Low Temperature Raman Spectra of Dichlorosulfane (SC12), Tetrachlorosulfurane (SC14), Dichlorodisulfane (S2C12) and Dichlorodiselane (Se2Cl2) [1]

The Raman spectrum of commercial "sulfur dichloride" shows strong lines due to SCl2 and S2Cl2 and weak Cl2 lines at 25 °C, but strong SCl2 and SCl4 signals at -100 °C (the latter are superimposed on the S2Cl2 lines). Thus, the intense Raman effect of SCl4 can be used to detect small amounts of chlorine in SCl2 . Mixtures of SCl2 and Cl2 (1:15) yield the Raman spectrum of SCl4 at -140 °C, while at 25 °C not trace of this compound can be detected. The spectra of SCl4 and α-SeCl4 are quite different, indicating different molecular and/or crystal structures, although ECl3 + ions (E = S, Se) are present in both cases. While Se2Cl2 dimerizes reversibly below -50 °C, S2Cl2 neither dimerizes nor isomerizes on cooling. The S2Cl2 dimer is characterized by a Raman line at 215 cm-1 the intensity of which was used to calculate an enthalpy of dimerization as of -17 kJ/mol

Spectroscopic Evidence for Pseudorotation of Seven-Membered Chalcogen Rings in Solution [1]

The 77Se NMR spectrum of l,2-Se2S5 exhibits one singlet at 1077.3 ppm indicating pseudorotation in solution; the same conclusion is reached from the solution Raman spectrum of S7 showing characteristic line broadening compared to the solid state spectrum

Scaling and Linear Response in the GOY Turbulence model

The GOY model is a model for turbulence in which two conserved quantities cascade up and down a linear array of shells. When the viscosity parameter, $\nu$, is small the model has a qualitative behavior which is similar to the Kolmogorov theories of turbulence. Here a static solution to the model is examined, and a linear stability analysis is performed to obtain response eigenvalues and eigenfunctions. Both the static behavior and the linear response show an inertial range with a relatively simple scaling structure. Our main results are: (i) The response frequencies cover a wide range of scales, with ratios which can be understood in terms of the frequency scaling properties of the model. (ii) Even small viscosities play a crucial role in determining the model's eigenvalue spectrum. (iii) As a parameter within the model is varied, it shows a ``phase transition'' in which there is an abrupt change in many eigenvalues from stable to unstable values. (iv) The abrupt change is determined by the model's conservation laws and symmetries. This work is thus intended to add to our knowledge of the linear response of a stiff dynamical systems and at the same time to help illuminate scaling within a class of turbulence models.Comment: 25 pages, figures on reques

Trigeminal neuralgia: new classification and diagnostic grading for practice and research

Trigeminal neuralgia (TN) is an exemplary condition of neuropathic facial pain. However, formally classifying TN as neuropathic pain based on the grading system of the International Association for the Study of Pain is complicated by the requirement of objective signs confirming an underlying lesion or disease of the somatosensory system. The latest version of the International Classification of Headache Disorders created similar difficulties by abandoning the term symptomatic TN for manifestations caused by major neurologic disease, such as tumors or multiple sclerosis. These diagnostic challenges hinder the triage of TN patients for therapy and clinical trials, and hamper the design of treatment guidelines. In response to these shortcomings, we have developed a classification of TN that aligns with the nosology of other neurologic disorders and neuropathic pain. We propose 3 diagnostic categories. Classical TN requires demonstration of morphologic changes in the trigeminal nerve root from vascular compression. Secondary TN is due to an identifiable underlying neurologic disease. TN of unknown etiology is labeled idiopathic. Diagnostic certainty is graded possible when pain paroxysms occur in the distribution of the trigeminal nerve branches. Triggered paroxysms permit the designation of clinically established TN and probable neuropathic pain. Imaging and neurophysiologic tests that establish the etiology of classical or secondary TN determine definite neuropathic pain

How the viscous subrange determines inertial range properties in turbulence shell models

We calculate static solutions of the 'GOY' shell model of turbulence and do a linear stability analysis. The asymptotic limit of large Reynolds numbers is analyzed. A phase diagram is presented which shows the range of stability of the static solution. We see an unexpected oscillatory dependence of the stability range upon $\lg \nu$, where $\nu$ is the viscosity. This effect depends upon the discrete structure of the shell model and goes to zero as the separation between the shells is brought to zero. These findings show how viscous effects play a role in determining inertial properties of shell models and give some hints for understanding the effects of viscous dissipation upon real turbulence.Comment: Physica D, in pres

Tapentadol in the management of chronic low back pain: a novel approach to a complex condition?

Chronic pain affects approximately 1 in 5 people in Europe, and around half of sufferers receive inadequate pain management. The most common location is the lower back. Pharmacological treatment of this condition is challenging because of the range of causative mechanisms and the difficulty of balancing analgesic efficacy and tolerability. An international panel of clinical pain specialists met in September, 2009, to discuss the treatment of chronic low back pain, and to review preclinical and clinical data relating to the new analgesic, tapentadol. A lack of consensus exists on the best treatment for low back pain. The range of regularly prescribed pharmacological agents extends from nonopioids (paracetamol, NSAIDs, and COX-2 inhibitors) to opioids, antidepressants and anticonvulsants. Pain relief may be compromised, however, by an undetected neuropathic component or intolerable side effects. Treatment is potentially life-long and effective analgesics are urgently needed, with demonstrable long-term safety. Combining separate agents with different mechanisms of action could overcome the limitations of present pharmacological therapy, but clinical evidence for this approach is currently lacking. Tapentadol combines μ-opioid agonism with noradrenaline reuptake inhibition in a single molecule. There is strong evidence of synergistic antinociception between these two mechanisms of action. In preclinical and clinical testing, tapentadol has shown efficacy against both nociceptive and neuropathic pain. Preclinical data indicate that tapentadol’s μ-opioid agonism makes a greater contribution to analgesia in acute pain, while noradrenaline reuptake inhibition makes a greater contribution in chronic neuropathic pain models. Tapentadol also produces fewer adverse events than oxycodone at equianalgesic doses, and thus may have a ‘μ-sparing effect’. Current evidence indicates that tapentadol’s efficacy/tolerability ratio may be better than those of classical opioids. However, further research is needed to establish its role in pain management

Developed turbulence: From full simulations to full mode reductions

Developed Navier-Stokes turbulence is simulated with varying wavevector mode reductions. The flatness and the skewness of the velocity derivative depend on the degree of mode reduction. They show a crossover towards the value of the full numerical simulation when the viscous subrange starts to be resolved. The intermittency corrections of the scaling exponents of the pth order velocity structure functions seem to depend mainly on the proper resolution of the inertial subrange. Universal scaling properties (i.e., independent of the degree of mode reduction) are found for the relative scaling exponents rho which were recently defined by Benzi et al.Comment: 4 pages, 5 eps-figures, replaces version from August 5th, 199

Adiabatic Pair Creation

We give here the proof that pair creation in a time dependent potentials is possible. It happens with probability one if the potential changes adiabatically in time and becomes overcritical, that is when an eigenvalue enters the upper spectral continuum. The potential may be assumed to be zero at large negative and positive times. The rigorous treatment of this effect has been lacking since the pioneering work of Beck, Steinwedel and Suessmann in 1963 and Gershtein and Zeldovich in 1970.Comment: 53 pages, 1 figure. Editorial changes on page 22 f

Holocene sea-ice dynamics in Petermann Fjord in relation to ice tongue stability and Nares Strait ice arch formation

The Petermann 2015 expedition to Petermann Fjord and adjacent Hall Basin recovered a transect of cores, extending from Nares Strait to underneath the 48&thinsp;km long ice tongue of Petermann glacier, offering a unique opportunity to study ice&ndash;ocean&ndash;sea ice interactions at the interface of these realms. First results suggest that no ice tongue existed in Petermann Fjord for large parts of the Holocene, raising the question of the role of the ocean and the marine cryosphere in the collapse and re-establishment of the ice tongue. Here we use a multi-proxy approach (sea-ice-related biomarkers, total organic carbon and its carbon isotopic composition, and benthic and planktonic foraminiferal abundances) to explore Holocene sea ice dynamics at OD1507-03TC-41GC-03PC in outer Petermann Fjord. Our results are in line with a tight coupling of the marine and terrestrial cryosphere in this region and, in connection with other regional sea ice reconstructions, give insights into the Holocene evolution of ice arches and associated landfast ice in Nares Strait. The late stages of the regional Holocene Thermal Maximum (6900&ndash;5500&thinsp;cal&thinsp;yr&thinsp;BP) were marked by reduced seasonal sea ice concentrations in Nares Strait and the lack of ice arch formation. This was followed by a transitional period towards Neoglacial cooling from 5500&ndash;3500&thinsp;cal&thinsp;yr&thinsp;BP, where a southern ice arch might have formed, but an early seasonal breakup and late formation likely caused a prolonged open water season and enhanced pelagic productivity in Nares Strait. Between 3500 and 1400&thinsp;cal&thinsp;yr&thinsp;BP, regional records suggest the formation of a stable northern ice arch only, with a short period from 2500&ndash;2100&thinsp;cal&thinsp;yr&thinsp;BP where a southern ice arch might have formed intermittently in response to atmospheric cooling spikes. A stable southern ice arch, or even double arching, is also inferred for the period after 1400&thinsp;cal&thinsp;yr&thinsp;BP. Thus, both the inception of a small Petermann ice tongue at &sim;&thinsp;2200&thinsp;cal&thinsp;yr&thinsp;BP and its rapid expansion at &sim;&thinsp;600&thinsp;cal&thinsp;yr&thinsp;BP are preceded by a transition towards a southern ice arch regime with landfast ice formation in Nares Strait, suggesting a stabilizing effect of landfast sea ice on Petermann Glacier. &nbsp;</p