part ... More
Adaptable Radiative Transfer Innovations for Submillimeter Telescopes (ARTIST)Feb 23 2011Submillimeter observations are a key for answering many of the big questions in modern-day astrophysics, such as how stars and planets form, how galaxies evolve, and how material cycles through stars and the interstellar medium. With the upcoming large ... More
L1448-MM observations by the Herschel Key program, "Dust, Ice, and Gas In Time" (DIGIT)Sep 09 2013We present Herschel/PACS observations of L1448-MM, a Class 0 protostar with a prominent outflow. Numerous emission lines are detected at 55 < lambda < 210 micrometer including CO, OH, H2O, and [O I]. We investigate the spatial distribution of each transition ... More
ALMA observations of the kinematics and chemistry of disc formationMay 06 2014May 12 2014Context: The R CrA cloud hosts a handful of Class 0/I low-mass young stellar objects. The chemistry and physics at scales $>500$ AU in this cloud are dominated by the irradiation from the nearby Herbig Be star R CrA. The luminous large-scale emission ... More
Dynamical structure of the inner 100 AU of the deeply embedded protostar IRAS 16293-2422Jun 03 2014A fundamental question about the early evolution of low-mass protostars is when circumstellar disks may form. High angular resolution observations of molecular transitions in the (sub)millimeter wavelength windows make it possible to investigate the kinematics ... More
Warm gas towards young stellar objects in Corona Australis - Herschel/PACS observations from the DIGIT key programmeNov 29 2013The effects of external irradiation on the chemistry and physics in the protostellar envelope around low-mass young stellar objects are poorly understood. The Corona Australis star-forming region contains the R CrA dark cloud, comprising several low-mass ... More
A Substellar-Mass Protostar and its Outflow of IRAS 15398-3359 Revealed by Subarcsecond-Resolution Observations of H$_2$CO and CCHOct 22 2014Sub-arcsecond ($0.^{\prime\prime}5$) images of H$_2$CO and CCH line emission have been obtained in the $0.8$ mm band toward the low-mass protostar IRAS 15398-3359 in the Lupus 1 cloud as one of the Cycle 0 projects of the Atacama Large Millimeter/Submillimeter ... More
Normally Regular DigraphsOct 30 2014A normally regular digraph with parameters $(v,k,\lambda,\mu)$ is a directed graph on $v$ vertices whose adjacency matrix $A$ satisfies the equation $AA^t=k I+\lambda (A+A^t)+\mu(J-I-A-A^t)$. This means that every vertex has out-degree $k$, a pair of ... More
Water around IRAS15398-3359 observed with ALMAAug 22 2016How protostars accrete mass is one of the fundamental problems of star formation. High column densities and complex kinematical structures make direct observations challenging and they only provide a snapshot. Chemical tracers provide an interesting alternative ... More
Dispersion Models for ExtremesDec 28 2007We propose extreme value analogues of natural exponential families and exponential dispersion models, and introduce the slope function as an analogue of the variance function. The set of quadratic and power slope functions characterize well-known families ... More
Curvature dependence of propagating velocity for a simplified calcium modelFeb 19 2014It is known that curvature relation plays a key role in the propagation of two-dimensional waves in an excitable model. Such a relation is believed to obey the eikonal equation for typical excitable models (e.g., the FitzHugh-Nagumo (FHN) model), which ... More
Imaging chemical differentiation around the low-mass protostar L483-mmMay 20 2004This paper presents a millimeter wavelength aperture-synthesis study of the spatial variations of the chemistry in the envelope around the deeply embedded low-mass protostar L483-mm on 1000 AU (5") scales. Lines of 8 molecular species including CN, C18O, ... More
Decompositions of factor codes and embeddings between shift spaces with unequal entropiesJan 03 2012Apr 16 2012Given a factor code between sofic shifts X and Y, there is a family of decompositions of the original code into factor codes such that the entropies of the intermediate subshifts arising from the decompositions are dense in the interval from the entropy ... More
Signature of deconfinement with spin down compression in cooling hybrid starsJan 02 2008Apr 05 2009The thermal evolution of neutron stars is coupled to their spin down and the resulting changes in structure and chemical composition. This coupling correlates stellar surface temperatures with rotational state as well as time. We report an extensive investigation ... More
A recent accretion burst in the low-mass protostar IRAS 15398-3359: ALMA imaging of its related chemistryDec 03 2013Low-mass protostars have been suggested to show highly variable accretion rates through-out their evolution. Such changes in accretion, and related heating of their ambient envelopes, may trigger significant chemical variations on different spatial scales ... More
Water in star-forming regions with Herschel: highly excited molecular emission from the NGC 1333 IRAS 4B outflowNov 03 2011Jan 18 2012During the embedded phase of pre-main sequence stellar evolution, a disk forms from the dense envelope while an accretion-driven outflow carves out a cavity within the envelope. Highly excited H2O emission in spatially unresolved Spitzer/IRS spectra of ... More
High-J CO survey of low-mass protostars observed with Herschel-HIFIJun 17 2013The evolution of deeply embedded young stellar objects (YSOs) has traditionally been traced through dust continuum spectral energy distributions (SEDs), but the use of CO excitation as an evolutionary probe has not yet been explored due to lack of high-J ... More
The young population of the Chamaeleon II dark cloudFeb 29 2008We discuss the results of the optical spectroscopic follow-up of pre-main sequence (PMS) objects and candidates selected in the Chamaeleon II dark cloud based on data from the Spitzer Legacy survey "From Molecular Cores to Planet Forming Disks" (c2d) ... More
Dimethyl ether in its ground state, v=0, and lowest two torsionally excited states, v11=1 and v15=1, in the high-mass star-forming region G327.3-0.6Feb 25 2013The goal of this paper is to determine the respective importance of solid state vs. gas phase reactions for the formation of dimethyl ether. This is done by a detailed analysis of the excitation properties of the ground state and the torsionally excited ... More
High D$_2$O/HDO ratio in the inner regions of the low-mass protostar NGC1333 IRAS2AJul 25 2014Aug 16 2014Water plays a crucial role both in the interstellar medium and on Earth. To constrain its formation mechanisms and its evolution through the star formation process, the determination of the water deuterium fractionation ratios is particularly suitable. ... More
An estimating equations approach to fitting latent exposure models with longitudinal health outcomesAug 20 2009The analysis of data arising from environmental health studies which collect a large number of measures of exposure can benefit from using latent variable models to summarize exposure information. However, difficulties with estimation of model parameters ... More
First-order convex feasibility algorithms for iterative image reconstruction in X-ray CTSep 05 2012Feb 21 2013Iterative image reconstruction (IIR) algorithms in Computed Tomography (CT) are based on algorithms for solving a particular optimization problem. Design of the IIR algorithm, therefore, is aided by knowledge of the solution to the optimization problem ... More
Convex optimization problem prototyping for image reconstruction in computed tomography with the Chambolle-Pock algorithmNov 23 2011Mar 08 2012The primal-dual optimization algorithm developed in Chambolle and Pock (CP), 2011 is applied to various convex optimization problems of interest in computed tomography (CT) image reconstruction. This algorithm allows for rapid prototyping of optimization ... More
Single Wall Carbon Nanotube Weak LinksMar 13 2007We have reproducibly contacted gated single wall carbon nanotubes (SWCNT) to superconducting leads based on niobium. The devices are identified to belong to two transparency regimes: The Coulomb blockade and the Kondo regime. Clear signature of the superconducting ... More
Self-Similarity and Lamperti Convergence for Families of Stochastic ProcessesSep 01 2010We define a new type of self-similarity for one-parameter families of stochastic processes, which applies to a number of important families of processes that are not self-similar in the conventional sense. This includes a new class of fractional Hougaard ... More
Phase Transition and Critical Dynamics in Diluted Josephson Junction ArraysOct 25 2006Measurements of the $IV$ characteristics of site-diluted Josephson-junction arrays have revealed intriguing effects of percolative disorder on the phase transition and the vortex dynamics in a two-dimensional XY system. Different from other types of phase ... More
The $3d$-Electron Heisenberg Pyrochlore Mn$_2$Sb$_2$O$_7$Nov 09 2016In frustrated magnetic systems, geometric constraints or the competition amongst interactions introduce extremely high degeneracy and prevent the system from readily selecting a low-temperature ground state. The most frustrated known spin arrangement ... More
Color singlet suppression of quark-gluon plasma formationFeb 01 1996The rate of quark-gluon plasma droplet nucleation in superheated hadronic matter is calculated within the MIT bag model. The requirements of color singletness and (to less extent) fixed momentum suppress the nucleation rate by many orders of magnitude, ... More
The HDO/H2O ratio in gas in the inner regions of a low-mass protostarNov 12 2010The HDO/H2O abundance ratio is thought to be a key diagnostic on the evolution of water during the star- and planet-formation process and thus on its origin on Earth. We here present millimeter-wavelength high angular resolution observations of the deeply ... More
First detection of cyanamide (NH$_2$CN) towards solar-type protostarsDec 27 2017Searches for the prebiotically-relevant cyanamide (NH$_2$CN) towards solar-type protostars have not been reported in the literature. We here present the first detection of this species in the warm gas surrounding two solar-type protostars, using data ... More
A young bipolar outflow from IRAS 15398-3359Jan 26 2016Changing physical conditions in the vicinity of protostars allow for a rich and interesting chemistry to occur. Heating and cooling of the gas allows molecules to be released from and frozen out on dust grains. These changes in physics, traced by chemistry, ... More
Strong irradiation of protostellar cores in Corona AustralisSep 21 2012Sep 24 2012The importance of the physical environment in the evolution of newly formed low-mass stars remains an open question. In particular, radiation from nearby more massive stars may affect both the physical and chemical structure of these kinds of young stars. ... More
Exploring the crowded central region of 10 Galactic globular clusters using EMCCDs. Variable star searches and new discoveriesDec 24 2015Obtain time-series photometry of the very crowded central regions of Galactic globular clusters with better angular resolution than previously achieved with conventional CCDs on ground-based telescopes to complete, or improve, the census of the variable ... More
Star and Planet Formation with ALMA: an OverviewAug 22 2007Submillimeter observations with ALMA will be the essential next step in our understanding of how stars and planets form. Key projects range from detailed imaging of the collapse of pre-stellar cores and measuring the accretion rate of matter onto deeply ... More
Mass Assembly of Stellar Systems and Their Evolution with the SMA (MASSES). Multiplicity and the Physical Environment in L1448NNov 03 2015Nov 05 2015We present continuum and molecular line observations at 230 GHz and 345 GHz from the Sub-millimeter Array (SMA) toward three protostars in the Perseus L1448N region. The data are from the large project "Mass Assembly of Stellar Systems and their Evolution ... More
Water Vapor in the Inner 25 AU of a Young Disk around a Low-Mass ProtostarJan 10 2010Water is one of the key molecules in the physical and chemical evolution of star- and planet-forming regions. We here report the first spatially resolved observation of thermal emission of (an isotopologue of) water with the Plateau de Bure Interferometer ... More
The Spitzer c2d Legacy Results: Star Formation Rates and Efficiencies; Evolution and LifetimesNov 06 2008(Abridged) The c2d Spitzer Legacy project obtained images and photometry with both IRAC and MIPS instruments for five large, nearby molecular clouds. This paper combines information drawn from studies of individual clouds into a combined and updated statistical ... More
Searching for variable stars in the cores of five metal rich globular clusters using EMCCD observationsOct 31 2014Jan 12 2015In this paper, we present the analysis of time-series observations from 2013 and 2014 of five metal rich ([Fe/H] $>$ -1) globular clusters: NGC~6388, NGC~6441, NGC~6528, NGC~6638, and NGC~6652. The data have been used to perform a census of the variable ... More
The Spitzer Survey of Interstellar Clouds in the Gould Belt. VI. The Auriga-California Molecular Cloud observed with IRAC and MIPSFeb 25 2014We present observations of the Auriga-California Molecular Cloud (AMC) at 3.6, 4.5, 5.8, 8.0, 24, 70 and 160 micron observed with the IRAC and MIPS detectors as part of the Spitzer Gould Belt Legacy Survey. The total mapped areas are 2.5 sq-deg with IRAC ... More
The Spitzer survey of interstellar clouds in the Gould Belt. II. The Cepheus Flare observed with IRAC and MIPSMar 24 2009We present Spitzer IRAC (~2 deg^2) and MIPS (~8 deg^2) observations of the Cepheus Flare which is associated with the Gould Belt, at an approximate distance of ~300 pc. Around 6500 sources are detected in all four IRAC bands, of which ~900 have MIPS 24 ... More
The Spitzer Survey of Interstellar Clouds in the Gould Belt. IV. Lupus V and VI Observed with IRAC and MIPSJan 24 2011We present Gould's Belt (GB) Spitzer IRAC and MIPS observations of the Lupus V and VI clouds and discuss them in combination with near-infrared (2MASS) data. Our observations complement those obtained for other Lupus clouds within the frame of the Spitzer ... More
The Spitzer c2d survey of Large, Nearby, Interstellar Clouds. V. Chamaeleon II Observed with IRACOct 27 2006We present IRAC (3.6, 4.5, 5.8, and 8.0 micron) observations of the Chamaeleon II molecular cloud. The observed area covers about 1 square degree defined by $A_V >2$. Analysis of the data in the 2005 c2d catalogs reveals a small number of sources (40) ... More
Experimental percolation studies of two-dimensional honeycomb lattice: Li2Mn1-xTixO3Jun 27 2014Li2MnO3 with a S=3/2 two-dimensional Mn honeycomb lattice has a Neel-type antiferromagnetic transition at TN=36 K with a broad maximum in the magnetic susceptibility at TM=48 K. We have investigated site percolation effects by replacing Mn with nonmagnetic ... More
Empirical average-case relation between undersampling and sparsity in x-ray CTNov 24 2012Aug 04 2014In x-ray computed tomography (CT) it is generally acknowledged that reconstruction methods exploiting image sparsity allow reconstruction from a significantly reduced number of projections. The use of such reconstruction methods is motivated by recent ... More
High Frame-rate Imaging Based Photometry, Photometric Reduction of Data from Electron-multiplying Charge Coupled Devices (EMCCDs)Feb 16 2012Apr 01 2012The EMCCD is a type of CCD that delivers fast readout times and negligible readout noise, making it an ideal detector for high frame rate applications which improve resolution, like lucky imaging or shift-and-add. This improvement in resolution can potentially ... More
Noise Robustness of a Combined Phase Retrieval and Reconstruction Method for Phase-Contrast TomographyMay 11 2015Sep 07 2015Classical reconstruction methods for phase-contrast tomography consist of two stages: phase retrieval and tomographic reconstruction. A novel algebraic method combining the two was suggested by Kostenko et al. (Opt. Express, 21, 12185, 2013) and preliminary ... More
Implementation of an Optimal First-Order Method for Strongly Convex Total Variation RegularizationMay 18 2011We present a practical implementation of an optimal first-order method, due to Nesterov, for large-scale total variation regularization in tomographic reconstruction, image deblurring, etc. The algorithm applies to $\mu$-strongly convex objective functions ... More
Ending the Anomaly: Achieving Low Latency and Airtime Fairness in WiFiFeb 28 2017Mar 06 2017With more devices connected, delays and jitter at the WiFi hop become more prevalent, and correct functioning during network congestion becomes more important. However, two important performance issues prevent modern WiFi from reaching its potential: ... More
Tunneling transport of mono- and few-layers magnetic van der Waals MnPS$_3$Aug 12 2016We have investigated the tunneling transport of mono- and few-layers of MnPS3 by using conductive atomic force microscopy. Due to the band alignment of indium tin oxide/MnPS3/Pt-Ir tip junction, the key features of both Schottky junction and Fowler-Nordheim ... More
Fabry-Perot interference, Kondo effect and Coulomb blockade in carbon nanotubesNov 13 2007High quality single wall carbon nanotube quantum dots have been made showing both metallic and semiconducting behavior. Some of the devices are identified as small band gap semiconducting nanotubes with relatively high broad conductance oscillations for ... More
Kondo resonance enhanced supercurrent in single wall carbon nanotube Josephson junctionsJan 17 2006May 10 2007We have contacted single wall carbon nanotubes grown by chemical vapor deposition to superconducting Ti/Al/Ti electrodes. The device, we here report on is in the Kondo regime exhibiting a four-fold shell structure, where a clear signature of the superconducting ... More
Photoproduction of the scalar mesons $f_0(500)$ and $f_0(980)$ off the nucleonAug 04 2016We investigate photoproduction of the scalar mesona off the nucleon, using the effective Lagrangians and the Regge approach. We first study $f_0(980)$ photoproduction, replacing the Feynman propagator with the Regge ones for the $\rho$-meson exchange ... More
Many new variable stars discovered in the core of the globular cluster NGC 6715 (M54) with EMCCD observationsMay 19 2016We show the benefits of using Electron-Multiplying CCDs and the shift-and-add technique as a tool to minimise the effects of the atmospheric turbulence such as blending between stars in crowded fields and to avoid saturated stars in the fields observed. ... More
Molecular abundances in low-mass protostellar envelopesNov 24 2002A study of the chemical structure of the envelopes around a sample protostars is introduced. Physical models for the envelopes derived using 1D radiative transfer modeling of their dust continuum emission are used as input for Monte Carlo modeling of ... More
Chemical tracers of episodic accretion in low-mass protostarsMar 17 2015Aims: Accretion rates in low-mass protostars can be highly variable in time. Each accretion burst is accompanied by a temporary increase in luminosity, heating up the circumstellar envelope and altering the chemical composition of the gas and dust. This ... More
The Multivariate Generalised von Mises: Inference and applicationsFeb 16 2016May 23 2016Circular variables arise in a multitude of data-modelling contexts ranging from robotics to the social sciences, but they have been largely overlooked by the machine learning community. This paper partially redresses this imbalance by extending some standard ... More
The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds. IV. Lupus Observed with MIPSJun 13 2007We present maps of 7.78 square degrees of the Lupus molecular cloud complex at 24, 70, and $160\:\mu$m. They were made with the Spitzer Space Telescope's Multiband Imaging Photometer for Spitzer (MIPS) instrument as part of the Spitzer Legacy Program, ... More
First results of the Herschel Key Program 'Dust, Ice and Gas in Time': Dust and Gas Spectroscopy of HD 100546May 19 2010We present far-infrared spectroscopic observations, taken with the Photodetector Array Camera and Spectrometer (PACS) on the Herschel Space Observatory, of the protoplanetary disk around the pre-main-sequence star HD 100546. These observations are the ... More
Current Star Formation in the Perseus Molecular Cloud: Constraints from Unbiased Submillimeter and Mid-Infrared SurveysOct 12 2006We present a census of the population of deeply embedded young stellar objects (YSOs) in the Perseus molecular cloud complex based on a combination of Spitzer Space Telescope mid-IR data from the c2d legacy team and JCMT/SCUBA submillimeter maps from ... More