Cis-cis and trans-perp HOONO: Action spectroscopy and isomerization kinetics

The weakly bound HOONO product of the OH + NO_2 + M reaction is studied using the vibrational predissociation that follows excitation of the first OH overtone (2nu1). We observe formation of both cis-cis and trans-perp conformers of HOONO. The trans-perp HOONO 2nu1 band is observed under thermal (223–238 K) conditions at 6971 cm^(–1). We assign the previously published (warmer temperature) HOONO spectrum to the 2nu1 band at 6365 cm^(–1) and 2nu1-containing combination bands of the cis-cis conformer of HOONO. The band shape of the trans-perp HOONO spectrum is in excellent agreement with the predicted rotational contour based on previous experimental and theoretical results, but the apparent origin of the cis-cis HOONO spectrum at 6365 cm^(–1) is featureless and significantly broader, suggesting more rapid intramolecular vibrational redistribution or predissociation in the latter isomer. The thermally less stable trans-perp HOONO isomerizes rapidly to cis-cis HOONO with an experimentally determined lifetime of 39 ms at 233 K at 13 hPa (in a buffer gas of predominantly Ar). The temperature dependence of the trans-perp HOONO lifetime in the range 223–238 K yields an isomerization barrier of 33±12 kJ/mol. New ab initio calculations of the structure and vibrational mode frequencies of the transition state perp-perp HOONO are performed using the coupled cluster singles and doubles with perturbative triples [CCSD(T)] model, using a correlation consistent polarized triple zeta basis set (cc-pVTZ). The energetics of cis-cis, trans-perp, and perp-perp HOONO are also calculated at this level [CCSD(T)/cc-pVTZ] and with a quadruple zeta basis set using the structure determined at the triple zeta basis set [CCSD(T)/cc-pVQZ//CCSD(T)/cc-pVTZ]. These calculations predict that the anti form of perp-perp HOONO has an energy of DeltaE0 = 42.4 kJ/mol above trans-perp HOONO, corresponding to an activation enthalpy of DeltaH298[double-dagger]0 = 41.1 kJ/mol. These results are in good agreement with statistical simulations based on a model developed by Golden, Barker, and Lohr. The simulated isomerization rates match the observed decay rates when modeled with a trans-perp to cis-cis HOONO isomerization barrier of 40.8 kJ/mol and a strong collision model. The quantum yield of cis-cis HOONO dissociation to OH and NO2 is also calculated as a function of photon excitation energy in the range 3500–7500 cm^(–1), assuming D0 = 83 kJ/mol. The quantum yield is predicted to vary from 0.15 to 1 over the observed spectrum at 298 K, leading to band intensities in the action spectrum that are highly temperature dependent; however, the observed relative band strengths in the cis-cis HOONO spectrum do not change substantially with temperature over the range 193–273 K. Semiempirical calculations of the oscillator strengths for 2nu1(cis-cis HOONO) and 2nu1(trans-perp HOONO) are performed using (1) a one-dimensional anharmonic model and (2) a Morse oscillator model for the OH stretch, and ab initio dipole moment functions calculated using Becke, Lee, Yang, and Parr density functional theory (B3LYP), Møller-Plesset pertubation theory truncated at the second and third order (MP2 and MP3), and quadratic configuration interaction theory using single and double excitations (QCISD). The QCISD level calculated ratio of 2nu1 oscillator strengths of trans-perp to cis-cis HOONO is 3.7:1. The observed intensities indicate that the concentration of trans-perp HOONO early in the OH + NO2 reaction is significantly greater than predicted by a Boltzmann distribution, consistent with statistical predictions of high initial yields of trans-perp HOONO from the OH + NO_2 + M reaction. In the atmosphere, trans-perp HOONO will isomerize nearly instantaneously to cis-cis HOONO. Loss of HOONO via photodissociation in the near-IR limits the lifetime of cis-cis HOONO during daylight to less than 45 h, other loss mechanisms will reduce the lifetime further

CEA Bolometer Arrays: the First Year in Space

The CEA/LETI and CEA/SAp started the development of far-infrared filled bolometer arrays for space applications over a decade ago. The unique design of these detectors makes possible the assembling of large focal planes comprising thousands of bolometers running at 300 mK with very low power dissipation. Ten arrays of 16x16 pixels were thoroughly tested on the ground, and integrated in the Herschel/PACS instrument before launch in May 2009. These detectors have been successfully commissioned and are now operating in their nominal environment at the second Lagrangian point of the Earth-Sun system. In this paper we briefly explain the functioning of CEA bolometer arrays, and we present the properties of the detectors focusing on their noise characteristics, the effect of cosmic rays on the signal, the repeatability of the measurements, and the stability of the system

Care Coordination and Comprehensive Electronic Health Records are Associated with Increased Transition Planning Activities

OBJECTIVE: Youth with Special Health Care Needs (YSHCN) require assistance from their pediatricians to transition to adult care. There is little data on what transition resources pediatricians have. This paper studies if care coordination and/or comprehensive electronic health record (CEHR) implementation are associated with improved transition processes. METHODS: Using AAP Periodic Survey #79, we report whether practices generated written transition plans, assisted in finding adult providers, and discussed confidentiality issues. Descriptive statistics and a logistic regression model were done to evaluate whether CEHR, care coordination, or practice and physician characteristics improve transition planning. RESULTS: Transition planning support in practices is low. Pediatricians with any care coordinator report more written transition plans for YSHCN (23% vs. 6%, p\u3c0.001), assistance identifying adult providers (59% vs. 39%, p\u3c0.001), and discussing confidentiality issues (50% vs. 33%, p\u3c0.001). Pediatricians with a CEHR compared to those without are more likely to report written transition plans for YSHCN (24% vs. 12 % p\u3c0.05) and discussing confidentiality issues (51% vs. 39%, p\u3c0.05). In the logistic regression model, having care coordination (AOR 11.1, 95% CI 5.9-21.3) and CEHR (AOR 2.6, 95% CI 1.5-5.0) are independently associated with higher odds of having a written transition plan. CONCLUSIONS: Only 1 in 5 pediatricians have a transition coordinator in their practice and just 15% have a CEHR, even as these resources are associated with improved transition processes for YSHCN. Policy decisions should be made to help practices with supports, such as care coordination and EHR implementation, in order to improve transitions to adulthood

A Reilly formula and eigenvalue estimates for differential forms

We derive a Reilly-type formula for differential p-forms on a compact manifold with boundary and apply it to give a sharp lower bound of the spectrum of the Hodge Laplacian acting on differential forms of an embedded hypersurface of a Riemannian manifold. The equality case of our inequality gives rise to a number of rigidity results, when the geometry of the boundary has special properties and the domain is non-negatively curved. Finally we also obtain, as a by-product of our calculations, an upper bound of the first eigenvalue of the Hodge Laplacian when the ambient manifold supports non-trivial parallel forms.Comment: 22 page

Temperature Dependence of the Reaction of Chlorine Atoms with CH_3OH and CH_3CHO

Rate constants of the reactions Cl + CH_3OH → CH_2OH + HCl (k_1) and Cl + CH_3CHO → CH_3C(O) + HCl (k_3) were measured at 100 Torr over the temperature range 230.3 - 297.1 K. Radical chemistry was initiated by pulsed laser photolysis of Cl_2 in mixtures of CH_3OH and CH_3CHO in a flow reactor. Heterodyne near-IR (NIR) wavelength modulation spectroscopy was used to directly detect HO_2 produced from the subsequent reaction of CH_2OH with O_2 in real-time to determine the rate of reaction of Cl with CH_3OH. The rate of Cl + CH_3CHO was measured relative to that of the Cl + CH_3OH reaction. Secondary chemistry, including that of the adducts HO_2·CH_3OH and HO_2·CH_3CHO, were taken into account. The Arrhenius expressions were found to be k_1(T) = 5.02^(+1.8)_(-1.5)×10^(-11)exp[(20±88)/T] cm^3 molecule^(-1) s^(-1) and k_3(T) =6.38^(+2.4)_(-2.0)×10^(-11)exp[(56±90)/T] cm^3 molecule^(-1) s^(-1) (2σ uncertainties). The average values of the rate constants over this temperature range were k_1 = (5.45±0.37)×10^(-11) cm^3 molecule^(-1) s^(-1) and k_3 = (8.00±1.27)×10^(-11)cm^3 molecule^(-1) s^(-1) (2σ uncertainties), consistent with current literature values

Temperature Dependence of the Reaction of Chlorine Atoms with CH_3OH and CH_3CHO

Rate constants of the reactions Cl + CH_3OH → CH_2OH + HCl (k_1) and Cl + CH_3CHO → CH_3C(O) + HCl (k_3) were measured at 100 Torr over the temperature range 230.3 - 297.1 K. Radical chemistry was initiated by pulsed laser photolysis of Cl_2 in mixtures of CH_3OH and CH_3CHO in a flow reactor. Heterodyne near-IR (NIR) wavelength modulation spectroscopy was used to directly detect HO_2 produced from the subsequent reaction of CH_2OH with O_2 in real-time to determine the rate of reaction of Cl with CH_3OH. The rate of Cl + CH_3CHO was measured relative to that of the Cl + CH_3OH reaction. Secondary chemistry, including that of the adducts HO_2·CH_3OH and HO_2·CH_3CHO, were taken into account. The Arrhenius expressions were found to be k_1(T) = 5.02^(+1.8)_(-1.5)×10^(-11)exp[(20±88)/T] cm^3 molecule^(-1) s^(-1) and k_3(T) =6.38^(+2.4)_(-2.0)×10^(-11)exp[(56±90)/T] cm^3 molecule^(-1) s^(-1) (2σ uncertainties). The average values of the rate constants over this temperature range were k_1 = (5.45±0.37)×10^(-11) cm^3 molecule^(-1) s^(-1) and k_3 = (8.00±1.27)×10^(-11)cm^3 molecule^(-1) s^(-1) (2σ uncertainties), consistent with current literature values

Face validity of a proposed tool for staging canine osteoarthritis: Canine OsteoArthritis Staging Tool (COAST)

Abstract Osteoarthritis (OA) is a common, progressive degenerative disease of synovial joints. It can develop subsequent to an acquired disorder such as joint trauma but is primarily driven by developmental orthopedic disease in young dogs. Therefore, it is essentially characterised as an early onset but lifelong disease that worsens with age. Early intervention using a multi-modal drug and non-drug approach, with or without surgery as required, has the greatest potential for the most effective management of the disease. Timely implementation of a continuing care plan provides an opportunity to slow the rate of deterioration by reducing the negative impacts of OA-associated pain, encouraging appropriate levels of activity and improving strength and posture. Unfortunately, many dogs are presented to veterinary clinics only when marked behavioural changes are observed and substantial deterioration of the musculoskeletal and somatosensory systems has already occurred. To assist veterinarians with early and stage-specific diagnosis of OA in dogs, the authors present a proposed, practical diagnostic aid called 'COAST' (Canine OsteoArthritis Staging Tool) with face validity. As indicated by the successful implementation of staging systems for other companion animal diseases, it is expected that standardized staging of OA in dogs will help guide disease management plans and improve monitoring. The items used to construct COAST have been developed using consensus opinion of international experts from nine countries, who are actively working in the fields of small animal orthopaedics, anaesthesia and pain management. Further validation (test-retest, discriminatory ability, responsiveness, criterion validation) of the tool under field conditions is now required and the authors invite input

Differential Geometry of Group Lattices

In a series of publications we developed "differential geometry" on discrete sets based on concepts of noncommutative geometry. In particular, it turned out that first order differential calculi (over the algebra of functions) on a discrete set are in bijective correspondence with digraph structures where the vertices are given by the elements of the set. A particular class of digraphs are Cayley graphs, also known as group lattices. They are determined by a discrete group G and a finite subset S. There is a distinguished subclass of "bicovariant" Cayley graphs with the property that ad(S)S is contained in S. We explore the properties of differential calculi which arise from Cayley graphs via the above correspondence. The first order calculi extend to higher orders and then allow to introduce further differential geometric structures. Furthermore, we explore the properties of "discrete" vector fields which describe deterministic flows on group lattices. A Lie derivative with respect to a discrete vector field and an inner product with forms is defined. The Lie-Cartan identity then holds on all forms for a certain subclass of discrete vector fields. We develop elements of gauge theory and construct an analogue of the lattice gauge theory (Yang-Mills) action on an arbitrary group lattice. Also linear connections are considered and a simple geometric interpretation of the torsion is established. By taking a quotient with respect to some subgroup of the discrete group, generalized differential calculi associated with so-called Schreier diagrams are obtained.Comment: 51 pages, 11 figure