Rossby wave dynamics of the North Pacific extra-tropical response to El Niño: importance of the basic state in coupled GCMs

The extra-tropical response to El Nino in a "low" horizontal resolution coupled climate model, typical of the Intergovernmental Panel on Climate Change fourth assessment report simulations, is shown to have serious systematic errors. A high resolution configuration of the same model has a much improved response that is similar to observations. The errors in the low resolution model are traced to an incorrect representation of the atmospheric teleconnection mechanism that controls the extra-tropical sea surface temperatures (SSTs) during El Nino. This is due to an unrealistic atmospheric mean state, which changes the propagation characteristics of Rossby waves. These erroneous upper tropospheric circulation anomalies then induce erroneous surface circulation features over the North Pacific. The associated surface wind speed and direction errors create erroneous surface flux and upwelling anomalies which finally lead to the incorrect extra-tropical SST response to El Nino in the low resolution model. This highlights the sensitivity of the climate response to a single link in a chain of complex climatic processes. The correct representation of these processes in the high resolution model indicates the importance of horizontal resolution in resolving such processes

Reconnaissance of the HR 8799 exosolar system. II. Astrometry and orbital motion

This is the final version of the article. Available from the American Astronomical Society / IOP Publishing via the DOI in this record.We present an analysis of the orbital motion of the four substellar objects orbiting HR 8799. Our study relies on the published astrometric history of this system augmented with an epoch obtained with the Project 1640 coronagraph with an integral field spectrograph (IFS) installed at the Palomar Hale telescope. We first focus on the intricacies associated with astrometric estimation using the combination of an extreme adaptive optics system (PALM-3000), a coronagraph, and an IFS. We introduce two new algorithms. The first one retrieves the stellar focal plane position when the star is occulted by a coronagraphic stop. The second one yields precise astrometric and spectrophotometric estimates of faint point sources even when they are initially buried in the speckle noise. The second part of our paper is devoted to studying orbital motion in this system. In order to complement the orbital architectures discussed in the literature, we determine an ensemble of likely Keplerian orbits for HR 8799bcde, using a Bayesian analysis with maximally vague priors regarding the overall configuration of the system. Although the astrometric history is currently too scarce to formally rule out coplanarity, HR 8799d appears to be misaligned with respect to the most likely planes of HR 8799bce orbits. This misalignment is sufficient to question the strictly coplanar assumption made by various authors when identifying a Laplace resonance as a potential architecture. Finally, we establish a high likelihood that HR 8799de have dynamical masses below 13 MJup, using a loose dynamical survival argument based on geometric close encounters. We illustrate how future dynamical analyses will further constrain dynamical masses in the entire system

Direct spectrum of the benchmark t dwarf HD 19467 B

This is the final version of the article. Available from the American Astronomical Society / IOP Publishing via the DOI in this record.HD 19467 B is presently the only directly imaged T dwarf companion known to induce a measurable Doppler acceleration around a solar-type star. We present spectroscopy measurements of this important benchmark object taken with the Project 1640 integral field unit at Palomar Observatory. Our high-contrast R ≈ 30 observations obtained simultaneously across the JH bands confirm the cold nature of the companion as reported from the discovery article and determine its spectral type for the first time. Fitting the measured spectral energy distribution to SpeX/IRTF T dwarf standards and synthetic spectra from BT-Settl atmospheric models, we find that HD 19467 B is a T5.5 ± 1 dwarf with effective temperature Teff = 978+20 -43 K. Our observations reveal significant methane absorption affirming its substellar nature. HD 19467 B shows promise to become the first T dwarf that simultaneously reveals its mass, age, and metallicity independent from the spectrum of light that it emits.The TrenDS high-contrast imaging program is supported by NASA Origins of Solar Systems grant NNX13AB03G and the NASA Early Career Fellowship program. A portion of this work was supported by the National Science Foundation under Grant Numbers AST-0215793, 0334916, 0520822, 0804417 and 1245018. This work was partially supported by NASA ADAP grant 11-ADAP11-0169 and NSF award AST 1211568. A portion of the research in this Letter was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. J.A. is supported by the National Physical Science Consortium. This research has benefitted from the SpeX Prism Spectral Libraries, maintained by Adam Burgasser.1

Technological literacy reconsidered: a model for enactment

The final publication is available at: http://link.springer.com/article/10.1007%2Fs10798-009-9108-6.This paper presents a model to describe technological literacy as enacted by individuals in the course of shaping their lives and the world around them. The model has two interrelated facets – the potential for and enactment of technological literacy – where enactment and potential mutually constitute each other. This potential is made up of knowledge of a particular situation, personal engagement with a situation, and social engagement in the world. Enactment requires a particular set of competencies in action, which together helps shape the situation: recognizing needs; articulating problems; contributing towards the technological process; and analysing consequences. The implications of this model for technological literacy in the context of the individual and society, and the role of technology education in developing technological literacy, are discussed

Project 1640 Observations of Brown Dwarf GJ 758 B: Near-infrared Spectrum and Atmospheric Modeling

The nearby Sun-like star GJ 758 hosts a cold substellar companion, GJ 758 B, at a projected separation of $\lesssim$30 AU, previously detected in high-contrast multi-band photometric observations. In order to better constrain the companion's physical characteristics, we acquired the first low-resolution ($R \sim 50$) near-infrared spectrum of it using the high-contrast hyperspectral imaging instrument Project 1640 on Palomar Observatory's 5-m Hale telescope. We obtained simultaneous images in 32 wavelength channels covering the $Y$, $J$, and $H$ bands ($\sim$952-1770 nm), and used data processing techniques based on principal component analysis to efficiently subtract chromatic background speckle-noise. GJ 758 B was detected in four epochs during 2013 and 2014. Basic astrometric measurements confirm its apparent northwest trajectory relative to the primary star, with no clear signs of orbital curvature. Spectra of SpeX/IRTF observed T dwarfs were compared to the combined spectrum of GJ 758 B, with ${\chi}^2$ minimization suggesting a best fit for spectral type T7.0$\pm$1.0, but with a shallow minimum over T5-T8. Fitting of synthetic spectra from the BT-Settl13 model atmospheres gives an effective temperature $T_{\text{eff}}=741 \pm 25$ K and surface gravity $\log g = 4.3 \pm 0.5$ dex (cgs). Our derived best-fit spectral type and effective temperature from modeling of the low-resolution spectrum suggest a slightly earlier and hotter companion than previous findings from photometric data, but do not rule out current results, and confirm GJ 758 B as one of the coolest sub-stellar companions to a Sun-like star to date

Project 1640 observations of the white dwarf HD 114174 B

We present the rst near infra-red spectrum of the faint white dwarf companion HD 114174 B, obtained with Project 1640. Our spectrum, covering the Y, J and H bands, combined with previous TRENDS photometry measurements, allows us to place fur- ther constraints on this companion. We suggest two possible scenarios; either this ob- ject is an old, low mass, cool H atmosphere white dwarf with Te 3800 K or a high mass white dwarf with Te > 6000 K, potentially with an associated cool (Te 700 K) brown dwarf or debris disk resulting in an infra-red excess in the L0 band. We also provide an additional astrometry point for 2014 June 12 and use the modelled companion mass combined with the RV and direct imaging data to place constraints on the orbital parameters for this companion

Prime movers : mechanochemistry of mitotic kinesins

Mitotic spindles are self-organizing protein machines that harness teams of multiple force generators to drive chromosome segregation. Kinesins are key members of these force-generating teams. Different kinesins walk directionally along dynamic microtubules, anchor, crosslink, align and sort microtubules into polarized bundles, and influence microtubule dynamics by interacting with microtubule tips. The mechanochemical mechanisms of these kinesins are specialized to enable each type to make a specific contribution to spindle self-organization and chromosome segregation

The impact of early emergency department allied health intervention on admission rates in older people: a non-randomized clinical study

<p>Abstract</p> <p>Background</p> <p>This study sought to determine whether early allied health intervention by a dedicated Emergency Department (ED) based team, occurring before or in parallel with medical assessment, reduces hospital admission rates amongst older patients presenting with one of ten index problems.</p> <p>Methods</p> <p>A prospective non-randomized trial in patients aged sixty five and over, conducted in two Australian hospital EDs. Intervention group patients, receiving early comprehensive allied health input, were compared to patients that received no allied health assessment. Propensity score matching was used to compare the two groups due to the non-randomized nature of the study. The primary outcome was admission to an inpatient hospital bed from the ED.</p> <p>Results</p> <p>Of five thousand two hundred and sixty five patients in the trial, 3165 were in the intervention group. The admission rate in the intervention group was 72.0% compared to 74.4% in the control group. Using propensity score probabilities of being assigned to either group in a conditional logistic regression model, this difference was of borderline statistical significance (<it>p </it>= 0.046, OR 0.88 (0.76-1.00)). On subgroup analysis the admission rate in patients with musculoskeletal symptoms and angina pectoris was less for those who received allied health intervention versus those who did not. This difference was significant.</p> <p>Conclusions</p> <p>Early allied health intervention in the ED has a significant but modest impact on admission rates in older patients. The effect appears to be limited to a small number of common presenting problems.</p