738 research outputs found
A Dynamical Study of the Non-Star Forming Translucent Molecular Cloud MBM16: Evidence for Shear Driven Turbulence in the Interstellar Medium
We present the results of a velocity correlation study of the high latitude
cloud MBM16 using a fully sampled CO map, supplemented by new CO
data. We find a correlation length of 0.4 pc. This is similar in size to the
formaldehyde clumps described in our previous study. We associate this
correlated motion with coherent structures within the turbulent flow. Such
structures are generated by free shear flows. Their presence in this non-star
forming cloud indicates that kinetic energy is being supplied to the internal
turbulence by an external shear flow. Such large scale driving over long times
is a possible solution to the dissipation problem for molecular cloud
turbulence.Comment: Uses AAS aasms4.sty macros. Accepted for publication in Ap
Scalp psoriasis associated with central centrifugal cicatricial alopecia
AbstractScalp psoriasis is a very common dermatological condition with a variety of presentations, but only rarely presents as severe alopecia. We present a case of a 50-year-old female with many years of recalcitrant hair loss that was thought to be secondary to central centrifugal cicatricial alopecia which was later diagnosed as psoriasis. This case highlights an interesting presentation and rare complication of a common disease
Oligomerization of Bacterially Expressed H1N1 Recombinant Hemagglutinin Contributes to Protection Against Viral Challenge
Vaccination is the most effective intervention to prevent influenza and control the spread of the virus. Alternatives are needed to the traditional egg-based vaccine strategy for a more rapid response to new outbreaks. Two different hemagglutinin (HA) fragments (rHA11-326 and rHA153-269) derived from influenza A virus subtype H1N1 were expressed in Escherichia coli and characterized by immunoblot, gel filtration, hemagglutination, and competitive binding assays. rHA11-326 included neutralizing epitopes and the trimerization domain, whereas rHA153-269 included only the head of HA with the neutralizing epitopes. Mice were immunized with rHA11-326 or rHA153-269, and sera were tested for the presence of neutralizing antibodies. Mice were then challenged with H1N1 and infection severity was monitored. rHA11-326 trimerized, whereas rHA153-269 was unable to form oligomers. Both rHA11-326 and rHA153-269 elicited the production of neutralizing antibodies, but only oligomerized rHA11-326 protected against live virus challenges in mice. This study demonstrated that bacterially expressed HA was capable of folding properly and eliciting the production of neutralizing antibodies, and that HA oligomerization contributed to protection against viral challenge. Therefore, prokaryotic-derived vaccine platforms can provide antigenic and structural requirements for viral protection, as well as allow for the rapid and cost-effective incorporation of multiple antigens for broader protection
California Solar Regatta
This Final Design Review report details the research, analysis, and design conducted by a Cal Poly Mechanical Engineering senior project team working on the propulsion system for a solar powered boat. Working in coordination with another senior project team responsible for making the hull, the two teams comprised the Cal Poly team who entered the Sacramento Municipal Utility District (SMUD) 2020 California Solar Regatta Competition. The SMUD Solar Regatta is an annual competition for high school and college students to design and build boats powered by solar power. The solar panels are provided by SMUD, and the battery storage is limited by competition regulations. The scope of this project was to design a propulsion system that would efficiently transfer energy, be easily integrated into the hull design and be competitive in the three races: endurance, slalom, and sprint. This document covers research conducted, objectives for the design, design concepts considered, the chosen final design, manufacturing and verification plans, and project management
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Admittance measurement for tuning bi-ventricular pacemakers
An apparatus for treating a heart of a patient includes a first lead and at least a second lead for pacing the heart adapted to be in electrical communication with the heart. The apparatus includes a microcontroller in communication with the first and second leads which triggers the first lead at either different times or the same time from when the microcontroller triggers the second lead. Alternatively, the apparatus includes a microcontroller in communication with the first and second leads that determines heart volume, including stroke volume, end-systolic volume, and calculated values including ejection fraction, from admittance from signals from the first and second leads and uses the admittance as feedback to control heart volume ejected, as measured by stroke volume, calculated values such as ejection fraction, and control end-systolic volume, with respect to the first and second leads. A method for treating the heart of a patient.Board of Regents, University of Texas Syste
Star Formation in Cold, Spherical, Magnetized Molecular Clouds
We present an idealized, spherical model of the evolution of a magnetized
molecular cloud due to ambipolar diffusion. This model allows us to follow the
quasi-static evolution of the cloud's core prior to collapse and the subsequent
evolution of the remaining envelope. By neglecting the thermal pressure
gradients in comparison with magnetic stresses and by assuming that the ion
velocity is small compared with the neutral velocity, we are able to find exact
analytic solutions to the MHD equations. We show that, in the case of a
centrally condensed cloud, a core of finite mass collapses into the origin
leaving behind a quasi-static envelope, whereas initially homogeneous clouds
never develop any structure in the absence of thermal stresses, and collapse as
a whole. Prior to the collapse of the core, the cloud's evolution is
characterized by two phases: a long, quasi-static phase where the relevant
timescale is the ambipolar diffusion time (treated in this paper), and a short,
dynamical phase where the characteristic timescale is the free-fall time. The
collapse of the core is an "outside-in" collapse. The quasi-static evolution
terminates when the cloud becomes magnetically supercritical; thereafter its
evolution is dynamical, and a singularity develops at the origin-a protostar.
After the initial formation of the protostar, the outer envelope continues to
evolve quasi-statically, while the region of dynamical infall grows with
time-an "inside-out" collapse. We use our solution to estimate the magnetic
flux trapped in the collapsing core and the mass accretion rate onto the newly
formed protostar. Our results agree, within factors of order unity, with the
numerical results of Fiedler & Mouschovias (1992) for the physical quantities
in the midplane ofComment: 18 postscript figures Accepted by The Astrophysical Journa
Altruism, Commitment, and Leadership in High School Mentors
This study investigated the effects of mentoring on selected attributes among high school mentors. Three attributes were explored: altruism, commitment to school, and student leadership. Seventy-four high school juniors and seniors participated as mentors to high school freshmen students. Mentors participated in a leadership training program prior to beginning their mentoring activities. Pre- and post-test measures of the three attributes were administered. Results showed no significant increase in altruism or commitment scores. Unexpectedly, the mentoring experience produced a significant decrease in the perception of leadership scores. Implications for implementing a mentoring program in a high school setting are discussed
Altruism, Commitment, and Leadership in High School Mentors
This study investigated the effects of mentoring on selected attributes among high school mentors. Three attributes were explored: altruism, commitment to school, and student leadership. Seventy-four high school juniors and seniors participated as mentors to high school freshmen students. Mentors participated in a leadership training program prior to beginning their mentoring activities. Pre- and post-test measures of the three attributes were administered. Results showed no significant increase in altruism or commitment scores. Unexpectedly, the mentoring experience produced a significant decrease in the perception of leadership scores. Implications for implementing a mentoring program in a high school setting are discussed
Quantitative Trait Loci (QTL) for Forage Traits in Intermediate Wheatgrass When Grown as Spaced-Plants versus Monoculture and Polyculture Swards
It has been hypothesized that the genetic control of forage traits, especially biomass, for grass plants growing as spaced-plants versus swards is different. Likewise, the genetic control of compatibility in grassâlegume polyculture mixtures is assumed to be different than for forage production in a grass monoculture. However, these hypotheses are largely unvalidated, especially at the DNA level. This study used an intermediate wheatgrass mapping population to examine the effect of three competition environments (spaced-plants, polyculture, and monoculture) on classical quantitative genetic parameters and quantitative trait loci (QTL) identification for biomass, morphology, and forage nutritive value. Moderate to high heritable variation was observed for biomass, morphological traits, and nutritive value within all three environments (H ranged from 0.50 to 0.87). Genetic correlations (rG) among environments for morphology and nutritive value were predominantly high, however, were moderately-low (0.30 to 0.48) for biomass. Six biomass QTL were identified, including three on linkage groups (LG) 1, 6, and 15 that were only expressed in the monoculture environment. Moreover, three biomass QTL on LG 10, 14, and 15 exhibited significant QTL by environment interactions. This study verified that the genetic control of grass biomass in a monoculture versus a grassâlegume mixture is only partially the same, with additional genes expressed in monoculture, and that biomass in widely spaced-plants versus swards is predominantly under different genetic control. These results indicate that selection for improved grass biomass will be most successful when conducted within the targeted monoculture or polyculture sward environment per se
A Mixture of LBG Overdensities in the Fields of Three Quasars: Implications for the Robustness of Photometric Selection
The most luminous quasars at are suspected to be both highly
clustered and reside in the most massive dark matter halos in the early
Universe, making them prime targets to search for galaxy overdensities and/or
protoclusters. We search for Lyman-break dropout-selected galaxies using HST
WFC3/ACS broadband imaging in the fields of three quasars, as well
as their simultaneously observed coordinated-parallel fields, and constrain
their photometric redshifts using EAZY. One field, J0305-3150, shows a volume
density 10 higher than the blank-field UV luminosity function (UVLF) at
M, with tentative evidence of a 3 overdensity in its
parallel field located 15 cMpc away. Another field, J2054-0005, shows an
angular overdensity within 500 ckpc from the quasar but still consistent with
UVLF predictions within 3, while the last field, J2348-3054, shows no
enhancement. We discuss methods for reducing uncertainty in overdensity
measurements when using photometric selection and show that we can robustly
select LBGs consistent with being physically associated with the quasar,
corroborated by existing JWST/NIRCam WFSS data in the J0305 field. Even
accounting for incompleteness, the overdensities in J0305 and J2054 are higher
for brighter galaxies at short angular separations, suggesting preferential
enhancement of more massive galaxies in the immediate vicinity of the quasar.
Finally, we compare the LBG population with previously-identified [CII] and
mm-continuum companions; the LBG overdensities are not accompanied by an
enhanced number of dusty galaxies, suggesting that the overdense quasar fields
are not in the bursty star-forming phase sometimes seen in high-redshift
protoclusters.Comment: 22 pages (main text), 12 figures, 10 tables, 2 appendices. Final
version after addressing referee report, accepted to ApJ May 202
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