1,4-Bis(4-nitrosophenyl)piperazine: novel bridging ligand in dinuclear complexes of rhodium(III) and iridium(III).

The synthesis, spectroscopic characterization and crystal structures of the first 1,4-bis(4-nitrosophenyl)piperazine (BNPP) (4) bridged dinuclear complexes of rhodium(III) and iridium(III) are presented. The reaction of the μ2-halogenido-bridged dimers [(η5-C5Me5)IrX2]2 [X = Cl (5a), Br (5b), I (5c)] and [(η5- C5Me5)RhCl2]2 (6a) with 4 yields the dinuclear complexes [(η5-C5Me5)IrX2]2-BNPP (7a–c) and [(η5-C5Me5)RhCl2]2-BNPP (8a). All new compounds were characterized by their NMR, IR and mass spectra. The X-ray structure analyses of the obtained half-sandwich complexes revealed a slightly distorted pseudo-octahedral configuration (“three-legged pianostool”) for the metal(III) centers. The bridging BNPP ligand is σ-N coordinated by both nitroso groups and shows different conformations of the piperazine ring depending on the solvent used for crystallization. Moreover the crystal structures of 1,4-bis(4-nitrosophenyl)piperazine (4) and its precursor 1,4-diphenylpiperazine (3) are reported

Higher spin algebras and large N=4\mathcal{N}=4 holography

A new family of higher spin algebras that arises upon restricting matrix extensions of $\mathfrak{shs}[\lambda]$ is found. We identify coset CFTs realising these symmetry algebras, and thus propose new higher spin-CFT dual pairs. These higher spin theories arise naturally as a subsector of string theory on ${\rm AdS}_3\times {\rm S}^3 \times {\rm S}^3 \times {\rm S}^1$ for specific ratios of the radii of the two spheres.Comment: 22 page

The perfect crime? : CCSVI not leaving a trace in MS

Background: Multiple sclerosis (MS) is a chronic, inflammatory demyelinating disease of the central nervous system, believed to be triggered by an autoimmune reaction to myelin. Recently, a fundamentally different pathomechanism termed ‘chronic cerebrospinal venous insufficiency’ (CCSVI) was proposed, provoking significant attention in the media and scientific community. Methods: Twenty MS patients (mean age 42.2±13.3 years; median Extended Disability Status Scale 3.0, range 0–6.5) were compared with 20 healthy controls. Extra- and intracranial venous flow direction was assessed by colour-coded duplex sonography, and extracranial venous cross-sectional area (VCSA) of the internal jugular and vertebral veins (IJV/VV) was measured in B-mode to assess the five previously proposed CCSVI criteria. IJV-VCSA≤0.3 cm2 indicated ‘stenosis,’ and IJV-VCSA decrease from supine to upright position ‘reverted postural control.’ The sonographer, data analyser and statistician were blinded to the patient/control status of the participants. Results: No participant showed retrograde flow of cervical or intracranial veins. IJV-VCSA≤0.3 cm2 was found in 13 MS patients versus 16 controls (p=0.48). A decrease in IJV-VCSA from supine to upright position was observed in all participants, but this denotes a physiological finding. No MS patient and one control had undetectable IJV flow despite deep inspiration (p=0.49). Only one healthy control and no MS patients fulfilled at least two criteria for CCSVI. Conclusions: This triple-blinded extra- and transcranial duplex sonographic assessment of cervical and cerebral veins does not provide supportive evidence for the presence of CCSVI in MS patients. The findings cast serious doubt on the concept of CCSVI in MS

Stem Cell Fate Analysis Revisited: Interpretation of Individual Clone Dynamics in the Light of a New Paradigm of Stem Cell Organization

Many experimental findings on heterogeneity, flexibility, and plasticity of tissue stem cells are currently challenging stem cell concepts that assume a cell intrinsically predefined, unidirectional differentiation program. In contrast to these classical concepts, nonhierarchical self-organizing systems provide an elegant and comprehensive alternative to explain the experimental data. Here we present the application of such a self-organizing concept to quantitatively describe the hematopoietic stem cell system. Focusing on the analysis of individual-stem-cell fates and clonal dynamics, we particularly discuss implications of the theoretical results on the interpretation of experimental findings. We demonstrate that it is possible to understand hematopoietic stem cell organization without assumptions on unidirectional developmental hierarchies, preprogrammed asymmetric division events or other assumptions implying the existence of a predetermined stem cell entity. The proposed perspective, therefore, changes the general paradigm of thinking about stem cells

Adverse cardiac events during catecholamine vasopressor therapy: a prospective observational study

Purpose: To determine the incidence of and risk factors for adverse cardiac events during catecholamine vasopressor therapy in surgical intensive care unit patients with cardiovascular failure. Methods: The occurrence of any of seven predefined adverse cardiac events (prolonged elevated heart rate, tachyarrhythmia, myocardial cell damage, acute cardiac arrest or death, pulmonary hypertension-induced right heart dysfunction, reduction of systemic blood flow) was prospectively recorded during catecholamine vasopressor therapy lasting at least 12h. Results: Fifty-four of 112 study patients developed a total of 114 adverse cardiac events, an incidence of 48.2% (95% CI, 38.8-57.6%). New-onset tachyarrhythmia (49.1%), prolonged elevated heart rate (23.7%), and myocardial cell damage (17.5%) occurred most frequently. Aside from chronic liver diseases, factors independently associated with the occurrence of adverse cardiac events included need for renal replacement therapy, disease severity (assessed by the Simplified Acute Physiology Score II), number of catecholamine vasopressors (OR, 1.73; 95% CI, 1.08-2.77; p=0.02) and duration of catecholamine vasopressor therapy (OR, 1.01; 95% CI, 1-1.01; p=0.002). Patients developing adverse cardiac events were on catecholamine vasopressors (p<0.001) and mechanical ventilation (p<0.001) for longer and had longer intensive care unit stays (p<0.001) and greater mortality (25.9 vs. 1.7%; p<0.001) than patients who did not. Conclusions: Adverse cardiac events occurred in 48.2% of surgical intensive care unit patients with cardiovascular failure and were related to morbidity and mortality. The extent and duration of catecholamine vasopressor therapy were independently associated with and may contribute to the pathogenesis of adverse cardiac event

Pattern formation in wet granular matter under vertical vibrations

Experiments on a thin layer of cohesive wet granular matter under vertical vibrations reveal kink separated domains that collide with the container at different phases. Due to the strong cohesion arising from the formation of liquid bridges between adjacent particles, the domains move collectively upon vibrations. Depending on the periodicity of this collective motion, the kink fronts may propagate, couple with each other and form rotating spiral patterns in the case of period tripling, or stay as standing wave patterns in the case of period doubling. Moreover, both patterns may coexist with granular `gas bubbles' - phase separation into a liquidlike and a gaslike state. Stability diagrams for the instabilities measured with various granular layer mass $m$ and container height $H$ are presented. The onsets for both types of patterns and their dependency on $m$ and $H$ can be quantitatively captured with a model considering the granular layer as a single particle colliding completely inelastically with the container.Comment: 8 pages, 7 figure