Basics of Modelling the Pedestrian Flow

For the modelling of pedestrian dynamics we treat persons as self-driven objects moving in a continuous space. On the basis of a modified social force model we qualitatively analyze the influence of various approaches for the interaction between the pedestrians on the resulting velocity-density relation. To focus on the role of the required space and remote force we choose a one-dimensional model for this investigation. For those densities, where in two dimensions also passing is no longer possible and the mean value of the velocity depends primarily on the interaction, we obtain the following result: If the model increases the required space of a person with increasing current velocity, the reproduction of the typical form of the fundamental diagram is possible. Furthermore we demonstrate the influence of the remote force on the velocity-density relation.Comment: 9 pages, 3 figures, Changes: Parameter e=0.51 corrected to e =0.07 (see Fig. 2) and prep. for subm. to Phys. Rev.

Extent of the Acidification by N7-Coordinated cis-Diammine-Platinum(II) on the Acidic Sites of Guanine Derivatives

Coordination of two monoprotonated 2'-deoxyguanosine 5'-monophosphate species, H(dGMP)−, via N7 to cis-(NH2)2Pt2+ gives the complex cis-(NH2)2Pt(H·dGMP)2 which is a four-protonic acid. The corresponding acidity constants were measured by potentiometric pH titrations (25℃; I = 0.1 M, NaNO3). The first two protons are released from the two -P(O)2(OH)− groups (PKa/1= 5.57; PKa/2 = 6.29) and the next two protons are from the H(N1) sites of the guanine residues (PKa/3 = 8.73; PKa/4 = 9.48). The micro acidity constants of the various sites are also evaluated. Comparison of these data with those determined for the three-protonic H2(dGMP)± (PKa/1 = 2.69 for the H+(N7) site; PKa/2 = 6.29 for -P(O)2(OH)− ;PKa/3 = 9.56 for H(N1)) shows that on average the N-7-coordinated Pt2+ acidifies the phosphate protons by Δ pKa = 0.36 and the H(N1) sites by Δ pKa = 0.46. These results are further compared with those obtained previously for cis-(NH2)2Pt(L)2, where L = 9-ethylguanine or monoprotonated 2'-deoxycytidine 5'-monophosphate. Conclusions regarding platinated DNA are also presented

Differential stabilization of adenine quartets by anions and cations

We have investigated the structures and stabilities of four different adenine quartets with alkali and halide ions in the gas phase and in water, using dispersion-corrected density functional theory at the BLYP-D/TZ2P level. First, we examine the empty quartets and how they interact with alkali cations and halide anions with formation of adenine quartet–ion complexes. Second, we examine the interaction in a stack, in which a planar adenine quartet interacts with a cation or anion in the periphery as well as in the center of the quartet. Interestingly, for the latter situation, we find that both cations and anions can stabilize a planar adenine quartet in a stack

A neutral Pt3 stack unsupported by any bridging ligand

Pt⋯Pt⋯Pt interactions via their d8 orbitals, combined with π–π stacking of deprotonated, chelating 2-(3′-pyrazolyl)pyridine (pyzpy) ligands, are responsible for trans-Pt(pyzpy)2 (2) crystallization in a stack of three molecules unsupported by any bridging ligand

Association of Chronic Covert Cerebral Infarctions and White Matter Hyperintensities With Atrial Fibrillation Detection on Post-Stroke Cardiac Rhythm Monitoring: A Cohort Study.

Background This study was conducted to explore the association of different phenotypes, count, and location of chronic covert brain infarctions (CBIs) with detection of atrial fibrillation (AF) on prolonged post-stroke cardiac rhythm monitoring (PCM). Methods and Results We conducted a cohort single-center study of consecutive first-ever ischemic stroke or transient ischemic attack patients undergoing PCM between January 2015 and December 2017. We blindly rated CBI phenotypes according to established definitions and white matter hyperintensities (WMHs) according to the age-related white matter changes rating scale. We used (multiple) regression models to assess the association of the imaging biomarkers and incident AF on PCM. A total of 795 patients (median [interquartile range]) aged 69 (57-78) years, 41% women, median National Institutes of Health Stroke Scale score 2 (0-5), median PCM duration 14 (7-14) days, and AF detection in 61 patients (7.7%) were included. On univariate analysis, WMHs (per point odds ratio, 1.35 [95% CI, 1.03-1.78]) but not CBIs (odds ratio, 0.90 [95% CI, 0.52-1.56]) were associated with AF detection. Neither CBI phenotype, count, nor location were associated with AF detection. After adjustment for age, hypertension, and stroke severity, neither increasing WMHs (per point adjusted odds ratio, 0.85 [95% CI, 0.60-1.20]) nor CBIs (adjusted odds ratio, 0.60 [95% CI, 0.33-1.09]) were independently associated with AF detection. Conclusions Although WMHs and CBIs represent surrogate biomarkers of vascular risk factors, neither WMHs nor CBIs, including their phenotypes, count, and location, were independently associated with AF detection on PCM. In patients with manifest ischemic stroke or transient ischemic attack, the presence of imaging biomarkers of chronic ischemic injury does not seem promising to further refine prediction tools for AF detection on PCM

Radiation chemistry of solid-state carbohydrates using EMR

We review our research of the past decade towards identification of radiation-induced radicals in solid state sugars and sugar phosphates. Detailed models of the radical structures are obtained by combining EPR and ENDOR experiments with DFT calculations of g and proton HF tensors, with agreement in their anisotropy serving as most important criterion. Symmetry-related and Schonland ambiguities, which may hamper such identification, are reviewed. Thermally induced transformations of initial radiation damage into more stable radicals can also be monitored in the EPR (and ENDOR) experiments and in principle provide information on stable radical formation mechanisms. Thermal annealing experi-ments reveal, however, that radical recombination and/or diamagnetic radiation damage is also quite important. Analysis strategies are illustrated with research on sucrose. Results on dipotassium glucose-1-phosphate and trehalose dihydrate, fructose and sorbose are also briefly discussed. Our study demonstrates that radiation damage is strongly regio-selective and that certain general principles govern the stable radical formation

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Platinum Pyrimidine Blues: Still a Challenge to Bioinorganic Chemists and a Treasure for Coordination Chemists

A class of intensely colored platinum complexes, derived from the hydrolysis product of the antitumor agent cisplatin, cis-[Pt(NH3)2(H2O)2]2+, and pyrimidine nucleobases (pym) and related cyclic or open amides, and generally termed 'Platinum Blues', is discussed. First reported over 30 years ago, major questions concerning their nature have been solved since then, for example their mixed valency and paramagnetism. Their modes of action as antitumor agents and as nucleic acid stains remain elusive, however. It has generally been assumed that the 'Blues' adopt linear chain structures, thus permitting short Pt•••Pt contacts, but more recent findings demonstrate that these ligands also allow cyclic structures to be formed (metallacalix[n]arenes). They provide a wealth of interesting properties with regard to host–guest chemistry and non-covalent DNA binding. These developments are reviewed