496 research outputs found
Palmetto Ave
This novel takes place in present-day Florida. Each chapter represents a different point of view from each family member as well as those people outside of the family. The Hewitt family faces several trying times, including the mental illness of their mother, abuse within the family, coming of age, and learning how to love not only oneself, but also how to love others.
A work of fiction by Rachel M. Wootten
A Proper Motion Study of the Haro 6-10 Outflow: Evidence for a Subarcsecond Binary
We present single-dish and VLBI observations of an outburst of water maser
emission from the young binary system Haro 6-10. Haro 6-10 lies in the Taurus
molecular cloud and contains a visible T Tauri star with an infrared companion
1.3" north. Using the Very Long Baseline Array, we obtained five observations
spanning 3 months and derived absolute positions for 20 distinct maser spots.
Three of the masers can be traced over 3 or more epochs, enabling us to extract
absolute proper motions and tangential velocities. We deduce that the masers
represent one side of a bipolar outflow that lies nearly in the plane of the
sky with an opening angle of ~45\deg. They are located within 50 mas of the
southern component of the binary, the visible T Tauri star Haro 6-10S. The mean
position angle on the sky of the maser proper motions (~220\deg) suggests they
are related to the previously observed giant Herbig-Haro (HH) flow which
includes HH410, HH411, HH412, and HH184A-E. A previously observed HH jet and
extended radio continuum emission (mean position angle of ~190\deg) must also
originate in the vicinity of Haro6-10S and represent a second, distinct outflow
in this region. We propose that a yet unobserved companion within 150 mas of
Haro6-10S is responsible for the giant HH/maser outflow while the visible star
is associated with the HH jet. Despite the presence of H_2 emission in the
spectrum of the northern component of the binary, Haro6-10N, none of
outflows/jets can be tied directly to this young stellar object
CH2D+, the Search for the Holy Grail
CH2D+, the singly deuterated counterpart of CH3+, offers an alternative way
to mediate formation of deuterated species at temperatures of several tens of
K, as compared to the release of deuterated species from grains. We report a
longstanding observational search for this molecular ion, whose rotational
spectroscopy is not yet completely secure. We summarize the main spectroscopic
properties of this molecule and discuss the chemical network leading to the
formation of CH2D+, with explicit account of the ortho/para forms of H2, H3+
and CH3+. Astrochemical models support the presence of this molecular ion in
moderately warm environments at a marginal level.Comment: 25 pages, 6 Figures Accepted in Journal of Physical Chemistry A. "Oka
Festschrift: Celebrating 45 years of Astrochemistry
HCOOCH3 as a probe of temperature and structure of Orion-KL
We studied the O-bearing molecule HCOOCH3 to characterize the physical
conditions of the different molecular source components in Orion-KL. We
identify 28 methyl formate emission peaks throughout the 50" field of
observations. The two strongest peaks are in the Compact Ridge (MF1) and in the
SouthWest of the Hot Core (MF2). Spectral confusion is still prevailing as half
of the expected transitions are blended over the region. Assuming that the
transitions are thermalized, we derive the temperature at the five main
emission peaks. At the MF1 position we find a temperature of 80K in a 1.8"x0.8"
beam size and 120K on a larger scale (3.6" x2.2"), suggesting an external
source of heating, whereas the temperature is about 130K at the MF2 position on
both scales. Transitions of HCOOCH3 in vt=1 are detected as well and the good
agreement of the positions on the rotational diagrams between the vt=0 and the
vt=1 transitions suggests a similar temperature. The velocity of the gas is
between 7.5 and 8.0km/s depending on the positions and column density peaks
vary from 1.6x10^16 to 1.6x10^17cm^-2. A second velocity component is observed
around 9-10 km/s in a North-South structure stretching from the Compact Ridge
up to the BN object; this component is warmer at the MF1 peak. The two other
C2H4O2 isomers are not detected and the derived upper limit for the column
density is <3x10^14cm^-2 for glycolaldehyde and <2x10^15cm^-2 for acetic acid.
From the 223GHz continuum map, we identify several dust clumps with associated
gas masses in the range 0.8 to 5.8Msun. Assuming that the HCOOCH3 is spatially
distributed as the dust, we find relative abundances of HCOOCH3 in the range
<0.1x10^-8 to 5.2x10^-8. We suggest a relation between the methyl formate
distribution and shocks as traced by 2.12 mum H2 emission.Comment: Accepted for publication in A&
Exploring Ligand Binding to Calcitonin Gene-Related Peptide Receptors
Class B1 G protein-coupled receptors (GPCRs) are important targets for many diseases, including cancer, diabetes, and heart disease. All the approved drugs for this receptor family are peptides that mimic the endogenous activating hormones. An understanding of how agonists bind and activate class B1 GPCRs is fundamental for the development of therapeutic small molecules. We combined supervised molecular dynamics (SuMD) and classic molecular dynamics (cMD) simulations to study the binding of the calcitonin gene-related peptide (CGRP) to the CGRP receptor (CGRPR). We also evaluated the association and dissociation of the antagonist telcagepant from the extracellular domain (ECD) of CGRPR and the water network perturbation upon binding. This study, which represents the first example of dynamic docking of a class B1 GPCR peptide, delivers insights on several aspects of ligand binding to CGRPR, expanding understanding of the role of the ECD and the receptor-activity modifying protein 1 (RAMP1) on agonist selectivity
ALMA and VLA Observations: Evidence for Ongoing Low-mass Star Formation near Sgr A*
Using the VLA, we recently detected a large number of protoplanetary disk
(proplyd) candidates lying within a couple of light years of the massive black
hole Sgr A*. The bow-shock appearance of proplyd candidates point toward the
young massive stars located near Sgr A*. Similar to Orion proplyds, the strong
UV radiation from the cluster of massive stars at the Galactic center is
expected to photoevaporate and photoionize the circumstellar disks around
young, low mass stars, thus allowing detection of the ionized outflows from the
photoionized layer surrounding cool and dense gaseous disks. To confirm this
picture, ALMA observations detect millimeter emission at 226 GHz from five
proplyd candidates that had been detected at 44 and 34 GHz with the VLA. We
present the derived disk masses for four sources as a function of the assumed
dust temperature. The mass of protoplanetary disks from cool dust emission
ranges between 0.03 -- 0.05 solar mass. These estimates are consistent with the
disk masses found in star forming sites in the Galaxy. These measurements show
the presence of on-going star formation with the implication that gas clouds
can survive near Sgr A* and the relative importance of high vs low-mass star
formation in the strong tidal and radiation fields of the Galactic center.Comment: 13 pages, 3 figures, MNRAS (in press
Efficient transformation of germinating Neurospora conidia using total nuclear DNA fragments.
Efficient transformation of germinating Neurospora conidia using total nuclear DNA fragments
Proper Motion of H2O Masers in IRAS 20050+2720 MMS1: An AU Scale Jet Associated with An Intermediate-Mass Class 0 Source
We conducted a 4 epoch 3 month VLBA proper motion study of HO masers
toward an intermediate-mass class 0 source IRAS 20050+2720 MMS1 (d=700 pc).
From milli-arcsecond (mas) resolution VLBA images, we found two groups of H2O
maser spots at the center of the submillimeter core of MMS1. One group consists
of more than intense maser spots; the other group consisting of
several weaker maser spots is located at 18 AU south-west of the intense group.
Distribution of the maser spots in the intense group shows an arc-shaped
structure which includes the maser spots that showed a clear velocity gradient.
The spatial and velocity structures of the maser spots in the arc-shape did not
significantly change through the 4 epochs. Furthermore, we found a relative
proper motion between the two groups. Their projected separation increased by
1.13+/-0.11 mas over the 4 epochs along a line connecting them. The spatial and
velocity structures of the intense group and the relative proper motions
strongly suggest that the maser emission is associated with a protostellar jet.
Comparing the observed LSR velocities with calculated radial velocities from a
simple biconical jet model, we conclude that the most of the maser emission are
likely to be associated with an accelerating biconical jet which has large
opening angle. The large opening angle of the jet traced by the masers would
support the hypothesis that poor jet collimation is an inherent property of
luminous (proto)stars.Comment: 14 pages, 10 figures, Fig.3 was downsized significantly. accepted for
publication in A&
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