Gender differences in paid and unpaid work: findings from a New Zealand birth cohort

This study uses data from a birth cohort of New Zealand-born 30-year-olds to examine gender differences in time use and satisfaction with time use. The specific aims of the study are: to examine gender difference in time spent in paid employment and unpaid work; to examine the extent to which males and females are satisfied with their time use

Temperature dependence of the charge carrier mobility in gated quasi-one-dimensional systems

The many-body Monte Carlo method is used to evaluate the frequency dependent conductivity and the average mobility of a system of hopping charges, electronic or ionic on a one-dimensional chain or channel of finite length. Two cases are considered: the chain is connected to electrodes and in the other case the chain is confined giving zero dc conduction. The concentration of charge is varied using a gate electrode. At low temperatures and with the presence of an injection barrier, the mobility is an oscillatory function of density. This is due to the phenomenon of charge density pinning. Mobility changes occur due to the co-operative pinning and unpinning of the distribution. At high temperatures, we find that the electron-electron interaction reduces the mobility monotonically with density, but perhaps not as much as one might intuitively expect because the path summation favour the in-phase contributions to the mobility, i.e. the sequential paths in which the carriers have to wait for the one in front to exit and so on. The carrier interactions produce a frequency dependent mobility which is of the same order as the change in the dc mobility with density, i.e. it is a comparably weak effect. However, when combined with an injection barrier or intrinsic disorder, the interactions reduce the free volume and amplify disorder by making it non-local and this can explain the too early onset of frequency dependence in the conductivity of some high mobility quasi-one-dimensional organic materials.Comment: 9 pages, 8 figures, to be published in Physical Review

Interferometric Evidence for Resolved Warm Dust in the DQ Tau System

We report on near-infrared (IR) interferometric observations of the double-lined pre-main sequence (PMS) binary system DQ Tau. We model these data with a visual orbit for DQ Tau supported by the spectroscopic orbit & analysis of \citet{Mathieu1997}. Further, DQ Tau exhibits significant near-IR excess; modeling our data requires inclusion of near-IR light from an 'excess' source. Remarkably the excess source is resolved in our data, similar in scale to the binary itself ($\sim$ 0.2 AU at apastron), rather than the larger circumbinary disk ($\sim$ 0.4 AU radius). Our observations support the \citet{Mathieu1997} and \citet{Carr2001} inference of significant warm material near the DQ Tau binary.Comment: 14 pgs, 3 figures, ApJL in pres

Short-term Osteoclastic Activity Induced by Locally High Concentrations of Recombinant Human Bone Morphogenetic Protein–2 in a Cancellous Bone Environment

Study Design. An experimental study investigating osteoclastic activity induced by rhBMP-2 in sheep. Objective. To examine the effects of increasing local rhBMP-2 concentration on osteoclastic response and peri-implant bone resorption. Summary of Background Data. Level I clinical studies have established the safe and effective volume and concentration of rhBMP-2 delivered on an absorbable collagen sponge. However, peri-implant bone resorption appearing as decreased mineral density has been observed radiographically in rare instances after implantation of rhBMP-2 on an absorbable collagen sponge (rhBMP-2/ACS). Methods. Bilateral corticocancellous defects were created in the distal femora of 30 adult sheep. Combinations of rhBMP-2/ACS implant volume (V) (1V = normal fill or 2V = overfilled) and rhBMP-2 solution concentration (⤫) (1 ⤫ normal concentration or 3.5 ⤫ = hyperconcentrated) resulted in local rhBMP-2 concentrations of 0⤫, 1⤫, 2⤫, 3.5⤫, and 7⤫ the estimated effective concentration for this model. Faxitron radiography, quantitative CT, histology, and quantitative histomorphometry were conducted in a blinded fashion to analyze the effect of the treatments. Results. At 1 week, the normal fill-normal concentration implants (1⤫) produced the least transient osteoclastic activity resulting in limited peri-implant resorption. Overfilledhyperconcentrated implants (2⤫, 3.5⤫) demonstrated moderate resorption zones. Overfilled-hyperconcentrated implants (7⤫) demonstrated extensive osteoclastic activity and marked resorption. Results at 4 and 8 weeks revealed dense osteoid and bone in the voids with progressive bony healing. Control defects showed no osteoclastic activity with little to no bony healing. Conclusion. Increasing the local rhBMP-2 concentration by overfilling the defect with rhBMP-2/ACS or hyper-concentrating the rhBMP-2 solution on the absorbable collagen sponge led to a concentration-dependent osteoclastic resorption of peri-implant bone. The osteoclastic effect was transient, and progressive healing took place over the 8-week survival period

The circumbinary disk of HD 98800B: Evidence for disk warping

The quadruple young stellar system HD 98800 consists of two spectroscopic binary pairs with a circumbinary disk around the B component. Recent work by Boden and collaborators using infrared interferometry and radial velocity data resulted in a determination of the physical orbit for HD 98800B. We use the resulting inclination of the binary and the measured extinction toward the B component stars to constrain the distribution of circumbinary material. Although a standard optically and geometrically thick disk model can reproduce the spectral energy distribution, it cannot account for the observed extinction if the binary and the disk are coplanar. We next constructed a dynamical model to investigate the influence of the A component, which is not in the Ba‐Bb orbital plane, on the B disk. We find that these interactions have a substantial impact on the inclination of the B circumbinary disk with respect to the Ba‐Bb orbital plane. The resulting warp would be sufficient to place material into the line of sight and the noncoplanar disk orientation may also cause the upper layers of the disk to intersect the line of sight if the disk is geometrically thick. These simulations also support that the dynamics of the Ba‐Bb orbit clear the inner region to a radius of~3 AU. We then discuss whether the somewhat unusual properties of the HD 98800B disk are consistent with material remnant from the star formation process or with more recent creation by collisions from larger bodies

The Gould's Belt distance survey

Very Long Baseline Interferometry (VLBI) observations can provide the position of compact radio sources with an accuracy of order 50 micro-arcseconds. This is sufficient to measure the trigonometric parallax and proper motions of any object within 500 pc of the Sun to better than a few percent. Because they are magnetically active, young stars are often associated with compact radio emission detectable using VLBI techniques. Here we will show how VLBI observations have already constrained the distance to the most often studied nearby regions of star-formation (Taurus, Ophiuchus, Orion, etc.) and have started to provide information on their internal structure and kinematics. We will then briefly describe a large project (called The Gould's Belt Distance Survey) designed to provide a detailed view of star-formation in the Solar neighborhood using VLBI observations.Comment: To be published in the Revista Mexicana de Astronomia y Astrofisica (Serie de Conferencias

VLBA Determination of the Distance to Nearby Star-forming Regions. IV. A Preliminary Distance to the Proto-Herbig AeBe Star EC 95 in the Serpens Core

Using the Very Long Base Array, we observed the young stellar object EC 95 in the Serpens cloud core at eight epochs from 2007 December to 2009 December. Two sources are detected in our field and are shown to form a tight binary system. The primary (EC 95a) is a 4-5 M_⊙ proto-Herbig AeBe object (arguably the youngest such object known), whereas the secondary (EC 95b) is most likely a low-mass T Tauri star. Interestingly, both sources are non-thermal emitters. While T Tauri stars are expected to power a corona because they are convective while they go down the Hayashi track, intermediate-mass stars approach the main sequence on radiative tracks. Thus, they are not expected to have strong superficial magnetic fields, and should not be magnetically active. We review several mechanisms that could produce the non-thermal emission of EC 95a and argue that the observed properties of EC 95a might be most readily interpreted if it possessed a corona powered by a rotation-driven convective layer. Using our observations, we show that the trigonometric parallax of EC 95 is π = 2.41 ± 0.02 mas, corresponding to a distance of 414.9^(+4.4)_ (–4.3) pc. We argue that this implies a distance to the Serpens core of 415 ± 5 pc and a mean distance to the Serpens cloud of 415 ± 25 pc. This value is significantly larger than previous estimates (d ~ 260 pc) based on measurements of the extinction suffered by stars in the direction of Serpens. A possible explanation for this discrepancy is that these previous observations picked out foreground dust clouds associated with the Aquila Rift system rather than Serpens itself

The experiences of inpatient nursing staff caring for young people with early psychosis

Background: Early intervention services aim to improve outcomes for people with first episode psychosis and, where possible, to prevent psychiatric hospital admission. When hospitalisation does occur, inpatient staff are required to support patients and families who may be less familiar with services, uncertain about possible outcomes, and may be experiencing a psychiatric hospital for the first time. Aims: Our study aimed to understand the process of hospitalisation in early psychosis, from the perspective of inpatient nursing staff. We were particularly interested in their experiences of working with younger people in the context of adult psychiatric wards. Methods: Nine inpatient nursing staff took part in semi-structured interviews, which were transcribed and then analysed using interpretative phenomenological analysis. Results: Five themes are outlined: ‘it’s all new and it’s all learning’; the threatening, unpredictable environment; care and conflict within the intergenerational relationship; motivation and hope; and coping and self-preservation. Conclusions: The phenomenological focus of our approach throws the relational component of psychiatric nursing into sharp relief. We reflect on the implications for organisations, staff, families and young people. We suggest that the conventional mode of delivering acute psychiatric inpatient care is not likely to support the best relational and therapeutic outcomes