The Rotation of Young Low-Mass Stars and Brown Dwarfs

We review the current state of our knowledge concerning the rotation and angular momentum evolution of young stellar objects and brown dwarfs from a primarily observational view point. Periods are typically accurate to 1% and available for about 1700 stars and 30 brown dwarfs in young clusters. Discussion of angular momentum evolution also requires knowledge of stellar radii, which are poorly known for pre-main sequence stars. It is clear that rotation rates at a given age depend strongly on mass; higher mass stars (0.4-1.2 M$_\odot$) have longer periods than lower mass stars and brown dwarfs. On the other hand, specific angular momentum is approximately independent of mass for low mass pre-main sequence stars and young brown dwarfs. A spread of about a factor of 30 is seen at any given mass and age. The evolution of rotation of solar-like stars during the first 100 Myr is discussed. A broad, bimodal distribution exists at the earliest observable phases ($\sim$1 Myr) for stars more massive than 0.4 M$_\odot$. The rapid rotators (50-60% of the sample) evolve to the ZAMS with little or no angular momentum loss. The slow rotators continue to lose substantial amounts of angular momentum for up to 5 Myr, creating the even broader bimodal distribution characteristic of 30-120 Myr old clusters. Accretion disk signatures are more prevalent among slowly rotating PMS stars, indicating a connection between accretion and rotation. Disks appear to influence rotation for, at most, $\sim$5 Myr, and considerably less than that for the majority of stars. If the dense clusters studied so far are an accurate guide, then the typical solar-like star may have only $\sim$1 Myr for this task. It appears that both disk interactions and stellar winds are less efficient at braking these objects.Comment: Review chapter for Protostars and Planets V. 15 page and 8 figure

Alien Registration- Mundt, Fred A. (Bethel, Oxford County)

https://digitalmaine.com/alien_docs/13235/thumbnail.jp

Functionalization of Indium-Based Quantum Dots for Use as a Non-Viral Gene Therapy Vector

This work aims to develop functionalized, water-soluble indium-based quantum dots (QDs) as a non-viral gene therapy vector. The QDs were solubilized in water by exchanging native hydrophobic surface ligands with 11-mercaptoundecanioc acid (MUA); an amphiphilic ligand providing terminal carboxylate groups that impart water solubility to the QDs. The aqueous QDs were then functionalized with a terminal tertiary amine to impart a positive surface charge, allowing negatively-charged DNA to complex with the nanoparticles. The QDs were characterized via electrophoresis to determine their ability to bind DNA. Results show that further work is needed to optimize DNA binding. In addition, this work explores QD bioconjugation with lactose as an intracellular targeting molecule, to direct QD complexes to the cellular nucleus. Conjugation with lactose was confirmed via nuclear magnetic resonance (NMR) spectroscopy. QD probes trafficking in N2a (mouse neuroblastoma) cells was visualized using fluorescence microscopy and immunocytochemistry (ICC). The images were analyzed via Manders’ coefficient to determine the degree of QD colocalization with different organelles inside the cell. Results proved inconclusive due to instrumental limitations

Kinematics and the origin of the internal structures in HL Tau jet (HH 151)

Knotty structures of Herbig-Haro jets are common phenomena, and knowing the origin of these structures is essential for understanding the processes of jet formation. Basically, there are two theoretical approaches: different types of instabilities in stationary flow, and velocity variations in the flow. We investigate the structures with different radial velocities in the knots of the HL Tau jet as well as its unusual behaviour starting from 20 arcsec from the source. Collation of radial velocity data with proper motion measurements of emission structures in the jet of HL Tau makes it possible to understand the origin of these structures and decide on the mechanism for the formation of the knotty structures in Herbig-Haro flows. We present observations obtained with a 6 m telescope (Russia) using the SCORPIO camera with scanning Fabry-Perot interferometer. Two epochs of the observations of the HL/XZ Tau region in Halpha emission (2001 and 2007) allowed us to measure proper motions for high and low radial velocity structures. The structures with low and high radial velocities in the HL Tau jet show the same proper motion. The point where the HL Tau jet bents to the north (it coincides with the trailing edge of so-called knot A) is stationary, i.e. does not have any perceptible proper motion and is visible in Halpha emission only. We conclude that the high- and low- velocity structures in the HL Tau jet represent bow-shocks and Mach disks in the internal working surfaces of episodic outflows. The bend of the jet and the brightness increase starting some distance from the source coincides with the observed stationary deflecting shock. The increase of relative surface brightness of bow-shocks could be the result of the abrupt change of the physical conditions of the ambient medium as well as the interaction of a highly collimated flow and the side wind from XZ Tau.Comment: To be published in Astronomy and Astrophysic

The Mass Dependence of Stellar Rotation in the Orion Nebula Cluster

We have determined new rotation periods for 404 stars in the Orion Nebula Cluster using the Wide Field Imager attached to the MPG/ESO 2.2 m telescope on La Silla, Chile. Mass estimates are available for 335 of these and most have M < 0.3 M_sun. We confirm the existence of a bimodal period distribution for the higher mass stars in our sample and show that the median rotation rate decreases with increasing mass for stars in the range 0.1 < M <0.4 M_sun. While the spread in angular momentum (J) at any given mass is more than a factor of 10, the majority of lower mass stars in the ONC rotate at rates approaching 30% of their critical break-up velocity, as opposed to 5-10% for solar-like stars. This is a consequence of both a small increase in observed specific angular momentum (j=J/M) and a larger decrease in the critical value of j with decreasing mass. Perhaps the most striking fact, however, is that j varies by so little - less than a factor of two - over the interval 0.1-1.0 M_sun. The distribution of rotation rates with mass in the ONC (age ~ 1 My) is similar in nature to what is found in the Pleiades (age ~ 100 My). These observations provide a significant new guide and test for models of stellar angular momentum evolution during the proto-stellar and pre-main sequence phases.Comment: 11 pages, 3 figure

Photoelectron spectra of anionic sodium clusters from time-dependent density-functional theory in real-time

We calculate the excitation energies of small neutral sodium clusters in the framework of time-dependent density-functional theory. In the presented calculations, we extract these energies from the power spectra of the dipole and quadrupole signals that result from a real-time and real-space propagation. For comparison with measured photoelectron spectra, we use the ionic configurations of the corresponding single-charged anions. Our calculations clearly improve on earlier results for photoelectron spectra obtained from static Kohn-Sham eigenvalues

Effects of planting density and the composition of wheat cultivar mixtures on stripe rust: an analysis taking into account limits to the replication of controls

The effect of plant density on disease is not well understood in populations of a single host plant genotype and has been studied even less in mixtures of host genotypes. We performed an experiment to evaluate the effect of wheat planting density on infection by Puccinia striiformis in experimental plots with a single wheat genotype and in plots with two genotypes making up a range of frequencies. Stripe rust severity in single-genotype plots increased with planting density in 1997 but decreased with planting density in 1998. Disease in host mixtures was compared to the weighted mean of disease levels in the corresponding single-genotype plots. The design of the field experiment included limited replication of these reference treatments (that is, there was not a unique pair of single-genotype plots for each mixture plot); therefore, we devised an analysis based on collapsing the data into independent mean observations. Disease reduction due to host diversity was less when one genotype predominated than when both host genotypes were present at nearly equal frequencies. The greatest mean host-diversity effect for reduced disease was at the intermediate planting density of 250 seeds per m2

Relationship between HER2 expression and efficacy with first-line trastuzumab emtansine compared with trastuzumab plus docetaxel in TDM4450g: a randomized phase II study of patients with previously untreated HER2-positive metastatic breast cancer.

IntroductionThe purpose of this study was to retrospectively explore the relationship between human epidermal growth factor receptor 2 (HER2) messenger RNA (mRNA) expression and efficacy in patients receiving trastuzumab plus docetaxel (HT) or trastuzumab emtansine (T-DM1).MethodsPatients with HER2-positive, locally advanced or metastatic breast cancer (MBC) were randomly assigned to HT (n=70) or T-DM1 (n=67). HER2 status was assessed locally using immunohistochemistry or fluorescence in situ hybridization and confirmed retrospectively by central testing. HER2 mRNA expression was assessed using quantitative reverse transcriptase polymerase chain reaction.ResultsHER2 mRNA levels were obtained for 116/137 patients (HT=61; T-DM1=55). Median pretreatment HER2 mRNA was 8.9. The risk of disease progression in the overall population was lower with T-DM1 than with HT (hazard ratio (HR)=0.59; 95% confidence interval (CI) 0.36 to 0.97). This effect was more pronounced in patients with HER2 mRNA≥median (HR=0.39; 95% CI 0.18 to 0.85) versus ConclusionsThis exploratory analysis suggests that while overall, patients with HER2-positive MBC show improved PFS with T-DM1 relative to HT, the effect is enhanced in patients with tumor HER2 mRNA ≥ median.Trial registrationClinicalTrials.gov NCT00679341

Natural Coronagraphic Observations of the Eclipsing T Tauri System KH 15D: Evidence for Accretion and Bipolar Outflow in a WTTS

We present high resolution (R $\sim$ 44,000) UVES spectra of the eclipsing pre-main sequence star KH 15D covering the wavelength range 4780 to 6810 {\AA} obtained at three phases: out of eclipse, near minimum light and during egress. The system evidently acts like a natural coronagraph, enhancing the contrast relative to the continuum of hydrogen and forbidden emission lines during eclipse. At maximum light the H$\alpha$ equivalent width was $\sim$2 {\AA} and the profile showed broad wings and a deep central absorption. During egress the equivalent width was much higher ($\sim$70 {\AA}) and the broad wings, which extend to $\pm$ 300 km/s, were prominent. During eclipse totality the equivalent width was less than during egress ($\sim$40 {\AA}) and the high velocity wings were much weaker. H$\beta$ showed a somewhat different behavior, revealing only the blue-shifted portion of the high velocity component during eclipse and egress. [OI] $\lambda\lambda$6300, 6363 lines are easily seen both out of eclipse and when the photosphere is obscured and exhibit little or no flux variation with eclipse phase. Our interpretation is that KH 15D, although clearly a weak-line T Tauri star by the usual criteria, is still accreting matter from a circumstellar disk, and has a well-collimated bipolar jet. As the knife-edge of the occulting matter passes across the close stellar environment it is evidently revealing structure in the magnetosphere of this pre-main sequence star with unprecedented spatial resolution. We also show that there is only a small, perhaps marginally significant, change in the velocity of the K7 star between the maximum light and egress phases probed here