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Sample records for enigmatic young brown

  1. Cloud Driven Variability on Young Brown Dwarfs and Giant Exoplanets

    NASA Astrophysics Data System (ADS)

    Biller, Beth

    2016-01-01

    Variability has now been robustly observed in a range of L and T type field brown dwarfs, primarily at near-IR and mid-IR wavelengths. The probable cause of this variability is surface inhomogeneities in the clouds of these objects, causing a semi-periodic variability signal when combined with the rotational modulation from the 3-12 hour period expected for these objects. Variability at similar or even higher amplitudes may be expected for young brown dwarfs and giant exoplanets, which share similar Teff as field brown dwarfs, but have considerably lower surface gravities. Variability studies of these objects relative to old field objects is then a direct probe of the effects of surface gravity on atmospheric structure. Here I discuss ongoing efforts to detect variability from these young objects, both for free-floating objects and companions to stars, including preliminary results from an ongoing survey of young, low surface gravity objects with NTT SOFI.

  2. Observational diagnostics of accretion on young stars and brown dwarfs

    NASA Astrophysics Data System (ADS)

    Stelzer, Beate; Argiroffi, Costanza

    I present a summary of recent observational constraints on the accretion properties of young stars and brown dwarfs with focus on the high-energy emission. In their T Tauri phase young stars assemble a few percent of their mass by accretion from a disk. Various observational signatures of disks around pre-main sequence stars and the ensuing accretion process are found in the IR and optical regime: e.g. excess emission above the stellar photosphere, strong and broad emission lines, optical veiling. At high energies evidence for accretion is less obvious, and the X-ray emission from stars has historically been ascribed to magnetically confined coronal plasmas. While being true for the bulk of the emission, new insight obtained from XMM-Newton and Chandra observations has unveiled contributions from accretion and outflow processes to the X-ray emission from young stars. Their smaller siblings, the brown dwarfs, have been shown to undergo a T Tauri phase on the basis of optical/IR observations of disks and measurements of accretion rates. Most re-cently, first evidence was found for X-rays produced by accretion in a young brown dwarf, complementing the suspected analogy between stars and substellar objects.

  3. Discovery of a nearby young brown dwarf binary candidate

    NASA Astrophysics Data System (ADS)

    Reiners, A.; Seifahrt, A.; Dreizler, S.

    2010-04-01

    In near-infrared NaCo observations of the young brown dwarf 2MASS J0041353-562112, we discovered a companion a little less than a magnitude fainter than the primary. The binary candidate has a separation of 143 mas, and the spectral types of the two components are M 6.5 and M 9.0. Colors and flux ratios of the components are consistent with their locations being at the same distance minimizing the probability of the secondary being a background object. The brown dwarf is known to exhibit Li absorption constraining the age to be younger than ~ 200 Myr, and has been suspected of experiencing ongoing accretion, which implies an age as young as ~ 10 Myr. We estimate distance and orbital parameters of the binary as a function of age. For an age of 10 Myr, the distance to the system is 50 pc, the orbital period is 126 yr, and the masses of the components are ~ 30 and ~ 15 MJup. The binary brown dwarf fills a so far unoccupied region in the parameters mass and age; it is a valuable new benchmark object for brown dwarf atmospheric and evolutionary models. Emmy Noether Fellow.

  4. MEASURING TINY MASS ACCRETION RATES ONTO YOUNG BROWN DWARFS

    SciTech Connect

    Herczeg, Gregory J.; Cruz, Kelle L.; Hillenbrand, Lynne A.

    2009-05-10

    We present low-resolution Keck I/LRIS spectra spanning from 3200 to 9000 A of nine young brown dwarfs and three low-mass stars in the TW Hya Association and in Upper Sco. The optical spectral types of the brown dwarfs range from M5.5 to M8.75, though two have near-IR spectral types of early L dwarfs. We report new accretion rates derived from excess Balmer continuum emission for the low-mass stars TW Hya and Hen 3-600A and the brown dwarfs 2MASS J12073347-3932540, UScoCTIO 128, SSSPM J1102-3431, USco J160606.29-233513.3, DENIS-P J160603.9-205644, and Oph J162225-240515B, and upper limits on accretion for the low-mass star Hen 3-600B and the brown dwarfs UScoCTIO 112, Oph J162225-240515A, and USco J160723.82-221102.0. For the six brown dwarfs in our sample that are faintest at short wavelengths, the accretion luminosity or upper limit is measurable only when the image is binned over large wavelength intervals. This method extends our sensitivity to accretion rate down to {approx}10{sup -13} M{sub sun}yr{sup -1} for brown dwarfs. Since the ability to measure an accretion rate from excess Balmer continuum emission depends on the contrast between excess continuum emission and the underlying photosphere, for objects with earlier spectral types the upper limit on accretion rate is much higher. Absolute uncertainties in our accretion rate measurements of {approx}3-5 include uncertainty in accretion models, brown dwarf masses, and distance. The accretion rate of 2 x 10{sup -12} M {sub sun} yr{sup -1} onto 2MASS J12073347-3932540 is within 15% of two previous measurements, despite large changes in the H{alpha} flux.

  5. Astronaut John Young displays drawing of Charlie Brown

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronaut John W. Young, Apollo 10 command module pilot, displays drawing of Charlie Brown in this color reproduction taken from the fourth telecast made by the color television camera aboard the Apollo 10 spacecraft. When this picture was made the Apollo 10 spacecraft was about half-way to the moon, or approximately 112,000 nautical miles from the earth. Charlie Brown will be the code name of the Command Module (CM) during Apollo 10 operations when the Lunar Module and CM are separated (34075); Young displays drawing of Snoopy in this reproduction taken from a television transmission. Snoopy will be the code name of the Lunar Module (LM) during Apollo 10 operations when the LM and CM are separated (34076).

  6. A Million Years Young: Determining the Ages of 11 Suspected Young Brown Dwarfs

    NASA Astrophysics Data System (ADS)

    Schwab, Ellie; DiTomasso, Victoria; Riedel, Adric R.; Rice, Emily L.; Cruz, Kelle L.; Faherty, Jacqueline K.; BDNYC

    2016-01-01

    Brown dwarfs continuously cool and fade with time, so knowing an object's age is necessary in order to estimate its mass. One of the most reliable ways to constrain the age is to identify objects as members of coeval moving groups with reliable ages based on higher mass members. Confirming membership requires knowledge of an object's parallax distance, proper motion, and radial velocity (RV), which requires a high-resolution spectrum. We obtained high-resolution NIRSPEC J-band data and measured radial velocities for a sample of 11 suspected young, nearby M and L dwarfs. We combined these RV values with previously calculated parallax distances and proper motions to determine the likelihood of young moving group membership using the LACeWING code (Riedel et al. 2015). We confirmed memberships in the Argus Association (~40 Myr) and Tucana-Horologium (~30 Myr) with a probability of >66.7% for two of the 11 brown dwarfs. Another one of the dwarfs had a >79.5% probability of membership in both the AB Doradus (110 Myr) and Hercules-Lyra (257 Myr) groups, which will require further inquiry to resolve. We also compare spectra of our 11 brown dwarfs to spectra of established young and field brown dwarfs in order to further understand spectral indicators of youth at high spectral resolution.

  7. The BASS survey for brown dwarfs in young moving groups

    NASA Astrophysics Data System (ADS)

    Gagne, Jonathan; Lafreniere, David; Doyon, Rene; Malo, Lison; Faherty, Jacqueline K.; Artigau, Etienne; Cruz, Kelle L.; Burgasser, Adam J.; Filippazzo, Joe; Naud, Marie-Eve; Albert, Loic; Bouchard, Sandie; Gizis, John; Robert, Jasmin; Nadeau, Daniel; Bowsher, Emily C.; Nicholls, Christine

    2016-01-01

    I will present in this dissertation talk the construction and follow-up of the BANYAN All-Sky Survey (BASS) that we led to identify dozens of new isolated young brown dwarfs in the Solar neighborhood, several of which have physical properties such as mass, age and temperature that make them similar to exoplanets that were recently discovered using the method of direct imaging.Such isolated analogs of the giant, gaseous exoplanets are precious benchmarks that will allow a deep characterization of their atmospheres using high-resolution and high signal-to-noise spectroscopy, which is made possible due to the absence of a nearby and bright host star.I will end by describing BASS-Ultracool, an extension of BASS that focuses on the identification of extremely cool isolated exoplanet analogs that display methane in their atmospheres. This survey has already uncovered the first bonafide T dwarf member of a moving group, the ~150 Myr AB Doradus T5, SDSS1110+0116.

  8. Discovery of two young brown dwarfs in an eclipsing binary system.

    PubMed

    Stassun, Keivan G; Mathieu, Robert D; Valenti, Jeff A

    2006-03-16

    Brown dwarfs are considered to be 'failed stars' in the sense that they are born with masses between the least massive stars (0.072 solar masses, M(o)) and the most massive planets (approximately 0.013M(o)); they therefore serve as a critical link in our understanding of the formation of both stars and planets. Even the most fundamental physical properties of brown dwarfs remain, however, largely unconstrained by direct measurement. Here we report the discovery of a brown-dwarf eclipsing binary system, in the Orion Nebula star-forming region, from which we obtain direct measurements of mass and radius for these newly formed brown dwarfs. Our mass measurements establish both objects as brown dwarfs, with masses of 0.054 +/- 0.005M(o) and 0.034 +/- 0.003M(o). At the same time, with radii relative to the Sun's of 0.669 +/- 0.034R(o) and 0.511 +/- 0.026R(o), these brown dwarfs are more akin to low-mass stars in size. Such large radii are generally consistent with theoretical predictions for young brown dwarfs in the earliest stages of gravitational contraction. Surprisingly, however, we find that the less-massive brown dwarf is the hotter of the pair; this result is contrary to the predictions of all current theoretical models of coeval brown dwarfs. PMID:16541067

  9. Determining the Locations of Brown Dwarfs in Young Star Clusters

    NASA Technical Reports Server (NTRS)

    Porter, Lauren A.

    2005-01-01

    Brown dwarfs are stellar objects with masses less than 0.08 times that of the Sun that are unable to sustain nuclear fusion. Because of the lack of fusion, they are relatively cold, allowing the formation of methane and water molecules in their atmospheres. Brown dwarfs can be detected by examining stars' absorption spectra in the near-infrared to see whether methane and water are present. The objective of this research is to determine the locations of brown dwarfs in Rho Ophiuchus, a star cluster that is only 1 million years old. The cluster was observed in four filters in the near-infrared range using the Wide-Field Infra-Red Camera (WIRC) on the 100" DuPont Telescope and Persson's Auxiliary Nasymith Infrared Camera (PANIC) on the 6.5-m Magellan Telescope. By comparing the magnitude of a star in each of the four filters, an absorption spectrum can be formed. This project uses standard astronomical techniques to reduce raw frames into final images and perform photometry on them to obtain publishable data. Once this is done, it will be possible to determine the locations and magnitudes of brown dwarfs within the cluster.

  10. Connecting Young Brown Dwarfs and Directly Imaged Gas-Giant Planets

    NASA Astrophysics Data System (ADS)

    Liu, Michael; Dupuy, Trent; Allers, Katelyn; Aller, Kimberly; Best, William; Magnier, Eugene

    2015-12-01

    Direct detections of gas-giant exoplanets and discoveries of young (~10-100 Myr) field brown dwarfs from all-sky surveys are strengthening the link between the exoplanet and brown dwarf populations, given the overlapping ages, masses, temperatures, and surface gravities. In light of the relatively small number of directly imaged planets and the modest associated datasets, the large census of young field brown dwarfsprovides a compelling laboratory for enriching our understanding of both classes of objects. However, work to date on young field objects has typically focused on individual discoveries.We present a large comprehensive study of the youngest field brown dwarfs, comprising both previously known objects and our new discoveries from the latest wide-field surveys (Pan-STARRS-1 and WISE). With masses now extending down to ~5 Jupiter masses, these objects have physical properties that largely overlap young gas-giant planets and thus are promising analogs for studying exoplanet atmospheres at unparalleled S/N, spectral resolution, and wavelength coverage. We combine high-quality spectra and parallaxes to determine spectral energy distributions, luminosities, temperatures, and ages for young field objects. We demonstrate that this population spans a continuum in the color-magnitude diagram, thereby forming a bridge between the hot and cool extremes of directly imaged planets. We find that the extremely dusty properties of the planets around 2MASS J1207-39 and HR 8799 do occur in some young brown dwarfs, but these properties do not have a simple correspondence with age, perhaps contrary to expectations. We find young field brown dwarfs can have unusually low temperatures and suggest a new spectral type-temperature scale appropriate for directly imaged planets.To help provide a reference for extreme-contrast imaging surveys, we establish a grid of spectral standards and benchmarks, based on membership in nearby young moving groups, in order to calibrate gravity

  11. Organochlorine residues in females and nursing young of the big brown bat (Eptesicus fuscus)

    USGS Publications Warehouse

    Clark, D.R., Jr.; Lamont, T.G.

    1976-01-01

    Carcasses and brains of 18 big brown bats from Gaithersburg, Maryland, were analyzed for residues of organochlorine insecticides and PCB's. Eleven bats were adult females, and six of these had seven nursing young associated with them....Young bats resembled their parents in microgram amounts of PCB and DDE present in carcasses. However, concentrations of chemicals (expressed as ppm) were significantly higher in young. Brains of three young contained detectable residues of PCB and DDE....Younger adult females contained higher levels of PCB and DDE than did older ones. However, among the oldest females, amounts appeared to begin rising again. This pattern resembles that in free-tailed bats from Bracken Cave, Texas, but differs from the continuous linear decline seen in a Laurel, Maryland population of big brown bats, in which initial levels among younger females were higher than those in the Gaithersburg population....DDE was transferred from female to young more readily than was PCB by nursing. Five of 51 neonate big brown bats from the Laurel population were thought to have been born dead because of residues of PCB that were transferred across the placenta. Present data show that even greater amounts of PCB may be transferred to young by lactation and nursing.

  12. The BANYAN All-Sky Survey for Brown Dwarf Members of Young Moving Groups

    NASA Astrophysics Data System (ADS)

    Gagné, Jonathan; Lafrenière, David; Doyon, René; Faherty, Jacqueline K.; Malo, Lison; Cruz, Kelle L.; Artigau, Étienne; Burgasser, Adam J.; Naud, Marie-Eve; Bouchard, Sandie; Gizis, John E.; Albert, Loïc

    2016-01-01

    We describe in this work the BASS survey for brown dwarfs in young moving groups of the solar neighborhood, and summarize the results that it generated. These include the discovery of the 2MASS J01033563-5515561 (AB)b and 2MASS J02192210-3925225 B young companions near the deuterium-burning limit as well as 44 new low-mass stars and 69 new brown dwarfs with a spectroscopically confirmed low gravity. Among those, ~20 have estimated masses within the planetary regime, one is a new L4 γ bona fide member of AB Doradus, three are TW Hydrae candidates with later spectral types (L1-L4) than all of its previously known members and six are among the first contenders for low-gravity >= L5 β/γ brown dwarfs, reminiscent of WISEP J004701.06+680352.1, PSO J318.5338-22.8603 and VHS J125601.92-125723.9 b. Finally, we describe a future version of this survey, BASS-Ultracool, that will specifically target >= L5 candidate members of young moving groups. First experimentations in designing the survey have already led to the discovery of a new T dwarf bona fide member of AB Doradus, as well as the serendipitous discoveries of an L9 subdwarf and an L5 + T5 brown dwarf binary.

  13. "Brown Paper Packages"? A Sociocultural Perspective on Young Children's Ideas in Science

    ERIC Educational Resources Information Center

    Robbins, Jill

    2005-01-01

    How do we see young children's thinking in science? Is it, as much previous research has led us to believe, that their ideas can be neatly boxed like "brown paper packages tied up with strings"--as the song from "The Sound of Music" goes? Or are their ideas like "wild geese that fly with the moon on their wings" ("Sound of Music"): fluid, complex,…

  14. Rotation Periods of Young Brown Dwarfs: K2 Survey in Upper Scorpius

    NASA Astrophysics Data System (ADS)

    Scholz, Alexander; Kostov, Veselin; Jayawardhana, Ray; Mužić, Koraljka

    2015-08-01

    We report rotational periods for 16 young brown dwarfs in the nearby Upper Scorpius association, based on 72 days of high-cadence, high-precision photometry from the Keplerspace telescope’s K2 mission. The periods range from a few hours to two days (plus one outlier at five days), with a median just above one day, confirming that brown dwarfs, except at the very youngest ages, are fast rotators. Interestingly, four of the slowest rotators in our sample exhibit mid-infrared excess emission from disks; at least two also show signs of disk eclipses and accretion in the light curves. Comparing these new periods with those for two other young clusters and simple angular momentum evolution tracks, we find little or no rotational braking in brown dwarfs between 1-10 Myr, in contrast to low-mass stars. Our findings show that disk braking, while still at work, is inefficient in the substellar regime, thus providing an important constraint on the mass dependence of the braking mechanism.

  15. Brown Dwarfs in Young Moving Groups from Pan-STARRS1. I. AB Doradus

    NASA Astrophysics Data System (ADS)

    Aller, Kimberly M.; Liu, Michael C.; Magnier, Eugene A.; Best, William M. J.; Kotson, Michael C.; Burgett, William S.; Chambers, Kenneth C.; Hodapp, Klaus W.; Flewelling, Heather; Kaiser, Nick; Metcalf, Nigel; Tonry, John L.; Wainscoat, Richard J.; Waters, Christopher

    2016-04-01

    Substellar members of young (≲150 Myr) moving groups are valuable benchmarks to empirically define brown dwarf evolution with age and to study the low-mass end of the initial mass function. We have combined Pan-STARRS1 (PS1) proper motions with optical–IR photometry from PS1, Two Micron All Sky Survey (2MASS), and WISE to search for substellar members of the AB Dor Moving Group within ≈50 pc and with spectral types of late M to early L, corresponding to masses down to ≈30 MJup at the age of the group (≈125 Myr). Including both photometry and proper motions allows us to better select candidates by excluding field dwarfs whose colors are similar to young AB Dor Moving Group members. Our near-IR spectroscopy has identified six ultracool dwarfs (M6–L4 ≈30–100 MJup) with intermediate surface gravities (int-g) as candidate members of the AB Dor Moving Group. We find another two candidate members with spectra showing hints of youth but consistent with field gravities. We also find four field brown dwarfs unassociated with the AB Dor Moving Group, three of which have int-g gravity classification. While signatures of youth are present in the spectra of our ≈125 Myr objects, neither their J – K nor W1 – W2 colors are significantly redder than field dwarfs with the same spectral types, unlike younger ultracool dwarfs. We also determined PS1 parallaxes for eight of our candidates and one previously identified AB Dor Moving Group candidate. Although radial velocities (and parallaxes, for some) are still needed to fully assess membership, these new objects provide valuable insight into the spectral characteristics and evolution of young brown dwarfs.

  16. SUBSTELLAR OBJECTS IN NEARBY YOUNG CLUSTERS (SONYC). V. NEW BROWN DWARFS IN {rho} OPHIUCHI

    SciTech Connect

    Muzic, Koraljka; Jayawardhana, Ray; Scholz, Alexander; Geers, Vincent; Tamura, Motohide

    2012-01-10

    SONYC-Substellar Objects in Nearby Young Clusters-is a survey program to investigate the frequency and properties of substellar objects with masses down to a few times that of Jupiter in nearby star-forming regions. For the {approx}1 Myr old {rho} Ophiuchi cluster, in our earlier paper we reported deep, wide-field optical and near-infrared imaging using Subaru, combined with Two Micron All Sky Survey and Spitzer photometry, as well as follow-up spectroscopy confirming three likely cluster members, including a new brown dwarf with a mass close to the deuterium-burning limit. Here we present the results of extensive new spectroscopy targeting a total of {approx}100 candidates in {rho} Oph, with Fiber Multi Object Spectrograph at the Subaru Telescope and SINFONI at the ESO's Very Large Telescope. We identify 19 objects with effective temperatures at or below 3200 K, eight of which are newly identified very low mass probable members of {rho} Oph. Among these eight, six objects have T{sub eff} {<=} 3000 K, confirming their likely substellar nature. These six new brown dwarfs comprise one-fifth of the known substellar population in {rho} Oph. We estimate that the number of missing substellar objects in our survey area is {approx}15, down to 0.003-0.03 M{sub Sun} and for A{sub V} = 0-15. The upper limit on the low-mass star to brown dwarf ratio in {rho} Oph is 5.1 {+-} 1.4, while the disk fractions are {approx}40% and {approx}60% for stars and brown dwarfs, respectively. Both results are in line with those for other nearby star-forming regions.

  17. New circumstellar disk candidates around young low mass stars and brown dwarfs

    NASA Astrophysics Data System (ADS)

    Boucher, Anne; Lafrenière, David; Gagné, Jonathan; Malo, Lison; Doyon, Rene

    2015-12-01

    It is now common knowledge that circumstellar disks are signposts of past or ongoing planetary system formation. Their presence and their properties, in relation to those of their host star, also bear valuable information about the process of star formation itself. To address these questions, we started a project to uncover new circumstellar disks around newly identified low mass star and brown dwarf candidates in nearby young kinematic associations. Being near the stellar/substellar mass boundary, these hosts - and their potential disks - are particularly interesting to study both star and planet formation. We used a least squares approach to fit synthetic spectra to the observed photometric data of each star, covering from 0.8 µm up to 22 µm, and then identified candidates showing a significant excess compared to the best fits. We then carefully looked at the data for these candidates to filter out those biased by contaminants or other artefacts. We ended up with a list of 4 young stars and brown dwarfs strongly suspected of being surrounded by a disk. Here we will present our search method and some properties of our newly identified disk-bearing candidates.

  18. `Brown Paper Packages'? A Sociocultural Perspective on Young Children's Ideas in Science

    NASA Astrophysics Data System (ADS)

    Robbins, Jill

    2005-09-01

    How do we see young children's thinking in science? Is it, as much previous research has led us to believe, that their ideas can be neatly boxed like “brown paper packages tied up with strings” - as the song from The Sound of Music goes? Or are their ideas like “wild geese that fly with the moon on their wings” ( Sound of Music): fluid, complex, rich. . .? Drawing on the author's research into young children's ideas about natural phenomena such as the rain and clouds, and on Rogoff's three foci of analysis (personal, interpersonal and contextual), this paper illustrates how a consideration of sociocultural theory can be useful in framing research with young children, and allow us to see beyond the boxes. Emphasis is placed on recognising that children's thinking in science is embedded within particular sociocultural contexts, is guided by others and integrated with their use of certain mental and physical cultural tools. Thus, the article aims to present an alternative method for the generation of data on young children's thinking. Specific analysis of this data will, it is intended, be presented in a subsequent article.

  19. Effect of Chronic Athletic Activity on Brown Fat in Young Women

    PubMed Central

    Singhal, Vibha; Maffazioli, Giovana D.; Ackerman, Kate E.; Lee, Hang; Elia, Elisa F.; Woolley, Ryan; Kolodny, Gerald; Cypess, Aaron M.; Misra, Madhusmita

    2016-01-01

    Background The effect of chronic exercise activity on brown adipose tissue (BAT) is not clear, with some studies showing positive and others showing negative associations. Chronic exercise is associated with increased resting energy expenditure (REE) secondary to increased lean mass and a probable increase in BAT. Many athletes are in a state of relative energy deficit suggested by lower fat mass and hypothalamic amenorrhea. States of severe energy deficit such as anorexia nervosa are associated with reduced BAT. There are no data regarding the impact of chronic exercise activity on BAT volume or activity in young women and it is unclear whether relative energy deficiency modifies the effects of exercise on BAT. Purpose We assessed cold induced BAT volume and activity in young female athletes compared with non-athletes, and further evaluated associations of BAT with measures of REE, body composition and menstrual status. Methods The protocol was approved by our Institutional Review Board. Written informed consent was obtained from all participants prior to study initiation. This was a cross-sectional study of 24 women (16 athletes and8 non-athletes) between 18–25 years of age. Athletes were either oligo-amenorrheic (n = 8) or eumenorrheic (n = 8).We used PET/CT scans to determine cold induced BAT activity, VMAX Encore 29 metabolic cart to obtain measures of REE, and DXA for body composition. Results Athletes and non-athletes did not differ for age or BMI. Compared with non-athletes, athletes had lower percent body fat (p = 0.002), higher percent lean mass (p = 0.01) and trended higher in REE (p = 0.09). BAT volume and activity in athletes trended lower than in non-athletes (p = 0.06; p = 0.07, respectively). We found negative associations of BAT activity with duration of amenorrhea (r = -0.46, p = 0.02).BAT volume correlated inversely with lean mass (r = -0.46, p = 0.02), and positively with percent body fat, irisin and thyroid hormones. Conclusions Our study

  20. A pulsation search among young brown dwarfs and very-low-mass stars

    SciTech Connect

    Cody, Ann Marie; Hillenbrand, Lynne A.

    2014-12-01

    In 2005, Palla and Baraffe proposed that brown dwarfs (BDs) and very-low-mass stars (VLMSs; < 0.1 solar masses) may be unstable to radial oscillations during the pre-main-sequence deuterium burning phase. With associated periods of one to four hours, this potentially new class of pulsation offers unprecedented opportunities to probe the interiors and evolution of low-mass objects in the 1-15 million year age range. Following up on reports of short-period variability in young clusters, we designed a high-cadence photometric monitoring campaign to search for deuterium-burning pulsation among a sample of 348 BDs and VLMSs in the four young clusters σ Orionis, Chamaeleon I, IC 348, and Upper Scorpius. In the resulting light curves we achieved sensitivity to periodic signals of amplitude several millimagnitudes, on timescales from 15 minutes to two weeks. Despite the exquisite data quality, we failed to detect any periodicities below seven hours. We conclude that D-burning pulsations are not able to grow to observable amplitudes in the early pre-main sequence. In spite of the nondetection, we did uncover a rich set of variability behavior—both periodic and aperiodic—on day to week timescales. We present new compilations of variable sources from our sample, as well as three new candidate cluster members in Chamaeleon I.

  1. ALMA OBSERVATIONS OF {rho}-Oph 102: GRAIN GROWTH AND MOLECULAR GAS IN THE DISK AROUND A YOUNG BROWN DWARF

    SciTech Connect

    Ricci, L.; Testi, L.; Natta, A.; Scholz, A.; De Gregorio-Monsalvo, I.

    2012-12-20

    We present ALMA continuum and spectral line observations of the young brown dwarf {rho}-Oph 102 at about 0.89 mm and 3.2 mm. We detect dust emission from the disk at these wavelengths and derive an upper limit on the radius of the dusty disk of {approx}40 AU. The derived variation of the dust opacity with frequency in the millimeter (mm) provides evidence for the presence of mm-sized grains in the disk's outer regions. This result demonstrates that mm-sized grains are found even in the low-density environments of brown dwarf disks and challenges our current understanding of dust evolution in disks. The CO map at 345 GHz clearly reveals molecular gas emission at the location of the brown dwarf, indicating a gas-rich disk as typically found for disks surrounding young pre-main-sequence stars. We derive a disk mass of {approx}0.3%-1% of the mass of the central brown dwarf, similar to the typical values found for disks around more massive young stars.

  2. Young Low-Mass Stars and Brown Dwarfs in IC 348

    NASA Astrophysics Data System (ADS)

    Luhman, K. L.

    1999-11-01

    I present new results from a continuing program to identify and characterize the low-mass stellar and substellar populations in the young cluster IC 348 (0.5-10 Myr). Optical spectroscopy has revealed young objects with spectral types as late as M8.25. The intrinsic J-H and H-K colors of these sources are dwarflike, whereas the R-I and I-J colors appear intermediate between the colors of dwarfs and giants. Furthermore, the spectra from 6500 to 9500 Å are reproduced well with averages of standard dwarf and giant spectra, suggesting that such averages should be used in the classification of young late-type sources. An H-R diagram is constructed for the low-mass population in IC 348 (K6-M8). The presumably coeval components of the young quadruple system GG Tau (White et al.) and the locus of stars in IC 348 are used as empirical isochrones to test the theoretical evolutionary models. The calculations of Burrows et al. do not appear to be consistent with the data at these earliest stages of stellar evolution. There is fair agreement between the data and the model isochrones of D'Antona & Mazzitelli, except near the hydrogen-burning limit. The agreement cannot be improved by changing the conversion between spectral types and effective temperatures. On the other hand, for the models of Baraffe et al., an adjustment of the temperature scale to progressively warmer temperatures at later M types, intermediate between dwarfs and giants, brings all components of GG Tau onto the same model isochrone and gives the population of IC 348 a constant age and age spread as a function of mass. When other observational constraints are considered, such as the dynamical masses of GM Aur, DM Tau, and GG Tau A, the models of Baraffe et al. are the most consistent with observations of young systems. With compatible temperature scales, the models of both D'Antona & Mazzitelli and Baraffe et al. suggest that the hydrogen-burning mass limit occurs near M6 at ages of <~10 Myr. Thus, several

  3. Accretion-ejection connection in the young brown dwarf candidate ISO-ChaI 217

    NASA Astrophysics Data System (ADS)

    Whelan, E. T.; Alcalá, J. M.; Bacciotti, F.; Nisini, B.; Bonito, R.; Antoniucci, S.; Stelzer, B.; Biazzo, K.; D'Elia, V.; Ray, T. P.

    2014-10-01

    As the number of observed brown dwarf outflows is growing it is important to investigate how these outflows compare to the well-studied jets from young stellar objects. A key point of comparison is the relationship between outflow and accretion activity and in particular the ratio between the mass outflow and accretion rates (M⊙out/M⊙acc). The brown dwarf candidate ISO-ChaI 217 was discovered by our group, as part of a spectro-astrometric study of brown dwarfs, to be driving an asymmetric outflow with the blue-shifted lobe having a position angle of ~20°. The aim here is to further investigate the properties of ISO-ChaI 217, the morphology and kinematics of its outflow, and to better constrain M⊙out/M⊙acc. The outflow is spatially resolved in the [S ii] λλ6716,6731 lines and is detected out to ~1.̋6 in the blue-shifted lobe and 1'' in the red-shifted lobe. The asymmetry between the two lobes is confirmed although the velocity asymmetry is less pronounced with respect to our previous study. Using thirteen different accretion tracers we measure log (M⊙acc) [M⊙/yr] = -10.6 ± 0.4. As it was not possible to measure the effect of extinction on the ISO-ChaI 217 outflow M⊙out was derived for a range of values of Av, up to a value of Av = 2.5 mag estimated for the source extinction. The logarithm of the mass outflow (M⊙out) was estimated in the range -11.7 to -11.1 for both jets combined. Thus M⊙out/M⊙acc [M⊙/yr] lies below the maximum value predicted by magneto-centrifugal jet launching models. Finally, both model fitting of the Balmer decrements and spectro-astrometric analysis of the Hα line show that the bulk of the H I emission comes from the accretion flow. Based on Observations collected with X-Shooter at the Very Large Telescope on Cerro Paranal (Chile), operated by the European Southern Observatory (ESO). Program ID: 089.C-0143(A).

  4. The Enigmatic Neutrino

    NASA Astrophysics Data System (ADS)

    Lincoln, Don; Miceli, Tia

    2015-09-01

    Through a century of work, physicists have refined a model to describe all fundamental particles, the forces they share, and their interactions on a microscopic scale. This masterpiece of science is called the Standard Model. While this theory is incredibly powerful, we know of at least one particle that exhibits behaviors that are outside of its scope and remain unexplained. These particles are called neutrinos and they are the enigmatic ghosts of the quantum world. Interacting only via the weak nuclear force, literally billions of them pass through you undetected every second. While we understand that particular spooky behavior, we do not understand in any fundamental way how it is that neutrinos can literally change their identity, much as if a house cat could turn into a lion and then a tiger before transitioning back into a house cat again.

  5. SUBSTELLAR OBJECTS IN NEARBY YOUNG CLUSTERS (SONYC). II. THE BROWN DWARF POPULATION OF {rho} OPHIUCHI

    SciTech Connect

    Geers, Vincent; Jayawardhana, Ray; Lee, Eve; Lafreniere, David; Scholz, Alexander; Tamura, Motohide

    2011-01-01

    SONYC-Substellar Objects in Nearby Young Clusters-is a survey program to investigate the frequency and properties of brown dwarfs (BDs) down to masses below the deuterium-burning limit in nearby star-forming regions. In this second paper, we present results on the {approx}1 Myr old cluster {rho} Ophiuchi, combining our own deep optical- and near-infrared imaging using Subaru with photometry from the Two Micron All Sky Survey and the Spitzer Space Telescope. Of the candidates selected from iJK{sub s} photometry, we have confirmed three-including a new BD with a mass close to the deuterium limit-as likely cluster members through low-resolution infrared spectroscopy. We also identify 27 substellar candidates with mid-infrared excess consistent with disk emission, of which 16 are new and 11 are previously spectroscopically confirmed BDs. The high and variable extinction makes it difficult to obtain the complete substellar population in this region. However, current data suggest that its ratio of low-mass stars to BDs is similar to those reported for several other clusters, though higher than what was found for NGC 1333 in Scholz et al.

  6. Do circumstellar disks regulate rotation in young very low mass stars and brown dwarfs?

    NASA Astrophysics Data System (ADS)

    Rodriguez-Ledesma, M. V.; Mundt, R.; Eislöffel, J.

    Rotational studies at a variety of ages and masses are important for con- straining the angular momentum evolution of young stellar objects. Of particular interest are the very low mass (VLM) stars and brown dwarfs (BDs), because of the significant lack of known rotational periods in that mass range. We present results of an extensive rotational study in the Orion Nebula Clus- ter from where 487 new rotational periods were measured. In order to inves- tigate a rotation-disk correlation, we derived near infrared (NIR) excesses (from IJHK photometry) for a sample of 732 very low mass periodic vari- ables. We found a highly significant rotation-disk correlation for objects with masses between 0.4-0.075 M , in which objects with NIR excess tend to rotate slower than objects without NIR excess. Interestingly we found no corre- lation in the substellar regime. We discuss possible scenarios which may explain the lack of rotation-disk connection in the substellar mass regime.

  7. The Initial Mass Function of Low-Mass Stars and Brown Dwarfs in Young Clusters

    NASA Astrophysics Data System (ADS)

    Luhman, K. L.; Rieke, G. H.; Young, Erick T.; Cotera, Angela S.; Chen, H.; Rieke, Marcia J.; Schneider, Glenn; Thompson, Rodger I.

    2000-09-01

    similarity of the IMFs among young clusters, (3) the lowest mass observed for brown dwarfs, and (4) the suggested connection between the stellar IMF and the mass function of prestellar clumps. In particular, most models do not predict the formation of the moderately large numbers of isolated objects down to 0.01 Msolar that we find in the Trapezium. Based on observations made with the Multiple Mirror Telescope operated by the Smithsonian Astrophysical Observatory and the University of Arizona. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with proposal ID 7217.

  8. Ozone induces glucose intolerance and systemic metabolic effects in young and aged brown Norway rats

    SciTech Connect

    Bass, V.; Gordon, C.J.; Jarema, K.A.; MacPhail, R.C.; Cascio, W.E.; Phillips, P.M.; Ledbetter, A.D.; Schladweiler, M.C.; Andrews, D.; Miller, D.; Doerfler, D.L.; Kodavanti, U.P.

    2013-12-15

    Air pollutants have been associated with increased diabetes in humans. We hypothesized that ozone would impair glucose homeostasis by altering insulin signaling and/or endoplasmic reticular (ER) stress in young and aged rats. One, 4, 12, and 24 month old Brown Norway (BN) rats were exposed to air or ozone, 0.25 or 1.0 ppm, 6 h/day for 2 days (acute) or 2 d/week for 13 weeks (subchronic). Additionally, 4 month old rats were exposed to air or 1.0 ppm ozone, 6 h/day for 1 or 2 days (time-course). Glucose tolerance tests (GTT) were performed immediately after exposure. Serum and tissue biomarkers were analyzed 18 h after final ozone for acute and subchronic studies, and immediately after each day of exposure in the time-course study. Age-related glucose intolerance and increases in metabolic biomarkers were apparent at baseline. Acute ozone caused hyperglycemia and glucose intolerance in rats of all ages. Ozone-induced glucose intolerance was reduced in rats exposed for 13 weeks. Acute, but not subchronic ozone increased α{sub 2}-macroglobulin, adiponectin and osteopontin. Time-course analysis indicated glucose intolerance at days 1 and 2 (2 > 1), and a recovery 18 h post ozone. Leptin increased day 1 and epinephrine at all times after ozone. Ozone tended to decrease phosphorylated insulin receptor substrate-1 in liver and adipose tissues. ER stress appeared to be the consequence of ozone induced acute metabolic impairment since transcriptional markers of ER stress increased only after 2 days of ozone. In conclusion, acute ozone exposure induces marked systemic metabolic impairments in BN rats of all ages, likely through sympathetic stimulation. - Highlights: • Air pollutants have been associated with increased diabetes in humans. • Acute ozone exposure produces profound metabolic alterations in rats. • Age influences metabolic risk factors in aging BN rats. • Acute metabolic effects are reversible and repeated exposure reduces these effects. • Ozone

  9. 2MASS J035523.37+113343.7: A Young, Dusty, Nearby, Isolated Brown Dwarf Resembling a Giant Exoplanet

    NASA Astrophysics Data System (ADS)

    Faherty, Jacqueline K.; Rice, Emily L.; Cruz, Kelle L.; Mamajek, Eric E.; Núñez, Alejandro

    2013-01-01

    We present parallax and proper motion measurements, near-infrared spectra, and Wide-field Infrared Survey Explorer photometry for the low surface gravity L5γ dwarf 2MASS J035523.37+113343.7 (2M0355). We use these data to evaluate photometric, spectral, and kinematic signatures of youth as 2M0355 is the reddest isolated L dwarf yet classified. We confirm its low-gravity spectral morphology and find a strong resemblance to the sharp triangular shaped H-band spectrum of the ~10 Myr planetary-mass object 2M1207b. We find that 2M0355 is underluminous compared to a normal field L5 dwarf in the optical and Mauna Kea Observatory J, H, and K bands and transitions to being overluminous from 3 to 12 μm, indicating that enhanced photospheric dust shifts flux to longer wavelengths for young, low-gravity objects, creating a red spectral energy distribution. Investigating the near-infrared color-magnitude diagram for brown dwarfs confirms that 2M0355 is redder and underluminous compared to the known brown dwarf population, similar to the peculiarities of directly imaged exoplanets 2M1207b and HR8799bcd. We calculate UVW space velocities and find that the motion of 2M0355 is consistent with young disk objects (<2-3 Gyr) and it shows a high likelihood of membership in the AB Doradus association.

  10. 2MASS J035523.37+113343.7: A YOUNG, DUSTY, NEARBY, ISOLATED BROWN DWARF RESEMBLING A GIANT EXOPLANET

    SciTech Connect

    Faherty, Jacqueline K.; Rice, Emily L.; Cruz, Kelle L.; Nunez, Alejandro; Mamajek, Eric E. E-mail: jfaherty@amnh.org

    2013-01-01

    We present parallax and proper motion measurements, near-infrared spectra, and Wide-field Infrared Survey Explorer photometry for the low surface gravity L5{gamma} dwarf 2MASS J035523.37+113343.7 (2M0355). We use these data to evaluate photometric, spectral, and kinematic signatures of youth as 2M0355 is the reddest isolated L dwarf yet classified. We confirm its low-gravity spectral morphology and find a strong resemblance to the sharp triangular shaped H-band spectrum of the {approx}10 Myr planetary-mass object 2M1207b. We find that 2M0355 is underluminous compared to a normal field L5 dwarf in the optical and Mauna Kea Observatory J, H, and K bands and transitions to being overluminous from 3 to 12 {mu}m, indicating that enhanced photospheric dust shifts flux to longer wavelengths for young, low-gravity objects, creating a red spectral energy distribution. Investigating the near-infrared color-magnitude diagram for brown dwarfs confirms that 2M0355 is redder and underluminous compared to the known brown dwarf population, similar to the peculiarities of directly imaged exoplanets 2M1207b and HR8799bcd. We calculate UVW space velocities and find that the motion of 2M0355 is consistent with young disk objects (<2-3 Gyr) and it shows a high likelihood of membership in the AB Doradus association.

  11. ROSAT X-ray detection of a young brown dwarf in the chamaeleon I dark cloud

    PubMed

    Neuhauser; Comeron

    1998-10-01

    Photometry and spectroscopy of the object Cha Halpha 1, located in the Chamaeleon I star-forming cloud, show that it is a approximately 10(6)-year-old brown dwarf with spectral type M7.5 to M8 and 0.04 +/- 0.01 solar masses. Quiescent x-ray emission was detected in a 36-kilosecond observation with 31.4 +/- 7.7 x-ray photons, obtained with the Rontgen Satellite (ROSAT), with 9final sigma detection significance. This corresponds to an x-ray luminosity of 2.57 x 10(28) ergs per second and an x-ray to bolometric luminosity ratio of 10(-3.44). These are typical values for late M-type stars. Because the interior of brown dwarfs may be similar to that of convective late-type stars, which are well-known x-ray sources, x-ray emission from brown dwarfs may indicate magnetic activity. PMID:9756481

  12. Emission line diagnostics for accretion and outflows in young very low-mass stars and brown dwarfs

    NASA Astrophysics Data System (ADS)

    Stelzer, B.; Alcalá, J. M.; Whelan, E.; Scholz, A.

    2014-01-01

    We discuss accretion and outflow properties of three very low-mass young stellar objects based on broad-band mid-resolution X-Shooter/VLT spectra. Our targets (FU Tau A, 2M1207-39, and Par-Lup3-4) have spectral types between M5 and M8, ages between 1Myr and ~ 10Myr, and are known to be accreting from previous studies. The final objective of our project is the determination of mass outflow to accretion rate for objects near or within the substellar regime as a probe for the T Tauri phase of brown dwarfs and the investigation of variability in the accretion and outflow processes.

  13. Evolutionary models for low-mass stars and brown dwarfs: Uncertainties and limits at very young ages

    NASA Astrophysics Data System (ADS)

    Baraffe, I.; Chabrier, G.; Allard, F.; Hauschildt, P. H.

    2002-02-01

    We analyse pre-Main Sequence evolutionary tracks for low mass stars with masses m <= 1.4 Msun based on the Baraffe et al. (\\cite{Bar98}) input physics. We also extend the recent Chabrier et al. (2000) evolutionary models based on dusty atmosphere to young brown dwarfs down to one mass of Jupiter. We analyse current theoretical uncertainties due to molecular line lists, convection and initial conditions. Simple tests on initial conditions show the high uncertainties of models at ages la 1 Myr. We find a significant sensitivity of atmosphere profiles to the treatment of convection at low gravity and Teff < 4000 K, whereas it vanishes as gravity increases. This effect adds another source of uncertainty on evolutionary tracks at very early phases. We show that at low surface gravity (log g <~ 3.5) the common picture of vertical Hayashi lines with constant Teff is oversimplified. The effect of a variation of initial deuterium abundance is studied. We compare our models with evolutionary tracks available in the literature and discuss the main differences. We finally analyse to what extent current observations of young systems provide a good test for pre-Main Sequence tracks.

  14. Opportunities for Laboratory Opacity Chemistry Studies to Facilitate Characterization of Young Giant Planets and Brown Dwarfs

    NASA Technical Reports Server (NTRS)

    Marley, Mark; Freedman, Richard S.

    2015-01-01

    The thermal emission spectra of young giant planets is shaped by the opacity of atoms and molecules residing in their atmospheres. While great strides have been made in improving the opacities of important molecules, particularly NH3 and CH4, at high temperatures, much more work is needed to understand the opacity and chemistry of atomic Na and K. The highly pressure broadened fundamental band of Na and K in the optical stretches into the near-infrared, strongly influencing the shape of the Y and K spectral bands. Since young giant planets are bright in these bands it is important to understand the influences on the spectral shape. Discerning gravity and atmospheric composition is difficult, if not impossible, without both good atomic opacities as well as an excellent understanding of the relevant atmospheric chemistry. Since Na and K condense at temperatures near 500 to 600 K, the chemistry of the condensation process must be well understood as well, particularly any disequilibrium chemical pathways. Comparisons of the current generation of sophisticated atmospheric models and available data, however, reveal important shortcomings in the models. We will review the current state of observations and theory of young giant planets and will discuss these and other specific examples where improved laboratory measurements for alkali compounds have the potential of substantially improving our understanding of these atmospheres.

  15. Late summer and fall use of stream margins by young-of year brown trout in a high-elevation stream

    USGS Publications Warehouse

    La Voie, W. J., IV; Hubert, W.A.

    1997-01-01

    We determined the relative abundance of young-of-year (YOY) brown trout (Salmo trutta) from late summer to fall during day and night in stream margin habitats of Douglas Creek, Wyoming. No significant differences in relative abundance were observed from August 14 through October 26. Few YOY brown trout were observed during the day over the entire sampling period, but significantly greater numbers were seen at night. Within stream margins, YOY brown trout of 36-75 mm total length primarily resided in concealment cover among interstices of cobbie during the day and emerged at night. Because no significant change in relative abundance was observed throughout the study period, we conclude that a shift to winter habitat did not occur up until three days prior to ice formation when the diurnal range in water temperature was 2.5-7.5??C.

  16. YOUNG BROWN DWARFS AT HIGH CADENCE: WARM SPITZER TIME SERIES MONITORING OF VERY LOW MASS {sigma} ORIONIS CLUSTER MEMBERS

    SciTech Connect

    Cody, Ann Marie; Hillenbrand, Lynne A.

    2011-11-01

    The continuous temporal coverage and high photometric precision afforded by space observatories have opened up new opportunities for the study of variability processes in young stellar cluster members. Of particular interest is the phenomenon of deuterium-burning pulsation in brown dwarfs (BDs) and very low mass stars, whose existence on 1-4 hr timescales has been proposed but not yet borne out by observations. To investigate short-timescale variability in young, low-mass objects, we carried out high-precision, high-cadence time series monitoring with the Warm Spitzer mission on 14 low mass stars and BDs in the {approx}3 Myr {sigma} Orionis cluster. The flux in many of our raw light curves is strongly correlated with subpixel position and can vary systematically by as much as 10%. We present a new approach to disentangle true stellar variability from this 'pixel-phase effect', which is more pronounced in Warm Spitzer observations as compared to the cryogenic mission. The light curves after correction reveal that most of the sample is devoid of variability down to the few-millimagnitude (mmag) level, on the minute to day timescales probed. However, one exceptional BD displays erratic brightness changes at the 10%-15% level, suggestive of variable obscuration by dusty material. The uninterrupted 24 hr datastream and sub-1% photometric precision enable limits on pulsation in the near-infrared. If this phenomenon is present in our light curves, then its amplitude must lie below 2-3 mmag. In addition, we present three field eclipsing binaries and one pulsator for which optical ground-based data are also available.

  17. BANYAN. V. A SYSTEMATIC ALL-SKY SURVEY FOR NEW VERY LATE-TYPE LOW-MASS STARS AND BROWN DWARFS IN NEARBY YOUNG MOVING GROUPS

    SciTech Connect

    Gagné, Jonathan; Lafrenière, David; Doyon, René; Malo, Lison; Artigau, Étienne

    2015-01-10

    We present the BANYAN All-Sky Survey (BASS) catalog, consisting of 228 new late-type (M4-L6) candidate members of nearby young moving groups (YMGs) with an expected false-positive rate of ∼13%. This sample includes 79 new candidate young brown dwarfs and 22 planetary-mass objects. These candidates were identified through the first systematic all-sky survey for late-type low-mass stars and brown dwarfs in YMGs. We cross-matched the Two Micron All Sky Survey and AllWISE catalogs outside of the galactic plane to build a sample of 98,970 potential ≥M5 dwarfs in the solar neighborhood and calculated their proper motions with typical precisions of 5-15 mas yr{sup –1}. We selected highly probable candidate members of several YMGs from this sample using the Bayesian Analysis for Nearby Young AssociatioNs II tool (BANYAN II). We used the most probable statistical distances inferred from BANYAN II to estimate the spectral type and mass of these candidate YMG members. We used this unique sample to show tentative signs of mass segregation in the AB Doradus moving group and the Tucana-Horologium and Columba associations. The BASS sample has already been successful in identifying several new young brown dwarfs in earlier publications, and will be of great interest in studying the initial mass function of YMGs and for the search of exoplanets by direct imaging; the input sample of potential close-by ≥M5 dwarfs will be useful to study the kinematics of low-mass stars and brown dwarfs and search for new proper motion pairs.

  18. BANYAN. V. A Systematic All-sky Survey for New Very Late-type Low-mass Stars and Brown Dwarfs in Nearby Young Moving Groups

    NASA Astrophysics Data System (ADS)

    Gagné, Jonathan; Lafrenière, David; Doyon, René; Malo, Lison; Artigau, Étienne

    2015-01-01

    We present the BANYAN All-Sky Survey (BASS) catalog, consisting of 228 new late-type (M4-L6) candidate members of nearby young moving groups (YMGs) with an expected false-positive rate of ~13%. This sample includes 79 new candidate young brown dwarfs and 22 planetary-mass objects. These candidates were identified through the first systematic all-sky survey for late-type low-mass stars and brown dwarfs in YMGs. We cross-matched the Two Micron All Sky Survey and AllWISE catalogs outside of the galactic plane to build a sample of 98,970 potential >=M5 dwarfs in the solar neighborhood and calculated their proper motions with typical precisions of 5-15 mas yr-1. We selected highly probable candidate members of several YMGs from this sample using the Bayesian Analysis for Nearby Young AssociatioNs II tool (BANYAN II). We used the most probable statistical distances inferred from BANYAN II to estimate the spectral type and mass of these candidate YMG members. We used this unique sample to show tentative signs of mass segregation in the AB Doradus moving group and the Tucana-Horologium and Columba associations. The BASS sample has already been successful in identifying several new young brown dwarfs in earlier publications, and will be of great interest in studying the initial mass function of YMGs and for the search of exoplanets by direct imaging; the input sample of potential close-by >=M5 dwarfs will be useful to study the kinematics of low-mass stars and brown dwarfs and search for new proper motion pairs.

  19. A Sample of Very Young Field L Dwarfs and Implications for the Brown Dwarf "Lithium Test" at Early Ages

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, J. Davy; Cruz, Kelle L.; Barman, Travis S.; Burgasser, Adam J.; Looper, Dagny L.; Tinney, C. G.; Gelino, Christopher R.; Lowrance, Patrick J.; Liebert, James; Carpenter, John M.; Hillenbrand, Lynne A.; Stauffer, John R.

    2008-12-01

    Using a large sample of optical spectra of late-type dwarfs, we identify a subset of late-M through L field dwarfs that, because of the presence of low-gravity features in their spectra, are believed to be unusually young. From a combined sample of 303 field L dwarfs, we find observationally that 7.6% +/- 1.6% are younger than 100 Myr. This percentage is in agreement with theoretical predictions once observing biases are taken into account. We find that these young L dwarfs tend to fall in the southern hemisphere (decl . < 0°) and may be previously unrecognized, low-mass members of nearby, young associations like Tucana-Horologium, TW Hydrae, β Pictoris, and AB Doradus. We use a homogeneously observed sample of ~150 optical spectra to examine lithium strength as a function of L/T spectral type and further corroborate the trends noted by Kirkpatrick and coworkers. We use our low-gravity spectra to investigate lithium strength as a function of age. The data weakly suggest that for early- to mid-L dwarfs the line strength reaches a maximum for a few × 100 Myr, whereas for much older (few Gyr) and much younger (<100 Myr) L dwarfs the line is weaker or undetectable. We show that a weakening of lithium at lower gravities is predicted by model atmosphere calculations, an effect partially corroborated by existing observational data. Larger samples containing L dwarfs of well-determined ages are needed to further test this empirically. If verified, this result would reinforce the caveat first cited by Kirkpatrick and coworkers that the lithium test should be used with caution when attempting to confirm the substellar nature of the youngest brown dwarfs. Most of the spectroscopic data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous

  20. Low mass stars, brown dwarf candidates and the mass function of the young open cluster NGC 2547

    NASA Astrophysics Data System (ADS)

    Jeffries, R. D.; Naylor, Tim; Devey, C. R.; Totten, E. J.

    2004-07-01

    We present a catalogue of RcIcZ photometry over an area of 0.855 square degrees, centred on the young open cluster NGC 2547. The survey is substantially complete to limits of Rc= 21.5, Ic= 19.5, Z= 19.5. We use the catalogue to define a sample of NGC 2547 candidates with model-dependent masses of about 0.05 -1.0 Msolar. After correcting for incompleteness and estimating contamination by foreground field dwarfs, we investigate the mass function of the cluster, its binary content, and search for evidence of mass segregation among the lower mass stars. There is ample evidence for mass segregation between high (>3 Msolar) and lower mass stars, but over the range 0.1 < M < 0.7 Msolar, the data are consistent with no further mass segregation. By fitting King profiles we conclude that at least 60 per cent of the low-mass stellar population are contained within our survey. The cluster mass function is remarkably similar to the Pleiades for 0.075 < M < 0.7 Msolar. Because of its age (~= 30 Myr), we demonstrate that this mass function is robust to a number of systematic uncertainties likely to affect older and younger clusters and is therefore one of the best available estimates for the initial mass function in young disc populations. For 0.05 < M < 0.075 Msolar there is some evidence for a deficit of brown dwarfs in NGC 2547 compared with other clusters. This deficit may extend to lower masses or may only be a dip, perhaps caused by an imperfect understanding of the mass-magnitude relationship at temperatures of around 2800 K. Incompleteness in both our survey and the luminosity functions from which we estimate contamination by foreground objects leave this question open. The binary fraction for systems with mass ratios greater than about 0.5 is 20-35 per cent for M dwarfs in NGC 2547, quite consistent with that found in the field and other young clusters. The full photometric catalogue and our lists of candidate cluster members are made available in electronic format.

  1. The Enigmatic Thirteen Micron Feature

    NASA Astrophysics Data System (ADS)

    de Queiroz e Souza, Nelson

    Low and intermediate mass stars (0.8--8 solar masses) will eventually evolve into Asymptotic Giant Branch (AGB) stars and pulsate out their atmosphere into the space around them. That ejected material will eventually cool and form dust. Understanding the nature and formation of cosmic dust is crucial to understanding the Universe. Evolved intermediate mass stars (i.e. AGB stars) are major contributors of dust to the cosmos. Dust around AGB stars are studied by means of infrared spectroscopy from which we observe several interesting spectral features. The observed AGB star spectra have been classified according to their shapes and wavelength positions of the dust features. Alongside the main spectral features around 8-12mum, there is an enigmatic 13mum feature that appears in about half the oxygen-rich AGB stars. The carrier of this feature has not yet been unequivocally identified but has been attributed to various dust species, including corundum (crystalline Al2O3), spinel (MgAl2O4), and silica (SiO2). While there have been several attempts to determine the cause of this 13mum feature, previous studies have been somewhat contradictory. In order to investigate the origin and characteristics of this spectral feature we observe variations in the 13mum feature over varying stellar parameters. We have also acquired spatially resolved spectroscopic observations of nearby O-rich AGB stars using Michelle on Gemini North. Here we present data on the 13mum feature strength mapped over space around their respective AGB star. The most popular hypothesis for the carrier of the 13mm feature is not supported by our findings.

  2. Brown adipose and central nervous system glucose uptake is lower during cold exposure in older compared to young men: a preliminary PET study.

    PubMed

    Kindred, John H; Tuulari, Jetro J; Simon, Stacey; Luckasen, Gary J; Bell, Christopher; Rudroff, Thorsten

    2016-06-01

    The purpose of this study was to determine the activity of brown adipose tissue (BAT) and the central nervous system (CNS) during cold exposure in young and older men. Two young, 24 and 21 years, and two older, 76 and 74 years, men participated in the study. Positron emission tomography images showed cold-induced BAT activity was absent in older men but clearly present in the clavicular region of the young men (Standardized Uptake Value: SUVmean: 3.12 and 3.71). Statistical parametric mapping revealed cortical brain activity was lower in the older men within areas of the frontal, parietal, temporal, and occipital lobes, and the thalamus (peak-level p uncorr  < 0.036). Cervical spinal cord SUVmean values tended to be lower for older (SUVmean: 1.64 and 1.61) compared to young men (SUVmean: 1.91 and 1.71). These preliminary findings suggest lower BAT activity in older men may in part be due to lower CNS activity. PMID:26754046

  3. Brown Syndrome

    MedlinePlus

    ... Does Brown syndrome cause eye problems besides abnormal eye movements? Some children with Brown syndrome have poor binocular ... In the congenital form of Brown syndrome, the eye movement problem is usually constant and unlikely to resolve ...

  4. The SEEDS High-Contrast Imaging Survey: Exoplanet and Brown Dwarf Survey for Nearby Young Stars Dated with Gyrochronology and Activity Age Indicators

    NASA Astrophysics Data System (ADS)

    Kuzuhara, Masayuki; Tamura, Motohide; Helminiak, Kris; Mede, Kyle; Brandt, Timothy; Janson, Markus; Kandori, Ryo; Kudo, Tomoyuki; Kusakabe, Nobuhiko; Hashimoto, Jun

    2015-12-01

    The SEEDS campaign has successfully discovered and characterized exoplanets, brown dwarfs, and circumstellar disks since it began in 2009, via the direct imaging technique. The survey has targeted nearby young stars, as well as stars associated to star-forming regions, the Pleiades open cluster, moving groups, and debris disks. We selected the nearby young stars that have been dated with age indicators based on stellar rotation periods (i.e., gyrochronology) and chromoshperic/coronal activities. Of these, nearly 40 were observed, with ages mainly between 100 and 1000 Myr and distances less than 40 pc. Our observations typically attain the contrast of ~6 x 10-6 at 1'' and better than ~1 x 10-6 beyond 2'', enabling us to detect a planetary-mass companion even around such old stars. Indeed, the SEEDS team reported the discovery that the nearby Sun-like star GJ 504 hosts a Jovian companion GJ 504b, which has a mass of 3-8.5 Jupiter masses that is inferred according to the hot-start cooling models and our estimated system age of 100-510 Myr. The remaining observations out of the selected ~40 stars have resulted in no detection of additional planets or brown dwarf companions. Meanwhile, we have newly imaged a low-mass stellar companion orbiting the G-type star HIP 10321, for which the presence of companion was previously announced via radial velocity technique. The astrometry and radial velocity measurements are simultaneously analyzed to determine the orbit, providing constraints on the dynamical mass of both objects and stellar evolution models. Here we summarize our direct imaging observations for the nearby young stars dated with gyrochrolorogy and activity age indicators. Furthermore, we report the analysis for the HIP 10321 system with the imaged low-mass companion.

  5. "... But ... But I Am Brown." The Ascribed Categories of Identity: Children and Young People of Mixed Parentage

    ERIC Educational Resources Information Center

    Goodyer, Annabel; Okitikpi, Toyin

    2007-01-01

    This paper explores the concept of the categorisation of social groups by looking at the issue of ascribed categories of identity for children and young people of mixed parentage. Our exploration of the knowledge-base in this area reveals that children and young people have clearly expressed views about their racial identity and that these views…

  6. IGFBP-2 is a negative predictor of cold-induced brown fat and bone mineral density in young non-obese women.

    PubMed

    Bredella, Miriam A; Fazeli, Pouneh K; Lecka-Czernik, Beata; Rosen, Clifford J; Klibanski, Anne

    2013-04-01

    Recent studies have shown a positive correlation between brown adipose tissue (BAT) and bone mineral density (BMD). However, mechanisms underlying this relationship are unknown. Insulin-like growth factor 1 (IGF-1) is an important regulator of stem cell differentiation promoting bone formation. IGF binding protein 2 (IGFBP-2) binds IGF-1 in the circulation and has been reported to inhibit bone formation in humans. IGF-1 is also a crucial regulator of brown adipocyte differentiation. We hypothesized that IGFBP-2 is a negative and IGF-1 a positive regulator of BAT-mediated osteoblastogenesis. We therefore investigated a cohort of 15 women (mean age 27.7±5.7years): 5 with anorexia nervosa (AN) in whom IGF-1 levels were low due to starvation, 5 recovered AN (AN-R), and 5 women of normal weight. All subjects underwent assessment of cold-activated BAT by PET/CT, BMD of the spine, hip, femoral neck, and total body by DXA, thigh muscle area by MRI, IGF-1 and IGFBP-2. There was a positive correlation between BAT and BMD and an inverse association between IGFBP-2 and both BAT and BMD. There was no association between IGF-1 and BAT. We show for the first time that IGFBP-2 is a negative predictor of cold-induced BAT and BMD in young non-obese women, suggesting that IGFBP-2 may serve as a regulator of BAT-mediated osteoblastogenesis. PMID:23291564

  7. Physical Properties of Young Brown Dwarfs and Very Low Mass Stars Inferred from High-resolution Model Spectra

    NASA Astrophysics Data System (ADS)

    Rice, Emily L.; Barman, T.; Mclean, Ian S.; Prato, L.; Kirkpatrick, J. Davy

    2010-01-01

    By comparing near-infrared spectra with atmospheric models, we infer the effective temperature, surface gravity, projected rotational velocity, and radial velocity for 21 very low mass stars and brown dwarfs. The unique sample consists of two sequences in spectral type from M6-M9, one of 5-10 Myr objects and one of >1 Gyr field objects. A third sequence is comprised of only ~M6 objects with ages ranging from <1 Myr to >1 Gyr. Spectra were obtained in the J band at medium (R ~ 2000) and high (R ~ 20,000) resolutions with NIRSPEC on the Keck II telescope. Synthetic spectra were generated from atmospheric structures calculated with the PHOENIX model atmosphere code. Using multi-dimensional least-squares fitting and Monte Carlo routines we determine the best-fit model parameters for each observed spectrum and note which spectral regions provide consistent results. We identify successes in the reproduction of observed features by atmospheric models, including pressure-broadened K I lines, and investigate deficiencies in the models, particularly missing FeH opacity, that will need to be addressed in order to extend our analysis to cooler objects. The precision that can be obtained for each parameter using medium- and high-resolution near-infrared spectra is estimated and the implications for future studies of very low mass stars and brown dwarfs are discussed.

  8. The enigmatic signifier and the decentred subject.

    PubMed

    Hinton, Ladson

    2009-11-01

    War, genocide, economic upheaval and terrorism have crushed belief in endlessly 'enlightened' progress. We more and more doubt the teleological nature of psychological events, including the activity of a Self or centre that guides the development of the subject. There is a growing view of a 'decentred' subject that develops in the face of an enigmatic Otherness. Jean Laplanche has created an extensive metapsychology describing this situation, emphasizing the original helplessness of an infant who is bathed in enigmatic messages from its very beginnings. These messages from the adult other are often sexualized, and are partly or largely unconscious to the sender. Laplanche calls this situation 'primal seduction'. The immature human cannot fully metabolize such adult messages, and through 'primal repression' they remain as the unconscious core of subjectivity. They disrupt psychological life, conveying a sense of signifying something to the subject. What they signify is an enigma, like finding a hieroglyph in the desert. The story of relationships and culture is the story of our repeated attempts to translate them, to respond to them. An analytic case illustrates these concepts as they appear in the transference, first as gaps and monsters, and then in the crucial and surprising appearance of transformative laughter. The vicissitudes of the clinical situation illustrate the vital importance of the enigmatic signifier in the development of the subject. PMID:19840157

  9. Behavioural Differences between Single Scandinavian Brown Bears (Ursus arctos) and Females with Dependent Young When Experimentally Approached by Humans

    PubMed Central

    Sahlén, Veronica; Ordiz, Andrés; Swenson, Jon E.; Støen, Ole Gunnar

    2015-01-01

    Carnivore-human encounters that result in human injury present a conservation and management challenge and it is therefore important to understand under what conditions such incidents occur. Females with cubs are often involved when humans are injured by brown bears Ursus arctos. In Scandinavia, this is particularly true for unarmed recreational forest users. Our aim was to document behavioural differences between single bears and females with cubs in order to develop recommendations to minimize the risk of injuries to recreational forest users. We documented the reactions of GPS-collared females with cubs and single brown bears to experimental approaches by humans to 50 m from the bear on 42 and 108 occasions, respectively. The majority of females with cubs (95%) and single bears (89%) left when approached. Bears that left were passed at shorter distances and were in more open areas than those that stayed. Both groups had similar flight initiation distances, which were longer for bears that were active at the time of the disturbance. Females with cubs selected more open habitat than single bears, also for the new site they selected following disturbance. Females with cubs, particularly active females with cubs of the year, moved greater distances and spent more time active following the approach. Females with cubs and single bears were seen or heard in 26% and 14% of the approaches, respectively. None of the bears displayed any aggressive behaviour during the approaches. Females with cubs selected more open habitat, perhaps predisposing them to encountering people that are not involved in hunting activities, which might be the primary explanation why females with cubs are most frequently involved when unarmed people are injured by bears in Scandinavia. To mitigate injury risks, one must consider factors that bring bears closer to human activity in the first place. PMID:25830333

  10. Toluene effects on the motor activity of adolescent, young-adult, middle-age and senescent male Brown Norway rats.

    EPA Science Inventory

    Life stage is an important risk factor for toxicity. Children and aging adults, for example, are more susceptible to certain chemicals than are young adults. In comparison to children, relatively little is known about susceptibility in older adults. Additionally, few studies have...

  11. Astrometric follow-up observations of directly imaged sub-stellar companions to young stars and brown dwarfs

    NASA Astrophysics Data System (ADS)

    Ginski, C.; Schmidt, T. O. B.; Mugrauer, M.; Neuhäuser, R.; Vogt, N.; Errmann, R.; Berndt, A.

    2014-11-01

    The formation of massive planetary or brown dwarf companions at large projected separations from their host star is not yet well understood. In order to put constraints on formation scenarios, we search for signatures in the orbit dynamics of the systems. We are specifically interested in the eccentricities and inclinations since those parameters might tell us about the dynamic history of the systems and where to look for additional low-mass sub-stellar companions. For this purpose, we utilized VLT/NACO to take several well-calibrated high-resolution images of six target systems and analyse them together with available literature data points of those systems as well as Hubble Space Telescope archival data. We used a statistical least-squares Monte Carlo approach to constrain the orbit elements of all systems that showed significant differential motion of the primary star and companion. We show for the first time that the GQ Lup system shows significant change in both separation and position angle. Our analysis yields best-fitting orbits for this system, which are eccentric (e between 0.21 and 0.69), but cannot rule out circular orbits at high inclinations. Given our astrometry, we discuss formation scenarios of the GQ Lup system. In addition, we detected an even fainter new companion candidate to GQ Lup, which is most likely a background object. We also updated the orbit constraints of the PZ Tel system, confirming that the companion is on a highly eccentric orbit with e > 0.62. Finally, we show with a high significance, that there is no orbital motion observed in the cases of the DH Tau, HD 203030 and 1RXS J160929.1-210524 systems, and give the most precise relative astrometric measurement of the UScoCTIO 108 system to date.

  12. WHO KILLED LAIUS?: ON SOPHOCLES' ENIGMATIC MESSAGE.

    PubMed

    Priel, Beatriz

    2002-04-01

    Using Laplanche's basic conceptualisation of the role of the other in unconscious processes, the author proposes a reading of Sophocles' tragedy, Oedipus the King, according to basic principles of dream interpretation. This reading corroborates contemporary literary perspectives suggesting that Sophocles' tragedy may not only convey the myth but also provide a critical analysis of how myths work. Important textual inconsistencies and incoherence, which have been noted through the centuries, suggest the existence of another, repressed story. Moreover, the action of the play points to enigmatic parental messages of infanticide and the silencing of Oedipus's story, as well as their translation into primordial guilt, as the origins of the tragic denouement. Oedipus's self-condemnation of parricide follows these enigmatic codes and is unrelated to, and may even contradict, the evidence offered in the tragedy as to the identity of Laius's murderers. Moreover, Sophocles' text provides a complex intertwining of hermeneutic and deterministic perspectives. Through the use of the mythical deterministic content, the formal characteristics of Sophocles' text, mainly its complex time perspective and extensive use of double meaning, dramatise in the act of reading an acute awareness of interpretation. This reading underscores the fundamental role of the other in the constitution of unconscious processes. PMID:12028701

  13. Who killed Laius?: On Sophocles' enigmatic message.

    PubMed

    Priel, Beatriz

    2002-04-01

    Using Laplanche's basic conceptualisation of the role of the other in unconscious processes, the author proposes a reading of Sophocles' tragedy, Oedipus the King, according to basic principles of dream interpretation. This reading corroborates contemporary literary perspectives suggesting that Sophocles' tragedy may not only convey the myth but also provide a critical analysis of how myths work. Important textual inconsistencies and incoherence, which have been noted through the centuries, suggest the existence of another, repressed story. Moreover, the action of the play points to enigmatic parental messages of infanticide and the silencing of Oedipus's story, as well as their translation into primordial guilt, as the origins of the tragic denouement. Oedipus's self-condemnation of parricide follows these enigmatic codes and is unrelated to, and may even contradict, the evidence offered in the tragedy as to the identity of Laius's murderers. Moreover, Sophocles' text provides a complex intertwining of hermeneutic and deterministic perspectives. Through the use of the mythical deterministic content, the formal characteristics of Sophocles' text, mainly its complex time perspective and extensive use of double meaning, dramatise in the act of reading an acute awareness of interpretation. This reading underscores the fundamental role of the other in the constitution of unconscious processes. PMID:12040706

  14. Endometriosis: A Disease That Remains Enigmatic

    PubMed Central

    Velasco, Irene

    2013-01-01

    Endometriosis, a gynecologic pathology, is defined by the presence of a tissue similar to uterine endometrium, which is located in places other than physiologically appropriate. These endometrial heterotopic islets contain glands and stroma and are functionally capable of responding to exogenous, endogenous, or local hormonal stimuli. Endometriosis affects 8%–10% of women of reproductive age; in 30% of the women, the condition is associated with primary or secondary infertility. In several instances, endometriosis persists as a minimal or mild disease, or it can resolve on its own. Other cases of endometriosis show severe symptomatology that ends when menopause occurs. Endometriosis can, however, reactivate in several postmenopausal women when iatrogenic or endogenous hormones are present. Endometriosis is occasionally accompanied by malignant ovarian tumors, especially endometrioid and clear cell carcinomas. Its pathogenesis is widely debated, and its variable morphology appears to represent a continuum of individual presentations and progressions. Endometriosis has no pathognomonic signs or symptoms; it is therefore difficult to diagnose. Because of its enigmatic etiopathogenesis, there is currently no satisfactory therapy for all patients with endometriosis. Treatments include medications, surgery, or combined therapies; currently, the only procedures that seem to cure endometriosis are hysterectomy and bilateral salpingo-oophorectomy. In this paper, we review the most controversial and enigmatic aspects of this disease. PMID:23956867

  15. Toluene effects on oxidative stress in brain regions of young-adult, middle-age, and senescent Brown Norway rats

    SciTech Connect

    Kodavanti, Prasada Rao S.; Royland, Joyce E.; Richards, Judy E.; Besas, Jonathan; MacPhail, Robert C.

    2011-11-15

    The influence of aging on susceptibility to environmental contaminants is not well understood. To extend knowledge in this area, we examined effects in rat brain of the volatile organic compound, toluene. The objective was to test whether oxidative stress (OS) plays a role in the adverse effects caused by toluene exposure, and if so, if effects are age-dependent. OS parameters were selected to measure the production of reactive oxygen species (NADPH Quinone oxidoreductase 1 (NQO1), NADH Ubiquinone reductase (UBIQ-RD)), antioxidant homeostasis (total antioxidant substances (TAS), superoxide dismutase (SOD), {gamma}-glutamylcysteine synthetase ({gamma}-GCS), glutathione transferase (GST), glutathione peroxidase (GPX), glutathione reductase (GRD)), and oxidative damage (total aconitase and protein carbonyls). In this study, Brown Norway rats (4, 12, and 24 months) were dosed orally with toluene (0, 0.65 or 1 g/kg) in corn oil. Four hours later, frontal cortex, cerebellum, striatum, and hippocampus were dissected, quick frozen on dry ice, and stored at - 80 Degree-Sign C until analysis. Some parameters of OS were found to increase with age in select brain regions. Toluene exposure also resulted in increased OS in select brain regions. For example, an increase in NQO1 activity was seen in frontal cortex and cerebellum of 4 and 12 month old rats following toluene exposure, but only in the hippocampus of 24 month old rats. Similarly, age and toluene effects on glutathione enzymes were varied and brain-region specific. Markers of oxidative damage reflected changes in oxidative stress. Total aconitase activity was increased by toluene in frontal cortex and cerebellum at 12 and 24 months, respectively. Protein carbonyls in both brain regions and in all age groups were increased by toluene, but step-down analyses indicated toluene effects were statistically significant only in 12 month old rats. These results indicate changes in OS parameters with age and toluene exposure

  16. Apple Browning.

    ERIC Educational Resources Information Center

    Chemecology, 1992

    1992-01-01

    Describes an activity in which students investigate the effects of selected natural and synthetic substances on the rate of apple browning. Includes background information for the teacher, a list of necessary materials, and student instructions. (KR)

  17. THE INITIAL MASS FUNCTION AND YOUNG BROWN DWARF CANDIDATES IN NGC 2264. IV. THE INITIAL MASS FUNCTION AND STAR FORMATION HISTORY

    SciTech Connect

    Sung, Hwankyung; Bessell, Michael S. E-mail: bessell@mso.anu.edu.a

    2010-12-15

    {approx} 2 M{sub sun}, but the second did not. We attribute the peak as an artifact of the SED fitting tool because there is no such IMF with a peak at m {approx} 2 M{sub sun}. The slope of the IMF of NGC 2264 for massive stars (log m {>=} 0.5) is -1.7 {+-} 0.1, which is somewhat steeper than the so-called standard Salpeter-Kroupa IMF. We also present data for 79 young brown dwarf candidates.

  18. Revisiting enigmatic cortical calretinin-expressing interneurons

    PubMed Central

    Cauli, Bruno; Zhou, Xiaojuan; Tricoire, Ludovic; Toussay, Xavier; Staiger, Jochen F.

    2014-01-01

    Cortical calretinin (CR)-expressing interneurons represent a heterogeneous subpopulation of about 10–30% of GABAergic interneurons, which altogether total ca. 12–20% of all cortical neurons. In the rodent neocortex, CR cells display different somatodendritic morphologies ranging from bipolar to multipolar but the bipolar cells and their variations dominate. They are also diverse at the molecular level as they were shown to express numerous neuropeptides in different combinations including vasoactive intestinal polypeptide (VIP), cholecystokinin (CCK), neurokinin B (NKB) corticotrophin releasing factor (CRF), enkephalin (Enk) but also neuropeptide Y (NPY) and somatostatin (SOM) to a lesser extent. CR-expressing interneurons exhibit different firing behaviors such as adapting, bursting or irregular. They mainly originate from the caudal ganglionic eminence (CGE) but a subpopulation also derives from the dorsal part of the medial ganglionic eminence (MGE). Cortical GABAergic CR-expressing interneurons can be divided in two main populations: VIP-bipolar interneurons deriving from the CGE and SOM-Martinotti-like interneurons originating in the dorsal MGE. Although bipolar cells account for the majority of CR-expressing interneurons, the roles they play in cortical neuronal circuits and in the more general metabolic physiology of the brain remained elusive and enigmatic. The aim of this review is, firstly, to provide a comprehensive view of the morphological, molecular and electrophysiological features defining this cell type. We will, secondly, also summarize what is known about their place in the cortical circuit, their modulation by subcortical afferents and the functional roles they might play in neuronal processing and energy metabolism. PMID:25009470

  19. The provenance of Borneo's enigmatic alluvial diamonds

    NASA Astrophysics Data System (ADS)

    White, Lloyd; Graham, Ian; Tanner, Dominique; Hall, Robert; Armstrong, Richard; Yaxley, Greg; Barron, Larry; Spencer, Lee; van Leeuwen, Theo

    2016-04-01

    Gem-quality diamonds occur in several alluvial deposits across central and southern Borneo. Borneo has been a known source of diamonds for centuries, but the location of their primary igneous source remains enigmatic. Numerous geological models have been proposed to explain the distribution of Borneo's diamonds. To assess these models, we used a variety of techniques to examine heavy minerals from Kalimantan's Cempaka paleoalluvial diamond deposit. This involved collecting U-Pb isotopic data, fission track and trace element geochemistry of zircon as well as major element geochemical data of spinels and morphological descriptions of zircon and diamond. Our results indicate that the Cempaka diamonds were likely derived from at least two sources, one which was relatively local and/or involved little reworking, and the other more distal recording several periods of reworking. The distal diamond source is interpreted to be diamond-bearing pipes that intruded the basement of a block that: (1) rifted from northwest Australia (East Java or SW Borneo) and the diamonds were recycled into its sedimentary cover, or: (2) were emplaced elsewhere (e.g. NW Australia) and transported to a block (e.g. East Java or SW Borneo). Both of these scenarios require the diamonds to be transported with the block when it rifted from NW Australia in the Late Jurassic. The 'local' diamonds could be associated with ophiolitic rocks that are exposed in the nearby Meratus Mountains, or could be diamondiferous diatremes associated with eroded Miocene high-K alkaline intrusions north of the Barito Basin. If this were the case, these intrusions would indicate that the lithosphere beneath SW Borneo is thick (~150 km or greater).

  20. An Enigmatic Source Towards The LMC

    NASA Astrophysics Data System (ADS)

    Fazio, Giovanni; Ashby, Matthew; Barmby, Pauline; Hora, Joseph; Kallivayalil, Nitya; Patten, Brian

    2006-05-01

    We are proposing to invest a small amount of Spitzer/IRS time to acquire a low resolution spectrum from 5.2-38 microns as part of a program to ascertain the physical nature of a 24-micron bright/IRAC faint enigmatic object seen in the direction of the LMC. This object just discovered while investigating the infrared SED of gravitational microlensing event MACHO-LMC-4, as a part of GTO program PID 118 "Macho Search". We serendipitously noted an object in both the IRAC and MIPS fields-of-view that was very bright at 24 microns (9 mJy), but had very low flux levels in all IRAC bandpasses (0.93 mJy at 8 microns). Because of the shape of the broadband SED as observed by IRAC and MIPS, we favor two basic possibilities as being the most likely explanation for the nature of his object: (1) A z~2 starburst galaxy, where the strong 24 micron emission is produced by 8 micron rest-frame PAH emission redshifted into the MIPS 24 micron bandpass or (2) A dust enshrouded luminous blue variable (LBV) in a pre-planetary nebula (pre-PN) evolutionary state. We will use the IRS in standard staring mode to acquire spectra with both low resolution modules in the range of 5.2 - 38 microns. A IRS low-resolution spectrum will reveal a more detailed picture of the shape of its SED. We estimate that no more than 1 hour will be required to obtain spectra with sufficient signal-to-noise to determine whether this object is a distant starburst galaxy (via a PAH emission peak) or a more nearby pre-PN LBV (a rising continuum that flattens off towards the mid-IR). The proposed observation represents the first stage of investigating nature of this object.

  1. Young

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Astronaut John W. Young, commander of the Apollo 16 lunar landing mission, jumps up from the lunar surface as he salutes the U.S. Flag at the Descartes landing site during the first Apollo 16 extravehicular activity (EVA-1). Astronaut Charles M. Duke Jr., lunar module pilot, took this picture. The Lunar Module (LM) 'Orion' is on the left. The Lunar Roving Vehicle is parked beside the LM. The object behind Young in the shade of the LM is the Far Ultraviolet Camera/Spectrograph. Stone Mountain dominates the background in this lunar scene.

  2. Unmaking Brown

    ERIC Educational Resources Information Center

    Lockette, Tim

    2010-01-01

    America's schools are more segregated now than they were in the late 1960s. More than 50 years after "Brown v. Board of Education," educators need to radically rethink the meaning of "school choice." For decades at Wake County, buses would pick up public school students in largely minority communities along the Raleigh Beltline. This system won…

  3. Another Look at an Enigmatic New World

    NASA Astrophysics Data System (ADS)

    2005-02-01

    centred at 2 microns. On the right is the NACO/SDI image of the same location showing Titan's surface through the 1.6 micron methane window. A spherical projection with coordinates on Titan is overplotted. ESO PR Photo 04b/05 is a map of Titan taken with NACO at 1.28 micron (a methane window allowing it to probe down to the surface). On the leading side of Titan, the bright equatorial feature ("Xanadu") is dominating. On the trailing side, the landing site of the Huygens probe is indicated. ESO PR Photo 04c/05 ESO PR Photo 04c/05 Titan, the Enigmatic Moon, and Huygens Landing Site (NACO-SDI/VLT and Cassini/ISS) [Preview - JPEG: 400 x 589 pix - 40k] [Normal - JPEG: 800 x 1178 pix - 290k] Caption: ESO PR Photo 04c/05 is a comparison between the NACO/SDI image and an image taken by Cassini/ISS while approaching Titan. The Cassini image shows the Huygens landing site map wrapped around Titan, rotated to the same position as the January NACO SDI observations. The yellow "X" marks the landing site of the ESA Huygens probe. The Cassini/ISS image is courtesy of NASA, JPL, Space Science Institute (see http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=36222). The coloured lines delineate the regions that were imaged by Cassini at differing resolutions. The lower-resolution imaging sequences are outlined in blue. Other areas have been specifically targeted for moderate and high resolution mosaicking of surface features. These include the site where the European Space Agency's Huygens probe has touched down in mid-January (marked with the yellow X), part of the bright region named Xanadu (easternmost extent of the area covered), and a boundary between dark and bright regions. ESO PR Photo 04d/05 ESO PR Photo 04d/05 Evolution of the Atmosphere of Titan (NACO/VLT) [Preview - JPEG: 400 x 902 pix - 40k] [Normal - JPEG: 800 x 1804 pix - 320k] Caption: ESO PR Photo 04d/05 is an image of Titan's atmosphere at 2.12 microns as observed with NACO on the VLT at three different epochs

  4. Planck Cold Clumps in the λ Orionis Complex. I. Discovery of an Extremely Young Class 0 Protostellar Object and a Proto-brown Dwarf Candidate in the Bright-rimmed Clump PGCC G192.32-11.88

    NASA Astrophysics Data System (ADS)

    Liu, Tie; Zhang, Qizhou; Kim, Kee-Tae; Wu, Yuefang; Lee, Chang Won; Lee, Jeong-Eun; Tatematsu, Ken'ichi; Choi, Minho; Juvela, Mika; Thompson, Mark; Goldsmith, Paul F.; Liu, Sheng-yuan; Naomi, Hirano; Koch, Patrick; Henkel, Christian; Sanhueza, Patricio; He, JinHua; Rivera-Ingraham, Alana; Wang, Ke; Cunningham, Maria R.; Tang, Ya-Wen; Lai, Shih-Ping; Yuan, Jinghua; Li, Di; Fuller, Gary; Kang, Miju; Nguyen Luong, Quang; Liu, Hauyu Baobab; Ristorcelli, Isabelle; Yang, Ji; Xu, Ye; Hirota, Tomoya; Mardones, Diego; Qin, Sheng-Li; Chen, Huei-Ru; Kwon, Woojin; Meng, FanYi; Zhang, Huawei; Kim, Mi-Ryang; Yi, Hee-Weon

    2016-01-01

    We are performing a series of observations with ground-based telescopes toward Planck Galactic cold clumps (PGCCs) in the λ Orionis complex in order to systematically investigate the effects of stellar feedback. In the particular case of PGCC G192.32-11.88, we discovered an extremely young Class 0 protostellar object (G192N) and a proto-brown dwarf candidate (G192S). G192N and G192S are located in a gravitationally bound bright-rimmed clump. The velocity and temperature gradients seen in line emission of CO isotopologues indicate that PGCC G192.32-11.88 is externally heated and compressed. G192N probably has the lowest bolometric luminosity (˜0.8 {L}⊙ ) and accretion rate (6.3 × 10-7 {M}⊙ yr-1) when compared with other young Class 0 sources (e.g., PACS Bright Red Sources) in the Orion complex. It has slightly larger internal luminosity (0.21 ± 0.01 {L}⊙ ) and outflow velocity (˜14 km s-1) than the predictions of first hydrostatic cores (FHSCs). G192N might be among the youngest Class 0 sources, which are slightly more evolved than an FHSC. Considering its low internal luminosity (0.08 ± 0.01 {L}⊙ ) and accretion rate (2.8 × 10-8 {M}⊙ yr-1), G192S is an ideal proto-brown dwarf candidate. The star formation efficiency (˜0.3%-0.4%) and core formation efficiency (˜1%) in PGCC G192.32-11.88 are significantly smaller than in other giant molecular clouds or filaments, indicating that the star formation therein is greatly suppressed owing to stellar feedback.

  5. Another Look at an Enigmatic New World

    NASA Astrophysics Data System (ADS)

    2005-02-01

    centred at 2 microns. On the right is the NACO/SDI image of the same location showing Titan's surface through the 1.6 micron methane window. A spherical projection with coordinates on Titan is overplotted. ESO PR Photo 04b/05 is a map of Titan taken with NACO at 1.28 micron (a methane window allowing it to probe down to the surface). On the leading side of Titan, the bright equatorial feature ("Xanadu") is dominating. On the trailing side, the landing site of the Huygens probe is indicated. ESO PR Photo 04c/05 ESO PR Photo 04c/05 Titan, the Enigmatic Moon, and Huygens Landing Site (NACO-SDI/VLT and Cassini/ISS) [Preview - JPEG: 400 x 589 pix - 40k] [Normal - JPEG: 800 x 1178 pix - 290k] Caption: ESO PR Photo 04c/05 is a comparison between the NACO/SDI image and an image taken by Cassini/ISS while approaching Titan. The Cassini image shows the Huygens landing site map wrapped around Titan, rotated to the same position as the January NACO SDI observations. The yellow "X" marks the landing site of the ESA Huygens probe. The Cassini/ISS image is courtesy of NASA, JPL, Space Science Institute (see http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=36222). The coloured lines delineate the regions that were imaged by Cassini at differing resolutions. The lower-resolution imaging sequences are outlined in blue. Other areas have been specifically targeted for moderate and high resolution mosaicking of surface features. These include the site where the European Space Agency's Huygens probe has touched down in mid-January (marked with the yellow X), part of the bright region named Xanadu (easternmost extent of the area covered), and a boundary between dark and bright regions. ESO PR Photo 04d/05 ESO PR Photo 04d/05 Evolution of the Atmosphere of Titan (NACO/VLT) [Preview - JPEG: 400 x 902 pix - 40k] [Normal - JPEG: 800 x 1804 pix - 320k] Caption: ESO PR Photo 04d/05 is an image of Titan's atmosphere at 2.12 microns as observed with NACO on the VLT at three different epochs

  6. Brown recluse spider (image)

    MedlinePlus

    The brown recluse is a venomous spider most commonly found in midwestern and southern states of the United States. It ... inch overall and has long skinny legs. The brown recluse is brown with a characteristic dark violin-shaped ...

  7. Brown Dwarfs at the Exoplanet Mass Boundary

    NASA Astrophysics Data System (ADS)

    Faherty, J. K.; Cruz, K. L.; Rice, E. L.; Riedel, A.

    2014-10-01

    Young brown dwarfs and directly-imaged exoplanets have enticingly similar photometric and spectroscopic characteristics, indicating that their cool, low gravity atmospheres should be studied in concert. Similarities between the peculiar shaped H band, near and mid-IR photometry as well as location on color magnitude diagrams provide important clues about how to extract physical properties of planets from current brown dwarf observations. Our team has assigned >30 brown dwarfs to 10-150 Myr nearby moving groups. In so doing, we have discovered important diversity among this extremely low-mass (10 - 30 M_{Jup}) age-calibrated sample indicating that cloud properties play a critical role in their observables.

  8. A CONSTRAINT ON BROWN DWARF FORMATION VIA EJECTION: RADIAL VARIATION OF THE STELLAR AND SUBSTELLAR MASS FUNCTION OF THE YOUNG OPEN CLUSTER IC 2391

    SciTech Connect

    Boudreault, S.; Bailer-Jones, C. A. L.

    2009-12-01

    We present the stellar and substellar mass function (MF) of the open cluster IC 2391, plus its radial dependence, and use this to put constraints on the formation mechanism of brown dwarfs (BDs). Our multi-band optical and infrared photometric survey with spectroscopic follow-up covers 11 deg{sup 2}, making it the largest survey of this cluster to date. We observe a radial variation in the MF over the range 0.072-0.3 M {sub sun}, but no significant variation in the MF below the substellar boundary at the three cluster radius intervals is analyzed. This lack of radial variation for low masses is what we would expect with the ejection scenario for BD formation, although considering that IC 2391 has an age about three times older than its crossing time, we expect that BDs with a velocity greater than the escape velocity have already escaped the cluster. Alternatively, the variation in the MF of the stellar objects could be an indication that they have undergone mass segregation via dynamical evolution. We also observe a significant variation across the cluster in the color of the (background) field star locus in color-magnitude diagrams and conclude that this is due to variable background extinction in the Galactic plane. From our preliminary spectroscopic follow-up, to confirm BD status and cluster membership, we find that all candidates are M dwarfs (in either the field or the cluster), demonstrating the efficiency of our photometric selection method in avoiding contaminants (e.g., red giants). About half of our photometric candidates for which we have spectra are spectroscopically confirmed as cluster members; two are new spectroscopically confirmed BD members of IC 2391.

  9. Ron Brown Scholar Program. Evaluation Summary

    ERIC Educational Resources Information Center

    Broton, Katie; Mueller, Dan

    2009-01-01

    The Ron Brown Scholar Program aims to be a major force in producing this nation's next generation of leaders by providing academic scholarships, service opportunities, and leadership experiences to exemplary young African Americans. The program is highly selective, with several hundred applicants per scholarship awarded. Students are selected…

  10. Brown Bodies, Racialisation and physical education

    ERIC Educational Resources Information Center

    Fitzpatrick, Katie

    2013-01-01

    This article explores how school physical education (PE) can both reinforce stereotyped notions of the brown body as inherently physical while also allowing young people to gain educational success. Drawing on a critical ethnographic study of Maori and Pasifika (Pacific Island) youth in PE in New Zealand, the article explores how the academic…

  11. Brown dwarf disks with ALMA

    SciTech Connect

    Ricci, L.; Isella, A.; Testi, L.; De Gregorio-Monsalvo, I.; Natta, A.; Scholz, A.

    2014-08-10

    We present Atacama Large Millimeter/submillimeter Array continuum and spectral line data at 0.89 mm and 3.2 mm for three disks surrounding young brown dwarfs and very low mass stars in the Taurus star forming region. Dust thermal emission is detected and spatially resolved for all the three disks, while CO(J = 3-2) emission is seen in two disks. We analyze the continuum visibilities and constrain the disks' physical structure in dust. The results of our analysis show that the disks are relatively large; the smallest one has an outer radius of about 70 AU. The inferred disk radii, radial profiles of the dust surface density, and disk to central object mass ratios lie within the ranges found for disks around more massive young stars. We derive from our observations the wavelength dependence of the millimeter dust opacity. In all the three disks, data are consistent with the presence of grains with at least millimeter sizes, as also found for disks around young stars, and confirm that the early stages of the solid growth toward planetesimals occur also around very low-mass objects. We discuss the implications of our findings on models of solids evolution in protoplanetary disks, the main mechanisms proposed for the formation of brown dwarfs and very low-mass stars, as well as the potential of finding rocky and giant planets around very low-mass objects.

  12. Discovery of a cool brown dwarf

    NASA Astrophysics Data System (ADS)

    Nakajima, T.; Oppenheimer, B. R.; Kulkarni, S. R.; Golimowski, D. A.; Matthews, K.; Durrance, S. T.

    1995-11-01

    BROWN dwarfs are starlike objects with masses less than 0.08 times that of the Sun, which are unable to sustain hydrogen fusion in their interiors1-4. They are very hard to detect, as most of the energy of gravitational contraction is radiated away within ~108 yr, leaving only a very low residual luminosity. Accordingly, almost all searches for brown dwarfs have been directed towards clusters of young stars-a strategy that has recently proved successful5,6. But there are only modest observable differences between young brown dwarfs and very lowmass stars, making it difficult to identify the former without appealing to sophisticated models7. Older brown dwarfs should have a more distinctive appearance, and if they are companions to nearby stars, their luminosity can be determined unambiguously. Here we report the discovery of a probable companion to the nearby star G1229, with no more than onetenth the luminosity of the least luminous hydro-gen-burning star. We conclude that the companion, G1229B, is a brown dwarf with a temperature of less than 1,200 K, and a mass ~20-50 times that of Jupiter.

  13. The enigmatic mossy cell of the dentate gyrus.

    PubMed

    Scharfman, Helen E

    2016-09-01

    Mossy cells comprise a large fraction of the cells in the hippocampal dentate gyrus, suggesting that their function in this region is important. They are vulnerable to ischaemia, traumatic brain injury and seizures, and their loss could contribute to dentate gyrus dysfunction in such conditions. Mossy cell function has been unclear because these cells innervate both glutamatergic and GABAergic neurons within the dentate gyrus, contributing to a complex circuitry. It has also been difficult to directly and selectively manipulate mossy cells to study their function. In light of the new data generated using methods to preferentially eliminate or activate mossy cells in mice, it is timely to ask whether mossy cells have become any less enigmatic than they were in the past. PMID:27466143

  14. The enigmatic fast leaflet rotation in Desmodium motorium

    PubMed Central

    Lev-Yadun, Simcha

    2013-01-01

    I propose that the enigmatic leaflet movements in elliptical circles every few minutes of the Indian telegraph (semaphore) plant Desmodium motorium ( = D. gyrans = Hedysarum gyrans = Codariocalyx motorius), which has intrigued scientists for centuries, is a new type of butterfly or general winged arthropod mimicry by this plant. Such leaflet movement may deceive a passing butterfly searching for an un-occupied site suitable to deposit its eggs, that the plant is already occupied. It may also attract insectivorous birds, reptiles or arthropods to the plant because it looks as if it is harboring a potential prey and while they patrol there, they can find insects or other invertebrates that indeed attack the plant. The possibility that diurnal mammalian herbivores may also be deterred by these movements should not be dismissed. PMID:23603964

  15. Interstitial Cystitis: Characterization and Management of an Enigmatic Urologic Syndrome

    PubMed Central

    Nickel, J. Curtis

    2002-01-01

    The enigmatic urologic condition known as interstitial cystitis has an estimated prevalence of 0.01% to 0.50% of the female population. Its etiology is unknown but may involve microbiologic, immunologic, mucosal, neurogenic, and/or other, as yet undefined, agents. There is no gold standard for the diagnosis of interstitial cystitis; rather, it is a diagnosis of exclusion. It is impossible to provide a purely evidence-based treatment strategy, but review of available evidence suggests that conservative supportive therapy (including diet modification); oral treatment with pentosan polysulfate, amitriptyline, hydroxyzine, or cimetidine; and intravesical treatments with heparinoids, dimethyl sulfoxide, alkalized lidocaine, or bacille Calmette-Guérin may be effective in some patients. PMID:16985667

  16. Brown recluse spider envenomation.

    PubMed

    Furbee, R Brent; Kao, Louise W; Ibrahim, Danyal

    2006-03-01

    Brown recluse spider bite is a common diagnosis in almost every state in America. In fact, cases have been reported in areas where the spider has never been seen. A review of medical literature reveals that most current concepts regarding brown recluse spider envenomation are based on supposition. In this article, we attempt to review critically our present understanding of brown recluse bites with a focus on the published evidence. PMID:16567232

  17. Testosterone (T)-induced changes in arcuate nucleus cocaine-amphetamine-regulated transcript and NPY mRNA are attenuated in old compared to young male brown Norway rats: contribution of T to age-related changes in cocaine-amphetamine-regulated transcript and NPY gene expression.

    PubMed

    Sohn, Elliott H; Wolden-Hanson, Tami; Matsumoto, Alvin M

    2002-03-01

    The age-related decrease in serum T levels is associated with impairments in food intake and weight regulation and alterations in brain peptides that regulate energy balance. To test the hypothesis that reduced T levels contribute to altered hypothalamic cocaine-amphetamine-regulated transcript (CART) and NPY gene expression, the mRNA content of these neuropeptides was measured by in situ hybridization in sham-operated (intact), castrated, and T-replaced castrated young and old male Brown Norway rats. T levels in T-replaced young and old rats were similar to those in intact young animals. Compared with castrated rats, arcuate nucleus CART mRNA was lower and NPY mRNA was higher in both young and old T-replaced castrated animals, suggesting reciprocal regulation of these peptides by T; these T-induced changes were localized primarily in the rostral arcuate and were markedly attenuated in old animals. Compared with intact animals, paraventricular nucleus CART mRNA was lower in castrated animals and similar in T-replaced young and old rats. We conclude that hypothalamic CART and NPY neurons remain responsive to T regulation in old rats, albeit less so than in young animals, suggesting that the age-related reduction of T contributes in part to altered brain neuropeptide gene expression favoring anorexia and wasting with aging. PMID:11861518

  18. Enigmatic MYC Conducts an Unfolding Systems Biology Symphony.

    PubMed

    Dang, Chi V

    2010-06-01

    The enigmatic MYC oncogene, which participates broadly in cancers, revealed itself recently as the maestro of an unfolding symphony of cell growth, proliferation, death, and metabolism. The study of MYC is arguably most challenging to its students but at the same time exhilarating when MYC reveals its deeply held secrets. It is the excitement of our richer understanding of MYC that is captured in each review of this special issue of Genes & Cancer. Collectively, our deeper understanding of MYC reveals that it is a symphony conductor, controlling a large orchestra of target genes. Although MYC controls many orchestra sections, which are necessary but not sufficient for Myc function, ribosome biogenesis stands out to reveal Myc's primordial function particularly in fruit flies. Because ribosome biogenesis and the associated translational machinery are bioenergetically demanding, Myc's other target genes involved in energy metabolism must be coupled with energy demand to ensure that cells can replicate their genome and produce daughter cells. Normal cells have feedback loops that diminish MYC expression when nutrients are scarce. On the other hand, when deregulated Myc transforms cells, their constitutive bioenergetic demand can trigger cell death when energy is unavailable. This special issue captures the unfolding symphony of MYC-mediated tumorigenesis through reviews that span from a timeline of MYC research, fundamental understanding of how the MYC gene itself is regulated, the study of Myc in model organisms, Myc function, and target genes to translational research in search of new therapeutic modalities for the treatment of cancer. PMID:21218193

  19. HIV-1 Vpr—a still “enigmatic multitasker”

    PubMed Central

    Guenzel, Carolin A.; Hérate, Cécile; Benichou, Serge

    2014-01-01

    Like other HIV-1 auxiliary proteins, Vpr is conserved within all the human (HIV-1, HIV-2) and simian (SIV) immunodeficiency viruses. However, Vpr and homologous HIV-2, and SIV Vpx are the only viral auxiliary proteins specifically incorporated into virus particles through direct interaction with the Gag precursor, indicating that this presence in the core of the mature virions is mainly required for optimal establishment of the early steps of the virus life cycle in the newly infected cell. In spite of its small size, a plethora of effects and functions have been attributed to Vpr, including induction of cell cycle arrest and apoptosis, modulation of the fidelity of reverse transcription, nuclear import of viral DNA in macrophages and other non-dividing cells, and transcriptional modulation of viral and host cell genes. Even if some more recent studies identified a few cellular targets that HIV-1 Vpr may utilize in order to perform its different tasks, the real role and functions of Vpr during the course of natural infection are still enigmatic. In this review, we will summarize the main reported functions of HIV-1 Vpr and their significance in the context of the viral life cycle. PMID:24744753

  20. Astrophysics: Illuminating brown dwarfs

    NASA Astrophysics Data System (ADS)

    Showman, Adam P.

    2016-05-01

    Objects known as brown dwarfs are midway between stars and planets in mass. Observations of a hot brown dwarf irradiated by a nearby star will help to fill a gap in our knowledge of the atmospheres of fluid planetary objects. See Letter p.366

  1. WISE and Brown Dwarfs

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, J. Davy; WISE Team

    2009-05-01

    The search for the nearest and coolest brown dwarfs will use WISE's two short-wavelength channels (W1 and W2), which are optimized for brown dwarf detection. W1 samples the methane fundamental absorption band at 3.3 microns, and W2 measures the relatively opacity-free portion of the brown dwarf atmosphere near 4.7 microns. Cool brown dwarfs will thus have very red [W1]-[W2] colors, maximizing our chances of identifying them. Extrapolating preferred mass functions to very low masses and assuming that the star formation rate has been constant over the last 10 Gyr, we can predict the number of brown dwarfs WISE is expected to image. At spectral types later than T7 (Teff > 850K), WISE is expected to find 500 brown dwarfs, which makes WISE uniquely suited among future surveys to measure the low-mass limit of star formation for the first time. This sample will also show whether a new spectral class beyond T, dubbed "Y", is needed at the lowest temperatures. Although the primary six-month WISE mission will cover the entire sky once, WISE should have sufficient cryogen to perform a second, complete pass of the sky. In this case, the identification of nearby brown dwarfs need not rely solely on color selection. Kinematics (proper motion) and geometry (parallax) can also be used to distinguish our closest brown dwarf neighbors, one of which may lie less distant than Proxima Centauri or even fall within our own Oort Cloud.

  2. Familial unilateral Brown syndrome

    PubMed Central

    Kenawy, Nihal; Pilz, Daniela T

    2008-01-01

    We present a two-generation family with Brown syndrome. The proband was a six and a half-year-old female who presented with a history of failure of dextro-elevation of her left eye. A full ophthalmic evaluation was consistent with a left Brown syndrome. Family history revealed that her mother was operated on as a child for left Brown syndrome and examination of her four and a half-year-old sibling showed similar affection in the left eye. Autosomal dominant inheritance has been postulated in this condition. To our knowledge this is the first report of three members of a two-generation family with left-sided Brown syndrome. Genetic counseling of Brown syndrome cases is advised; nevertheless, identification of the responsible gene should shed more light on its genetics. PMID:18711279

  3. Characterization of Enigmatic Saturn's Ring B by Cassini Radio Occultations

    NASA Astrophysics Data System (ADS)

    Marouf, E. A.; French, R. G.; Rappaprt, N. J.; McGhee, C. A.; Thomson, F. S.; Wong, K.; Anabtawi, A.

    2007-12-01

    Cassini radio occultation observations of the extinction and near-forward scattering of 0.94, 3.6, and 13 cm- wavelengths sinusoidal signals have shed much new light on the structure and physical properties of Saturn's main ring system, especially enigmatic Ring B. As of June 2007, the occultations covered 15 distinct ring longitudes and roughly two distinct ranges of ring opening angle B; the first 12 covered B = 19.5-23.5 deg, and the last three B =14-15 deg. Four sub-regions of Ring B, identified as B1 to B4 (bounded by rough ring radius = 92, 99, 104.5, 110, 117.5 thousand km) exhibit clearly distinct structure (Marouf et al., 38th DPS Meeting, 38.05, 2006). Region B2, in particular, is characterized by remarkable 'bi-stable' states, where the optical depth abruptly flip-flops between optical depth of about 2 and more than 5. We consider observational evidence that bear on physical characterization of the observed structure (particle sizes, particle-cluster-sizes and orientation, spatial cluster density, vertical ring profile and physical thickness, ...). On the signal extinction side, this includes differential extinction of the three radio signals, and apparent variation of optical depth with observation longitude and ring opening angle (azimuthal asymmetry). On the forward scattered signal side, it includes strength, bandwidth, spectral shape and Doppler drift-rate of observed spectrogram features. We present representative results for selected features in regions B1, B2, and B4. Of particular interest is the detection of quasi-periodic ring structure of period roughly 100 meters in region B2 (and perhaps B4). In contrast with the prevalent gravitational wakes, the periodic structure is not azimuthally inclined and appears to be an independent structure superposed on the background wake structure (Thomson et al., submitted 2007).

  4. On the origins of enigmatic stellar populations in Local Group galactic nuclei

    NASA Astrophysics Data System (ADS)

    Leigh, Nathan W. C.; Antonini, Fabio; Stone, Nicholas C.; Shara, Michael M.; Merritt, David

    2016-08-01

    We consider the origins of enigmatic stellar populations in four Local Group galactic nuclei, specifically the Milky Way, M31, M32 and M33. These are centrally concentrated blue stars, found in three out of the four nuclear star clusters (NSCs) considered here. Their origins are unknown, but could include blue straggler (BS) stars, extended horizontal branch stars and young recently formed stars. Here, we calculate order-of-magnitude estimates for various collision rates, as a function of the host NSC environment and distance from the cluster centre. These rates are sufficiently high that BSs, formed via collisions between main sequence (MS) stars, could contribute non-negligibly (˜ 1-10% in mass) to every surface brightness profile, with the exception of the Milky Way. Stellar evolution models show that the envelopes of red giant branch (RGB) stars must be nearly completely stripped to significantly affect their photometric appearance, which requires multiple collisions. Hence, the collision rates for individual RGB stars are only sufficiently high in the inner ≲ 0.1 pc of M31 and M32 for RGB destruction to occur. Collisions between white dwarfs and MS stars, which should ablate the stars, could offer a steady and significant supply of gas in every NSC in our sample. The gas could either fragment to form new stars, or accrete onto old MS stars already present. Thus, collisional processes could contribute significantly to the observed blue excesses in M31 and M33; future studies should be aimed at better constraining theoretical predictions to compliment existing and future observational data.

  5. Discovery of a brown dwarf in the Pleiades star cluster

    NASA Astrophysics Data System (ADS)

    Rebolo, R.; Zapatero Osorio, M. R.; Martín, E. L.

    1995-09-01

    BROWN dwarfs are cool star-like objects that have insufficient mass to maintain stable nuclear fusion in their interiors. Although brown dwarfs are not stars, they are expected to form in the same way, and their frequency of occurrence should reflect the trends seen in the birthrates of low-mass stars. But finding brown dwarfs has proved to be difficult, because of their low intrinsic luminosity. The nearby Pleiades star cluster is widely recognized as a likely host for detectable brown dwarfs because of its young age - the still-contracting brown dwarfs should radiate a large fraction of their gravitational energy at near-infrared wavelengths. Here we report the discovery of a brown dwarf near the centre of the Pleiades. The luminosity and temperature of this object are so low that its mass must be less than 0.08 solar masses, the accepted lower limit on the mass of a true star1-3. The detection of only one brown dwarf within our survey area is consistent with a smooth extrapolation of the stellar mass function of the Pleiades4, suggesting that brown dwarfs, although probably quite numerous in the Galactic disk, are unlikely to comprise more than ~1% of its mass.

  6. Brown Recluse Spider

    MedlinePlus

    ... to a group of spiders commonly known as violin spiders or fiddlebacks. The characteristic fiddle-shaped pattern ... 4-19.1mm) • Color: Golden brown • A dark violin/fiddle shape (see top photo) is located on ...

  7. Phylogenetic placement of enigmatic percomorph families (Teleostei: Percomorphaceae).

    PubMed

    Sanciangco, Millicent D; Carpenter, Kent E; Betancur-R, Ricardo

    2016-01-01

    Percomorphs are a large and diverse group of spiny-finned fishes that have come to be known as the "bush at the top" due to their persistent lack of phylogenetic resolution. Recently, the broader Euteleost Tree of Life project (EToL) inferred a well-supported phylogenetic hypothesis that groups the diversity of percomorphs into nine well-supported series (supraordinal groups): Ophidiaria, Batrachoidaria, Gobiaria, Syngnatharia, Pelagiaria, Anabantaria, Carangaria, Ovalentaria, and Eupercaria. The EToL also provided, for the first time, a monophyletic definition of Perciformes - the largest order of vertebrates. Despite significant progress made in accommodating the diversity of percomorph taxa into major clades, some 62 families (most previously placed in "Perciformes", as traditionally defined) were not examined by the EToL. Here, we provide evidence for the phylogenetic affinities of 10 of those 62 families, seven of which have largely remained enigmatic. This expanded taxonomic sampling also provides further support for the nine EToL supraordinal series. We examined sequences from 21 genes previously used by the EToL and added two fast-evolving mitochondrial markers in an attempt to increase resolution within the rapid percomorph radiations. We restricted the taxonomic sampling to 1229 percomorph species, including expanded sampling from recent studies. Results of maximum likelihood analysis revealed that bathyclupeids (Bathyclupeidae), galjoen fishes (Dichistiidae), kelpfishes (Chironemidae), marblefishes (Aplodactylidae), trumpeters (Latridae), barbeled grunters (Hapalogenyidae), slopefishes (Symphysanodontidae), and picarel porgies (formerly Centracanthidae) are members of the series Eupercaria ("new bush at the top"). The picarel porgies and porgies (Sparidae) are now placed in the same family (Sparidae). Our analyses suggest a close affinity between the orders Spariformes (including Lethrinidae, Nemipteridae and Sparidae) and Lobotiformes (including the

  8. Plasmodesmata of brown algae.

    PubMed

    Terauchi, Makoto; Nagasato, Chikako; Motomura, Taizo

    2015-01-01

    Plasmodesmata (PD) are intercellular connections in plants which play roles in various developmental processes. They are also found in brown algae, a group of eukaryotes possessing complex multicellularity, as well as green plants. Recently, we conducted an ultrastructural study of PD in several species of brown algae. PD in brown algae are commonly straight plasma membrane-lined channels with a diameter of 10-20 nm and they lack desmotubule in contrast to green plants. Moreover, branched PD could not be observed in brown algae. In the brown alga, Dictyota dichotoma, PD are produced during cytokinesis through the formation of their precursor structures (pre-plasmodesmata, PPD). Clustering of PD in a structure termed "pit field" was recognized in several species having a complex multicellular thallus structure but not in those having uniseriate filamentous or multiseriate one. The pit fields might control cell-to-cell communication and contribute to the establishment of the complex multicellular thallus. In this review, we discuss fundamental morphological aspects of brown algal PD and present questions that remain open. PMID:25516500

  9. Topographic Constraints on the Mode of Formation of an Enigmatic Flow in Cerberus Fossae, Mars

    NASA Astrophysics Data System (ADS)

    Mouginis-Mark, P. J.; Wilson, L.

    2013-12-01

    We use a digital elevation model (DEM), derived from stereo Context Camera (CTX) images referenced to Mars Orbiter Laser Altimeter (MOLA) data, and shadow length measurements made from High Resolution Imaging Science Experiment (HiRISE) images, to investigate the geometry of a young enigmatic flow in S.W. Cerberus Fossae, Mars. The flow originates from an almost circular (1.2 x 1.5 km) pit within a remnant of a yardang at 0o 35'N, 155o 17'E, within the lower unit of the Medusae Fossae Formation. The flow is ~42 km long and 0.5 to 2.0 km wide, and MOLA data indicate that the flow falls ~50 m along its length. The flow has a broad distal fan of material ~8 x 14 km in size that has a platey surface texture. The source area of the flow displays several sets of semi-concentric ridges with different centers of curvature, and the CTX DEM shows this depression is ~20 m deep, implying a volume of ~0.03 km3 for the removed material. Measurements made from the DEM of the height of the bounding walls of several 160 - 200 m wide constrictions, where 'over-spill' from the flow forms a clear disrupted margin to the flow on the adjacent hills, indicate that the flow was never more than ~8 - 10 m thicker than it currently appears. The total surface area of the flow is ~153 km2 and 25 shadow length measurements made from HiRISE images of the flow margins at 16 different places along the flow give a typical thickness of ~4 m. These measurements imply a volume for the flow of ~0.6 km3, which is 20 times larger than the volume of the flow's source area, thereby demonstrating that a significant amount of new material was erupted to form the flow. The available morphologic and topographic data raise the intriguing probability that the flow is most likely not a lava flow, but is instead a mud flow produced by water reaching the surface within the yardang materials and the subsequent mobilization of the unconsolidated material that comprised the yardang. This proposed mud flow origin

  10. Changes in the use of young bulls

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Availability of genomic information since 2008 has increased accuracy of genetic evaluations for young bulls in Holstein (HO), Jersey (JE), and Brown Swiss (BS). As a result, AI organizations have been aggressively promoting young bulls and producers have been using young bulls more extensively. Num...

  11. Formation of Brown Dwarfs LTSA 2001

    NASA Technical Reports Server (NTRS)

    Luhman, Kevin L.; Oliversen, Ronald J. (Technical Monitor)

    2003-01-01

    The goals of the work funded by this grant are: 1) The measurement of the mass function and minimum mass of free-floating brown dwarfs down to the mass of Jupiter; 2) The measurement of the frequency of wide brown dwarf and planetary companions down to the mass of Jupiter as function of primary mass (0.02-2 Msun), age (1-10 Myr), and environment (clusters vs. dispersed regions). For the first objective, we have completed the design of guaranteed SIRTF observations of nearby star-forming regions. With the successful launch of the SIRTF mission in August of 2003, we now await the execution of these observations, which should begin in early 2004. In support of these upcoming observations, in the fall of 2002 and spring of 2003 we obtained optical spectroscopy at the MMT, the 1.5 meter telescope at Fred Lawrence Whipple Observatory, and Magellan Observatory for several hundred candidate young low-mass stars and brown dwarfs in the IC348, Taurus, and Chamaeleon star-forming regions. All of these data have been published in three papers in The Astrophysical Journal. We also recently used the MMT to obtain deep near-IR images of IC348 to accompany the SIRTF images and have time in the next month at the IRTF and Keck for spectroscopy of candidate brown dwarfs in IC348 and Taurus. We have submitted proposals for deep optical and near-IR imaging of the SIRTF fields in Chamaeleon and Ophiuchus for spring 2004 with Magellan and the AAT. Results from this research have been presented in invited talks at UU Symposium 221 (July 2003) and at the SIRTF Galactic Science Workshop (August 2003). For the second objective, we have used deep HST WFPC2 images to search for young giant planets and brown dwarfs around approx. 100 low-mass stars and brown dwarfs in the nearby cluster IC348. We have completed all data reduction and have checked these data for candidate companions. We expect to submit the paper describing these observations to The Astrophysical Journal by the end of the year

  12. Brown Dwarfs: Discovery and Detailed Studies

    NASA Technical Reports Server (NTRS)

    Kulkarni, Shrinivas R.

    2003-01-01

    The grant supported my research and that of my student (Ben Lane) and post-doctoral fellow (Zapatero Osorio). We were productive as can be seen from the list of publications below. In particular, we note three firsts. Using the exquisite angular resolution provided by the AO system at Keck we were able to directly determine the masses of two objects and show that one was a brown dwarf -- the first direct determination of the mass of a brown dwarf. Next, Mr. Lane reported the first direct demonstration of pulsations of a Cepheid star (this report received attention in the popular press). Finally, Dr. Zapatero Osorio continued her work on the search for young brown dwarfs and planets in young clusters with considerable success -- namely the detection of objects with mass below 10 M_J (these can be plausibly argued to be freely floating planets). Mr. Lane graduated and is now a Pappalardo Fellow at MIT and Dr. Zapatero Osorio obtained a position back in her home country.

  13. X-Rays Found From a Lightweight Brown Dwarf

    NASA Astrophysics Data System (ADS)

    2003-04-01

    Using NASA's Chandra X-ray Observatory, scientists have detected X-rays from a low mass brown dwarf in a multiple star system, which is as young as 12 million years old. This discovery is an important piece in an increasingly complex picture of how brown dwarfs - and perhaps the very massive planets around other stars - evolve. Chandra's observations of the brown dwarf, known as TWA 5B, clearly resolve it from a pair of Sun-like stars known as TWA 5A. The system is about 180 light years from the Sun and a member of a group of about a dozen young stars in the southern constellation Hydra. The brown dwarf orbits the binary stars at a distance about 2.75 times that of Pluto's orbit around the Sun. This is first time that a brown dwarf this close to its parent star(s) has been resolved in X-rays. "Our Chandra data show that the X-rays originate from the brown dwarf's coronal plasma which is some 3 million degrees Celsius," said Yohko Tsuboi of Chuo University in Tokyo and lead author of the April 10th issue of Astrophysical Journal Letters paper describing these results. "The brown dwarf is sufficiently far from the primary stars that the reflection of X-rays is unimportant, so the X-rays must come the brown dwarf itself." TWA 5B is estimated to be only between 15 and 40 times the mass of Jupiter, making it one of the least massive brown dwarfs known. Its mass is rather near the currently accepted boundary (about 12 Jupiter masses) between planets and brown dwarfs. Therefore, these results may also have implications for very massive planets, including those that have been discovered as extrasolar planets in recent years. Brown Dwarf size comparison schematic Brown Dwarf size comparison schematic "This brown dwarf is as bright as the Sun today in X-ray light, while it is fifty times less massive than the Sun," said Tsuboi. "This observation, thus, raises the possibility that even massive planets might emit X-rays by themselves during their youth!" This research on TWA 5

  14. Clouds in brown dwarfs and giant planets

    NASA Astrophysics Data System (ADS)

    Metchev, S.; Apai, D.; Radigan, J.; Artigau, É.; Heinze, A.; Helling, C.; Homeier, D.; Littlefair, S.; Morley, C.; Skemer, A.; Stark, C.

    2013-02-01

    A growing body of observational and theoretical evidence points toward the importance of clouds in the atmospheres of ultra-cool brown dwarfs and giant planets. Empirically, the presence of clouds is inferred from the red, likely dusty atmospheres of young substellar objects, and from detections of periodic variability in a fraction of brown dwarfs - as expected from rotation and a patchy cloud cover. Theoretical models have progressed alongside by including ever more comprehensive atomic and molecular opacity tables, incorporating the treatment of non-equilibrium chemistry and clouds through vertical mixing and grain size/sedimentation parameters, and employing 3-D hydrodynamical simulations. In this proceeding we summarize the key issues raised during the first gathering of observers and theorists to discuss clouds and atmospheric circulation in non-irradiated ultra-cool dwarfs and giant planets.

  15. Coulomb Interactions in Hanbury Brown-Twiss Experiments with Electrons

    ERIC Educational Resources Information Center

    Shen, Kan

    2009-01-01

    This dissertation examines the effect of Coulomb interactions in Hanbury Brown-Twiss (HBT) type experiments with electrons. HBT experiments deal with intensity interference, which is related to the second-order correlation function of the particle field. This is an extension of the usual amplitude interference experiment, such as Young's…

  16. Origin of Enigmatic Galactic-center Filaments Revealed

    NASA Astrophysics Data System (ADS)

    2004-06-01

    Twenty years ago, astronomers discovered a number of enigmatic radio-emitting filaments concentrated near the center of the Milky Way Galaxy. These features initially defied explanation, but a new study of radio images of the Galactic center may point to their possible source. By combining data from the National Science Foundation's Very Large Array (VLA) and Robert C. Byrd Green Bank Telescope (GBT) astronomer Farhad Yusef-Zadeh of Northwestern University has found evidence that at least some of the filaments spring from the concentrated star-formation regions that populate the Galactic center. Galatic Center Combined VLA and GBT image (green) of the Galactic center, with red inset of GBT data only (red). Bright region on right is location of supermassive black hole. Linear filaments are visible above this area. CREDIT: NRAO/AUI/NSF Yusef-Zadeh, et.al. (Click on Image for Larger Version) Yusef-Zadeh presented his findings at the Denver, Colorado, meeting of the American Astronomical Society. William Cotton of the National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia, and William Hewitt of Northwestern University also contributed to this research. "Astronomers have long puzzled over the cause of these striking features," said Yusef-Zadeh, "and the turbulent nature of the Galactic center has made detailed analysis difficult. With new multi-wavelength radio images of the Galactic center, however, we can finally see a link between areas of starburst activity and these long-linear filaments." The filaments, which range from 10 to 100 light-years in length and are perhaps little more than 1 to 3 light-years across, occur only in a very narrow area, within approximately two degrees of the Galactic center (which translates to approximately 900 light-years across). Early theories about the origin of these filaments suggested that they were somehow related to the Milky Way’s own magnetic field. This was due to the fact that the first filaments detected

  17. "Brown's" Far Reaching Impact

    ERIC Educational Resources Information Center

    Chinn, Philip C.

    2004-01-01

    Although the 1954 "Brown v. Board of Education" U.S. Supreme Court decision changed the face of American education forever, few individuals at that time could have fully realized its far-reaching implications. Certainly, the National Association for the Advancement of Colored People Legal Director Thurgood Marshall in his arguments was focusing on…

  18. Outflows and disks of brown dwarfs with SMA, CARMA and ALMA

    NASA Astrophysics Data System (ADS)

    Phan-Bao, Ngoc; Lee, Chin-Fei; Ho, Paul; Martín, Eduardo; Tho, Do D.

    2013-04-01

    Brown dwarfs are on the dividing line between planets and stars. Up to date, about 1,000 brown dwarfs, including the coolest known brown dwarfs with temperatures of ˜300 K as cool as the human body, have been discovered. However, the origin of these objects is still not well understood. Here we report our study of molecular outflows and disks of young very-low mass stars and brown dwarfs in ρ Ophiuchi and Taurus using the Submillimeter Array (SMA) and the Combined Array for Research in Millimeter-wave Astronomy (CARMA). The observations of brown dwarfs at early stages provide key information to understand their formation mechanism as well as planet formation around these very low-mass objects. We also discuss future observations of brown dwarfs with the Atacama Large Millimeter/submillimeter Array (ALMA).

  19. Polar and brown bear genomes reveal ancient admixture and demographic footprints of past climate change.

    PubMed

    Miller, Webb; Schuster, Stephan C; Welch, Andreanna J; Ratan, Aakrosh; Bedoya-Reina, Oscar C; Zhao, Fangqing; Kim, Hie Lim; Burhans, Richard C; Drautz, Daniela I; Wittekindt, Nicola E; Tomsho, Lynn P; Ibarra-Laclette, Enrique; Herrera-Estrella, Luis; Peacock, Elizabeth; Farley, Sean; Sage, George K; Rode, Karyn; Obbard, Martyn; Montiel, Rafael; Bachmann, Lutz; Ingólfsson, Olafur; Aars, Jon; Mailund, Thomas; Wiig, Oystein; Talbot, Sandra L; Lindqvist, Charlotte

    2012-09-01

    Polar bears (PBs) are superbly adapted to the extreme Arctic environment and have become emblematic of the threat to biodiversity from global climate change. Their divergence from the lower-latitude brown bear provides a textbook example of rapid evolution of distinct phenotypes. However, limited mitochondrial and nuclear DNA evidence conflicts in the timing of PB origin as well as placement of the species within versus sister to the brown bear lineage. We gathered extensive genomic sequence data from contemporary polar, brown, and American black bear samples, in addition to a 130,000- to 110,000-y old PB, to examine this problem from a genome-wide perspective. Nuclear DNA markers reflect a species tree consistent with expectation, showing polar and brown bears to be sister species. However, for the enigmatic brown bears native to Alaska's Alexander Archipelago, we estimate that not only their mitochondrial genome, but also 5-10% of their nuclear genome, is most closely related to PBs, indicating ancient admixture between the two species. Explicit admixture analyses are consistent with ancient splits among PBs, brown bears and black bears that were later followed by occasional admixture. We also provide paleodemographic estimates that suggest bear evolution has tracked key climate events, and that PB in particular experienced a prolonged and dramatic decline in its effective population size during the last ca. 500,000 years. We demonstrate that brown bears and PBs have had sufficiently independent evolutionary histories over the last 4-5 million years to leave imprints in the PB nuclear genome that likely are associated with ecological adaptation to the Arctic environment. PMID:22826254

  20. Polar and brown bear genomes reveal ancient admixture and demographic footprints of past climate change

    USGS Publications Warehouse

    Miller, Webb; Schuster, Stephan C.; Welch, Andreanna J.; Ratan, Aakrosh; Bedoya-Reina, Oscar C.; Zhao, Fangqing; Kim, Hie Lim; Burhans, Richard C.; Drautz, Daniela I.; Wittekindt, Nicola E.; Tomsho, Lynn P.; Ibarra-Laclette, Enrique; Herrera-Estrella, Luis; Peacock, Elizabeth; Farley, Sean; Sage, George K.; Rode, Karyn; Obbard, Martyn E.; Montiel, Rafael; Bachmann, Lutz; Ingólfsson, Ólafur; Aars, Jon; Mailund, Thomas; Wiig, Øystein; Talbot, Sandra L.; Lindqvist, Charlotte

    2012-01-01

    Polar bears (PBs) are superbly adapted to the extreme Arctic environment and have become emblematic of the threat to biodiversity from global climate change. Their divergence from the lower-latitude brown bear provides a textbook example of rapid evolution of distinct phenotypes. However, limited mitochondrial and nuclear DNA evidence conflicts in the timing of PB origin as well as placement of the species within versus sister to the brown bear lineage. We gathered extensive genomic sequence data from contemporary polar, brown, and American black bear samples, in addition to a 130,000- to 110,000-y old PB, to examine this problem from a genome-wide perspective. Nuclear DNA markers reflect a species tree consistent with expectation, showing polar and brown bears to be sister species. However, for the enigmatic brown bears native to Alaska's Alexander Archipelago, we estimate that not only their mitochondrial genome, but also 5–10% of their nuclear genome, is most closely related to PBs, indicating ancient admixture between the two species. Explicit admixture analyses are consistent with ancient splits among PBs, brown bears and black bears that were later followed by occasional admixture. We also provide paleodemographic estimates that suggest bear evolution has tracked key climate events, and that PB in particular experienced a prolonged and dramatic decline in its effective population size during the last ca. 500,000 years. We demonstrate that brown bears and PBs have had sufficiently independent evolutionary histories over the last 4–5 million years to leave imprints in the PB nuclear genome that likely are associated with ecological adaptation to the Arctic environment.

  1. Herschel survey of brown dwarf disks in ρ Ophiuchi

    NASA Astrophysics Data System (ADS)

    Alves de Oliveira, C.; Ábrahám, P.; Marton, G.; Pinte, C.; Kiss, Cs.; Kun, M.; Kóspál, Á.; André, P.; Könyves, V.

    2013-11-01

    Context. Young brown dwarfs are known to possess circumstellar disks, a characteristic that is fundamental to the understanding of their formation process, and raises the possibility that these objects harbour planets. Aims: We want to characterise the far-IR emission of disks around the young brown dwarf population of the ρ Ophiuchi cluster in LDN 1688. Methods: Recent observations of the ρ Ophiuchi cluster with the Herschel Space Observatory allow us to probe the spectral energy distribution (SED) of the brown dwarf population in the far-IR, where the disk emission peaks. We performed aperture photometry at 70, 100, and 160 μm, and constructed SEDs for all previously known brown dwarfs detected. These were complemented with ancillary photometry at shorter wavelengths. We compared the observed SEDs to a grid of synthetic disks produced with the radiative transfer code MCFOST, and used the relative figure of merit estimated from the Bayesian inference of each disk parameter to analyse the structural properties. Results: We detected 12 Class II brown dwarfs with Herschel, which corresponds to one-third of all currently known brown dwarf members of ρ Ophiuchi. We did not detect any of the known Class III brown dwarfs. Comparison to models reveals that the disks are best described by an inner radius between 0.01 and 0.07 AU, and a flared disk geometry with a flaring index between 1.05 and 1.2. Furthermore, we can exclude values of the disk scale-height lower than 10 AU (measured at a fiducial radius of 100 AU). We combined the Herschel data with recent ALMA observations of the brown dwarf GY92 204 (ISO-Oph 102), and by comparing its SED to the same grid of disk models, we derived an inner disk radius of 0.035 AU, a scale height of 15 AU with a flaring index of β ~ 1.15, an exponent for dust settling of -1.5, and a disk mass of 0.001 M⊙. This corresponds to a disk-to-central object mass ratio of ~1%. Conclusions: The structural parameters constrained by the

  2. FIRST LIGHT LBT AO IMAGES OF HR 8799 bcde AT 1.6 AND 3.3 {mu}m: NEW DISCREPANCIES BETWEEN YOUNG PLANETS AND OLD BROWN DWARFS

    SciTech Connect

    Skemer, Andrew J.; Hinz, Philip M.; Rodigas, Timothy J.; Close, Laird; McCarthy, Don; Kulesa, Craig; Apai, Daniel; Bailey, Vanessa; Esposito, Simone; Arcidiacono, Carmelo; Mannucci, Filippo; Agapito, Guido; Argomedo, Javier; Briguglio, Runa; Burrows, Adam; Leisenring, Jarron; Skrutskie, Michael; Desidera, Silvano; Mesa, Dino; Boutsia, Konstantina; and others

    2012-07-01

    As the only directly imaged multiple planet system, HR 8799 provides a unique opportunity to study the physical properties of several planets in parallel. In this paper, we image all four of the HR 8799 planets at H band and 3.3 {mu}m with the new Large Binocular Telescope adaptive optics system, PISCES, and LBTI/LMIRCam. Our images offer an unprecedented view of the system, allowing us to obtain H and 3.3 {mu}m photometry of the innermost planet (for the first time) and put strong upper limits on the presence of a hypothetical fifth companion. We find that all four planets are unexpectedly bright at 3.3 {mu}m compared to the equilibrium chemistry models used for field brown dwarfs, which predict that planets should be faint at 3.3 {mu}m due to CH{sub 4} opacity. We attempt to model the planets with thick-cloudy, non-equilibrium chemistry atmospheres but find that removing CH{sub 4} to fit the 3.3 {mu}m photometry increases the predicted L' (3.8 {mu}m) flux enough that it is inconsistent with observations. In an effort to fit the spectral energy distribution of the HR 8799 planets, we construct mixtures of cloudy atmospheres, which are intended to represent planets covered by clouds of varying opacity. In this scenario, regions with low opacity look hot and bright, while regions with high opacity look faint, similar to the patchy cloud structures on Jupiter and L/T transition brown dwarfs. Our mixed-cloud models reproduce all of the available data, but self-consistent models are still necessary to demonstrate their viability.

  3. Apelin Enhances Brown Adipogenesis and Browning of White Adipocytes*

    PubMed Central

    Than, Aung; He, Hui Ling; Chua, Si Hui; Xu, Dan; Sun, Lei; Leow, Melvin Khee-Shing; Chen, Peng

    2015-01-01

    Brown adipose tissue expends energy in the form of heat via the mitochondrial uncoupling protein UCP1. Recent studies showed that brown adipose tissue is present in adult humans and may be exploited for its anti-obesity and anti-diabetes actions. Apelin is an adipocyte-derived hormone that plays important roles in energy metabolism. Here, we report that apelin-APJ signaling promotes brown adipocyte differentiation by increasing the expressions of brown adipogenic and thermogenic transcriptional factors via the PI3K/Akt and AMPK signaling pathways. It is also found that apelin relieves the TNFα inhibition on brown adipogenesis. In addition, apelin increases the basal activity of brown adipocytes, as evidenced by the increased PGC1α and UCP1 expressions, mitochondrial biogenesis, and oxygen consumption. Finally, we provide both in vitro and in vivo evidence that apelin is able to increase the brown-like characteristics in white adipocytes. This study, for the first time, reveals the brown adipogenic and browning effects of apelin and suggests a potential therapeutic route to combat obesity and related metabolic disorders. PMID:25931124

  4. Apelin Enhances Brown Adipogenesis and Browning of White Adipocytes.

    PubMed

    Than, Aung; He, Hui Ling; Chua, Si Hui; Xu, Dan; Sun, Lei; Leow, Melvin Khee-Shing; Chen, Peng

    2015-06-01

    Brown adipose tissue expends energy in the form of heat via the mitochondrial uncoupling protein UCP1. Recent studies showed that brown adipose tissue is present in adult humans and may be exploited for its anti-obesity and anti-diabetes actions. Apelin is an adipocyte-derived hormone that plays important roles in energy metabolism. Here, we report that apelin-APJ signaling promotes brown adipocyte differentiation by increasing the expressions of brown adipogenic and thermogenic transcriptional factors via the PI3K/Akt and AMPK signaling pathways. It is also found that apelin relieves the TNFα inhibition on brown adipogenesis. In addition, apelin increases the basal activity of brown adipocytes, as evidenced by the increased PGC1α and UCP1 expressions, mitochondrial biogenesis, and oxygen consumption. Finally, we provide both in vitro and in vivo evidence that apelin is able to increase the brown-like characteristics in white adipocytes. This study, for the first time, reveals the brown adipogenic and browning effects of apelin and suggests a potential therapeutic route to combat obesity and related metabolic disorders. PMID:25931124

  5. Brown Dwarfs: A New Class of Stellar Lighthouse

    NASA Astrophysics Data System (ADS)

    2007-04-01

    Brown dwarfs, thought just a few years ago to be incapable of emitting any significant amounts of radio waves, have been discovered putting out extremely bright "lighthouse beams" of radio waves, much like pulsars. A team of astronomers made the discovery using the National Science Foundation's Very Large Array (VLA) radio telescope. Artist's Conception of Brown Dwarf Artist's conception of "mini-aurorae" at poles of brown dwarf, producing beams of strong radio emission. CREDIT: Hallinan et al., NRAO/AUI/NSF Click on image for page of graphics and full information "These beams rotate with the brown dwarf, and we see them when the beam passes over the Earth. This is the same way we see pulses from pulsars," said Gregg Hallinan of the National University of Ireland Galway. "We now think brown dwarfs may be a missing link between pulsars and planets in our own Solar System, which also emit, but more weakly," he added. Brown dwarfs are enigmatic objects that are too small to be stars but too large to be planets. They are sometimes called "failed stars" because they have too little mass to trigger hydrogen fusion reactions at their cores, the source of the energy output in larger stars. With roughly 15 to 80 times the mass of Jupiter, the largest planet in our Solar System, brown dwarfs were long thought to exist. However, it was not until 1995 that astronomers were able to actually find one. A few dozen now are known. In 2001, a group of summer students at the National Radio Astronomy Observatory used the VLA to observe a brown dwarf, even though they had been told by seasoned astronomers that brown dwarfs are not observable at radio wavelengths. Their discovery of a strong flare of radio emission from the object surprised astronomers and the students' scientific paper on the discovery was published in the prestigous scientific journal Nature. Hallinan and his team observed a set of brown dwarfs with the VLA last year, and found that three of the objects emit extremely

  6. New material of the enigmatic reptile Khurendukhosaurus (Diapsida: Choristodera) from Mongolia

    NASA Astrophysics Data System (ADS)

    Matsumoto, Ryoko; Suzuki, Shigeru; Tsogtbaatar, Khisigjav; Evans, Susan E.

    2009-02-01

    New material of the enigmatic diapsid Khurendukhosaurus is described from the Mongolian type locality, Khuren Dukh, providing additional data on the vertebral column, pelvis, and hind limb. It confirms the choristoderan status of the genus and permits a more detailed phylogenetic analysis that supports a relationship between Khurendukhosaurus and the long-necked Asian Hyphalosauridae. The existence of tall caudal neural spines implies that Khurendukhosaurus was a deep-tailed swimmer. This and the open sacral costocentral sutures suggest a primarily aquatic lifestyle.

  7. K2 Discovery of Young Eclipsing Binaries in Upper Scorpius: Direct Mass and Radius Determinations for the Lowest Mass Stars and Initial Characterization of an Eclipsing Brown Dwarf Binary

    NASA Astrophysics Data System (ADS)

    David, Trevor J.; Hillenbrand, Lynne A.; Cody, Ann Marie; Carpenter, John M.; Howard, Andrew W.

    2016-01-01

    We report the discovery of three low-mass double-lined eclipsing binaries in the pre-main sequence Upper Scorpius association, revealed by K2 photometric monitoring of the region over ˜78 days. The orbital periods of all three systems are <5 days. We use the K2 photometry plus multiple Keck/HIRES radial velocities (RVs) and spectroscopic flux ratios to determine fundamental stellar parameters for both the primary and secondary components of each system, along with the orbital parameters. We present tentative evidence that EPIC 203868608 is a hierarchical triple system comprised of an eclipsing pair of ˜25 MJup brown dwarfs with a wide M-type companion. If confirmed, it would constitute only the second double-lined eclipsing brown dwarf binary system discovered to date. The double-lined system EPIC 203710387 is composed of nearly identical M4.5-M5 stars with fundamentally determined masses and radii measured to better than 3% precision ({M}1=0.1183+/- 0.0028{M}⊙ , {M}2=0.1076+/- 0.0031{M}⊙ and {R}1=0.417+/- 0.010{R}⊙ , {R}2=0.450+/- 0.012{R}⊙ ) from combination of the light curve and RV time series. These stars have the lowest masses of any stellar mass double-lined eclipsing binary to date. Comparing our derived stellar parameters with evolutionary models, we suggest an age of ˜10-11 Myr for this system, in contrast to the canonical age of 3-5 Myr for the association. Finally, EPIC 203476597 is a compact single-lined system with a G8-K0 primary and a likely mid-K secondary whose lines are revealed in spectral ratios. Continued measurement of RVs and spectroscopic flux ratios will better constrain fundamental parameters and should elevate the objects to benchmark status. We also present revised parameters for the double-lined eclipsing binary UScoCTIO 5 ({M}1=0.3336+/- 0.0022{M}⊙ , {M}2=0.3200+/- 0.0022{M}⊙ and {R}1=0.862+/- 0.012, {R}2=0.852+/- 0.013{R}⊙ ), which are suggestive of a system age younger than previously reported. We discuss the

  8. [Brown recluse bite].

    PubMed

    Nehemya, Moshe

    2008-01-01

    Spider bites are not uncommon in our warm climate. The most prevalent species of venomous spiders in Israel are the brown recluse and the black widow. Although the black widow is more notorious than the recluse, for every bite by a black widow there are hundreds of recluse bites reported. Despite the numerous bites, there is little awareness amongst physicians with regard to the clinical signs of recluse bites, and very often the wrong diagnosis is made, resulting in complex and unnecessary treatments. The basis of this error stems from the numerous clinical diagnoses which closely imitate a recluse bite, the relative scarceness of documented recluse bites and the fact that in most cases the spider is not witnessed by the victim. The following article describes three cases of children admitted to our department, presenting with high fever, a necrotic lesion and an extensive maculopapular rash. The children were eventually diagnosed with brown recluse bites. Furthermore, the article summarizes the literature regarding the clinical signs of recluse bites, possible complications and treatment options. The objective of this review is to increase awareness towards recluse bites, thereby preventing misdiagnoses and unnecessary treatments. PMID:18935751

  9. Inhibition of browning in foodstuffs

    NASA Technical Reports Server (NTRS)

    Rosenthal, N. A.

    1969-01-01

    Addition of water-soluble sulfur-containing compounds, thio compounds or potential thio compounds, to a mixture of carbohydrates, and either proteins, peptides, or amino acids can retard or completely eliminate the browning process. Determining factor is dependent upon the concentration of the anti-browning agent in the aqueous media.

  10. Using Clustering Algorithms to Identify Brown Dwarf Characteristics

    NASA Astrophysics Data System (ADS)

    Choban, Caleb

    2016-06-01

    Brown dwarfs are stars that are not massive enough to sustain core hydrogen fusion, and thus fade and cool over time. The molecular composition of brown dwarf atmospheres can be determined by observing absorption features in their infrared spectrum, which can be quantified using spectral indices. Comparing these indices to one another, we can determine what kind of brown dwarf it is, and if it is young or metal-poor. We explored a new method for identifying these subgroups through the expectation-maximization machine learning clustering algorithm, which provides a quantitative and statistical way of identifying index pairs which separate rare populations. We specifically quantified two statistics, completeness and concentration, to identify the best index pairs. Starting with a training set, we defined selection regions for young, metal-poor and binary brown dwarfs, and tested these on a large sample of L dwarfs. We present the results of this analysis, and demonstrate that new objects in these classes can be found through these methods.

  11. Brown Tumour in a Patient with Secondary Hyperparathyroidism Resistant to Medical Therapy: Case Report on Successful Treatment after Subtotal Parathyroidectomy

    PubMed Central

    Di Daniele, Nicola; Condò, Stefano; Ferrannini, Michele; Bertoli, Marta; Rovella, Valentina; Di Renzo, Laura; De Lorenzo, Antonino

    2009-01-01

    Brown tumour represents a serious complication of hyperparathyroidism. Differential diagnosis, based on histological examination, is only presumptive and clinical, radiological and laboratory data are necessary for definitive diagnosis. Here we describe a case of a brown tumour localised in the maxilla due to secondary hyperparathyroidism in a young women with chronic renal failure. Hemodialysis and pharmacological treatment were unsuccessful in controlling secondary hyperparathyroidism making it necessary to proceed with a subtotal parathyroidectomy. The proper timing of the parathyroidectomy and its favourable effect on regression of the brown tumor made it possible to avoid a potentially disfiguring surgical removal of the brown tumor. PMID:20011058

  12. Spectroscopic confirmation of young planetary-mass companions on wide orbits

    SciTech Connect

    Bowler, Brendan P.; Liu, Michael C.; Mann, Andrew W.; Kraus, Adam L.

    2014-03-20

    We present moderate-resolution (R ∼ 4000-5000) near-infrared integral field spectroscopy of the young (1-5 Myr) 6-14 M {sub Jup} companions ROXs 42B b and FW Tau b obtained with Keck/OSIRIS and Gemini-North/NIFS. The spectrum of ROXs 42B b exhibits clear signs of low surface gravity common to young L dwarfs, confirming its extreme youth, cool temperature, and low mass. Overall, it closely resembles the free-floating 4-7 M {sub Jup} L-type Taurus member 2MASS J04373705+2331080. The companion to FW Tau AB is more enigmatic. Our optical and near-infrared spectra show strong evidence of outflow activity and disk accretion in the form of line emission from [S II], [O I], Hα, Ca II, [Fe II], Paβ, and H{sub 2}. The molecular hydrogen emission is spatially resolved as a single lobe that stretches ≈0.''1 (15 AU). Although the extended emission is not kinematically resolved in our data, its morphology resembles shock-excited H{sub 2} jets primarily seen in young Class 0 and Class I sources. The near-infrared continuum of FW Tau b is mostly flat and lacks the deep absorption features expected for a cool, late-type object. This may be a result of accretion-induced veiling, especially in light of its strong and sustained Hα emission (EW(Hα) ≳ 290 Å). Alternatively, FW Tau b may be a slightly warmer (M5-M8) accreting low-mass star or brown dwarf (0.03-0.15 M {sub ☉}) with an edge-on disk. Regardless, its young evolutionary stage is in stark contrast to its Class III host FW Tau AB, indicating a more rapid disk clearing timescale for the host binary system than for its wide companion. Finally, we present near-infrared spectra of the young (∼2-10 Myr) low-mass (12-15 M {sub Jup}) companions GSC 6214-210 B and SR 12 C and find they best resemble low-gravity M9.5 and M9 substellar templates.

  13. Spectroscopic Confirmation of Young Planetary-mass Companions on Wide Orbits

    NASA Astrophysics Data System (ADS)

    Bowler, Brendan P.; Liu, Michael C.; Kraus, Adam L.; Mann, Andrew W.

    2014-03-01

    We present moderate-resolution (R ~ 4000-5000) near-infrared integral field spectroscopy of the young (1-5 Myr) 6-14 M Jup companions ROXs 42B b and FW Tau b obtained with Keck/OSIRIS and Gemini-North/NIFS. The spectrum of ROXs 42B b exhibits clear signs of low surface gravity common to young L dwarfs, confirming its extreme youth, cool temperature, and low mass. Overall, it closely resembles the free-floating 4-7 M Jup L-type Taurus member 2MASS J04373705+2331080. The companion to FW Tau AB is more enigmatic. Our optical and near-infrared spectra show strong evidence of outflow activity and disk accretion in the form of line emission from [S II], [O I], Hα, Ca II, [Fe II], Paβ, and H2. The molecular hydrogen emission is spatially resolved as a single lobe that stretches ≈0.''1 (15 AU). Although the extended emission is not kinematically resolved in our data, its morphology resembles shock-excited H2 jets primarily seen in young Class 0 and Class I sources. The near-infrared continuum of FW Tau b is mostly flat and lacks the deep absorption features expected for a cool, late-type object. This may be a result of accretion-induced veiling, especially in light of its strong and sustained Hα emission (EW(Hα) >~ 290 Å). Alternatively, FW Tau b may be a slightly warmer (M5-M8) accreting low-mass star or brown dwarf (0.03-0.15 M ⊙) with an edge-on disk. Regardless, its young evolutionary stage is in stark contrast to its Class III host FW Tau AB, indicating a more rapid disk clearing timescale for the host binary system than for its wide companion. Finally, we present near-infrared spectra of the young (~2-10 Myr) low-mass (12-15 M Jup) companions GSC 6214-210 B and SR 12 C and find they best resemble low-gravity M9.5 and M9 substellar templates. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National

  14. Brown assails Congressional earmarking

    NASA Astrophysics Data System (ADS)

    Jones, Richard

    Since President Bush first submitted his budget to Congress it was clear that it would be difficult, if not impossible, to fully support all of the NASA activities contained in the budget. Now the appropriations bill containing NASA funding for fiscal year 1992 is sitting on the president's desk. Many space science programs were cut, ranging from the Earth Observing System (-$65 million) to the CRAF/Cassini program (-$117 million).Nevertheless, powerful members of Congress sitting on the appropriations committees managed to find money for many projects in their home districts and states via special earmarking of funds. During House consideration of the final version of H.R. 2519 on October 2, George E. Brown, Jr. (D-Calif.), chairman of the House Science, Space, and Technology Committee, spoke out against earmarking.

  15. Brown spider envenomation.

    PubMed

    Peterson, Michael E

    2006-11-01

    The venom from spiders of the genus Loxosceles, the most famous being Loxosceles recluse (the most brown recluse spider) can cause serious poisoning. These spiders inhabit the south and south central states from Georgia through Texas and north to southern Wisconsin. They are commonly called violin spiders because of the violin-shaped marking on the dorsum of the cephalothorax. Many dermonecrotic lesions are incorrectly diagnosed as Brown recluse bites, as up to 50% of the diagnoses are in geographic regions of the country which do not have Loxosceles spiders. Sphingomyelinase D is the primary venom dermonecrotic factor. The toxin depletes serum hemolytic complement, prolongs the activated partial thromboplastin time and depletes clotting factors VIII, IX, XI, and XII. The venom induces rapid coagulation and occlusion of small capillaries, causing subsequent tissue necrosis. A classic "bulls eye" lesion develops, an erythematous area inside of which is a pale ischemic region that develops a dark necrotic center as the lesion matures. Healing is slow, and these ulcers may persist for months leaving a deep scar. Systemic signs occur less commonly but can be life threatening. The most prevalent sign is a hemolytic anemia with significant hemoglobinuria. There is no specific antidote. Dapsone a leukocyte inhibitor has been shown to be effective in treating dermal lesions in animal models. Conservative therapy includes several cleanings daily with Burrow's solution and hydrogen peroxide. Systemic signs of Loxosceles envenomation are potentially fatal and should be aggressively addressed. Hospitalization and intravenous fluid therapy may be needed to maintain adequate hydration and to protect renal function. PMID:17265904

  16. The Luminosities of the Coldest Brown Dwarfs

    NASA Astrophysics Data System (ADS)

    Tinney, C. G.; Faherty, Jacqueline K.; Kirkpatrick, J. Davy; Cushing, Mike; Morley, Caroline V.; Wright, Edward L.

    2014-11-01

    In recent years, brown dwarfs have been extended to a new Y-dwarf class with effective temperatures colder than 500 K and masses in the range of 5-30 Jupiter masses. They fill a crucial gap in observable atmospheric properties between the much colder gas-giant planets of our own solar system (at around 130 K) and both hotter T-type brown dwarfs and the hotter planets that can be imaged orbiting young nearby stars (both with effective temperatures in the range of 1500-1000 K). Distance measurements for these objects deliver absolute magnitudes that make critical tests of our understanding of very cool atmospheres. Here we report new distances for nine Y dwarfs and seven very late T dwarfs. These reveal that Y dwarfs do indeed represent a continuation of the T-dwarf sequence to both fainter luminosities and cooler temperatures. They also show that the coolest objects display a large range in absolute magnitude for a given photometric color. The latest atmospheric models show good agreement with the majority of these Y-dwarf absolute magnitudes. This is also the case for WISE0855-0714, the coldest and closest brown dwarf to the Sun, which shows evidence for water ice clouds. However, there are also some outstanding exceptions, which suggest either binarity or the presence of condensate clouds. The former is readily testable with current adaptive optics facilities. The latter would mean that the range of cloudiness in Y dwarfs is substantial with most hosting almost no clouds—while others have dense clouds, making them prime targets for future variability observations to study cloud dynamics. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

  17. The luminosities of the coldest brown dwarfs

    SciTech Connect

    Tinney, C. G.; Faherty, Jacqueline K.; Kirkpatrick, J. Davy; Cushing, Mike; Morley, Caroline V.; Wright, Edward L.

    2014-11-20

    In recent years, brown dwarfs have been extended to a new Y-dwarf class with effective temperatures colder than 500 K and masses in the range of 5-30 Jupiter masses. They fill a crucial gap in observable atmospheric properties between the much colder gas-giant planets of our own solar system (at around 130 K) and both hotter T-type brown dwarfs and the hotter planets that can be imaged orbiting young nearby stars (both with effective temperatures in the range of 1500-1000 K). Distance measurements for these objects deliver absolute magnitudes that make critical tests of our understanding of very cool atmospheres. Here we report new distances for nine Y dwarfs and seven very late T dwarfs. These reveal that Y dwarfs do indeed represent a continuation of the T-dwarf sequence to both fainter luminosities and cooler temperatures. They also show that the coolest objects display a large range in absolute magnitude for a given photometric color. The latest atmospheric models show good agreement with the majority of these Y-dwarf absolute magnitudes. This is also the case for WISE0855-0714, the coldest and closest brown dwarf to the Sun, which shows evidence for water ice clouds. However, there are also some outstanding exceptions, which suggest either binarity or the presence of condensate clouds. The former is readily testable with current adaptive optics facilities. The latter would mean that the range of cloudiness in Y dwarfs is substantial with most hosting almost no clouds—while others have dense clouds, making them prime targets for future variability observations to study cloud dynamics.

  18. Acceptance of brown-shelled eggs in a white-shelled egg market.

    PubMed

    Johnston, N P; Jefferies, L K; Rodriguez, B; Johnston, D E

    2011-05-01

    Brown eggs have gradually entered the traditional white-egg markets as a distinctive mode for packaging specialty eggs. A test was conducted at the Brigham Young University Sensory Laboratory (Provo, UT) to understand how consumers view attributes of the brown egg relative to the white egg. The objectives were to see how the consumer viewed properties of eggs by color and to examine the preference for brown color intensity. The 52 panelists were all women who routinely purchased and consumed eggs. Some women (53.8%) consumed eggs twice weekly, and 40.4% purchased them at least every 2 wk. Purchases included specialty eggs (14.6%) consisting of cage-free (50.0%), organic (28.6%), and n-3 enhanced (21.4%) eggs. The panelists preferred white eggs (90.4%). Though brown-shelled eggs did not exceed white eggs in preference, they were perceived positively (white-shelled %:brown-shelled %) as being more nutritious (65:29), having more flavor (27:14) and n-3 content (62:39), having a farm-flock origin (46:44), and being from organically fed hens (56:31) To test the preference for shade of brown eggs, a set of 6 eggs with varying intensities of brown color was evaluated for accepted appearance using a 9-point hedonic scale. The egg color intensities were measured using a Hunter Colorflex spectrophotometer (Hunter Associates Laboratory, Reston, VA) and the CIE system. The lightness (L*) values ranged from 83.2 for the white egg to 63.6 to 46.5 for the brown eggs. A significant (P < 0.05) preference was found for the 2 lighter shades of brown-shelled eggs (L* 63.6 and 57.5). Using the 9-point scale, panelists then compared brown eggs side by side with white eggs. Again, the 2 most light-tinted brown eggs were found most comparable with the white egg in acceptability and better (P < 0.05) than the darker brown eggs. In conclusion, white eggs were preferred over brown eggs; however, brown eggs gained in acceptance but did not exceed white as likely to be more nutritious or

  19. A Brief History of the Study of Nearby Young Moving Groups and Their Members

    NASA Astrophysics Data System (ADS)

    Kastner, Joel H.

    2016-01-01

    Beginning with the enigmatic (and now emblematic) TW Hya, the scutiny of individual stars and star-disk systems has both motivated and benefitted from the identification of nearby young moving groups (NYMGs). I briefly outline the emergence of this relatively new subfield of astronomy over the past two decades, and offer a few examples illustrating how the study of NYMGs and their members enables unique investigations of pre-main sequence stellar evolution, evolved protoplanetary disks, and young exoplanets.

  20. [Brown fat tissue in humans].

    PubMed

    Medvedev, L N; Elsukova, E I

    2002-01-01

    Brown adipose tissue (BAT) is universally present in mammals. Thermal production in such tissue is physiologically important for maintaining temperature homeostasis and regulation of body mass in small-size homoiotherms. At present it is clearly established that unlike other large mammals, brown adipose in man and primates is retained throughout the whole postnatal othogenesis. Therefore, BAT appears as a possible effector of pharmacogenetic protection from human excessive adiposis. Systematic reserach of various functioning aspects of this unique organ of mammals were started abroad as early as 1960-es, and are actively developing at present. Domestic research of energy circulation physiology and of thermoregulation developed mostly outside the brown adipose tissue. Therefore, the principal objective of this publication is to draw attention of experimental and clinical researches to an intriguing aspect of the issue of energy circulation in humans--the issue of brown adipose functioning. PMID:12004574

  1. Faces of Marshall: Arthur Brown

    NASA Video Gallery

    Several Marshall employees were interviewed as part of Marshall's 50th Anniversary activities. Metallurgist Arthur Brown shares how his high school drafting and welding success led him to a NASA ca...

  2. Extreme Planet-Like Systems: Brown Dwarfs at the Exoplanet Mass Boundary

    NASA Astrophysics Data System (ADS)

    Faherty, Jacqueline Kelly

    2015-12-01

    Brown dwarfs have long been the observational anchors for our theoretical understanding of giant gas planets. Recent studies have uncovered a population of nearby young sources that rival the age and mass of many planetary mass companions. From detailed observations, we postulate that objects in this young population have dynamic atmospheres ripe with exotic, thick condensate cloud species that drive extreme photometric and spectroscopic characteristics. In this talk I will review how we are using these so-called exoplanet analogs to establish luminosity, temperature, age, and mass relations for brown dwarf into planetary mass objects.

  3. NTT Observations Indicate that Brown Dwarfs Form Like Stars

    NASA Astrophysics Data System (ADS)

    2001-06-01

    Dusty Disks Detected around Very Young Substellar Objects in the Orion Nebula Summary An international team of astronomers [2] is announcing today the discovery of dusty disks surrounding numerous very faint objects that are believed to be recently formed Brown Dwarfs in the Orion Nebula [3]. This finding is based on detailed observations with SOFI, a specialised infrared-sensitive instrument at the ESO 3.5-m New Technology Telescope at the La Silla Observatory. It is of special interest because it sheds light on the origin and nature of substellar objects, known as "Brown Dwarfs" . In particular, these results suggest that Brown Dwarfs share a common origin with stars and that Brown Dwarfs are more similar in nature to stars than to planets and, like stars, have the potential to form with accompanying systems of planets. Moreover, the presence of dusty protoplanetary disks around the faintest objects in the Orion Nebula cluster confirms both the membership of these faint stars in the cluster and their nature as bona-fide substellar objects, making this the largest population of Brown Dwarf objects yet known . These important results are being reported today to the American Astronomical Society Meeting in Pasadena (California, USA). PR Photo 22a/01 : Infrared picture of the Orion Nebula (NTT + SOFI). PR Photo 22b/01 : "Finding Chart" for Very Young Brown Dwarfs in the Orion Nebula. PR Photo 22c/01 : Animated GIF presentation of PR Photos 22a+b/01. Faint substellar objects in the Milky Way Over the past 5 years, several groups of astronomers have identified a type of very faint, substellar objects within our Milky Way galaxy. These gaseous objects have very low masses and will never shine like normal stars because they cannot achieve central temperatures high enough for sustained thermal nuclear reactions to occur in their cores. Such objects weigh less than about 7% of our Sun and have been variously called "Brown Dwarfs" , "Failed Stars" or "Super Planets

  4. DIFFERENTIAL PROPER-MOTION STUDY OF THE CIRCUMSTELLAR DUST SHELL OF THE ENIGMATIC OBJECT, HD 179821

    SciTech Connect

    Ferguson, Brian A.; Ueta, Toshiya

    2010-03-10

    HD 179821 is an enigmatic evolved star that possesses characteristics of both a post-asymptotic giant branch (post-AGB) star and a yellow hypergiant, and there has been no evidence that unambiguously defines its nature. These two hypotheses are products of an indeterminate distance, presumed to be 1 kpc or 6 kpc. We have obtained the two-epoch Hubble Space Telescope Wild Field Planetary Camera 2 data of its circumstellar shell, which shows multiple concentric arcs extending out to about 8''. We have performed differential proper-motion measurements on distinct structures within the circumstellar shell of this mysterious star in hopes of determining the distance to the object, and thereby distinguishing the nature of this enigmatic stellar source. Upon investigation, rather than azimuthal radially symmetric expansion, we discovered a bulk motion of the circumstellar shell of (2.41 +- 0.43, 2.97 +- 0.32) mas yr{sup -1}. This corresponded to a translational interstellar medium (ISM) flow of (1.28 +- 0.95, 7.27 +- 0.75) mas yr{sup -1} local to the star. This finding implies that the distance to HD 179821 should be rather small in order for its circumstellar shell to preserve its highly intact spherical structure in the presence of the distorting ISM flow, therefore favoring the proposition that HD 179821 is a post-AGB object.

  5. Tetracapsuloides bryosalmonae infection affects the expression of genes involved in cellular signal transduction and iron metabolism in the kidney of the brown trout Salmo trutta.

    PubMed

    Kumar, Gokhlesh; Sarker, Subhodeep; Menanteau-Ledouble, Simon; El-Matbouli, Mansour

    2015-06-01

    Tetracapsuloides bryosalmonae is an enigmatic endoparasite which causes proliferative kidney disease in various species of salmonids in Europe and North America. The life cycle of the European strain of T. bryosalmonae generally completes in an invertebrate host freshwater bryozoan and vertebrate host brown trout (Salmo trutta) Linnaeus, 1758. Little is known about the gene expression in the kidney of brown trout during the developmental stages of T. bryosalmonae. In the present study, quantitative real-time PCR was applied to quantify the target genes of interest in the kidney of brown trout at different time points of T. bryosalmonae development. PCR primers specific for target genes were designed and optimized, and their gene expression levels were quantified in the cDNA kidney samples using SYBR Green Supermix. Expression of Rab GDP dissociation inhibitor beta, integral membrane protein 2B, NADH dehydrogenase 1 beta subcomplex subunit 6, and 26S protease regulatory subunit S10B were upregulated significantly in infected brown trout, while the expression of the ferritin M middle subunit was downregulated significantly. These results suggest that host genes involved in cellular signal transduction, proteasomal activities, including membrane transporters and cellular iron storage, are differentially upregulated or downregulated in the kidney of brown trout during parasite development. The gene expression pattern of infected renal tissue may support the development of intraluminal sporogonic stages of T. bryosalmonae in the renal tubular lumen of brown trout which may facilitate the release of viable parasite spores to transmit to the invertebrate host bryozoan. PMID:25786607

  6. Understanding Young Exoplanet Analogs with WISE

    NASA Astrophysics Data System (ADS)

    Rice, Emily

    We propose to tackle outstanding questions about the fundamental properties of young brown dwarfs, which are atmospheric analogs to massive gas giant exoplanets, using public archive data from the Wide-field Infrared Survey Explorer (WISE) combined with our extensive dataset of optical and near-infrared observations, including spectra, proper motions, and parallaxes. Using WISE data we will construct color-color diagrams, color- magnitude diagrams, and spectral energy distributions for our sample of candidate young brown dwarfs. We will fully characterize the spectral properties of the candidates and evaluate their membership in nearby young moving groups in order to obtain independent age estimates. The practical outcomes of this project will allow the research community to use observed colors and spectra to reliably constrain the properties - including effective temperature, gravity, and dust/cloud properties - of both brown dwarfs and gas giant exoplanets. We will also search for new young brown dwarfs in the WISE archive using colors and proper motions. The expanded sample of young brown dwarfs will be used to create a self-contained feedback loop to identify and address the shortcomings of cool atmosphere models and low-mass evolutionary tracks, both of which are already being used to infer the properties of massive exoplanets. Disentangling the effects of physical parameters on the observed properties of young brown dwarfs is directly relevant to studies of exoplanets. Direct observations of exoplanets are currently very limited, and young brown dwarfs are the laboratories in which we can solve existing problems before the onslaught of new observations from instruments capable of directly imaging exoplanets, including the Gemini Planet Imager, Project 1640 at the Palomar Observatory, SPHERE on the VLT, and the James Webb Space Telescope. This project addresses the goal of the NASA Science Mission Directorate to discover how the universe works; in particular

  7. HUBBLE SPIES BROWN DWARFS IN NEARBY STELLAR NURSERY

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Probing deep within a neighborhood stellar nursery, NASA's Hubble Space Telescope uncovered a swarm of newborn brown dwarfs. The orbiting observatory's near-infrared camera revealed about 50 of these objects throughout the Orion Nebula's Trapezium cluster [image at right], about 1,500 light-years from Earth. Appearing like glistening precious stones surrounding a setting of sparkling diamonds, more than 300 fledgling stars and brown dwarfs surround the brightest, most massive stars [center of picture] in Hubble's view of the Trapezium cluster's central region. All of the celestial objects in the Trapezium were born together in this hotbed of star formation. The cluster is named for the trapezoidal alignment of those central massive stars. Brown dwarfs are gaseous objects with masses so low that their cores never become hot enough to fuse hydrogen, the thermonuclear fuel stars like the Sun need to shine steadily. Instead, these gaseous objects fade and cool as they grow older. Brown dwarfs around the age of the Sun (5 billion years old) are very cool and dim, and therefore are difficult for telescopes to find. The brown dwarfs discovered in the Trapezium, however, are youngsters (1 million years old). So they're still hot and bright, and easier to see. This finding, along with observations from ground-based telescopes, is further evidence that brown dwarfs, once considered exotic objects, are nearly as abundant as stars. The image and results appear in the Sept. 20 issue of the Astrophysical Journal. The brown dwarfs are too dim to be seen in a visible-light image taken by the Hubble telescope's Wide Field and Planetary Camera 2 [picture at left]. This view also doesn't show the assemblage of infant stars seen in the near-infrared image. That's because the young stars are embedded in dense clouds of dust and gas. The Hubble telescope's near-infrared camera, the Near Infrared Camera and Multi-Object Spectrometer, penetrated those clouds to capture a view of those

  8. Students Use VLA to Make Startling Brown-Dwarf Discovery

    NASA Astrophysics Data System (ADS)

    2001-03-01

    A group of summer students making a long-shot astronomical gamble with the National Science Foundation's (NSF) Very Large Array (VLA) have found the first radio emission ever detected from a brown dwarf, an enigmatic object that is neither a star nor a planet, but something in between. Their surprising discovery is forcing experts to re-think their theories about how brown dwarfs work. The Very Large Array "Many astronomers are surprised at this discovery, because they didn't expect such strong radio emission from this object," said Shri Kulkarni, a Caltech professor who was on the team that first discovered a brown dwarf in 1995, and advisor to one of the students. "What is so cool is that this is research that probably nobody else would have tried to do because of its low chance of success. That made it ideal for summer students -- we had almost nothing to lose," said Kate Becker, a student at Oberlin College in Ohio. "The radio emission these students discovered coming from this brown dwarf is 10,000 times stronger than anyone expected," said Dale Frail, an astronomer at the National Radio Astronomy Observatory (NRAO) in Socorro, NM. "This student project is going to open up a whole new area of research for the VLA," Frail added. The students, in addition to Becker, are: Edo Berger from Caltech; Steven Ball from New Mexico Tech in Socorro, NM; Melanie Clarke from Carleton College in Northfield, MN; Therese Fukuda from the University of Denver; Ian Hoffman from the University of New Mexico in Albuquerque; Richard Mellon from The Pennsylvania State University; Emmanuel Momjian from the University of Kentucky; Nathanial Murphy from Amherst College in Amherst, MA; Stacey Teng from the University of Maryland; Timothy Woodruff from Southwestern University in Georgetown, TX; Ashley Zauderer from Agnes Scott College in Decatur, GA; and Robert Zavala from New Mexico State University in Las Cruces, NM. Frail also is an author of the research paper, published in the March

  9. A Keck LGS AO Search for Brown Dwarf and Planetary Mass Companions to Upper Scorpius Brown Dwarfs

    NASA Astrophysics Data System (ADS)

    Biller, Beth; Allers, Katelyn; Liu, Michael; Close, Laird M.; Dupuy, Trent

    2011-03-01

    We searched for binary companions to 20 young brown dwarfs in the Upper Scorpius association (145 pc, 5 Myr, nearest OB association) with the Laser Guide Star adaptive optics system and the facility infrared camera NIRC2 on the 10 m Keck II telescope. We discovered a 0farcs14 companion (20.9 ± 0.4 AU) to the <0.1 M sun object SCH J16091837-20073523. From spectral deconvolution of integrated-light near-IR spectroscopy of SCH1609 using the SpeX spectrograph (Rayner et al. 2003), we estimate primary and secondary spectral types of M6 ± 0.5 and M7 ± 1.0, corresponding to masses of 79 ± 17 M Jup and 55 ± 25 M Jup at an age of 5 Myr and masses of 84 ± 15 M Jup and 60 ± 25 M Jup at an age of 10 Myr. For our survey objects with spectral types later than M8, we find an upper limit on the binary fraction of <9% (1σ) at separations of 10-500 AU. We combine the results of our survey with previous surveys of Upper Sco and similar young regions to set the strongest constraints to date on binary fraction for young substellar objects and very low mass stars. The binary fraction for low-mass (<40 M Jup) brown dwarfs in Upper Sco is similar to that for T dwarfs in the field; for higher mass brown dwarfs and very low mass stars, there is an excess of medium-separation (10-50 AU projected separation) young binaries with respect to the field. These medium-separation binaries will likely survive to late ages.

  10. Brown's syndrome: diagnosis and management.

    PubMed Central

    Wright, K W

    1999-01-01

    PURPOSE: To better understand the various etiologies of Brown's syndrome, define specific clinical characteristics of Brown's syndrome, describe the natural history of Brown's syndrome, and evaluate the longterm outcome of a novel surgical procedure: the silicone tendon expander. Also, to utilize a computer model to simulate the pattern of strabismus seen clinically with Brown's syndrome and manipulate the model to show potential surgical outcomes of the silicone tendon expander. METHODS: Charts were reviewed on patients with the diagnosis of Brown's syndrome seen at a children's hospital ophthalmology clinic from 1982 to 1997, or seen in the author's private practice. Objective fundus torsion was assessed in up gaze, down gaze, and primary position in 7 Brown's syndrome patients and in 4 patients with primary superior oblique overaction. A fax survey was taken of members of the American Association of Ophthalmology and Strabismus (AAPOS) listed in the 1997-1998 directory regarding their results using the silicone tendon expander procedure for the treatment of Brown's syndrome. A computer model of Brown's syndrome was created using the Orbit 1.8 program by simulating a shortened superior oblique tendon or by changing stretch sensitivity to create an inelastic muscle. RESULTS: A total of 96 patients were studied: 85 with Brown's syndrome (38 with congenital and 47 with acquired disease), 6 with masquerade syndromes, 1 with Brown's syndrome operated on elsewhere, and 4 with primary superior oblique overaction in the torsion study. Three original clinical observations were made: 1. Significant limitation of elevation in abduction occurs in 70% of Brown's syndrome cases surgically verified as caused by a tight superior oblique tendon. Contralateral pseudo-inferior oblique overaction is associated with limited elevation in abduction. 2. Traumatic Brown's syndrome cases have larger hypotropias than nontraumatic cases (P < .001). There was no significant hypotropia in

  11. An Enigmatic Death in Farm Chopping Machine: Is This the Perfect Murder?

    PubMed

    Gioia, Sara; Lancia, Massimo; Bacci, Mauro; Suadoni, Fabio

    2015-09-01

    Forensic autopsy, like the other sectors in medicine, has benefited from the technological progress and the creation of multidisciplinary teams to unveil more and more finely planned criminal intents.Forensic pathologists, however, can sometimes deal with very enigmatic cases, meeting so with the limits of their own knowledge. Therefore, in these cases, they must not allow themselves to be pressured by inquiring agencies, remaining instead always faithful to empiric observations.With regard to that, we present a peculiar case of death by shredding inside a grinding machinery. The magistrature consequently opened a dossier for willful murder. Lots of figures were appointed to solve the case and among them is the forensic pathologist. However, a great number of obstacles were put in the investigators' inquiries.Was it a perfect murder? PMID:26010054

  12. Enigmatic eight-meter trace fossils in the Lower Pennsylvanian Lee sandstone, central Appalachian basin, Tennessee

    USGS Publications Warehouse

    Wnuk, C.; Maberry, J.O.

    1990-01-01

    Enigmatic tubular trace fossils up to eight meters long occur in the Lower Pennsylvanian Middlesboro Member of the Lee Formation. Two morphotypes occur: type 1 trace fossils are plain, smooth, vertical, nonbranching, parallel-walled, tubular structures, type 2 trace fossils branch, have walls with faint vertical striations, regularly or irregularly spaced nodes, and funnel-shaped terminations. Sandstone casts filling type 2 structures have helical spiral morphology, and, in rare individuals, faint meniscate fills have been observed. Both trace-fossil morphotypes have poorly cemented wall linings containing framboidal pyrite, amorphous carbon, quartz sand, and poorly preserved fecal material. The trace fossils occur in a massive, structureless, channel-form sandstone, originating at the contact between a channel lag and the overlying massive fill representing a barrier island transgressing an estuarine facies. Origin of these structures is uncertain. -from Authors

  13. Complete mitochondrial genome of an enigmatic dragonfly, Epiophlebia superstes (Odonata, Epiophlebiidae).

    PubMed

    Wang, Jo-Fan; Chen, Ming-Yu; Chaw, Shu-Miaw; Morii, Yuta; Yoshimura, Mayumi; Sota, Teiji; Lin, Chung-Ping

    2015-01-01

    This study reported the 15,435 bp-long complete mitochondrial genome of the relict Epiophlebia superstes (Odonata, Epiophlebiidae), an enigmatic dragonfly of the paraphyletic 'Anisozygoptera' possessing characteristics similar to members of both extant odonate suborders, the Zygoptera and the Anisoptera. This mitogenome comprises the common set of 37 genes and an A + T-rich control region, and has a gene arrangement identical to those of all available odonates. The genome contains three non-coding inter-genic spacers (s1-s3), which occurs in all of other known odonates, but it lacks the inter-genic spacer s5 typically found in the Anisoptera. This result suggests that E. superstes possesses a mitogenmic organization more closely related to that of the Zygoptera than that of the Anizoptera. PMID:24397757

  14. Takotsubo syndrome: Advances in the understanding and management of an enigmatic stress cardiomyopathy.

    PubMed

    Mejía-Rentería, Hernán David; Núñez-Gil, Iván J

    2016-07-26

    Takotsubo cardiomyopathy is a syndrome mimicking an acute myocardial infarction in absence of obstructive epicardial coronary artery disease to explain the degree of the wall motion abnormalities. Typically more common in the elderly women, this condition is usually triggered by unexpected emotional or physical stress situations, and is associated with electrocardiogram abnormalities and slight elevation of cardiac biomarkers. The pathophysiological mechanism is not clear yet, but it is believed that a high circulating concentration of catecholamines causes an acute dysfunction of the coronary microcirculation and metabolism of cardiomyocytes, leading to a transient myocardial stunning. Typically, it presents with acute left ventricular systolic dysfunction that in most cases is completely resolved at short term. Recurrences are rare and it is thought that the long-term prognosis is good. We present here a review of the clinical features, pathophysiology and management of this enigmatic condition. PMID:27468334

  15. Moments of complexity and enigmatic action: a Jungian view of the therapeutic field.

    PubMed

    Cambray, Joseph

    2011-06-01

    In presenting clinical case material for a panel on archetypes and/or primal phantasies an initial discussion of archetypes as emergent phenomena organizing 'moments of complexity' is given(1) . The relationship of such moments to 'moments of meeting' as developed by the Boston Change Process Study Group is commented on and explored within the context of the case. A condensed report of a multi-year analytic treatment of a bipolar patient having a severe trauma history is offered for discussion. Several unusual, enigmatic events are detailed to illustrate the occurrence of moments of complexity. Dreams highlighting psychological transformation stemming from a changing relationship to emerging archetypal material related to a psychotic process in the patient are offered to further detailed moments of complexity. PMID:21675974

  16. Takotsubo syndrome: Advances in the understanding and management of an enigmatic stress cardiomyopathy

    PubMed Central

    Mejía-Rentería, Hernán David; Núñez-Gil, Iván J

    2016-01-01

    Takotsubo cardiomyopathy is a syndrome mimicking an acute myocardial infarction in absence of obstructive epicardial coronary artery disease to explain the degree of the wall motion abnormalities. Typically more common in the elderly women, this condition is usually triggered by unexpected emotional or physical stress situations, and is associated with electrocardiogram abnormalities and slight elevation of cardiac biomarkers. The pathophysiological mechanism is not clear yet, but it is believed that a high circulating concentration of catecholamines causes an acute dysfunction of the coronary microcirculation and metabolism of cardiomyocytes, leading to a transient myocardial stunning. Typically, it presents with acute left ventricular systolic dysfunction that in most cases is completely resolved at short term. Recurrences are rare and it is thought that the long-term prognosis is good. We present here a review of the clinical features, pathophysiology and management of this enigmatic condition. PMID:27468334

  17. The enigmatic fast leaflet rotation in Desmodium motorium: butterfly mimicry for defense?

    PubMed

    Lev-Yadun, Simcha

    2013-06-01

    I propose that the enigmatic leaflet movements in elliptical circles every few minutes of the Indian telegraph (semaphore) plant Desmodium motorium ( = D. gyrans = Hedysarum gyrans = Codariocalyx motorius), which has intrigued scientists for centuries, is a new type of butterfly or general winged arthropod mimicry by this plant. Such leaflet movement may deceive a passing butterfly searching for an un-occupied site suitable to deposit its eggs, that the plant is already occupied. It may also attract insectivorous birds, reptiles or arthropods to the plant because it looks as if it is harboring a potential prey and while they patrol there, they can find insects or other invertebrates that indeed attack the plant. The possibility that diurnal mammalian herbivores may also be deterred by these movements should not be dismissed. PMID:23603964

  18. Radially excited axial mesons and the enigmatic Zc and Zb in a coupled-channel model

    NASA Astrophysics Data System (ADS)

    Coito, Susana

    2016-07-01

    The enigmatic charged states Zc(3900 ), Zc(4020 ), Zc(4050 ), Zb(10610 ), and Zb(10650 ) are studied within a coupled-channel Schrödinger model, where radially excited quark-antiquark pairs, with the same angular momenta and isospin as the a1(1260 ) and b1(1235 ), are strongly coupled to their Okubo-Zweig-Iizuka-allowed decay channels D D¯*+D ¯D* and D*D¯*, or B B¯*+B ¯B* and B*B¯*, in S and D waves. Poles, matching the experimental mass and width of the above states, are found by varying only two free parameters. From the wave-function analysis of each resonance, the probability of each of the components contributing to the coupled system is estimated, and predictions can be made for the relative decay fractions among the coupled open-charm or open-bottom decay channels.

  19. Molecular Insights into the Enigmatic Metabolic Regulator, SnRK1.

    PubMed

    Emanuelle, Shane; Doblin, Monika S; Stapleton, David I; Bacic, Antony; Gooley, Paul R

    2016-04-01

    Sucrose non-fermenting-1 (SNF1)-related kinase 1 (SnRK1) lies at the heart of metabolic homeostasis in plants and is crucial for normal development and response to stress. Evolutionarily related to SNF1 in yeast and AMP-activated kinase (AMPK) in mammals, SnRK1 acts protectively to maintain homeostasis in the face of fluctuations in energy status. Despite a conserved function, the structure and regulation of the plant kinase differ considerably from its relatively well-understood opisthokont orthologues. In this review, we highlight the known plant-specific modes of regulation involving SnRK1 together with new insights based on a 3D molecular model of the kinase. We also summarise how these differences from other orthologues may be specific adaptations to plant metabolism, and offer insights into possible avenues of future inquiry into this enigmatic enzyme. PMID:26642889

  20. [A comparison of some methods for administering the Ca-dependent photoprotein obelin into the adipocytes of the brown fat in the rat].

    PubMed

    Elsukova, E I; Medvedev, L N; Luzhnov, Iu P

    1995-01-01

    An attempt was taken to incorporate Ca2(+)-dependent photoprotein obelin into young brown adipocytes using the three methods: 1) osmotic lysis of pinocytotic vesicles; 2) electroporation in a high electric field; 3) hypoosmotic shock. The young adipocytes were isolated from rat interscapular brown fat. The maximum incorporation of obelin into these cells was achieved using the hypoosmotic shock technique. A constant luminescence of intact cells loaded with obelin following hypoosmotic shock was observed in three independent experiments. PMID:8658972

  1. A Brown Dwarf Joins the Jet-Set

    NASA Astrophysics Data System (ADS)

    2007-05-01

    Jets of matter have been discovered around a very low mass 'failed star', mimicking a process seen in young stars. This suggests that these 'brown dwarfs' form in a similar manner to normal stars but also that outflows are driven out by objects as massive as hundreds of millions of solar masses down to Jupiter-sized objects. The brown dwarf with the name 2MASS1207-3932 is full of surprises [1]. Its companion, a 5 Jupiter-mass giant, was the first confirmed exoplanet for which astronomers could obtain an image (see ESO 23/04 and 12/05), thereby opening a new field of research - the direct detection of alien worlds. It was then later found (see ESO 19/06) that the brown dwarf has a disc surrounding it, not unlike very young stars. ESO PR Photo 24/07 ESO PR Photo 24/07 Jets from a Brown Dwarf (Artist's Impression) Now, astronomers using ESO's Very Large Telescope (VLT) have found that the young brown dwarf is also spewing jets, a behaviour again quite similar to young stars. The mass of the brown dwarf is only 24 Jupiter-masses. Hence, it is by far the smallest object known to drive an outflow. "This leads us to the tantalizing prospect that young giant planets could also be associated with outflows," says Emma Whelan, the lead-author of the paper reporting the results. The outflows were discovered using an amazing technique known as spectro-astrometry, based on high resolution spectra taken with UVES on the VLT. Such a technique was required due to the difficulty of the task. While in normal young stars - known as T-Tauri stars for the prototype of their class - the jets are large and bright enough to be seen directly, this is not the case around brown dwarfs: the length scale of the jets, recovered with spectro-astrometry is only about 0.1 arcsecond long, that is, the size of a two Euro coin seen from 40 km away. The jets stretch about 1 billion kilometres and the material is rushing away from the brown dwarf with a speed of a few kilometres per second. The

  2. Brown tumour of the jaw

    PubMed Central

    Nair, Preeti P; Gharote, Harshkant P; Thomas, Shaji; R, Guruprasad; Singh, Neha

    2011-01-01

    Brown tumours are classic bony lesions that arise as a result of the effect of parathyroid hormone on bone tissue in some patients with hyperparathyroidism. They are erosive bony lesions caused by rapid osteolysis and peritrabecular fibrosis, resulting in a local destructive phenomenon. Facial skeleton is involved in about 2% of all cases of which the mandible is frequently affected. A 35-year-old female who was diagnosed with osteomalacia and brown tumour in posterior mandible as the sign of secondary hyperparathyroidism secondary to vitamin D deficiency is presented. PMID:22669885

  3. Finding the Kool Mixx: how Brown & Williamson used music marketing to sell cigarettes

    PubMed Central

    Hafez, Navid; Ling, Pamela M

    2006-01-01

    Objective To describe the history of Kool's music‐themed promotions and analyse the role that music played in the promotion of the brand. Methods Analysis of previously secret tobacco industry documents, legal documents, and promotional materials. Results Brown & Williamson started Kool sponsorship of musical events in 1975 with Kool Jazz concerts. Music was considered to be an effective marketing tool because: (1) music helped consumers make emotional connections with the brand; (2) music concerts were effective for targeted marketing; (3) music tied together an integrated marketing campaign; and (4) music had potential to appeal widely to a young audience. Brown & Williamson's first music campaigns successfully targeted young African‐American male audiences. Subsequent campaigns were less effective, exploring different types of music to achieve a broader young adult appeal. Conclusions This case study suggests Brown & Williamson used music most successfully for targeted marketing, but they failed to develop a wider audience using music because their attempts lacked consistency with the Kool brand's established identity. The 2004 “Kool Mixx” campaign both returned to Brown & Williamson's historic practice targeting young African‐American males, and also exploited a musical genre with much more potential to bring Kool more universal appeal, as hip‐hop music is increasingly popular among diverse audiences. Tobacco control efforts led by African‐American community activists to oppose these marketing strategies should continue; expanding these coalitions to include the hip‐hop community may further increase their effectiveness. PMID:16998169

  4. A Mistaken Account of the Age-Crime Curve: Response to Males and Brown (2013)

    ERIC Educational Resources Information Center

    Shulman, Elizabeth P.; Steinberg, Laurence; Piquero, Alex R.

    2014-01-01

    The present article responds to Males and Brown's "Teenagers' High Arrest Rates: Features of Young Age or Youth Poverty?" which claims that the widely observed pattern of crime rates peaking in late adolescence or early adulthood is an artifact of age differences in poverty. We note that the authors' interpretation of…

  5. Hypotension- and osmotically induced thirst in old Brown Norway rats

    PubMed Central

    Thunhorst, Robert L.; Beltz, Terry G.; Johnson, Alan Kim

    2009-01-01

    Compared to young cohorts, old rats drink less water in response to several thirst-inducing stimuli. In these experiments, we characterized water drinking in response to hypotension and cellular dehydration in young (4 mo), middle-aged adult (12 mo) and old (29–30 mo) male Brown Norway rats. We injected the vasodilator, minoxidil as an intravenous bolus in a range of doses (0–20 mg/kg), so that drinking responses could be compared at equivalent reductions of arterial pressure. Old rats had greatly diminished reflex tachycardia and became significantly more hypotensive after minoxidil compared with young and middle-aged rats. When compared at equivalent reductions of arterial pressure, old rats drank one-third as much as middle-aged rats, and one-fifth as much as young rats. In addition, there were age-related deficits in drinking in response to a range of administered loads of sodium (0.15–2 M NaCl, 2 ml/100 g body wt). Urinary excretion of water and sodium in response to the loads was equivalent across ages. Both middle-aged and old rats were less able than young rats to repair their water deficits after sodium loading, attributable almost entirely to their reduced drinking responses compared with young rats. Lastly, age-related declines in drinking appeared to be more severe in response to hypotension than in response to cellular dehydration. PMID:19420291

  6. African-American Heritage profile - Maikeyza Brown

    NASA Video Gallery

    Maikeyza Brown is a contract management specialist at NASA's Dryden Flight Research Center, Edwards, Calif. A native of Washington, D.C., Brown overcame obstacles to receive honors in high school a...

  7. Search for exoplanets and brown dwarfs with VLBI.

    NASA Astrophysics Data System (ADS)

    Katarzyński, K.; Gawroński, M.; Goździewski, K.

    2016-06-01

    The main aim of this work is to estimate possible radio GHz emission of extrasolar planets and brown dwarfs and to check if such radiation can be detected by Very Large Baseline Interferometers (VLBI). In the estimation we assume that the emission may originate in processes similar to those observed in the Jupiter system. The frequency of the radio emission that is produced in this system depends mostly on the magnetic field strength. Jupiter's magnetic field (˜9 G on average) allows for radiation from kHz frequencies up to 40 MHz. This is is well below the frequency range of VLBI. However, it was demonstrated that the magnetic field strength in massive and young object may be up to two orders of magnitude higher than for Jupiter, which is especially relevant for planets around short-lived A type stars. This should extend the range of the emission up to GHz frequencies. We calculated expected flux densities of radio emission for a variety of hypothetical young planetary systems. We analysed two different emission scenarios, and found that the radiation induced by moons (process similar to Jupiter-Io interactions) appears to be less efficient than the emission generated by a stellar wind on a planetary magnetosphere. We also estimated hypothetical emission of planets and brown dwarfs located around relatively young and massive main sequence A-type stars. Our results show that the emission produced by stellar winds could be detected by currently operating VLBI networks.

  8. Search for exoplanets and brown dwarfs with VLBI

    NASA Astrophysics Data System (ADS)

    Katarzyński, K.; Gawroński, M.; Goździewski, K.

    2016-09-01

    The main aim of this work is to estimate possible radio GHz emission of extrasolar planets and brown dwarfs and to check if such radiation can be detected by Very Large Baseline Interferometers (VLBI). In the estimation we assume that the emission may originate in processes similar to those observed in the Jupiter system. The frequency of the radio emission that is produced in this system depends mostly on the magnetic field strength. Jupiter's magnetic field (˜9 G on average) allows for radiation from kHz frequencies up to 40 MHz. This is well below the frequency range of VLBI. However, it was demonstrated that the magnetic field strength in massive and young object may be up to two orders of magnitude higher than for Jupiter, which is especially relevant for planets around short-lived A type stars. This should extend the range of the emission up to GHz frequencies. We calculated expected flux densities of radio emission for a variety of hypothetical young planetary systems. We analysed two different emission scenarios, and found that the radiation induced by moons (process similar to Jupiter-Io interactions) appears to be less efficient than the emission generated by a stellar wind on a planetary magnetosphere. We also estimated hypothetical emission of planets and brown dwarfs located around relatively young and massive main-sequence A-type stars. Our results show that the emission produced by stellar winds could be detected by currently operating VLBI networks.

  9. 21 CFR 184.1120 - Brown algae.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Brown algae. 184.1120 Section 184.1120 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DIRECT FOOD....1120 Brown algae. (a) Brown algae are seaweeds of the species Analipus japonicus, Eisenia...

  10. 21 CFR 184.1120 - Brown algae.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Brown algae. 184.1120 Section 184.1120 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1120 Brown algae. (a) Brown algae are seaweeds of the species...

  11. 21 CFR 184.1120 - Brown algae.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Brown algae. 184.1120 Section 184.1120 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1120 Brown algae. (a) Brown algae are seaweeds of the species...

  12. 21 CFR 184.1120 - Brown algae.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Brown algae. 184.1120 Section 184.1120 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1120 Brown algae. (a) Brown algae are seaweeds of the species...

  13. 21 CFR 184.1120 - Brown algae.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Brown algae. 184.1120 Section 184.1120 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1120 Brown algae. (a) Brown algae are seaweeds of the species...

  14. Brown Root Rot of Alfalfa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This bulletin describes the disease of alfalfa called brown root rot (BRR) including: the disease symptoms, the fungal pathogen and its biology, its distribution, and disease management. Since the 1920s, BRR has been regarded as an important disease of forage legumes, including alfalfa, in northern ...

  15. Brown at 50: Keeping Promises

    ERIC Educational Resources Information Center

    Wu, Frank H.

    2004-01-01

    The story of Brown is compelling. Blacks and Whites alike understood that the Jim Crow system of "separate but equal" was a convenient fiction. There was no actual effort to ensure that Whites and Blacks were provided the same services. Invariably, the White schools had higher funding, better buildings, newer supplies and so on. Indeed, in many…

  16. Chandra Captures Flare From Brown Dwarf

    NASA Astrophysics Data System (ADS)

    2000-07-01

    The first flare ever seen from a brown dwarf, or failed star, was detected by NASA's Chandra X-ray Observatory. The bright X-ray flare has implications for understanding the explosive activity and origin of magnetic fields of extremely low mass stars. Chandra detected no X-rays at all from LP 944-20 for the first nine hours of a twelve hour observation, then the source flared dramatically before it faded away over the next two hours. "We were shocked," said Dr. Robert Rutledge of the California Institute of Technology in Pasadena, the lead author on the discovery paper to appear in the July 20 issue of Astrophysical Journal Letters. "We didn't expect to see flaring from such a lightweight object. This is really the 'mouse that roared.'" Chandra LP 944-20 X-ray Image Press Image and Caption The energy emitted in the brown dwarf flare was comparable to a small solar flare, and was a billion times greater than observed X-ray flares from Jupiter. The flaring energy is believed to come from a twisted magnetic field. "This is the strongest evidence yet that brown dwarfs and possibly young giant planets have magnetic fields, and that a large amount of energy can be released in a flare," said Dr. Eduardo Martin, also of Caltech and a member of the team. Professor Gibor Basri of the University of California, Berkeley, the principal investigator for this observation, speculated that the flare "could have its origin in the turbulent magnetized hot material beneath the surface of the brown dwarf. A sub-surface flare could heat the atmosphere, allowing currents to flow and give rise to the X-ray flare -- like a stroke of lightning." LP 944-20 is about 500 million years old and has a mass that is about 60 times that of Jupiter, or 6 percent that of the Sun. Its diameter is about one-tenth that of the Sun and it has a rotation period of less than five hours. Located in the constellation Fornax in the southern skies, LP 944-20 is one of the best studied brown dwarfs because it is

  17. COULD THE PLANETS AROUND HR 8799 BE BROWN DWARFS?

    SciTech Connect

    Moro-Martin, Amaya; Rieke, George H.; Su, Kate Y. L.

    2010-10-01

    We consider the limiting case for orbital stability of the companions to HR 8799. This case is only consistent with ages for the system of {approx}100 Myr, not with the 1 Gyr age proposed from asteroseismology. The discrepancy probably arises because the inclination of the star is smaller than assumed in analyzing the asteroseismology data. Given this young age, the best estimates of the companion masses place them by a small margin on the planet side of the division between planets and brown dwarfs.

  18. [Case report Brown-Vialetto-Van laere syndrome].

    PubMed

    Introini, S; Sasso, G M; Moioli, G; Morandini, W L

    2003-01-01

    A case of a young man (36 years old) suffering from a progressive bulbo-pontine palsy, bilateral central deafness and respiratory failure, clinically known as Brown-Vialetto-Van Laere syndrome (BVVL) is reported. The illness occurred at 24 years and, after a period of quiescence of 12 years, led to a serious dependence from mechanical ventilation. In tyhis report the most important points of view about resuscitation and intensive treatment, such as neuromuscular failure and locked-in condition, are discussed. PMID:12677164

  19. Assessment of brown adipose tissue function

    PubMed Central

    Virtue, Sam; Vidal-Puig, Antonio

    2013-01-01

    In this review we discuss practical considerations for the assessment of brown adipose tissue in rodent models, focusing on mice. The central aim of the review is to provide a critical appraisal of the utility of specialized techniques for assessing brown adipose tissue function in vivo. We cover several of the most common specialized methods for analysing brown adipose tissue function in vivo, including assessment of maximal thermogenic capacity by indirect calorimetry and the measurement of sympathetic tone to brown adipose tissue. While these techniques are powerful, they are not readily available to all laboratories; therefore we also cover several simple measurements that, particularly in combination, can be used to determine if a mouse model is likely to have alterations in brown adipose tissue function. Such techniques include: pair feeding, analysis of brown adipose tissue lipid content and mRNA and protein markers of brown adipose tissue activation. PMID:23760815

  20. Planets and Brown Dwarfs and Stars, Oh My! --- Companions Along the Road to the Nearest Stars

    NASA Astrophysics Data System (ADS)

    Henry, Todd J.; Davison, C. L.; Dieterich, S. B.; Ianna, P. A.; Jao, W. C.; Koerner, D. W.; Subasavage, J. P.; Tanner, A. M.; White, R. J.; RECONS

    2012-01-01

    RECONS (www.recons.org, REsearch Consortium On Nearby Stars) has been using astrometric techniques since 1999 to search for massive planets orbiting more than 130 nearby red and white dwarfs. Because of their proximity, nearby stars are natural locations to search for other solar systems --- the stars provide increased fluxes, larger astrometric perturbations, and higher probabilities for eventual resolution of planets than similar stars at larger distances. Unlike radial velocity searches, our astrometric effort is most sensitive to Jovian planets in Jovian orbits, i.e. those that span decades. We have discovered stellar companions with masses of a few hundred Jupiters, brown dwarf companions with masses of a few tens of Jupiters, and are now pushing into the realm of planets with masses of a few Jupiters around the nearest red dwarfs. Several previously unknown companions have been imaged via Gemini-AO observations, but we have also detected perturbations caused by enigmatic companions that elude direct detection. As we sweep through the mass regimes of stars to exoplanets for companions, we are now able to assess the various populations --- stars are common as companions, whereas brown dwarfs and massive planets are rare. We outline what we have discovered so far and place our exoplanet search results in context with an overview of the census of more than 60 stars with exoplanets known within 25 pc. This effort is supported by the NSF through grant AST-0908402 and via observations made possible by the SMARTS Consortium.

  1. The Disk around the Brown Dwarf KPNO Tau 3

    NASA Astrophysics Data System (ADS)

    Broekhoven-Fiene, Hannah; Matthews, Brenda; Duchêne, Gaspard; Di Francesco, James; Scholz, Aleks; Chrysostomou, Antonio; Jayawardhana, Ray

    2014-07-01

    We present submillimeter observations of the young brown dwarfs KPNO Tau 1, KPNO Tau 3, and KPNO Tau 6 at 450 μm and 850 μm taken with the Submillimetre Common-User Bolometer Array on the James Clerk Maxwell Telescope. KPNO Tau 3 and KPNO Tau 6 have been previously identified as Class II objects hosting accretion disks, whereas KPNO Tau 1 has been identified as a Class III object and shows no evidence of circumsubstellar material. Our 3σ detection of cold dust around KPNO Tau 3 implies a total disk mass of (4.0 ± 1.1) × 10-4 M ⊙ (assuming a gas to dust ratio of 100:1). We place tight constraints on any disks around KPNO Tau 1 or KPNO Tau 6 of <2.1 × 10-4 M ⊙ and <2.7 × 10-4 M ⊙, respectively. Modeling the spectral energy distribution of KPNO Tau 3 and its disk suggests the disk properties (geometry, dust mass, and grain size distribution) are consistent with observations of other brown dwarf disks and low-mass T-Tauri stars. In particular, the disk-to-host mass ratio for KPNO Tau 3 is congruent with the scenario that at least some brown dwarfs form via the same mechanism as low-mass stars.

  2. The disk around the brown dwarf KPNO Tau 3

    SciTech Connect

    Broekhoven-Fiene, Hannah; Matthews, Brenda; Di Francesco, James; Duchêne, Gaspard; Scholz, Aleks; Chrysostomou, Antonio; Jayawardhana, Ray

    2014-07-10

    We present submillimeter observations of the young brown dwarfs KPNO Tau 1, KPNO Tau 3, and KPNO Tau 6 at 450 μm and 850 μm taken with the Submillimetre Common-User Bolometer Array on the James Clerk Maxwell Telescope. KPNO Tau 3 and KPNO Tau 6 have been previously identified as Class II objects hosting accretion disks, whereas KPNO Tau 1 has been identified as a Class III object and shows no evidence of circumsubstellar material. Our 3σ detection of cold dust around KPNO Tau 3 implies a total disk mass of (4.0 ± 1.1) × 10{sup –4} M{sub ☉} (assuming a gas to dust ratio of 100:1). We place tight constraints on any disks around KPNO Tau 1 or KPNO Tau 6 of <2.1 × 10{sup –4} M{sub ☉} and <2.7 × 10{sup –4} M{sub ☉}, respectively. Modeling the spectral energy distribution of KPNO Tau 3 and its disk suggests the disk properties (geometry, dust mass, and grain size distribution) are consistent with observations of other brown dwarf disks and low-mass T-Tauri stars. In particular, the disk-to-host mass ratio for KPNO Tau 3 is congruent with the scenario that at least some brown dwarfs form via the same mechanism as low-mass stars.

  3. Personality Variation in Little Brown Bats

    PubMed Central

    Menzies, Allyson K.; Timonin, Mary E.; McGuire, Liam P.; Willis, Craig K. R.

    2013-01-01

    Animal personality or temperament refers to individual differences in behaviour that are repeatable over time and across contexts. Personality has been linked to life-history traits, energetic traits and fitness, with implications for the evolution of behaviour. Personality has been quantified for a range of taxa (e.g., fish, songbirds, small mammals) but, so far, there has been little work on personality in bats, despite their diversity and potential as a model taxon for comparative studies. We used a novel environment test to quantify personality in little brown bats (Myotis lucifugus) and assess the short-term repeatability of a range of behaviours. We tested the hypothesis that development influences values of personality traits and predicted that trait values associated with activity would increase between newly volant, pre-weaning young-of-the-year (YOY) and more mature, self-sufficient YOY. We identified personality dimensions that were consistent with past studies of other taxa and found that these traits were repeatable over a 24-hour period. Consistent with our prediction, older YOY captured at a fall swarming site prior to hibernation had higher activity scores than younger YOY bats captured at a maternity colony, suggesting that personality traits vary as development progresses in YOY bats. Thus, we found evidence of short-term consistency of personality within individuals but with the potential for temporal flexibility of traits, depending on age. PMID:24312205

  4. Proliferative kidney disease in brown trout: infection level, pathology and mortality under field conditions.

    PubMed

    Schmidt-Posthaus, Heike; Hirschi, Regula; Schneider, Ernst

    2015-05-21

    Proliferative kidney disease (PKD) is an emerging disease threatening wild salmonid populations. In temperature-controlled aquaria, PKD can cause mortality rates of up to 85% in rainbow trout. So far, no data about PKD-related mortality in wild brown trout Salmo trutta fario are available. The aim of this study was to investigate mortality rates and pathology in brown trout kept in a cage within a natural river habitat known to harbor Tetracapsuloides bryosalmonae. Young-of-the-year (YOY) brown trout, free of T. bryosalmonae, were exposed in the River Wutach, in the northeast of Switzerland, during 3 summer months. Samples of wild brown trout caught by electrofishing near the cage location were examined in parallel. The incidence of PKD in cage-exposed animals (69%) was not significantly different to the disease prevalence of wild fish (82 and 80% in the upstream and downstream locations, respectively). The mortality in cage-exposed animals, however, was as low as 15%. At the termination of the exposure experiment, surviving fish showed histological lesions typical for PKD regression, suggesting that many YOY brown trout survive the initial infection. Our results at the River Wutach suggest that PKD in brown trout does not always result in high mortality under natural conditions. PMID:25993888

  5. Suspension feeding in the enigmatic Ediacaran organism Tribrachidium demonstrates complexity of Neoproterozoic ecosystems.

    PubMed

    Rahman, Imran A; Darroch, Simon A F; Racicot, Rachel A; Laflamme, Marc

    2015-11-01

    The first diverse and morphologically complex macroscopic communities appear in the late Ediacaran period, 575 to 541 million years ago (Ma). The enigmatic organisms that make up these communities are thought to have formed simple ecosystems characterized by a narrow range of feeding modes, with most restricted to the passive absorption of organic particles (osmotrophy). We test between competing feeding models for the iconic Ediacaran organism Tribrachidium heraldicum using computational fluid dynamics. We show that the external morphology of Tribrachidium passively directs water flow toward the apex of the organism and generates low-velocity eddies above apical "pits." These patterns of fluid flow are inconsistent with osmotrophy and instead support the interpretation of Tribrachidium as a passive suspension feeder. This finding provides the oldest empirical evidence for suspension feeding at 555 to 550 Ma, ~10 million years before the Cambrian explosion, and demonstrates that Ediacaran organisms formed more complex ecosystems in the latest Precambrian, involving a larger number of ecological guilds, than currently appreciated. PMID:26702439

  6. Morphology and Molecules Reveal Unexpected Cryptic Diversity in the Enigmatic Genus Sinobirma Bryk, 1944 (Lepidoptera: Saturniidae)

    PubMed Central

    Rougerie, Rodolphe; Naumann, Stefan; Nässig, Wolfgang A.

    2012-01-01

    The wild silkmoth genus Sinobirma Bryk, 1944 is a poorly known monotypic taxon from the eastern end of the Himalaya Range. It was convincingly proposed to be closely related to some members of an exclusively Afro-tropical group of Saturniidae, but its biogeographical and evolutionary history remains enigmatic. After examining recently collected material from Tibet, northern India, and northeastern Myanmar, we realized that this unique species, S. malaisei Bryk, 1944 only known so far from a few specimens and from a very restricted area near the border between north-eastern Myanmar and the Yunnan province of China, may in fact belong to a group of closely related cryptic species. In this work, we combined morphological comparative study, DNA barcoding, and the sequences of a nuclear marker (D2 expansion segment of the 28S rRNA gene) to unequivocally delimit three distinct species in the genus Sinobirma, of which two are described as new to science: S. myanmarensis sp. n. and S. bouyeri sp. n. An informative DNA barcode sequence was obtained from the female holotype of S. malaisei—collected in 1934—ensuring the proper assignation of this name to the newly collected and studied specimens. Our findings represent another example of the potential of coupling traditional taxonomy and DNA barcoding for revealing and solving difficult cases of cryptic diversity. This approach is now being generalized to the world fauna of Saturniidae, with the participation of most of the taxonomists studying these moths. PMID:23028478

  7. Morphology and molecules reveal unexpected cryptic diversity in the enigmatic genus Sinobirma Bryk, 1944 (Lepidoptera: Saturniidae).

    PubMed

    Rougerie, Rodolphe; Naumann, Stefan; Nässig, Wolfgang A

    2012-01-01

    The wild silkmoth genus Sinobirma Bryk, 1944 is a poorly known monotypic taxon from the eastern end of the Himalaya Range. It was convincingly proposed to be closely related to some members of an exclusively Afro-tropical group of Saturniidae, but its biogeographical and evolutionary history remains enigmatic. After examining recently collected material from Tibet, northern India, and northeastern Myanmar, we realized that this unique species, S. malaisei Bryk, 1944 only known so far from a few specimens and from a very restricted area near the border between north-eastern Myanmar and the Yunnan province of China, may in fact belong to a group of closely related cryptic species. In this work, we combined morphological comparative study, DNA barcoding, and the sequences of a nuclear marker (D2 expansion segment of the 28S rRNA gene) to unequivocally delimit three distinct species in the genus Sinobirma, of which two are described as new to science: S. myanmarensis sp. n. and S. bouyeri sp. n. An informative DNA barcode sequence was obtained from the female holotype of S. malaisei--collected in 1934--ensuring the proper assignation of this name to the newly collected and studied specimens. Our findings represent another example of the potential of coupling traditional taxonomy and DNA barcoding for revealing and solving difficult cases of cryptic diversity. This approach is now being generalized to the world fauna of Saturniidae, with the participation of most of the taxonomists studying these moths. PMID:23028478

  8. Phylogenetic position of the enigmatic Lepidogalaxias salamandroides with comment on the orders of lower euteleostean fishes.

    PubMed

    Li, Jun; Xia, Rong; McDowall, R M; López, J Andrés; Lei, Guangchun; Fu, Cuizhang

    2010-11-01

    This study examines phylogenetic placement of the enigmatic Western Australian Lepidogalaxias, and extends previous studies by including eight new taxa to enable re-examination phylogenetic relationships of lower euteleostean fishes at the ordinal level, based on mitochondrial genomes from 39 ingroup taxa and 17 outgroups. Our results suggest that Lepidogalaxias occupies a basal position among all euteleosts, in contrast with earlier hypotheses that variously suggested a closer relationship to esocid fishes, or to the galaxiid Lovettia. In addition our evidence shows that Osmeriformes should be restricted Retropinnidae, Osmeridae, Plecoglossidae and Salangidae. This reduced Osmeriformes is supported in our results as the sister group of Stomiiformes. Galaxiidae, which is often closely linked to Osmeriformes, emerges as sister group of a combined Osmeriformes, Stomiiformes, Salmoniformes, Esociformes and Argentiformes, and we give Galaxiiformes the rank of order to include all remaining galaxioid fishes (Galaxias and allied taxa, Aplochiton and Lovettia). Our results also support a sister group relationship between Salmoniformes and Esociformes, which are together the sister group of Argentiniformes. PMID:20674753

  9. Suspension feeding in the enigmatic Ediacaran organism Tribrachidium demonstrates complexity of Neoproterozoic ecosystems

    PubMed Central

    Rahman, Imran A.; Darroch, Simon A. F.; Racicot, Rachel A.; Laflamme, Marc

    2015-01-01

    The first diverse and morphologically complex macroscopic communities appear in the late Ediacaran period, 575 to 541 million years ago (Ma). The enigmatic organisms that make up these communities are thought to have formed simple ecosystems characterized by a narrow range of feeding modes, with most restricted to the passive absorption of organic particles (osmotrophy). We test between competing feeding models for the iconic Ediacaran organism Tribrachidium heraldicum using computational fluid dynamics. We show that the external morphology of Tribrachidium passively directs water flow toward the apex of the organism and generates low-velocity eddies above apical “pits.” These patterns of fluid flow are inconsistent with osmotrophy and instead support the interpretation of Tribrachidium as a passive suspension feeder. This finding provides the oldest empirical evidence for suspension feeding at 555 to 550 Ma, ~10 million years before the Cambrian explosion, and demonstrates that Ediacaran organisms formed more complex ecosystems in the latest Precambrian, involving a larger number of ecological guilds, than currently appreciated. PMID:26702439

  10. Cambrian origins and affinities of an enigmatic fossil group of arthropods.

    PubMed

    Vaccari, N E; Edgecombe, G D; Escudero, C

    2004-07-29

    Euthycarcinoids are one of the most enigmatic arthropod groups, having been assigned to nearly all major clades of Arthropoda. Recent work has endorsed closest relationships with crustaceans or a myriapod-hexapod assemblage, a basal position in the Euarthropoda, or a placement in the Hexapoda or hexapod stem group. Euthycarcinoids are known from 13 species ranging in age from Late Ordovician or Early Silurian to Middle Triassic, all in freshwater or brackish water environments. Here we describe a euthycarcinoid from marine strata in Argentina dating from the latest Cambrian period, extending the group's record back as much as 50 million years. Despite its antiquity and marine occurrence, the Cambrian species demonstrates that morphological details were conserved in the transition to fresh water. Trackways in the same unit as the euthycarcinoid strengthen arguments that similar traces of subaerial origin from Cambro-Ordovician rocks were made by euthycarcinoids. Large mandibles in euthycarcinoids are confirmed by the Cambrian species. A morphology-based phylogeny resolves euthycarcinoids as stem-group Mandibulata, sister to the Myriapoda and Crustacea plus Hexapoda. PMID:15282604

  11. A new enigmatic Late Miocene mylodontoid sloth from northern South America.

    PubMed

    Rincón, Ascanio D; McDonald, H Gregory; Solórzano, Andrés; Flores, Mónica Núñez; Ruiz-Ramoni, Damián

    2015-02-01

    A new genus and species of sloth (Eionaletherium tanycnemius gen. et sp. nov.) recently collected from the Late Miocene Urumaco Formation, Venezuela (northern South America) is herein described based on a partial skeleton including associated femora and tibiae. In order to make a preliminary analysis of the phylogenetic affinities of this new sloth we performed a discriminate analysis based on several characters of the femur and tibia of selected Mylodontoidea and Megatherioidea sloths. The consensus tree produced indicates that the new sloth, E. tanycnemius, is a member of the Mylodontoidea. Surprisingly, the new taxon shows some enigmatic features among Neogene mylodontoid sloths, e.g. femur with a robust lesser trochanter that projects medially and the straight distinctly elongated tibia. The discovery of E. tanycnemius increases the diversity of sloths present in the Urumaco sequence to ten taxa. This taxon supports previous studies of the sloth assemblage from the Urumaco sequence as it further indicates that there are several sloth lineages present that are unknown from the better sampled areas of southern South America. PMID:26064594

  12. A new enigmatic Late Miocene mylodontoid sloth from northern South America

    PubMed Central

    Rincón, Ascanio D.; McDonald, H. Gregory; Solórzano, Andrés; Flores, Mónica Núñez; Ruiz-Ramoni, Damián

    2015-01-01

    A new genus and species of sloth (Eionaletherium tanycnemius gen. et sp. nov.) recently collected from the Late Miocene Urumaco Formation, Venezuela (northern South America) is herein described based on a partial skeleton including associated femora and tibiae. In order to make a preliminary analysis of the phylogenetic affinities of this new sloth we performed a discriminate analysis based on several characters of the femur and tibia of selected Mylodontoidea and Megatherioidea sloths. The consensus tree produced indicates that the new sloth, E. tanycnemius, is a member of the Mylodontoidea. Surprisingly, the new taxon shows some enigmatic features among Neogene mylodontoid sloths, e.g. femur with a robust lesser trochanter that projects medially and the straight distinctly elongated tibia. The discovery of E. tanycnemius increases the diversity of sloths present in the Urumaco sequence to ten taxa. This taxon supports previous studies of the sloth assemblage from the Urumaco sequence as it further indicates that there are several sloth lineages present that are unknown from the better sampled areas of southern South America. PMID:26064594

  13. Molecular systematics of the Amazonian genus Aldina, a phylogenetically enigmatic ectomycorrhizal lineage of papilionoid legumes.

    PubMed

    Ramos, Gustavo; de Lima, Haroldo Cavalcante; Prenner, Gerhard; de Queiroz, Luciano Paganucci; Zartman, Charles E; Cardoso, Domingos

    2016-04-01

    Aldina (Leguminosae) is among the very few ecologically successful ectomycorrhizal lineages in a family largely marked by the evolution of nodulating symbiosis. The genus comprises 20 species predominantly distributed in Amazonia and has been traditionally classified in the tribe Swartzieae because of its radial flowers with an entire calyx and numerous free stamens. The taxonomy of Aldina is complicated due to its poor representation in herbaria and the lack of a robust phylogenetic hypothesis of relationship. Recent phylogenetic analyses of matK and trnL sequences confirmed the placement of Aldina in the 50-kb inversion clade, although the genus remained phylogenetically isolated or unresolved in the context of the evolutionary history of the main early-branching papilionoid lineages. We performed maximum likelihood and Bayesian analyses of combined chloroplast datasets (matK, rbcL, and trnL) and explored the effect of incomplete taxa or missing data in order to shed light on the enigmatic phylogenetic position of Aldina. Unexpectedly, a sister relationship of Aldina with the Andira clade (Andira and Hymenolobium) is revealed. We suggest that a new tribal phylogenetic classification of the papilionoid legumes should place Aldina along with Andira and Hymenolobium. These results highlight yet another example of the independent evolution of radial floral symmetry within the early-branching Papilionoideae, a large collection of florally heterogeneous lineages dominated by papilionate or bilaterally symmetric flower morphology. PMID:26748266

  14. A review of the structure, petrology, and dynamic deformation characteristics of some enigmatic terrestrial structures

    NASA Astrophysics Data System (ADS)

    Officer, Charles B.; Carter, Neville L.

    1991-03-01

    We review three categories of enigmatic terrestrial structures that have a variety of macroscopic and microscopic dynamic deformation features. The first category includes the Midcontinent, United States cryptoexplosion structures. They are of shallow origin and illustrate the effects that might be expected from a meteorite impact on a sedimentary rock terrane. The second category includes the well known Vredefort and Sudbury plutons or basement uplifts; the lesser known Precambrian basement uplifts at Steen River, Manson, and Carswell; and the diatreme breccia dikes at the Slate Islands. They are of relatively deep seated origin and illustrate the effects that might be expected from deep crustal or mantle processes of an explosive nature. The third category includes the large landslides in areas of crystalline rocks at Koefels and Langtang. The dynamic deformation features at these latter locations appear to be related to high strain rate tectonic processes associated with the landslide itself. We conclude that microscopic dynamic deformation features which occur in natural materials may have originated from meteorite impacts, from internal explosions, or from high strain rate tectonic process.

  15. Radiative Transfer Modeling of the Enigmatic Scattering Polarization in the Solar Na I D1 Line

    NASA Astrophysics Data System (ADS)

    Belluzzi, Luca; Trujillo Bueno, Javier; Landi Degl'Innocenti, Egidio

    2015-12-01

    The modeling of the peculiar scattering polarization signals observed in some diagnostically important solar resonance lines requires the consideration of the detailed spectral structure of the incident radiation field as well as the possibility of ground level polarization, along with the atom's hyperfine structure and quantum interference between hyperfine F-levels pertaining either to the same fine structure J-level, or to different J-levels of the same term. Here we present a theoretical and numerical approach suitable for solving this complex non-LTE radiative transfer problem. This approach is based on the density-matrix metalevel theory (where each level is viewed as a continuous distribution of sublevels) and on accurate formal solvers of the transfer equations and efficient iterative methods. We show an application to the D-lines of Na i, with emphasis on the enigmatic D1 line, pointing out the observable signatures of the various physical mechanisms considered. We demonstrate that the linear polarization observed in the core of the D1 line may be explained by the effect that one gets when the detailed spectral structure of the anisotropic radiation responsible for the optical pumping is taken into account. This physical ingredient is capable of introducing significant scattering polarization in the core of the Na i D1 line without the need for ground-level polarization.

  16. A genome-wide perspective on the evolutionary history of enigmatic wolf-like canids

    PubMed Central

    vonHoldt, Bridgett M.; Pollinger, John P.; Earl, Dent A.; Knowles, James C.; Boyko, Adam R.; Parker, Heidi; Geffen, Eli; Pilot, Malgorzata; Jedrzejewski, Wlodzimierz; Jedrzejewska, Bogumila; Sidorovich, Vadim; Greco, Claudia; Randi, Ettore; Musiani, Marco; Kays, Roland; Bustamante, Carlos D.; Ostrander, Elaine A.; Novembre, John; Wayne, Robert K.

    2011-01-01

    High-throughput genotyping technologies developed for model species can potentially increase the resolution of demographic history and ancestry in wild relatives. We use a SNP genotyping microarray developed for the domestic dog to assay variation in over 48K loci in wolf-like species worldwide. Despite the high mobility of these large carnivores, we find distinct hierarchical population units within gray wolves and coyotes that correspond with geographic and ecologic differences among populations. Further, we test controversial theories about the ancestry of the Great Lakes wolf and red wolf using an analysis of haplotype blocks across all 38 canid autosomes. We find that these enigmatic canids are highly admixed varieties derived from gray wolves and coyotes, respectively. This divergent genomic history suggests that they do not have a shared recent ancestry as proposed by previous researchers. Interspecific hybridization, as well as the process of evolutionary divergence, may be responsible for the observed phenotypic distinction of both forms. Such admixture complicates decisions regarding endangered species restoration and protection. PMID:21566151

  17. Recovery of breeding success in a population of brown pelicans

    USGS Publications Warehouse

    Mendenhall, V.M.; Prouty, R.M.

    1978-01-01

    Breeding populations of the brown pelican (Pelecanus occidentalis) declined during the 1960's on both east and west coasts of the United States. In 1969, colonies in South Carolina fledged an average of 0.78 young per nest, and those in California only 0.004. The minimum production for population stability has been estimated to be 1.0 to 1.2 fledglings per nest. The South Carolina population may have decreased by as much as 80% during the previous decade. Organochlorine pesticides were implicated as a cause of population decline. Eggs from South Carolina contained an average of 5.4 parts per million (ppm) of DDE (wet weight basis) in 1969, and those from California about 70 ppm wet weight. Shells of South Carolina brown pelican eggs were,17% thinner than normal, and those from California were 30% thinner, compared with shells of eggs laid before DDE was introduced in 1947; crushed eggs were common in the colonies. DDE was the primary cause of shell thinning, but dieldrin was also associated with breeding failure, and both may be embryotoxic. Brown pelicans also declined in Louisiana and Texas during this period, in association with shell thinning and relatively high organochlorine levels. Eggs of pelicans in Florida, however, contained lower residues, and numbers have remained stable. In 1969, the Patuxent Wildlife Research Center and Cape Romain National Wildlife Refuge initiated an intensive study of the South Carolina population. Size of the breeding colonies, production, eggshell thickness, and organochlorine residues were monitored each year. Between 1969 and 1976 organochlorines in the eggs declined gradually, reproductive success improved, and the breeding population doubled. We have continued to monitor the South Carolina brown pelican population. Results for 1977 and 1978 are presented here, with an evaluation of the significance and possible causes of current breeding success.

  18. Young Planetary disks

    NASA Astrophysics Data System (ADS)

    Lecavelier Des Etangs, A.

    2007-07-01

    The present review focuses on UV observations of young planetary disks and consequently mostly on the gaseous content of those disks. Few examples are taken to illustrate the capability of the UV observatories to scrutinize in detail the gas content of low density circumstellar disks if they are seen edge-on or nearly edge-on. For instance, in the case of HD100546, FUSE observations re- vealed signatures of outflow and infall in the disk caused by interaction of the stellar magnetosphere with the circumstellar disk. Observations of numerous absorption lines from H2 around young stars give constrains on the gas temper- ature and density, and physical size of the absorbing layer. In the case of T-Tauri stars and one brown dwarf, emissions from exited H2 have been detected. In the case of Beta Pictoris, the observation of CO in the UV and search for H2 with FUSE demonstrated that the evaporation of frozen bodies like comets must produce the CO seen in the disk. Extensive observations of spectral variability of Beta Pictoris are now interpreted by extrasolar comets evaporating in the vicinity of the central star of this young planetary system.

  19. Seasonality of brown recluse populations is reflected by numbers of brown recluse envenomations

    PubMed Central

    Rader, RK; Stoecker, WV; Malters, JM; Marr, MT; Dyer, JA

    2012-01-01

    A significant seasonal correlation was recently shown for brown recluse spider activity. Vetter (2011) observed brown recluse spiders were submitted by the general public predominantly during April–October. For patients with suspected brown recluse spider bites (BRSB), we have observed the same seasonality. Among 45 cases with features consistent of a BRSB, 43 (95.6%) occurred during April–October. Both the Vetter study and our study serve to demonstrate seasonal activity for brown recluse spiders. PMID:22465494

  20. Seasonality of brown recluse populations is reflected by numbers of brown recluse envenomations.

    PubMed

    Rader, R K; Stoecker, W V; Malters, J M; Marr, M T; Dyer, J A

    2012-07-01

    A significant seasonal correlation was recently shown for brown recluse spider activity. Vetter (2011) observed brown recluse spiders were submitted by the general public predominantly during April-October. For patients with suspected brown recluse spider bites (BRSB), we have observed the same seasonality. Among 45 cases with features consistent of a BRSB, 43 (95.6%) occurred during April-October. Both the Vetter study and our study serve to demonstrate seasonal activity for brown recluse spiders. PMID:22465494

  1. The Engrailed-1 Gene Stimulates Brown Adipogenesis

    PubMed Central

    Zhang, Chuanhai; Weng, Yibing; Shi, Fangxiong; Jin, Wanzhu

    2016-01-01

    As a thermogenic organ, brown adipose tissue (BAT) has received a great attention in treating obesity and related diseases. It has been reported that brown adipocyte was derived from engrailed-1 (EN1) positive central dermomyotome. However, functions of EN1 in brown adipogenesis are largely unknown. Here we demonstrated that EN1 overexpression increased while EN1 knockdown decreased lipid accumulation and the expressions of key adipogenic genes including PPARγ2 and C/EBPα and mitochondrial OXPHOS as well as BAT specific marker UCP1. Taken together, our findings clearly indicate that EN1 is a positive regulator of brown adipogenesis. PMID:27148369

  2. Unravelling the enigmatic origin of calcitic nanofibres in soils and caves: purely physicochemical or biogenic processes?

    NASA Astrophysics Data System (ADS)

    Bindschedler, S.; Cailleau, G.; Braissant, O.; Millière, L.; Job, D.; Verrecchia, E. P.

    2014-01-01

    Calcitic nanofibres are ubiquitous habits of secondary calcium carbonate (CaCO3) accumulations observed in calcareous vadose environments. Despite their widespread occurrence, the origin of these nanofeatures remains enigmatic. Three possible mechanisms fuel the debate: (i) purely physicochemical processes, (ii) mineralization of rod-shaped bacteria, and (iii) crystal precipitation on organic templates. Nanofibres can be either mineral (calcitic) or organic in nature. They are very often observed in association with Needle Fibre Calcite (NFC), another typical secondary CaCO3 habit in terrestrial environments. This association has contributed to some confusion between both habits, however they are truly two distinct calcitic features and their recurrent association is likely to be an important fact to help understanding the origin of nanofibres. In this manuscript the different hypotheses that currently exist to explain the origin of calcitic nanofibres are critically reviewed. In addition to this, a new hypothesis for the origin of nanofibres is proposed based on the fact that current knowledge attributes a fungal origin to NFC. As this feature and nanofibres are recurrently observed together, a possible fungal origin for nanofibres which are associated with NFC is investigated. Sequential enzymatic digestion of the fungal cell wall of selected fungal species demonstrates that the fungal cell wall can be a source of organic nanofibres. The obtained organic nanofibres show a striking morphological resemblance when compared to their natural counterparts, emphasizing a fungal origin for part of the organic nanofibres observed in association with NFC. It is further hypothesized that these organic nanofibres may act as templates for calcite nucleation in a biologically-influenced mineralization process, generating calcitic nanofibres. This highlights the possible involvement of Fungi in CaCO3 biomineralization processes, a role still poorly documented at present

  3. Unravelling the enigmatic origin of calcitic nanofibres in soils and caves: purely physicochemical or biogenic processes?

    NASA Astrophysics Data System (ADS)

    Bindschedler, S.; Cailleau, G.; Braissant, O.; Millière, L.; Job, D.; Verrecchia, E. P.

    2014-05-01

    Calcitic nanofibres are ubiquitous habits of secondary calcium carbonate (CaCO3) accumulations observed in calcareous vadose environments. Despite their widespread occurrence, the origin of these nanofeatures remains enigmatic. Three possible mechanisms fuel the debate: (i) purely physicochemical processes, (ii) mineralization of rod-shaped bacteria, and (iii) crystal precipitation on organic templates. Nanofibres can be either mineral (calcitic) or organic in nature. They are very often observed in association with needle fibre calcite (NFC), another typical secondary CaCO3 habit in terrestrial environments. This association has contributed to some confusion between both habits, however they are truly two distinct calcitic features and their recurrent association is likely to be an important fact to help understanding the origin of nanofibres. In this paper the different hypotheses that currently exist to explain the origin of calcitic nanofibres are critically reviewed. In addition to this, a new hypothesis for the origin of nanofibres is proposed based on the fact that current knowledge attributes a fungal origin to NFC. As this feature and nanofibres are recurrently observed together, a possible fungal origin for nanofibres which are associated with NFC is investigated. Sequential enzymatic digestion of the fungal cell wall of selected fungal species demonstrates that the fungal cell wall can be a source of organic nanofibres. The obtained organic nanofibres show a striking morphological resemblance when compared to their natural counterparts, emphasizing a fungal origin for part of the organic nanofibres observed in association with NFC. It is further hypothesized that these organic nanofibres may act as templates for calcite nucleation in a biologically influenced mineralization process, generating calcitic nanofibres. This highlights the possible involvement of fungi in CaCO3 biomineralization processes, a role still poorly documented. Moreover, on a global

  4. HIGH-ENERGY PROPERTIES OF THE ENIGMATIC Be STAR γ CASSIOPEIAE

    SciTech Connect

    Shrader, C. R.; Hamaguchi, K.; Sturner, S. J.; Petre, R.; Almeyda, T.

    2015-01-20

    We present the results of a broadband X-ray study of the enigmatic Be star Gamma Cassiopeiae (herein γ Cas) based on observations made with both the Suzaku and INTEGRAL observatories. γ Cas has long been recognized as the prototypical example of a small subclass of Be stars with moderately strong X-ray emission dominated by a hot thermal component in the 0.5-12 keV energy range (L {sub x} ≈ 10{sup 32}-10{sup 33} erg s{sup –1}). This places them at the high end of the known luminosity distribution for stellar emission, but several orders of magnitude below typical accretion-powered Be X-ray binaries. The INTEGRAL observations spanned an eight-year baseline and represent the deepest measurement to date at energies above ∼50 keV. We find that the INTEGRAL data are consistent within statistics to a constant intensity source above 20 keV, with emission extending up to ∼100 keV, and that searches for all of the previously reported periodicities of the system at lower energies led to null results. We further find that our combined Suzaku and INTEGRAL spectrum, which we suggest is the most accurate broadband X-ray measurement of γ Cas to date, is fitted extremely well with a thermal plasma emission model with a single absorption component. We found no compelling need for an additional non-thermal high-energy component. We discuss these results in the context of a currently favored models for γ Cas and its analogs.

  5. Identification of the first neuropeptides from the enigmatic hexapod order Protura.

    PubMed

    Christie, Andrew E; Chi, Megan

    2015-12-01

    The Hexapoda consists of two classes, the Entognatha and the Insecta, with the former group considered basal to the latter. The Protura is a basal order within the Entognatha, the members of which are minute soil dwellers first identified in the early 20th century. Recently, a transcriptome shotgun assembly (TSA) was generated for the proturan Acerentomon sp., providing the first significant molecular resource for this enigmatic hexapod order. As part of an ongoing effort to predict peptidomes for little studied members of the Arthropoda, we have mined this TSA dataset for transcripts encoding putative neuropeptide precursors and predicted the structures of mature peptides from the deduced proteins. Forty-seven peptide-encoding transcripts were mined from the Acerentomon TSA dataset, with 202 distinct peptides predicted from them. The peptides identified included isoforms of adipokinetic hormone, adipokinetic hormone-corazonin-like peptide, allatostatin A, allatostatin B, allatostatin C, allatotropin, bursicon α, bursicon β, CCHamide, corazonin, crustacean cardioactive peptide, crustacean hyperglycemic hormone/ion transport peptide, diuretic hormone 31, diuretic hormone 44, ecdysis-triggering hormone, eclosion hormone, FMRFamide-like peptide, GSEFLamide, insulin-like peptide, intocin, leucokinin, myosuppressin, neuropeptide F, orcokinin, proctolin, pyrokinin, RYamide, short neuropeptide F, SIFamide, sulfakinin and tachykinin-related peptide; these are the first neuropeptides described from any proturan. Comparison of the Acerentomon precursors and mature peptides with those from other arthropods revealed features characteristic of both the insects and the crustaceans, which is consistent with the hypothesized phylogenetic position of the Protura within the Pancrustacea, i.e. at or near the point of divergence of the hexapods from the crustaceans. PMID:26055220

  6. Enigmatic Cranial Superstructures among Chamorro Ancestors from the Mariana Islands: Gross Anatomy and Microanatomy

    PubMed Central

    Heathcote, Gary M.; Bromage, Timothy G.; Sava, Vincent J.; Hanson, Douglas B.; Anderson, Bruce E.

    2014-01-01

    This study focuses on the gross anatomy, anatomic relations, microanatomy, and meaning of three enigmatic, geographically-patterned, quasi-continuous superstructures of the posterior cranium. Collectively known as occipital superstructures (OSS), these traits are the occipital torus tubercle (TOT), retromastoid process (PR), and posterior supramastoid tubercle (TSP). When present, TOT, PR and TSP develop at posterior cranial attachment sites of the upper trapezius, superior oblique and sternocleidomastoid muscles, respectively. Marked expression and co-occurrence of these OSS are virtually circumscribed within Oceania and reach highest recorded frequencies in proto-historic Chamorros (CHamoru) of the Mariana Islands. Prior to undertaking scanning electron microscopy (SEM) work, our working multifactorial model for OSS development was that early-onset, long-term, chronic activity-related microtrauma at enthesis sites led to exuberant reactive or reparative responses in a substantial minority of genetically predisposed (and mostly male) individuals. SEM imaging, however, reveals topographic patterning that questions, but does not negate, activity-induction of these superstructures. While OSS appear macroscopically as relatively large and discrete phenomena, SEM findings reveal a unique, widespread and seemingly systemic distribution of structures over the occipital surface that have the appearance of OSS microforms. Nevertheless, apparent genetic underpinnings, anatomic relationships with muscle entheses, and positive correlation of OSS development with humeral robusticity continue to suggest that these superstructures have potential to at once bear witness to Chamorro population history and inform osteobiographical constructions of chronic activity patterns in individuals bearing them. Further work is outlined that would illuminate the proximate and ultimate meanings of OSS. PMID:24753475

  7. Observations of mixed-aged litters in brown bears

    USGS Publications Warehouse

    Swenson, J.E.; Haroldson, M.A.

    2008-01-01

    We report on 3 cases of mixed-aged litters (young born in different years) in brown bears (Ursus arctos); in 1 instance the cub-of-the-year (hereafter called cubs) died in the den. Two cases occurred in Sweden after mothers were separated from their young during the breeding season. In one, the mother was separated from the accompanying cub for at least 12.5 hours and possibly up to 3.3 days, and later possibly separated for 4 days. In the other, the mother was separated from her yearling at least 3 times for 1-14, 1-6 and 1-6 days. She was with a male during the first separation. Specific events that produced the mixed-aged litter observed in Greater Yellowstone Ecosystem were unknown and our interpretation is based on estimates of ages of accompanying young from photographs. The observation of only 2 mixed-aged litters, after den emergence, from a sample of 406 observed cub litters accompanying radiomarked females confirms the rarity of this phenomenon. The mechanism apparently includes a short separation of mother and young, and, in the case of cubs, the mother must mate while lactating. Better understanding of the physiological mechanisms that allow mixed-age litters would help us in the debate about the occurrence of sexually selected infanticide in bears.

  8. Direct action of capsaicin in brown adipogenesis and activation of brown adipocytes.

    PubMed

    Kida, Ryosuke; Yoshida, Hirofumi; Murakami, Masaru; Shirai, Mitsuyuki; Hashimoto, Osamu; Kawada, Teruo; Matsui, Tohru; Funaba, Masayuki

    2016-01-01

    The ingestion of capsaicin, the principle pungent component of red and chili peppers, induces thermogenesis, in part, through the activation of brown adipocytes expressing genes related to mitochondrial biogenesis and uncoupling such as peroxisome proliferator-activated receptor (Ppar) γ coactivator-1α (Pgc-1α) and uncoupling protein 1 (Ucp1). Capsaicin has been suggested to induce the activation of brown adipocytes, which is mediated by the stimulation of sympathetic nerves. However, capsaicin may directly affect the differentiation of brown preadipocytes, brown adipocyte function, or both, through its significant absorption. We herein demonstrated that Trpv1, a capsaicin receptor, is expressed in brown adipose tissue, and that its expression level is increased during the differentiation of HB2 brown preadipocytes. Furthermore, capsaicin induced calcium influx in brown preadipocytes. A treatment with capsaicin in the early stage of brown adipogenesis did not affect lipid accumulation or the expression levels of Fabp4 (a gene expressed in mature adipocytes), Pparγ2 (a master regulator of adipogenesis) or brown adipocyte-selective genes. In contrast, a treatment with capsaicin in the late stage of brown adipogenesis slightly increased the expression levels of Fabp4, Pparγ2 and Pgc-1α. Although capsaicin did not affect the basal expression level of Ucp1, Ucp1 induction by forskolin was partially inhibited by capsaicin, irrespective of the dose of capsaicin. The results of the present study suggest the direct effects of capsaicin on brown adipocytes or in the late stage of brown adipogenesis. PMID:26781688

  9. 50 Years after Brown v. the Board of Education: An Interview with Cheryl Brown Henderson

    ERIC Educational Resources Information Center

    Carriuolo, Nancy E.

    2004-01-01

    This spring marks the 50th anniversary (May 17, 1954-2004) of the Supreme Courts' decision to outlaw segregation by ruling unanimously in favor of the plaintiffs in Brown v. the Board of Education. Of course, segregation never really ended, as will be explained in this interview with Cheryl Brown Henderson, daughter of Oliver Brown, the 10th of…

  10. Brown Fat and Browning for the Treatment of Obesity and Related Metabolic Disorders

    PubMed Central

    Kim, So Hun

    2016-01-01

    Brown fat is a specialized fat depot that can increase energy expenditure and produce heat. After the recent discovery of the presence of active brown fat in human adults and novel transcription factors controlling brown adipocyte differentiation, the field of the study of brown fat has gained great interest and is rapidly growing. Brown fat expansion and/or activation results in increased energy expenditure and a negative energy balance in mice and limits weight gain. Brown fat is also able to utilize blood glucose and lipid and results in improved glucose metabolism and blood lipid independent of weight loss. Prolonged cold exposure and beta adrenergic agonists can induce browning of white adipose tissue. The inducible brown adipocyte, beige adipocyte evolving by thermogenic activation of white adipose tissue have different origin and molecular signature from classical brown adipocytes but share the characteristics of high mitochondria content, UCP1 expression and thermogenic capacity when activated. Increasing browning may also be an efficient way to increase whole brown fat activity. Recent human studies have shown possibilities that findings in mice can be reproduced in human, making brown fat a good candidate organ to treat obesity and its related disorders. PMID:26912151

  11. Youngest Brown Dwarf Yet in a Multiple Stellar System

    NASA Astrophysics Data System (ADS)

    2000-07-01

    ... and the Sharpest Optical Image (0.18 arcsec) from the VLT so far...! Astronomers are eager to better understand the formation of stars and planets - with an eye on the complex processes that lead to the emergence of our own solar system some 4600 million years ago. Brown Dwarfs (BDs) play a special role in this context. Within the cosmic zoo, they represent a class of "intermediate" objects. While they are smaller than normal stars, they shine by their own energy for a limited time, in contrast to planets. Recent observations with the ESO Very Large Telescope (VLT) of a "young" Brown Dwarf in a multiple stellar system are taking on a particular importance in this connection. An evaluation of the new data by an international team of astronomers [1] shows that it is by far the youngest of only four such objects found in a stellar system so far. The results are now providing new insights into the stellar formation process. This small object is known as TWA-5 B and with a mass of only 15 - 40 times that of Jupiter, it is near the borderline between planets and Brown Dwarfs, cf. the explanatory Appendix to this Press Release. However, visible and infrared VLT spectra unambiguously classify it in the latter category. Accurate positional measurements with the Hubble Space Telescope (HST) and the VLT hint that it is orbiting the central, much heavier and brighter star in this system, TWA-5 A (itself a close double star of which each component presumably has a mass of 0.75 solar masses), with a period that may be as long as 900 years. And, by the way, an (I-band) image of the TWA-5 system is the sharpest delivered by the VLT so far, with an image size of only 0.18 arcsec [2]! Brown Dwarfs: a cool subject In current astronomical terminology, Brown Dwarfs (BDs) are objects whose masses are below those of normal stars - the borderline is believed to be about 8% of the mass of our Sun - but larger than those of planets, cf. [3]. Unlike normal stars, Brown Dwarfs are unable

  12. Effects of glucocorticoids on human brown adipocytes.

    PubMed

    Barclay, Johanna L; Agada, Hadiya; Jang, Christina; Ward, Micheal; Wetzig, Neil; Ho, Ken K Y

    2015-02-01

    Clinical cases of glucocorticoid (GC) excess are characterized by increased fat mass and obesity through the accumulation of white adipocytes. The effects of GCs on growth and function of brown adipose tissue are unknown and may contribute to the negative energy balance observed clinically. This study aims to evaluate the effect of GCs on proliferation, differentiation, and metabolic function of brown adipocytes. Human brown adipocytes sourced from supraclavicular fat biopsies were grown in culture and differentiated to mature adipocytes. Human white adipocytes sourced from subcutaneous abdominal fat biopsies were cultured as controls. Effects of dexamethasone on growth, differentiation (UCP1, CIDEA, and PPARGC1A expression), and function (oxygen consumption rate (OCR)) of brown adipocytes were quantified. Dexamethasone (1 μM) significantly stimulated the proliferation of brown preadipocytes and reduced that of white preadipocytes. During differentiation, dexamethasone (at 0.1, 1, and 10 μM) stimulated the expression of UCP1, CIDEA, and PPARGC1A in a concentration-dependent manner and enhanced by fourfold to sixfold the OCR of brown adipocytes. Isoprenaline (100 nM) significantly increased (P<0.05) expression of UCP1 and OCR of brown adipocytes. These effects were significantly reduced (P<0.05) by dexamethasone. Thus, we show that dexamethasone stimulates the proliferation, differentiation, and function of human brown adipocytes but inhibits adrenergic stimulation of the functioning of brown adipocytes. We conclude that GCs exert complex effects on development and function of brown adipocytes. These findings provide strong evidence for an effect of GCs on the biology of human brown adipose tissue (BAT) and for the involvement of the BAT system in the metabolic manifestation of Cushing's syndrome. PMID:25385872

  13. The brain and brown fat

    PubMed Central

    Gonzalez, Francisco; Fernø, Johan; Diéguez, Carlos; Rahmouni, Kamal; Nogueiras, Rubén

    2015-01-01

    Brown adipose tissue (BAT) is a specialized organ responsible for thermogenesis, a process required for maintaining body temperature. BAT is regulated by the sympathetic nervous system (SNS), which activates lipolysis and mitochondrial uncoupling in brown adipocytes. For many years, BAT was considered to be important only in small mammals and newborn humans, but recent data have shown that BAT is also functional in adult humans. On the basis of this evidence, extensive research has been focused on BAT function, where new molecules, such as irisin and bone morphogenetic proteins, particularly BMP7 and BMP8B, as well as novel central factors and new regulatory mechanisms, such as orexins and the canonical ventomedial nucleus of the hypothalamus (VMH) AMP- activated protein kinase (AMPK)–SNS–BAT axis, have been discovered and emerged as potential drug targets to combat obesity. In this review we provide an overview of the complex central regulation of BAT and how different neuronal cell populations co-ordinately work to maintain energy homeostasis. PMID:24915455

  14. Brown recluse spider bite on the breast.

    PubMed

    Norris, Kori; Misra, Subhasis

    2014-05-01

    Brown recluse spiders are one of two types of spiders in the United States that can cause significant tissue damage and, in rare cases, death. Brown recluse spider bites are most often benign and self-limiting, but in a few cases can cause severe necrotic skin lesions. PMID:24758975

  15. On Browne's Solution for Oblique Procrustes Rotation

    ERIC Educational Resources Information Center

    Cramer, Elliot M.

    1974-01-01

    A form of Browne's (1967) solution of finding a least squares fit to a specified factor structure is given which does not involve solution of an eigenvalue problem. It suggests the possible existence of a singularity, and a simple modification of Browne's computational procedure is proposed. (Author/RC)

  16. Education in the Post-Brown Era.

    ERIC Educational Resources Information Center

    Coleman, James S.

    The Brown decision of 1954 occurred when Blacks, who were migrating into the North in large numbers, became a highly visible political minority. Widespread interest in school integration on the part of the dominant majority stemmed more from a concern about societal integration than about the welfare of disadvantaged children. The Brown decision…

  17. Remembering "Brown": Silence, Loss, Rage, and Hope

    ERIC Educational Resources Information Center

    Banks, James A.

    2004-01-01

    The author was in the seventh grade at the Newsome Training School in Aubrey, Arkansas when the Supreme Court handed down "Brown v. Board of Education" on May 17, 1954. His most powerful memory of the "Brown" decision is that he has no memory of it being rendered or mentioned by his parents, teachers, or preachers. In his rural southern Black…

  18. Speaking Personally--With John Seely Brown

    ERIC Educational Resources Information Center

    American Journal of Distance Education, 2008

    2008-01-01

    This article presents an interview with John Seely Brown, a visiting scholar at the University of Southern California and a former chief scientist of Xerox Corporation and director of its Palo Alto Research Center (PARC)--a position he held for nearly two decades. While head of PARC, Brown expanded the role of corporate research to include such…

  19. Calcifying Sorting and Segregating: "Brown" at 60

    ERIC Educational Resources Information Center

    Graff, Cristina Santamaria; Kozleski, Elizabeth

    2014-01-01

    The 2007 "Parents Involved in Community Schools v. Seattle School District No. 1". Supreme Court 5:4 decision suggests that the Court is divided in its interpretation of "Brown" and its intent in addressing racial segregation. Although "Brown" intended equal educational opportunities through desegregation practices,…

  20. Brown and the Politics of Equality.

    ERIC Educational Resources Information Center

    Brown, Frank

    1994-01-01

    Assesses the progress of equality since Brown v Topeka Board of Education and argues that there still has not been a full implementation of that Supreme Court decree. School integration is shown to be declining. It is recommended that The court could merge the equality standards of Plessy v Ferguson with Brown to provide quality education. (GR)

  1. Some Aspects of Enzymatic Browning in Apples

    ERIC Educational Resources Information Center

    Liffen, C. L.; Cleeve, H. N.

    1975-01-01

    Describes material modified from the Nuffield advanced chemistry course to make it meaningful and relevant to pupils in the middle school. Discusses a series of simple experiments on apple browning and summarizes the browning process and its control. (Author/GS)

  2. Anthony H.D. Brown: Conservation Geneticist

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This volume of Plant Breeding Reviews is dedicated to Anthony (Tony) H. D. Brown known internationally for his research in conservation and population genetics and plant breeding. Dr. Brown's primary contributions in the area of conservation genetics followed two major themes – optimum sampling str...

  3. DISCOVERY OF A PLANETARY-MASS COMPANION TO A BROWN DWARF IN TAURUS

    SciTech Connect

    Todorov, K.; Luhman, K. L.; McLeod, K. K.

    2010-05-01

    We have performed a survey for substellar companions to young brown dwarfs in the Taurus star-forming region using the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. In these data, we have discovered a candidate companion at a projected separation of 0.''105 from one of the brown dwarfs, corresponding to 15 AU at the distance of Taurus. To determine if this object is a companion, we have obtained images of the pair at a second epoch with the adaptive optics system at Gemini Observatory. The astrometry from the Hubble and Gemini data indicates that the two objects share similar proper motions and thus are likely companions. We estimate a mass of 5-10 M {sub Jup} for the secondary based on a comparison of its bolometric luminosity to the predictions of theoretical evolutionary models. This object demonstrates that planetary-mass companions to brown dwarfs can form on a timescale of {tau} {approx}< 1 Myr. Companion formation on such a rapid timescale is more likely to occur via gravitational instability in a disk or fragmentation of a cloud core than through core accretion. The Gemini images also reveal a possible substellar companion ({rho} = 0.''23) to a young low-mass star that is 12.''4 from the brown dwarf targeted by Hubble. If these four objects comprise a quadruple system, then its hierarchical configuration would suggest that the fragmentation of molecular cloud cores can produce companions below 10 M {sub Jup}.

  4. Bending the Bars of the Identity Cage: Amy Brown and the Development of Teacher Identity in British Columbia

    ERIC Educational Resources Information Center

    Raptis, Helen

    2010-01-01

    In September 1939, Amy (Brown) Dauphinee took up her first teaching appointment at Tate Creek, British Columbia where 518 refugees had recently settled after fleeing Czechoslovakia's Sudetenland. Amy--an avowed Social Democrat and member of the Young Socialist League--quickly embraced the refugees who were largely trade union activists and Social…

  5. The Mysterious Case of the Detective as Child Hero: Sherlock Holmes, Encyclopedia Brown and Nancy Drew as Role Models?

    ERIC Educational Resources Information Center

    Sugarman, Sally

    In the mystery genre, the one characteristic that the enduring figures of Sherlock Holmes, Nancy Drew, and Encyclopedia Brown have in common is a rational mind. The source of their strength is their ability to think and think well. A study examined some typical examples of the mystery genre in young adult literature and surveyed children and…

  6. The enigmatic Zerelia twin-lakes (Thessaly, Central Greece): two potential meteorite impact Craters

    NASA Astrophysics Data System (ADS)

    Dietrich, V. J.; Lagios, E.; Reusser, E.; Sakkas, V.; Gartzos, E.; Kyriakopoulos, K.

    2013-09-01

    Two circular permanent lakes of 150 and 250 m diameter and 6-8 m depth to an unconsolidated muddy bottom occur 250 m apart from each other in the agricultural fields SW of the town of Almiros (Thessaly, central Greece). The age of the lakes is assumed to be Late Pliocene to Early Holocene with a minimum age of approx. 7000 yr BP. The abundant polymict, quartz-rich carbonate breccia and clasts with a clay rich matrix in the shallow embankments of the lakes show weak stratification but no volcanic structures. The carbonate clasts and particles often display spheroidal shapes and consist of calcite aggregates with feathery, arborescent, variolitic to micro-sparitic textures and spheroidal fabrics, recrystallized and deformed glass-shaped fragments, calcite globules in quartz; thus indications of possible carbonate melting, quenching and devitrification. The carbonatic matrix includes small xenomorphic phases, such as chromspinel, zircon with blurred granular and skeletal textures, skeletal rutile and ilmenite, which are interpreted as relicts of partial melting and quenching under high temperatures of 1240-1800 °C. Only a few quartz fragments exhibit indistinct planar fractures. In several cases they include exotic Al-Si- and sulfur bearing Fe-phases, < 1-10 μm as globules. The modeled "Residual Gravity" profiles through the lakes indicate negative gravity anomalies of bowl-type structures down to 150 m for the eastern lake and down to 250 m for the larger western lake. Several hypotheses can be drawn upon to explain the origin of these enigmatic twin-lakes: (a) Maar-type volcanic craters; (b) hydrothermal or CO2/hydrocarbon gas explosion craters; (c) and (d) doline holes due to karstification; or (e) small meteorite impact craters, the latter being a plausible explanation due to geologic, petrologic, and geophysical evidence. The morphology and dimensions of the lakes as well as the density contrast tomography of the bedrock favor a meteorite impact hypothesis of a

  7. Across the Baltic: a new record for an enigmatic black scavenger fly, Zuskamira inexpectata (Pont, 1987) (Sepsidae) in Finland

    PubMed Central

    Rohner, Patrick Thomas; Meier, Rudolf

    2015-01-01

    Abstract Specimens of the enigmatic, monotypic European genus Zuskamira Pont, 1987 (Sepsidae) were initially collected only from the lower central Swedish provinces of Darlana, Uppland and Västmanland. However, the same species was subsequently found much more south in Lower-Saxony and Schleswig-Holstein although Germany is overall well sampled for sepsid flies. Here we report a further (longitudinal) range expansion based on new localities in Southern Finland. New localities for Finland and Sweden are here added and we discuss briefly the habitat requirements of the species. PMID:26175608

  8. Erratum: The Enigmatic X-Ray Point Sources at the Central Stars of NGC 6543 and NGC 7293

    NASA Astrophysics Data System (ADS)

    Guerrero, Martín A.; Chu, You-Hua; Gruendl, Robert A.; Williams, Rosa M.; Kaler, James B.

    2001-06-01

    In the Letter ``The Enigmatic X-Ray Point Sources at the Central Stars of NGC 6543 and NGC 7293'' by Martín A. Guerrero, You-Hua Chu, Robert A. Gruendl, Rosa M. Williams, and James B. Kaler (ApJ, 553, L55 [2001]), the reference to the companion paper by Chu et al. (in the same issue, 2001 May 20) reads ``ApJ, L000'' and has no volume number. It should read ``ApJ, 553, L69.''

  9. Near-infrared Spectroscopy of Brown Dwarf and Planetary-Mass Members in Upper Scorpius

    NASA Astrophysics Data System (ADS)

    Lodieu, Nicolas

    2016-01-01

    In these proceedings, I present new VLT/X-shooter near-infrared spectroscopy of brown dwarf and planetary-mass candidates with masses below 30 Jupiter masses identified in a deep VISTA ZYJ survey of 13.5 square degrees in the Upper Scorpius (USco) association. These spectra represent new benchmarks at 5-10 Myr to compare with known and future discoveries of members in nearby moving groups and other young regions.

  10. Enigmatic organosiliceous rocks in the 2000 Ma petrified oil field in Russian Fennoscandia

    NASA Astrophysics Data System (ADS)

    Deines, Yu.; Melezhik, V.; Lepland, A.; Filippov, M.; Romashkin, A.; Rychanchik, D.

    2009-04-01

    The c. 2000 Ma, 900 m-thick, Zaonezhskaja Formation in the Onega basin, Russian Fennoscandia, contains one of the greatest accumulations of organic matter (OM) in the Early Precambrian. It also represents a unique preservation of a supergiant petrified oil field. Zaonezhskaja Formation rocks are greenschist-facies volcaniclastic greywackes (distal turbidites), dolostone and limestones, mafic tuffs and lavas intruded by numerous mafic sills. Several sedimentary beds are enriched in OM with the overall content of total organic carbon (TOC) ranging from 0.1 to 16 wt.% whereas d13C varies between -44 and -17 per mil(V-PDB). The formation contains plentiful evidence of generation and migration of oil (now petrified) as well as oil traps. Results of geophysical surveys combined with drillcore data, including results recently obtained within the framework of the Fennoscandian Arctic Russia - Drilling Early Earth Project (FAR-DEEP), revealed numerous bodies of organosiliceous rocks (OSR) containing mainly silica (c. 57 wt.% SiO2), organic carbon (up to 40 wt.%), Al2O3 (c. 5 wt.%), S (c. 2 wt.%), and minor K, Mg, Fe, Ca and Ti. d13C of the OSR ranges between -40 and -20 per mil. The OSR form crudely stratified beds, cupola-like bodies or veins. The cupola-like bodies show cross-cutting (intrusive) contacts with the host turbiditic greywackes, reach thicknesses of 120 m with a lateral extent of several hundreds of metres. Veins are a few tens of centimetres thick. The OSR show close spatial association with gabbro sills. Although different fabrics have been recognised in the OSR, syngenetic macro- and microbreccias per se are the most common rock types. Fragments of different sedimentary rocks, as well as those with alternating C-rich and C-poor concentric lamina are present. The latter suggests precipitation from hydrothermal fluids. The nature of the OSR remains enigmatic. Several models have been advanced for explanation of origin of the OSR. However, neither of them

  11. Variability of Young Stars: the Importance of Keeping an Eye on Children

    NASA Astrophysics Data System (ADS)

    Herbst, W.

    2013-06-01

    (Abstract only) I will review the state of our understanding of young stars with an emphasis on how and why they vary in brightness. The main causes of the variations will be reviewed, including the rotation of spotted weak-lined T Tauri stars, accretion onto classical T Tauri stars, the eruptive behavior of FUors, and the enigmatic variations of the UXors. The important role that amateurs have and will continue to play in these studies is highlighted. I will also discuss the latest results on two unusual young binaries, BM Orionis in the Trapezium asterism and KH 15D in NGC 2264.

  12. Brown adipose tissue and bone

    PubMed Central

    Lidell, M E; Enerbäck, S

    2015-01-01

    Brown adipose tissue (BAT) is capable of transforming chemically stored energy, in the form of triglycerides, into heat. Recent studies have shown that metabolically active BAT is present in a large proportion of adult humans, where its activity correlates with a favorable metabolic status. Hence, the tissue is now regarded as an interesting target for therapies against obesity and associated diseases such as type 2 diabetes, the hypothesis being that an induction of BAT would be beneficial for these disease states. Apart from the association between BAT activity and a healthier metabolic status, later studies have also shown a positive correlation between BAT volume and both bone cross-sectional area and bone mineral density, suggesting that BAT might stimulate bone anabolism. The aim of this review is to give the reader a brief overview of the BAT research field and to summarize and discuss recent findings regarding BAT being a potential player in bone metabolism. PMID:27152171

  13. Auroral Phenomena in Brown Dwarf Atmospheres

    NASA Astrophysics Data System (ADS)

    Pineda, J. Sebastian; Hallinan, Gregg

    2016-01-01

    Since the unexpected discovery of radio emission from brown dwarfs some 15 years ago, investigations into the nature of this emission have revealed that, despite their cool and neutral atmospheres, brown dwarfs harbor strong kG magnetic fields, but unlike the warmer stellar objects, they generate highly circularly polarized auroral radio emission, like the giant planets of the Solar System. Our recent results from Keck LRIS monitoring of the brown dwarf LSR1835+32 definitively confirm this picture by connecting the auroral radio emission to spectroscopic variability at optical wavelengths as coherent manifestations of strong large-scale magnetospheric auroral current systems. I present some of the results of my dissertation work to understand the nature brown dwarf auroral phenomena. My efforts include a survey of Late L dwarfs and T dwarfs, looking for auroral Hα emission and a concurrent survey looking for the auroral emission of H3+ from brown dwarfs with radio pulse detections. I discuss the potential connection of this auroral activity to brown dwarf weather phenomena and how brown dwarf aurorae may differ from the analogous emission of the magnetized giant planets in the Solar System.

  14. The Coolest Isolated Brown Dwarf Candidate Member of TWA

    NASA Astrophysics Data System (ADS)

    Gagné, Jonathan; Faherty, Jacqueline K.; Cruz, Kelle; Lafrenière, David; Doyon, René; Malo, Lison; Artigau, Étienne

    2014-04-01

    We present two new late-type brown dwarf candidate members of the TW Hydrae association (TWA): 2MASS J12074836-3900043 and 2MASS J12474428-3816464, which were found as part of the BANYAN all-sky survey (BASS) for brown dwarf members of nearby young associations. We obtained near-infrared (NIR) spectroscopy for both objects (NIR spectral types are respectively L1 and M9), as well as optical spectroscopy for J1207-3900 (optical spectral type is L0γ), and show that both display clear signs of low gravity, and thus youth. We use the BANYAN II Bayesian inference tool to show that both objects are candidate members to TWA with a very low probability of being field contaminants, although the kinematics of J1247-3816 seem slightly at odds with that of other TWA members. J1207-3900 is currently the latest-type and the only isolated L-type candidate member of TWA. Measuring the distance and radial velocity of both objects is still required to claim them as bona fide members. Such late-type objects are predicted to have masses down to 11-15 M Jup at the age of TWA, which makes them compelling targets to study atmospheric properties in a regime similar to that of currently known imaged extrasolar planets.

  15. THE COOLEST ISOLATED BROWN DWARF CANDIDATE MEMBER OF TWA

    SciTech Connect

    Gagné, Jonathan; Lafrenière, David; Doyon, René; Malo, Lison; Artigau, Étienne; Faherty, Jacqueline K.; Cruz, Kelle E-mail: jfaherty17@gmail.com

    2014-04-10

    We present two new late-type brown dwarf candidate members of the TW Hydrae association (TWA): 2MASS J12074836-3900043 and 2MASS J12474428-3816464, which were found as part of the BANYAN all-sky survey (BASS) for brown dwarf members of nearby young associations. We obtained near-infrared (NIR) spectroscopy for both objects (NIR spectral types are respectively L1 and M9), as well as optical spectroscopy for J1207-3900 (optical spectral type is L0γ), and show that both display clear signs of low gravity, and thus youth. We use the BANYAN II Bayesian inference tool to show that both objects are candidate members to TWA with a very low probability of being field contaminants, although the kinematics of J1247-3816 seem slightly at odds with that of other TWA members. J1207-3900 is currently the latest-type and the only isolated L-type candidate member of TWA. Measuring the distance and radial velocity of both objects is still required to claim them as bona fide members. Such late-type objects are predicted to have masses down to 11-15 M {sub Jup} at the age of TWA, which makes them compelling targets to study atmospheric properties in a regime similar to that of currently known imaged extrasolar planets.

  16. S Orionis 70: Just a Foreground Field Brown Dwarf?

    NASA Astrophysics Data System (ADS)

    Burgasser, Adam J.; Kirkpatrick, J. Davy; McGovern, Mark R.; McLean, Ian S.; Prato, L.; Reid, I. Neill

    2004-04-01

    We examine recent claims that the T-type brown dwarf S Ori 053810.1-203626 (S Ori 70) is a spectroscopically verified low-mass (3+5-1 MJup) member of the 1-8 Myr σ Orionis cluster. Comparative arguments by Martín & Zapatero Osorio asserting that S Ori 70 exhibits low surface gravity spectral features indicative of youth and low mass are invalidated by the fact that their comparison object was not the field T dwarf 2MASS 0559-1404, but rather a nearby background star. Instead, we find that the 1-2.5 μm spectra of S Ori 70 are well matched to older (age~few Gyr) field T6-T7 dwarfs. Moreover, we find that spectral model fits to late-type field T dwarf spectra tend to yield low surface gravities (logg=3.0-3.5), and thus young ages (<~5 Myr) and low masses (<~3 MJup), inconsistent with expected and/or empirical values. Finally, we show that the identification of one T dwarf in the field imaged by Zapatero Osorio et al. is statistically consistent with the expected foreground contamination. Based on the reexamined evidence, we conclude that S Ori 70 may simply be an old, massive (30-60 MJup) field brown dwarf lying in the foreground of the σ Orionis cluster. This interpretation should be considered before presuming the existence of so-called ``cluster planets.''

  17. The Enigmatic Bench Unit of Endeavour Crater Rim in Meridiani Planum, Mars

    NASA Astrophysics Data System (ADS)

    Ruff, S. W.

    2013-12-01

    Cape York bench clearly presents Grasberg rocks above Burns rocks. Erosion of a plunging synclinal form could explain this apparent inverted relationship, or it reveals that the Grasberg unit is younger than Burns formation. But this latter interpretation implies that Grasberg rocks, which have been observed only at the Endeavour rim, have been stripped off of Burns formation everywhere else. The Grasberg bench unit has recently been encountered in an isthmus setting between two low knobs of presumed Shoemaker formation called Nobbys Head and Sutherland Point just south of Cape York. The isthmus also presents Grasberg as topographically elevated above the Burns formation rocks. Despite its broad, smooth exposure, no remnants of Burns formation have been found on top of Grasberg at this location or anywhere on the Cape York bench. So the stratigraphic relationship between Grasberg and Burns rocks remains enigmatic. At the time of writing, Opportunity is at the edge of Solander Point, another bench feature on the northern tip of a rim segment known as Cape Tribulation. The erosional expression of this example appears different from those examined previously and perhaps offers the best chance to understand stratigraphic relationships. 1. S. W. Squyres et al., Ancient impact and aqueous processes at Endeavour Crater, Mars. Science 336, 570 (2012).

  18. School Choice Discourse and the Legacy of "Brown"

    ERIC Educational Resources Information Center

    Stulberg, Lisa M.

    2006-01-01

    Fifty years after the "Brown" decision, and in the context of persistent racial and economic segregation and inequality in schooling, it is still important to examine "Brown"'s legacy. In this focus on school choice, the rhetoric and the ways in which the legacy of "Brown" has been emphatically invoked in charter school and voucher debates is…

  19. Storage stability of flour-blasted brown rice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Brown rice was blasted with rice flour rather than sand in a sand blaster to make microscopic nicks and cuts so that water can easily penetrate into the brown rice endosperm and cook the rice in a shorter time. The flour-blasted American Basmati brown rice, long grain brown rice, and parboiled long...

  20. Brown recluse spider bites: a case report.

    PubMed

    Nunnelee, Janice D

    2006-02-01

    The brown recluse spider is found more commonly in the Southeast and the Central Midwest. Its bite is not common because it is a shy spider that only bites if cornered. A severe bite may necrose a large area that requires skin grafting; systemic reactions rarely occur. This article discusses the brown recluse spider and presents a case study of a patient with two spider bites that did require extensive grafting. PMID:16446239

  1. Interim reliability evaluation program, Browns Ferry 1

    SciTech Connect

    Mays, S.E.; Poloski, J.P.; Sullivan, W.H.; Trainer, J.E.; Bertucio, R.C.; Leahy, T.J.

    1981-01-01

    Probabilistic risk analysis techniques, i.e., event tree and fault tree analysis, were utilized to provide a risk assessment of the Browns Ferry Nuclear Plant Unit 1. Browns Ferry 1 is a General Electric boiling water reactor of the BWR 4 product line with a Mark 1 (drywell and torus) containment. Within the guidelines of the IREP Procedure and Schedule Guide, dominant accident sequences that contribute to public health and safety risks were identified and grouped according to release categories.

  2. Ukrainian mineral wax from brown coal

    SciTech Connect

    Shabad, T.

    1986-07-01

    An unusual mineral enterprise is the mineral wax plant of Semenovskoye in the Aleksandriya brown coal basin of the Ukraine. The only plant of its kind in the Soviet Union, it has been in operation since 1959, extracting mineral wax from the local bitumen-rich brown coal. The plant yields about 7.5 tons of mineral wax a day (about 2700 tons a year), for use in a variety of applications.

  3. How Long? Cosby, Brown and Racial Progress

    ERIC Educational Resources Information Center

    Malveaux, Julianne

    2004-01-01

    Bill Cosby ruffled feathers, raised eyebrows and said a mouthful when, at a Howard University black-tie celebration of the 50th anniversary of Brown v. Board of Education, he launched into a rift about "the lower economic people" not holding up their end of the bargain in the wake of Brown. "We can't blame White people," Cosby said, for an array…

  4. What Brown saw and you can too

    NASA Astrophysics Data System (ADS)

    Pearle, Philip; Collett, Brian; Bart, Kenneth; Bilderback, David; Newman, Dara; Samuels, Scott

    2010-12-01

    A discussion of Robert Brown's original observations of particles ejected by pollen of the plant Clarkia pulchella undergoing what is now called Brownian motion is given. We consider the nature of those particles and how he misinterpreted the Airy disk of the smallest particles to be universal organic building blocks. Relevant qualitative and quantitative investigations with a modern microscope and with a "homemade" single lens microscope similar to Brown's are presented.

  5. Enzymatic browning reactions in apple and apple products.

    PubMed

    Nicolas, J J; Richard-Forget, F C; Goupy, P M; Amiot, M J; Aubert, S Y

    1994-01-01

    This review examines the parameters of enzymatic browning in apple and apple products that is, phenolic compounds, polyphenoloxidases, and other factors (ascorbic acid and peroxidases), both qualitatively and quantitatively. Then the relationships between intensity of browning and the browning parameters are discussed, including a paragraph on the methods used for browning evaluation. Finally, the different methods for the control of browning are presented. PMID:8011143

  6. Constraining the Evolution of Brown Dwarf Binarity as a Function of Age: A Keck LGS AO Search for Brown Dwarf and Planetary Mass Companions to Upper Scorpius Brown Dwarfs

    NASA Astrophysics Data System (ADS)

    Biller, B.; Allers, K.; Liu, M.; Close, L. M.; Dupuy, T.

    2011-12-01

    We searched for binary companions to 20 brown dwarfs in Upper Scorpius (145 pc, 5 Myr, nearest OB association) with the facility infrared camera NIRC2 and the Laser Guide Star adaptive optics system on the 10 m Keck II telescope. We discovered a close companion (0.14″, 20.9±0.4 AU) to the very low mass object SCH J16091837-20073523. From spectral deconvolution of integrated-light near-IR spectroscopy of SCH1609 using the SpeX spectrograph (Rayner et al. 2003), we estimate primary and secondary spectral types of M6±0.5 and M7±1.0, corresponding to masses of 79±17 MJup and 55±25 MJup at an age of 5 Myr and masses of 84±15 MJup and 60±25 MJup at an age of 10 Myr. For our survey objects with spectral types later than M8, we find an upper limit on the binary fraction of <9% (1-σ) at separations greater than 10 AU. We combine the results of our survey with previous surveys of Upper Sco and similar young regions to set the strongest constraints to date on binary fraction for young substellar objects and very low mass stars. The binary fraction for low mass (<40 MJup) brown dwarfs in Upper Sco is similar to that for T dwarfs in the field; for higher mass brown dwarfs and very low mass stars, there is an excess of medium-separation (10-50 AU projected separation) young binaries with respect to the field. These medium separation binaries will likely survive to late ages.

  7. Fellatio in captive brown bears: evidence of long-term effects of suckling deprivation?

    PubMed

    Sergiel, Agnieszka; Maślak, Robert; Zedrosser, Andreas; Paśko, Łukasz; Garshelis, David L; Reljić, Slaven; Huber, Djuro

    2014-01-01

    Sexually stimulating behaviors that are not linked to reproduction are rare among non-human (especially non-primate) mammals. Such behaviors may have a function in the hierarchy of social species. In solitary species, such behaviors are more enigmatic, and possibly indicative of something abnormal. Here, we report on a case of two male brown bears, raised in captivity since being orphaned as cubs, which engaged in recurrent fellatio multiple times per day until at least 10 years old. The roles of provider and receiver in the act remained unchanged, and the behavior itself became highly ritualized. The provider always initiated the contact involving vigorous penile sucking that appeared to result in ejaculation. We suggest that the behavior began as a result of early deprivation of maternal suckling, and persisted through life, possibly because it remained satisfying for both individuals. This constitutes the first descriptive report of fellatio in bears, and suggests that some bears may suffer lifelong behavioral consequences from being orphaned at an early age. PMID:24899532

  8. Accretion in brown dwarfs: An infrared view

    NASA Astrophysics Data System (ADS)

    Natta, A.; Testi, L.; Muzerolle, J.; Randich, S.; Comerón, F.; Persi, P.

    2004-09-01

    This paper presents a study of the accretion properties of 19 very low mass objects (M*˜ 0.01-0.1 M⊙) in the regions Chamaeleon I and ρ Oph. For 8 objects we obtained high resolution Hα profiles and determined mass accretion rate \\dot Mac and accretion luminosity Lac. Pa\\beta is detected in emission in 7 of the 10 ρ Oph objects, but only in one in Cha I. Using objects for which we have both a determination of Lac from Hα and a Paβ detection,} we show that the correlation between the Paβ luminosity and luminosity Lac, found by Muzerolle et al. (\\cite{Mea98}) for T Tauri stars in Taurus, extends to objects with mass ˜0.03 M⊙; L(Paβ) can be used to measure Lac also in the substellar regime. The results were less conclusive for Brγ, which was detected only in 2 objects, neither of which had an Hα estimate of \\dot Mac. Using the relation between L(Pa\\beta) and Lac we determined the accretion rate for all the objects in our sample (including those with no Hα spectrum), } more than doubling the number of substellar objects with known \\dot Mac. When plotted as a function of the mass of the central object together with data from the literature, our results confirm the trend of lower \\dot Mac for lower M*, although with a large spread. Some of the spread is probably due to an age effect; our very young objects in ρ Oph have on average an accretion rate at least one order of magnitude higher than objects of similar mass in older regions. As a side product, we found that the width of Hα measured at 10% peak intensity is not only a qualitative indicator of the accreting nature of very low mass objects, but can be used to obtain a quantitative, although not very accurate, estimate of \\dot Mac over a large mass range, from T Tauri stars to brown dwarfs. Finally, we found that some of our objects show evidence of mass-loss in their optical spectra. Based on observations collected at the European Southern Observatory, Chile. Table 2 is only available in

  9. EXPLOSIVE DISINTEGRATION OF A MASSIVE YOUNG STELLAR SYSTEM IN ORION

    SciTech Connect

    Zapata, Luis A.; Schmid-Burgk, Johannes; Menten, Karl M.; Ho, Paul T. P.; Rodriguez, Luis F.

    2009-10-10

    Young massive stars in the center of crowded star clusters are expected to undergo close dynamical encounters that could lead to energetic, explosive events. However, there has so far never been clear observational evidence of such a remarkable phenomenon. We here report new interferometric observations that indicate the well-known enigmatic wide-angle outflow located in the Orion BN/KL star-forming region to have been produced by such a violent explosion during the disruption of a massive young stellar system, and that this was caused by a close dynamical interaction about 500 years ago. This outflow thus belongs to a totally different family of molecular flows that is not related to the classical bipolar flows that are generated by stars during their formation process. Our molecular data allow us to create a three-dimensional view of the debris flow and to link this directly to the well-known Orion H{sub 2} 'fingers' farther out.

  10. Explosive Disintegration of a Massive Young Stellar System in Orion

    NASA Astrophysics Data System (ADS)

    Zapata, Luis A.; Schmid-Burgk, Johannes; Ho, Paul T. P.; Rodríguez, Luis F.; Menten, Karl M.

    2009-10-01

    Young massive stars in the center of crowded star clusters are expected to undergo close dynamical encounters that could lead to energetic, explosive events. However, there has so far never been clear observational evidence of such a remarkable phenomenon. We here report new interferometric observations that indicate the well-known enigmatic wide-angle outflow located in the Orion BN/KL star-forming region to have been produced by such a violent explosion during the disruption of a massive young stellar system, and that this was caused by a close dynamical interaction about 500 years ago. This outflow thus belongs to a totally different family of molecular flows that is not related to the classical bipolar flows that are generated by stars during their formation process. Our molecular data allow us to create a three-dimensional view of the debris flow and to link this directly to the well-known Orion H2 "fingers" farther out.

  11. The Enigmatic Longevity of Granular Materials on Mars: The Case for Geologically Episodic Dune Formation

    NASA Technical Reports Server (NTRS)

    Marshall, J.

    1999-01-01

    Martian sand dunes are concentrated in vast sand seas in the circumpolar belt of the planet's northern hemisphere, but they are also pervasive over the whole planet. Their occurrence is to be expected on a super-arid planetary surface subjected to boundary layer drag from a continually active atmosphere. Whilst their occurrence is to be expected, their survival is enigmatic. But the enigma only arises if the martian system is considered similar to Earth's --where sand is moved highly frequently, more or less on a seasonal basis. Experimentally it is readily demonstrated that active sand will soon wear down to small grains and eventually diminish to below the critical sand size required to sustain dune formation. According to conventional wisdom, sand moves at higher speeds on Mars than on Earth, and if it were to move as frequently as it does on Earth, then the dune-forming sand population should have long since disappeared, given the great longevity of the martian aeolian system (Sagan coined the term "kamikaze" grains to express this disappearance). No supply of sand could keep pace with this depletion, especially in light of the fact that Mars does not have very active weathering, nor significant crustal differentiation. On Earth, plate tectonics, magmatic activity, and general crustal differentiation over geological time have produced great concentrations of quartz crystals in the continental crustal masses. Not only are these quartz grains chemically and mechanically resilient, they are about the right size for being transported by either wind or water. Add to this, the geologically recent contribution of glacial grinding, and it is easy to see why there are dune field on Earth. So what are the martian dunes composed of, and how does the material survive the eons of attrition? In addition to experimental demonstrations of sand comminution in laboratory aeolian simulations, the problem can be approached from first principles. Sagan showed that by simple

  12. a Faint and Lonely Brown Dwarf in the Solar Vicinity

    NASA Astrophysics Data System (ADS)

    1997-04-01

    identical to other known Brown Dwarfs, its measured characteristics indicate that it must be located at a distance of only 10 parsecs, that is about 33 light-years, from the solar system. Its temperature is obviously below 1700 degrees C (where TiO and VO condense as dust grains [3] so that the spectral lines of these molecules are no longer seen). Its mass can be no more than 75 times that of Jupiter, or 6 percent of that of the Sun. During recent years, several Brown Dwarf candidates have been de-masked as low-mass stars and only recently a few Brown Dwarfs were identified in the Pleiades star cluster. Those Brown Dwarfs are quite young and therefore comparatively hotter and brighter. Contrarily, KELU-1 is most probably somewhat older and its unique location so close to us greatly facilitates future investigations. Moreover, it is not at all `disturbed' by the presence of other objects in its immediate surroundings, as this is the case for all other known objects of this type. It will now be important to obtain accurate measurements of KELU-1's parallax , that is, the small annual change of its position in the sky that is caused by the Earth's motion around the Sun and thus the viewing angle of an Earth-based observer. This should be possible within the next year. Moreover, high resolution spectral investigations with large telescope facilities, soon to include the ESO Very Large Telescope at the Paranal observatory in northern Chile, will now for the first time enable us to investigate the processes that take place in the relatively cold upper layers of Brown Dwarfs. For instance, the observed presence of lithium shows that its atmosphere must be different from that of low-mass stars. KELU-1 and the `Dark Matter' From the fact that KELU-1 is so faint that it was barely detectable on the ESO Schmidt plates, it is possible to estimate that the total volume so far surveyed for this type of objects by this research programme is rather small, only about 23 cubic parsecs (800

  13. New remains of the enigmatic cetartiodactyl Bugtitherium grandincisivum Pilgrim, 1908, from the upper Oligocene of the Bugti Hills (Balochistan, Pakistan)

    NASA Astrophysics Data System (ADS)

    Métais, Grégoire; Antoine, Pierre-Olivier; Baqri, Syed Rafiqul Hassan; Benammi, Mouloud; Crochet, Jean-Yves; de Franceschi, Dario; Marivaux, Laurent; Welcomme, Jean-Loup

    2006-07-01

    Newly discovered fossil material of the enigmatic cetartiodactyl Bugtitherium grandincisivum from the upper Oligocene of the Bugti Member of the Chitarwata Formation in the Bugti Hills (Balochistan, Pakistan) is reported. These new specimens consist of two fragmentary muzzles (one preserving the first incisors and belonging to a juvenile) and a fragmentary right mandible with m3. The morphologies of the anterior dentition and m3 provided by these new specimens confirm the validity of the genus Bugtitherium and advocate probable anthracotheriid affinity for the genus rather than entelodontid or suoid affinities, but do not definitively close the debate about Bugtitherium’s familial affinities within Cetartiodactyla. Although still poorly documented, this large-sized anthracotheriid-like cetartiodactyl is a possible key form for understanding the early evolution of hippos, and, in turn, the ancestry of whales, because of both its morphological similarities with hippos and primitive Paleogene whales and its Tethysian distribution.

  14. On the origin of Acochlidia and other enigmatic euthyneuran gastropods, with implications for the systematics of Heterobranchia

    PubMed Central

    2010-01-01

    Background A robust phylogenetic hypothesis of euthyneuran gastropods, as a basis to reconstructing their evolutionary history, is still hindered by several groups of aberrant, more or less worm-like slugs with unclear phylogenetic relationships. As a traditional "order" in the Opisthobranchia, the Acochlidia have a long history of controversial placements, among others influenced by convergent adaptation to the mainly meiofaunal habitats. The present study includes six out of seven acochlidian families in a comprehensive euthyneuran taxon sampling with special focus on minute, aberrant slugs. Since there is no fossil record of tiny, shell-less gastropods, a molecular clock was used to estimate divergence times within Euthyneura. Results Our multi-locus molecular study confirms Acochlidia in a pulmonate relationship, as sister to Eupulmonata. Previous hypotheses of opisthobranch relations, or of a common origin with other meiofaunal Euthyneura, are clearly rejected. The enigmatic amphibious and insectivorous Aitengidae incerta sedis clusters within Acochlidia, as sister to meiofaunal and brackish Pseudunelidae and limnic Acochlidiidae. Euthyneura, Opisthobranchia and Pulmonata as traditionally defined are non-monophyletic. A relaxed molecular clock approach indicates a late Palaeozoic diversification of Euthyneura and a Mesozoic origin of the major euthyneuran diversity, including Acochlidia. Conclusions The present study shows that the inclusion of small, enigmatic groups is necessary to solve deep-level phylogenetic relationships, and underlines that "pulmonate" and "opisthobranch" phylogeny, respectively, cannot be solved independently from each other. Our phylogenetic hypothesis requires reinvestigation of the traditional classification of Euthyneura: morphological synapomorphies of the traditionally defined Pulmonata and Opisthobranchia are evaluated in light of the presented phylogeny, and a redefinition of major groups is proposed. It is demonstrated that

  15. Prdm16 is required for the maintenance of brown adipocyte identity and function in adult mice

    PubMed Central

    Harms, Matthew J.; Ishibashi, Jeff; Wang, Wenshan; Lim, Hee-Woong; Goyama, Susumu; Sato, Tomohiko; Kurokawa, Mineo; Won, Kyoung-Jae; Seale, Patrick

    2014-01-01

    Summary Prdm16 is a transcription factor that regulates the thermogenic gene program in brown and beige adipocytes. However, whether Prdm16 is required for the development or physiological function of brown adipose tissue (BAT) in vivo has been unclear. By analyzing mice that selectively lacked Prdm16 in the brown adipose lineage, we found that Prdm16 was dispensable for embryonic BAT development. However, Prdm16 was required in young mice to suppress the expression of white fat-selective genes in BAT through recruitment of the histone methyltransferase Ehmt1. Additionally, Prdm16-deficiency caused a severe adult-onset decline in the thermogenic character of interscapular BAT. This resulted in BAT dysfunction and cold sensitivity but did not predispose the animals to obesity. Interestingly, the loss of brown fat identity due to ablation of Prdm16 was accelerated by concurrent deletion of the closely related Prdm3 gene. Together, these results show that Prdm16 and Prdm3 control postnatal BAT identity and function. PMID:24703692

  16. Brown Adipose Tissue Growth and Development

    PubMed Central

    Symonds, Michael E.

    2013-01-01

    Brown adipose tissue is uniquely able to rapidly produce large amounts of heat through activation of uncoupling protein (UCP) 1. Maximally stimulated brown fat can produce 300 watts/kg of heat compared to 1 watt/kg in all other tissues. UCP1 is only present in small amounts in the fetus and in precocious mammals, such as sheep and humans; it is rapidly activated around the time of birth following the substantial rise in endocrine stimulatory factors. Brown adipose tissue is then lost and/or replaced with white adipose tissue with age but may still contain small depots of beige adipocytes that have the potential to be reactivated. In humans brown adipose tissue is retained into adulthood, retains the capacity to have a significant role in energy balance, and is currently a primary target organ in obesity prevention strategies. Thermogenesis in brown fat humans is environmentally regulated and can be stimulated by cold exposure and diet, responses that may be further modulated by photoperiod. Increased understanding of the primary factors that regulate both the appearance and the disappearance of UCP1 in early life may therefore enable sustainable strategies in order to prevent excess white adipose tissue deposition through the life cycle. PMID:24278771

  17. MICROLENSING BINARIES WITH CANDIDATE BROWN DWARF COMPANIONS

    SciTech Connect

    Shin, I.-G.; Han, C.; Gould, A.; Skowron, J.; Udalski, A.; Szymanski, M. K.; Kubiak, M.; Soszynski, I.; Pietrzynski, G.; Poleski, R.; Ulaczyk, K.; Pietrukowicz, P.; Kozlowski, S.; Wyrzykowski, L.; Sumi, T.; Dominik, M.; Beaulieu, J.-P.; Tsapras, Y.; Bozza, V.; Abe, F.; Collaboration: OGLE Collaboration; MOA Collaboration; muFUN Collaboration; and others

    2012-12-01

    Brown dwarfs are important objects because they may provide a missing link between stars and planets, two populations that have dramatically different formation histories. In this paper, we present the candidate binaries with brown dwarf companions that are found by analyzing binary microlensing events discovered during the 2004-2011 observation seasons. Based on the low mass ratio criterion of q < 0.2, we found seven candidate events: OGLE-2004-BLG-035, OGLE-2004-BLG-039, OGLE-2007-BLG-006, OGLE-2007-BLG-399/MOA-2007-BLG-334, MOA-2011-BLG-104/OGLE-2011-BLG-0172, MOA-2011-BLG-149, and MOA-201-BLG-278/OGLE-2011-BLG-012N. Among them, we are able to confirm that the companions of the lenses of MOA-2011-BLG-104/OGLE-2011-BLG-0172 and MOA-2011-BLG-149 are brown dwarfs by determining the mass of the lens based on the simultaneous measurement of the Einstein radius and the lens parallax. The measured masses of the brown dwarf companions are 0.02 {+-} 0.01 M {sub Sun} and 0.019 {+-} 0.002 M {sub Sun} for MOA-2011-BLG-104/OGLE-2011-BLG-0172 and MOA-2011-BLG-149, respectively, and both companions are orbiting low-mass M dwarf host stars. More microlensing brown dwarfs are expected to be detected as the number of lensing events with well-covered light curves increases with new-generation searches.

  18. A search for companions to nearby brown dwarfs: the binary DENIS-P J1228.2-1547

    PubMed

    Martin; Brandner; Basri

    1999-03-12

    Hubble Space Telescope imaging observations of two nearby brown dwarfs, DENIS-P J1228.2-1547 and Kelu 1, made with the near-infrared camera and multiobject spectrometer (NICMOS), show that the DENIS object is resolved into two components of nearly equal brightness with a projected separation of 0.275 arc second (5 astronomical units for a distance of 18 parsecs). This binary system will be able to provide the first dynamical measurement of the masses of two brown dwarfs in only a few years. Upper limits to the mass of any unseen companion in Kelu 1 yield a planet of 7 Jupiter masses aged 0. 5 x 10(9) years, which would have been detected at a separation larger than about 4 astronomical units. This example demonstrates that giant planets could be detected by direct imaging if they exist in Jupiter-like orbits around nearby young brown dwarfs. PMID:10073933

  19. Kinematics and luminosities of brown dwarfs with the BDNYC group .

    NASA Astrophysics Data System (ADS)

    Riedel, A. R.

    Due to magnitude limits, the Gaia survey will not delve as deeply into the local population of brown dwarfs as it will other stellar populations. While hundreds or thousands of brown dwarfs will be measured by Gaia, we propose a different, indirect method wherein studies using Gaia data will help teach us about brown dwarfs: Identifying moving groups that contain brown dwarfs. This use of Gaia data will directly help attempts to disentangle the effects of age and mass on brown dwarf spectra, which opens the possibilities for determining empirical constraints on brown dwarf evolution.

  20. Searching for Classical Brown Fat in Humans: Development of a Novel Human Fetal Brown Stem Cell Model.

    PubMed

    Di Franco, Alessandra; Guasti, Daniele; Squecco, Roberta; Mazzanti, Benedetta; Rossi, Francesca; Idrizaj, Eglantina; Gallego-Escuredo, José M; Villarroya, Francesc; Bani, Daniele; Forti, Gianni; Vannelli, Gabriella Barbara; Luconi, Michaela

    2016-06-01

    The potential therapeutic applications of targeting brown adipose tissue open new clinical avenues in fighting against metabolic pathologies. However, due to the limited extension in adult humans of brown depots, which are dramatically reduced after birth, solid cell models to study human brown adipogenesis and its regulatory factors in pathophysiology are urgently needed. Here, we generated a novel human model of brown adipose stem cells, hfB-ASC, derived for the first time from fetal interscapular brown fat depots. Besides the characterization of their stem and classical brown adipose properties, we demonstrated that these cells retain a specific intrinsic differentiation program to functional brown adipocytes, even spontaneously generating organoid structures with brown features. Moreover, for the first time, we investigated the thermogenic and electrophysiological activity of the in vitro-derived fetal brown adipocytes compared to their undifferentiated precursors hfB-ASC, in basal and norepinephrine-induced conditions. In conclusion, from interscapular brown fat of the human fetus we developed and functionally characterized a novel physiological brown adipose stem cell model early programmed to brown differentiation, which may represent a unique opportunity for further studies on brown adipogenesis processes in humans as well as the most suitable target to study novel therapeutic approaches for stimulating brown activity in metabolic pathologies. Stem Cells 2016;34:1679-1691. PMID:26866833

  1. GROWTH OF GRAINS IN BROWN DWARF DISKS

    SciTech Connect

    Meru, Farzana; Galvagni, Marina; Olczak, Christoph

    2013-09-01

    We perform coagulation and fragmentation simulations using the new physically motivated model by Garaud et al. to determine growth locally in brown dwarf disks. We show that large grains can grow and that if brown dwarf disks are scaled-down versions of T Tauri disks (in terms of stellar mass, disk mass, and disk radius) growth at an equivalent location with respect to the disk truncation radius can occur to the same size in both disks. We show that similar growth occurs because the collisional timescales in the two disks are comparable. Our model may therefore potentially explain the recent observations of grain growth to millimeter sizes in brown dwarf disks, as seen in T Tauri disks.

  2. Brown Fat Fuel Utilization and Thermogenesis

    PubMed Central

    Townsend, Kristy L.; Tseng, Yu-Hua

    2014-01-01

    Brown adipose tissue (BAT) dissipates energy as heat to maintain optimal thermogenesis and to contribute to energy expenditure, in rodents and possibly humans. The energetic processes executed by BAT require a readily available fuel supply, which includes glucose and fatty acids (FAs). FAs become available by cellular uptake, de novo lipogenesis, and from multilocular lipid droplets in brown adipocytes. BAT also possesses a great capacity for glucose uptake and metabolism, and an ability to regulate insulin sensitivity. These properties make BAT an appealing target for the treatment of obesity, diabetes and other metabolic disorders. Recent research has revealed a better understanding of the processes of fuel utilization carried out by brown adipocytes, which is the focus of the current review. PMID:24389130

  3. Mitochondria in White, Brown, and Beige Adipocytes

    PubMed Central

    Cedikova, Miroslava; Kripnerová, Michaela; Dvorakova, Jana; Pitule, Pavel; Grundmanova, Martina; Babuska, Vaclav; Mullerova, Dana; Kuncova, Jitka

    2016-01-01

    Mitochondria play a key role in energy metabolism in many tissues, including cardiac and skeletal muscle, brain, liver, and adipose tissue. Three types of adipose depots can be identified in mammals, commonly classified according to their colour appearance: the white (WAT), the brown (BAT), and the beige/brite/brown-like (bAT) adipose tissues. WAT is mainly involved in the storage and mobilization of energy and BAT is predominantly responsible for nonshivering thermogenesis. Recent data suggest that adipocyte mitochondria might play an important role in the development of obesity through defects in mitochondrial lipogenesis and lipolysis, regulation of adipocyte differentiation, apoptosis, production of oxygen radicals, efficiency of oxidative phosphorylation, and regulation of conversion of white adipocytes into brown-like adipocytes. This review summarizes the main characteristics of each adipose tissue subtype and describes morphological and functional modifications focusing on mitochondria and their activity in healthy and unhealthy adipocytes. PMID:27073398

  4. Brown adipogenesis of mouse embryonic stem cells in alginate microstrands

    NASA Astrophysics Data System (ADS)

    Unser, Andrea Mannarino

    The ability of brown adipocytes (fat cells) to dissipate energy as heat shows great promise for the treatment of obesity and other metabolic disorders. Employing pluripotent stem cells, with an emphasis on directed differentiation, may overcome many issues currently associated with primary fat cell cultures. However, brown adipocytes are difficult to transplant in vivo due to the instability of fat, in terms of necrosis and neovascularization, once injected. Thus, 3D cell culture systems that have the potential to mimic adipogenic microenvironments are needed, not only to advance brown fat implantation, but also to better understand the role of brown adipocytes in treating obesity. To address this need, we created 3D "Brown-Fat-in-Microstrands" by microfluidic synthesis of alginate hydrogel microstrands that encapsulated cells and directly induced cell differentiation into brown adipocytes, using mouse embryonic stem cells (ESCs) as a model of pluripotent stem cells and brown preadipocytes as a positive control. The effect of hydrogel formation parameters on brown adipogenesis was studied, leading to the establishment of "Brown-Fat-in-Microstrands". Brown adipocyte differentiation within microstrands was confirmed by lipid droplet accumulation, immunocytochemistry and qPCR analysis of gene expression of brown adipocyte marker uncoupling protein 1 (UCP1) in addition to adipocyte marker expression. Compared to a 2D approach, 3D differentiated "Brown-Fat-in-Microstrands" exhibited higher level of brown adipocyte marker expression. The functional analysis of "Brown-Fat-in-Microstrands" was attempted by measuring the mitochondrial activity of ESC-differentiated brown adipocytes in 3D using Seahorse XF24 3 Extracellular Flux Analyzer. The ability to create "Brown-Fat-in-Microstrands" from pluripotent stem cells opens up a new arena to understanding brown adipogenesis and its implications in obesity and metabolic disorders.

  5. Fuel briquettes from brown coals of Yakutia

    SciTech Connect

    L.A. Nikolaeva; V.G. Latyshev; O.N. Burenina

    2009-04-15

    Experimental data on the development of technology for the manufacture of briquetted fuel from brown coals with the use of various petroleum binders are presented. The influence of the moisture content, the coal particle-size composition, the binder type and concentration, the compacting pressure, and heat treatment regimes on the mechanical properties of the materials was studied. The optimal compositions and optimal values of the engineering parameters for the production of graded briquetted fuel from brown coals of the Kangalassy deposit in the Republic of Sakha (Yakutia) were established.

  6. Hanbury Brown-Twiss interference of anyons.

    PubMed

    Campagnano, Gabriele; Zilberberg, Oded; Gornyi, Igor V; Feldman, Dmitri E; Potter, Andrew C; Gefen, Yuval

    2012-09-01

    We present a study of a Hanbury Brown-Twiss interferometer realized with anyons. Such a device can directly probe entanglement and fractional statistics of initially uncorrelated particles. We calculate Hanbury Brown-Twiss cross correlations of Abelian Laughlin anyons. The correlations we calculate exhibit partial bunching similar to bosons, indicating a substantial statistical transmutation from the underlying electronic degrees of freedom. We also find qualitative differences between the anyonic signal and the corresponding bosonic or fermionic signals, indicating that anyons cannot be simply thought of as intermediate between bosons and fermions. PMID:23005316

  7. Intercohort density dependence drives brown trout habitat selection

    NASA Astrophysics Data System (ADS)

    Ayllón, Daniel; Nicola, Graciela G.; Parra, Irene; Elvira, Benigno; Almodóvar, Ana

    2013-01-01

    Habitat selection can be viewed as an emergent property of the quality and availability of habitat but also of the number of individuals and the way they compete for its use. Consequently, habitat selection can change across years due to fluctuating resources or to changes in population numbers. However, habitat selection predictive models often do not account for ecological dynamics, especially density dependent processes. In stage-structured population, the strength of density dependent interactions between individuals of different age classes can exert a profound influence on population trajectories and evolutionary processes. In this study, we aimed to assess the effects of fluctuating densities of both older and younger competing life stages on the habitat selection patterns (described as univariate and multivariate resource selection functions) of young-of-the-year, juvenile and adult brown trout Salmo trutta. We observed all age classes were selective in habitat choice but changed their selection patterns across years consistently with variations in the densities of older but not of younger age classes. Trout of an age increased selectivity for positions highly selected by older individuals when their density decreased, but this pattern did not hold when the density of younger age classes varied. It suggests that younger individuals are dominated by older ones but can expand their range of selected habitats when density of competitors decreases, while older trout do not seem to consider the density of younger individuals when distributing themselves even though they can negatively affect their final performance. Since these results may entail critical implications for conservation and management practices based on habitat selection models, further research should involve a wider range of river typologies and/or longer time frames to fully understand the patterns of and the mechanisms underlying the operation of density dependence on brown trout habitat

  8. Use of Brown Algae to Demonstrate Natural Products Techniques.

    ERIC Educational Resources Information Center

    Porter, Lee A.

    1985-01-01

    Background information is provided on the natural products found in marine organisms in general and the brown algae in particular. Also provided are the procedures needed to isolate D-mannitol (a primary metabolite) and cholesterol from brown algae. (JN)

  9. DDE in brown and white fat of hibernating bats

    USGS Publications Warehouse

    Clark, D.R., Jr.; Krynitsky, A.J.

    1983-01-01

    Samples of brown and white fat from hibernating bats (big brown bat, Eptesicus fuscus; little brown bat, Myotis lucifugus; and eastern pipistrelle, Pipistrellus subflavus) collected in western Maryland, USA, were analysed to determine lipid and DDE content. Amounts of brown fat, expressed as percentages of total bat weight, were the same for all three species. Lipid content of brown fat was significantly less than that of white fat. Lipids of brown fat contained significantly higher (28%) concentrations of DDE than did lipids of white fat. In our mixed-species sample of 14 bats, concentrations of DDE increased exponentially in both brown and white fat as white fat reserves declined. Brown fat facilitates arousal from hibernation by producing heat through rapid metabolism of triglycerides. The question is raised whether organochlorine residues, such as DDE, may be concentrated and then liberated in lethal amounts by the processes of hibernation and arousal.

  10. 2. OVERALL VIEW OF BROWN DUCK LAKE, LOOKING WEST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. OVERALL VIEW OF BROWN DUCK LAKE, LOOKING WEST - High Mountain Dams in Upalco Unit, Brown Duck Lake Dam, Ashley National Forest, 4.4 miles North of Miners Gulch Campground, Mountain Home, Duchesne County, UT