115 research outputs found
Anomalous diffusion as a signature of collapsing phase in two dimensional self-gravitating systems
A two dimensional self-gravitating Hamiltonian model made by
fully-coupled classical particles exhibits a transition from a collapsing phase
(CP) at low energy to a homogeneous phase (HP) at high energy. From a dynamical
point of view, the two phases are characterized by two distinct single-particle
motions : namely, superdiffusive in the CP and ballistic in the HP. Anomalous
diffusion is observed up to a time that increases linearly with .
Therefore, the finite particle number acts like a white noise source for the
system, inhibiting anomalous transport at longer times.Comment: 10 pages, Revtex - 3 Figs - Submitted to Physical Review
Migration, communities-on-the-move and international innovation networks: An empirical analysis of Spanish regions
This paper investigates the impact of migration on innovation networks between regions and foreign countries. We posit that immigrants (emigrants) act as a transnational knowledge bridge between the host (home) regions and their origin (destination) countries, thus facilitating their co-inventorship networks. We also argue that the social capital of both the hosting and the moving communities reinforces such a bridging role, along with language commonality and migrants’ human capital. Focusing on Spain, as a country that hosted an intense process of migration over the past two decades, we combine patent data with national data on residents and electors abroad and we apply a gravity model to the co-inventorship between Spanish provinces (NUTS3 regions) and a number of foreign countries. Both immigrants and emigrants affect the kind of innovation networking at stake. The social capital of both the moving and the hosting communities actually moderate this impact in a positive way. The effect of migration is stronger for more skilled migrants and with respect to non-Spanish speaking countries, pointing to a language-bridging role of migrants. Policy implications are drawn accordingly
Recommended from our members
A new generation of 99.999% enriched 28Si single crystals for the determination of Avogadro's constant
A metrological challenge is currently underway to replace the present definition of the kilogram. One prerequisite for this is that the Avogadro constant, NA, which defines the number of atoms in a mole, needs to be determined with a relative uncertainty of better than 2 × 10−8. The method applied in this case is based on the x-ray crystal density experiment using silicon crystals. The first attempt, in which silicon of natural isotopic composition was used, failed. The solution chosen subsequently was the usage of silicon highly enriched in 28Si from Russia. First, this paper reviews previous efforts from the very first beginnings to an international collaboration with the goal of producing a 28Si single crystal with a mass of 5 kg, an enrichment greater than 0.9999 and of sufficient chemical purity. Then the paper describes the activities of a follow-up project, conducted by PTB, to produce a new generation of highly enriched silicon in order to demonstrate the quasi-industrial and reliable production of more than 12 kg of the 28Si material with enrichments of five nines. The intention of this project is also to show the availability of 28Si single crystals as a guarantee for the future realisation of the redefined kilogram
Equilibrium and dynamical properties of two dimensional self-gravitating systems
A system of N classical particles in a 2D periodic cell interacting via
long-range attractive potential is studied. For low energy density a
collapsed phase is identified, while in the high energy limit the particles are
homogeneously distributed. A phase transition from the collapsed to the
homogeneous state occurs at critical energy U_c. A theoretical analysis within
the canonical ensemble identifies such a transition as first order. But
microcanonical simulations reveal a negative specific heat regime near .
The dynamical behaviour of the system is affected by this transition : below
U_c anomalous diffusion is observed, while for U > U_c the motion of the
particles is almost ballistic. In the collapsed phase, finite -effects act
like a noise source of variance O(1/N), that restores normal diffusion on a
time scale diverging with N. As a consequence, the asymptotic diffusion
coefficient will also diverge algebraically with N and superdiffusion will be
observable at any time in the limit N \to \infty. A Lyapunov analysis reveals
that for U > U_c the maximal exponent \lambda decreases proportionally to
N^{-1/3} and vanishes in the mean-field limit. For sufficiently small energy,
in spite of a clear non ergodicity of the system, a common scaling law \lambda
\propto U^{1/2} is observed for any initial conditions.Comment: 17 pages, Revtex - 15 PS Figs - Subimitted to Physical Review E - Two
column version with included figures : less paper waste
Treatment of Open-Angle Glaucoma and Ocular Hypertension with Preservative-Free Tafluprost/Timolol Fixed-Dose Combination Therapy : The VISIONARY Study
Funding Information: Funding was provided by Santen SA for the study, medical writing services and Rapid Service Fees. All authors had full access to all of the data in this study and take complete responsibility for the integrity of the data and accuracy of the data analysis. The contribution of IRCCS Fondazione Bietti to this work was supported by the Italian Ministry of Health and by Fondazione Roma. Publisher Copyright: © 2020, The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Introduction: A non-interventional, multicenter, European, prospective evaluation of the effectiveness, tolerability, and safety of a topical preservative-free tafluprost (0.0015%) and timolol (0.5%) fixed-dose combination (PF tafluprost/timolol FC) in adults with open-angle glaucoma (OAG) and ocular hypertension (OHT) demonstrating insufficient response to topical beta-receptor blockers or prostaglandin analogue (PGA) monotherapy. Methods: Mean intraocular pressure (IOP) change from baseline was measured at study visits following a switch to PF tafluprost/timolol FC. Primary endpoint was absolute mean IOP change at month 6. Change from baseline concerning ocular signs and symptoms was also explored. Results: Analyses included 577 patients (59.6% female). Mean age (SD) was 67.8 (11.67) years. Mean (SD) IOP reduction from baseline was significant at all study visits; 5.4 (3.76) mmHg (23.7%) at week 4, 5.9 (3.90) mmHg (25.6%) at week 12, and 5.7 (4.11) mmHg (24.9%) at month 6 (p < 0.0001 for all visits). At month 6, 69.2%, 53.6%, 40.0%, and 25.8% were responders based on ≥ 20%, ≥ 25%, ≥ 30%, and ≥ 35% cutoff values for mean IOP, respectively. Significant reductions were observed concerning corneal fluorescein staining (p < 0.0001), dry eye symptoms, irritation, itching, and foreign body sensation (p < 0.001 for each parameter). Conjunctival hyperemia was significantly reduced at all study visits (p < 0.0001 at each visit). Overall, 69 treatment-related adverse events (AEs) were reported, one of which was serious (status asthmaticus). Most AEs were mild to moderate in severity, and the majority had resolved or were resolving at the end of the study period. Conclusion: In clinical practice, PF tafluprost/timolol FC provided statistically and clinically significant IOP reductions in patients with OAG and OHT insufficiently controlled on or intolerant to PGA or beta-receptor blocker monotherapy. The full IOP reduction appeared at week 4 and was maintained over the 6-month study period. Key symptoms of ocular surface health improved. Trial Registration: European Union electronic Register of Post-Authorisation Studies (EU PAS) register number, EUPAS22204.publishersversionPeer reviewe
Qualitative Real-Time Schlieren and Shadowgraph Imaging of Human Exhaled Airflows: An Aid to Aerosol Infection Control
Using a newly constructed airflow imaging system, airflow patterns were visualized that were associated with common, everyday respiratory activities (e.g. breathing, talking, laughing, whistling). The effectiveness of various interventions (e.g. putting hands and tissues across the mouth and nose) to reduce the potential transmission of airborne infection, whilst coughing and sneezing, were also investigated. From the digital video footage recorded, it was seen that both coughing and sneezing are relatively poorly contained by commonly used configurations of single-handed shielding maneuvers. Only some but not all of the forward momentum of the cough and sneeze puffs are curtailed with various hand techniques, and the remaining momentum is disseminated in a large puff in the immediate vicinity of the cougher, which may still act as a nearby source of infection. The use of a tissue (in this case, 4-ply, opened and ready in the hand) proved to be surprisingly effective, though the effectiveness of this depends on the tissue remaining intact and not ripping apart. Interestingly, the use of a novel ‘coughcatcher’ device appears to be relatively effective in containing coughs and sneezes. One aspect that became evident during the experimental procedures was that the effectiveness of all of these barrier interventions is very much dependent on the speed with which the user can put them into position to cover the mouth and nose effectively
The preparation of HEMA-MPC films for ocular drug delivery
There is a need to prolong drug residence time using a biocompatible formulation in the subconjunctival space after surgery to treat glaucoma. Drug releasing discs were prepared with 2-(hydroxyethyl)methacrylate (HEMA) and 2-methacryloyl-oxyethyl phosphorylcholine (MPC). The ratio of bound water (Wb) to free water (Wf) ratio increased from 1:0.3 to 1:6.8 with increasing MPC (0 to 50%, w/w). The optimal balance between water content, SR and mechanical strength were obtained with 10% MPC (w/w) hydrogels. Water-alcohol mixtures were examined to facilitate loading of poorly soluble drugs, and they showed greater hydrogel swelling than either water or alcohol alone. The SR was 1.2 ± 0.02 and 3.3 ± 0.1 for water and water:ethanol (1:1) respectively. HEMA-MPC (10%) discs were loaded with dexamethasone using either water:ethanol (1:1) or methanol alone. Drug release was examined in an outflow rig model that mimics the subconjunctival space in the eye. Dexamethasone loading increased from 0.3 to 1.9 mg/disc when the solvent was changed from water:ethanol (1:1) to methanol with the dexamethasone half-life (t½) increasing from 1.9 to 9.7 days respectively. These encouraging results indicate that HEMA-MPC hydrogels have the potential to sustain the residence time of a drug in the subconjunctival space of the eye
Phylogeographic Study of Apodemus ilex (Rodentia: Muridae) in Southwest China
BACKGROUND: The Mountains of southwest China have complex river systems and a profoundly complex topography and are among the most important biodiversity hotspots in the world. However, only a few studies have shed light on how the mountains and river valleys promote genetic diversity. Apodemus ilex is a fine model for investigating this subject. METHODOLOGY/PRINCIPAL FINDINGS: To assess the genetic diversity and biogeographic patterns of Apodemus ilex, the complete cytochrome b gene sequences (1,140 bp) were determined from 203 samples of A. draco/ilex that were collected from southwest China. The results obtained suggested that A. ilex and A. draco are sistergroups and diverged from each other approximately 2.25 million years ago. A. ilex could be divided into Eastern and Western phylogroups, each containing two sub-groups and being widespread in different geographical regions of the southern Hengduan Mountains and the western Yunnan - Guizhou Plateau. The population expansions of A. ilex were roughly from 0.089 Mya to 0.023 Mya. CONCLUSIONS: Our result suggested that A. ilex is a valid species rather than synonym of A. draco. As a middle-high elevation inhabitant, the phylogenetic pattern of A. ilex was strongly related to the complex geographical structures in southwest China, particularly the existence of deep river valley systems, such as the Mekong and Salween rivers. Also, it appears that the evolutionary history of A. ilex, such as lineage divergences and population expansions were strongly affected by climate fluctuation in the Late Pleistocene
- …