Chemical modeling of the L1498 and L1517B prestellar cores: CO and HCO+ depletion

Prestellar cores exhibit a strong chemical differentiation, which is mainly caused by the freeze-out of molecules onto the grain surfaces. Understanding this chemical structure is important, because molecular lines are often used as probes to constrain the core physical properties. Here we present new observations and analysis of the C18O (1-0) and H13CO+ (1-0) line emission in the L1498 and L1517B prestellar cores, located in the Taurus-Auriga molecular complex. We model these observations with a detailed chemistry network coupled to a radiative transfer code. Our model successfully reproduces the observed C18O (1-0) emission for a chemical age of a few 10^5 years. On the other hand, the observed H13CO+ (1-0) is reproduced only if cosmic-ray desorption by secondary photons is included, and if the grains have grown to a bigger size than average ISM grains in the core interior. This grain growth is consistent with the infrared scattered light ("coreshine") detected in these two objects, and is found to increase the CO abundance in the core interior by about a factor four. According to our model, CO is depleted by about 2-3 orders of magnitude in the core center.Comment: Accepted for publication in A&

Mind the Gap: The Equality Bill and Sharia Arbitration in the United Kingdom

The observance of Sharia principles in Islamic arbitration tribunals operating in the United Kingdom has been heralded for its ability to provide Muslim communities with internal, community-based fora for dispute resolution. Although the judgments issued by these faith-based arbitration tribunals lack binding legal authority, British lawmakers ex-press concerns centered on threats to the existing national legal system and to England’s deeply rooted social policy of equality and non-discrimination. Introduced to address these concerns in 2011, the Equality Bill proposes a legislative solution to further maintain the principle of equality within alternative dispute resolution channels. This Note argues that, despite the Equality Bill’s laudable effort to curb discrimination and violations of England’s policy of equality, legislative reform alone will be unlikely to affect the Bill’s desired goals

Pathophysiology and clinical implications of lower respiratory tract infection (LRTI) with respiratory enteric orphan virus (reovirus): Background and experimental evidence

Background. Respiratory viral infection early in life is a predominant factor in the inception of episodic wheezing and development of asthma amongst young children [1] and a serious health challenge. Previous studies of lower respiratory tract infections (LRTI) with respiratory syncytial virus (RSV) in animal models have indicated that early life viral exposure results in dysregulated neuroimmune interactions and altered synthesis/release of pro-inflammatory neuropeptides generating increased airway reactivity and neurogenic-inflammation. Similar to RSV, respiratory enteric orphan virus (Reovirus) is a common respiratory pathogen associated with pulmonary infections in children. Also, reovirus pulmonary infection has been shown to induce increased collagen deposition and be associated with the pathogenesis of bronchiolitis obliterans with organizing pneumonia (BOOP). In this study, we investigated the effects of reovirus exposure on physiological airway responses and whether these responses were associated with neurogenic inflammation and airway remodeling.;Methods. Adult (12 weeks) and weanling (2 weeks) Fisher-344 (F-344) rats were infected with reovirus or a pathogen-free vehicle and the changes in airway vascular permeability, neurotrophin expression, inflammatory response and protein content were measured at either 5 or 30 days after infection to determine changes in neurogenic inflammation and airway remodeling.;Results. Neurogenic inflammation increased in all treated animals 5 days after inoculation and up to 30 days in adult rats. This effect was not associated with any changes in nerve growth factor (NGF) and brain-derived neurotrphic factor (BDNF) expression in any animals at both time points. All treated animals developed acute pneumonia which resolved at 30 days. However, weanling rats showed mild peri-alveolar fibrosis at 30 days.;Conclusions. Reovirus potentiates neurogenic inflammation in rat airways. This effect is not associated with changes in neurotrophin expression. In weanling rats, reovirus infection induced peri-alveolar fibrosis suggesting that early exposure may carry long-term effects which may be clinically relevant

Quantum theory of dynamic multiple light scattering

We formulate a quantum theory of dynamic multiple light scattering in fluctuating disordered media and calculate the fluctuation and the autocorrelation function of photon number operator for light transmitted through a disordered slab. The effect of disorder on the information capacity of a quantum communication channel operating in a disordered environment is estimated and the use of squeezed light in diffusing-wave spectroscopy is discussed.Comment: Revised text, additional figur

Multispeckle diffusing-wave spectroscopy: a tool to study slow relaxation and time-dependent dynamics

A multispeckle technique for efficiently measuring correctly ensemble-averaged intensity autocorrelation functions of scattered light from non-ergodic and/or non-stationary systems is described. The method employs a CCD camera as a multispeckle light detector and a computer-based correlator, and permits the simultaneous calculation of up to 500 correlation functions, where each correlation function is started at a different time. The correlation functions are calculated in real time and are referenced to a unique starting time. The multispeckle nature of the CCD camera detector means that a true ensemble average is calculated; no time averaging is necessary. The technique thus provides a "snapshot" of the dynamics, making it particularly useful for non-stationary systems where the dynamics are changing with time. Delay times spanning the range from 1 ms to 1000 s are readily achieved with this method. The technique is demonstrated in the multiple scattering limit where diffusing-wave spectroscopy theory applies. The technique can also be combined with a recently-developed two-cell technique that can measure faster decay times. The combined technique can measure delay times from 10 ns to 1000 s. The method is peculiarly well suited for studying aging processes in soft glassy materials, which exhibit both short and long relaxation times, non-ergodic dynamics, and slowly-evolving transient behavior.Comment: 11 pages 13 figures Accepted in Review of Scientific Instrument (june 02

Elastic Behavior of a Two-dimensional Crystal near Melting

Using positional data from video-microscopy we determine the elastic moduli of two-dimensional colloidal crystals as a function of temperature. The moduli are extracted from the wave-vector-dependent normal mode spring constants in the limit $q\to 0$ and are compared to the renormalized Young's modulus of the KTHNY theory. An essential element of this theory is the universal prediction that Young's modulus must approach $16 \pi$ at the melting temperature. This is indeed observed in our experiment.Comment: 4 pages, 3 figure