2,810 research outputs found
Original approach for thrombolytic therapy in patients with Ilio-femoral deep vein thrombosis: 2 years follow-up
Objective: The aim of the study was to discuss the results of catheter-directed thrombolysis and complementary procedures to treat acute iliofemoral deep vein thrombosis (DVT) evaluating the safety and effectivness of an easy access such as the Great Saphenous Vein. Methods and materials: A total of 22 consecutive patients with iliofemoral thrombosis and two patients with femoro-popliteal thrombosis on recent onset diagnosed with Ultrasound Doppler and contrast venography underwent intrathrombus drip infusion of urokinase while intravenous heparin was continued using saphenical access. Residual venous stenosis were treated in six patients by percutaneous balloon Angioplasty and stenting. All patients underwent routine venous duplex imaging at 30 days, 3 months, 6 months and every 6 months thereafter. Results: Complete patency of thrombosed veins was restored in 22 patients (91 %) with prompt symptomatic relief. There were no major complications in the immediate outcomes. At follow-up, two patients reported a persistant slim iliac vein stenosis, two patients had post-thrombotic syndrome, and two patients showed Deep Vein Reflux. Conclusion: Local thrombolysis using saphenical access was a safe and effective approach for the treatment of acute iliofemoral deep vein thrombosis. It seems to be a valid, easy and safe alternative, reducing the risks of haematoma and venous lesions, which can be observed when using femoral, popliteal, and trans-jugular access
The Milagro anticenter hot spots: cosmic rays from the Geminga supernova ?
The Milagro experiment has announced the discovery of an excess flux of TeV
cosmic rays from the general direction of the heliotail, also close to the
Galactic anticenter. We investigate the hypothesis that the excess cosmic rays
were produced in the SN explosion that gave birth to the Geminga pulsar. The
assumptions underlying our proposed scenario are that the Geminga supernova
occurred about 3.4 10^5 years ago (as indicated by the spin down timescale),
that a burst of cosmic rays was injected with total energy 10^49 erg (i.e.,
about 1% of a typical SN output), and that the Geminga pulsar was born with a
positive radial velocity of 100--200 km s^-1. We find that our hypothesis is
consistent with the available information. In a first variant (likely
oversimplified), the cosmic rays have diffused according to the Bohm
prescription (i.e., with a diffusion coefficient on the order of c times r_L,
with c the speed of light and r_L the Larmor radius). An alternative scheme
assumes that diffusion only occurred initially, and the final propagation to
the Sun was a free streaming in a diverging magnetic field. If the observed
cosmic ray excess does indeed arise from the Geminga SN explosion, the
long--sought "smoking gun" connecting cosmic rays with supernovae would finally
be at hand. It could be said that, while looking for the "smoking gun", we were
hit by the bullets themselves.Comment: Astronomy and Astrophysics, accepted; includes modifications
suggested by the referee; 4 pages and 1 figur
The vanishing of two-point functions for three-loop superstring scattering amplitudes
In this paper we show that the two-point function for the three-loop chiral
superstring measure ansatz proposed by Cacciatori, Dalla Piazza, and van Geemen
vanishes. Our proof uses the reformulation of ansatz in terms of even cosets,
theta functions, and specifically the theory of the linear system
on Jacobians introduced by van Geemen and van der Geer.
At the two-loop level, where the amplitudes were computed by D'Hoker and
Phong, we give a new proof of the vanishing of the two-point function (which
was proven by them). We also discuss the possible approaches to proving the
vanishing of the two-point function for the proposed ansatz in higher genera
Spectral decomposition of starbursts and AGNs in 5-8 micron Spitzer IRS spectra of local ULIRGs
We present an analysis of the 5-8 micron Spitzer-IRS spectra of a sample of
68 local Ultraluminous Infrared Galaxies (ULIRGs). Our diagnostic technique
allows a clear separation of the active galactic nucleus (AGN) and starburst
(SB) components in the observed mid-IR emission, and a simple analytic model
provides a quantitative estimate of the AGN/starburst contribution to the
bolometric luminosity. We show that AGNs are ~30 times brighter at 6 micron
than starbursts with the same bolometric luminosity, so that even faint AGNs
can be detected. Star formation events are confirmed as the dominant power
source for extreme infrared activity, since ~85% of ULIRG luminosity arises
from the SB component. Nonetheless an AGN is present in the majority (46/68) of
our sources.Comment: 5 Pages, 3 figures. MNRAS Letters, Accepte
Demographic Change and the Urban–Rural Divide: Understanding the Role of Density and Agglomeration in Fertility Transitions
Assuming fertility variations across urban–rural gradients, our study focuses on the traditional polarization in urban and rural fertility, offering a refined interpretation of demographic processes associated with population density. More specifically, we tested the intimate relationship between local fertility and population density, comparing the outcomes of a classical urban–rural model (reflecting a linear relationship between the two variables) with those of a more complex quadratic model (implying the so-called ‘suburban fertility hypothesis’) in Greece. We considered fertility dynamics in three districts (urban, suburban, and rural) of 51 Greek prefectures for the last two decades (2000–2009 and 2010–2019) and controlled for the diverging impact of local contexts at different population density levels. Taken as a measure of ‘maturity’ of regional systems, urban fertility surpassed rural fertility in almost all prefectures of Greece. An additional sign of maturity in metropolitan systems indicates that suburban birth rates are higher than urban birth rates in prefectures with high population density (Athens, Thessaloniki, Heraklion, and Patras). The regression outcomes document a specific response of fertility to regional development, evidencing a spatially differentiated shift from classical urban–rural disparities toward a more complex model with the emergence of suburban poles. From this perspective, fertility divides reflect the evolutions of socioeconomic forces (more or less rapidly) along the urban gradient
Unraveling urban form and collision risk: The spatial distribution of traffic accidents in Zanjan, Iran
Official statistics demonstrate the role of traffic accidents in the increasing number of fa-talities, especially in emerging countries. In recent decades, the rate of deaths and injuries caused by traffic accidents in Iran, a rapidly growing economy in the Middle East, has risen significantly with respect to that of neighboring countries. The present study illustrates an exploratory spatial analysis’ framework aimed at identifying and ranking hazardous locations for traffic accidents in Zanjan, one of the most populous and dense cities in Iran. This framework quantifies the spatiotem-poral association among collisions, by comparing the results of different approaches (including Kernel Density Estimation (KDE), Natural Breaks Classification (NBC), and Knox test). Based on descriptive statistics, five distance classes (2–26, 27–57, 58–105, 106–192, and 193–364 meters) were tested when predicting location of the nearest collision within the same temporal unit. The empirical results of our work demonstrate that the largest roads and intersections in Zanjan had a significantly higher frequency of traffic accidents than the other locations. A comparative analysis of distance bandwidths indicates that the first (2–26 m) class concentrated the most intense level of spatiotem-poral association among traffic accidents. Prevention (or reduction) of traffic accidents may benefit from automatic identification and classification of the most risky locations in urban areas. Thanks to the larger availability of open-access datasets reporting the location and characteristics of car accidents in both advanced countries and emerging economies, our study demonstrates the potential of an integrated analysis of the level of spatiotemporal association in traffic collisions over metropolitan regions
Economic Downturns, Urban Growth and Suburban Fertility in a Mediterranean Context
Despite the wealth of micro–macro data on short-term demographic dynamics, the impact of metropolitan growth and economic downturns on local fertility is still under-investigated in advanced economies. Recent studies in low-fertility contexts have assumed suburban birth rates as being systematically higher than urban and rural rates. This assumption (hereafter, known as the ‘suburban fertility hypothesis’) was grounded on stylized facts and spatial regularities that imply a significant role of both macro (contextual) and micro (behavioral) factors positively influencing fertility in suburban locations. To verify such a hypothesis from a macro (contextual) perspective, the present study compares the general fertility rate of urban, suburban, and rural settlements of the Athens’ metropolitan region (Greece) at various observation years between 1860 and 2020. Long-term Athens’ growth represented a sort of ‘quasi-experiment’ for Mediterranean Europe, linking sequential urban stages and distinctive waves of economic expansion and recession. Using multivariate exploratory analysis and global/local econometric models, a dominant ‘rural’ fertility regime was recorded for 1860 and 1884. A characteristic ‘urban’ fertility regime was, instead, found over a relatively long, intermediate period between 1956 and 1990. Higher fertility in suburban settlements (10 km away from downtown Athens, on average) was, finally, observed since 2000. Considering a sufficiently long-time interval, the existence of multiple fertility regimes along the distance gradient has demonstrated how fertility dynamics are intrinsically bonded with metropolitan growth, economic downturns, and social transformations in Mediterranean Europe
Radio-induced low-grade glioma: report of two cases and review of the literature
With the increasing number of cancer survivors,
we can observe a population that will present a higher
risk of developing secondary long-term toxicities related to
adjuvant chemo and radiotherapy regimens. Among these,
children surviving from acute lymphoblastic leukemia
(ALL) that were treated with prophylactic cranial irradiation
represent a group of patients at a high risk of
developing secondary brain tumors. Radiation-induced
intracranial tumors have been documented since 1950, and
today, more than one-hundred cases have been described.
We report our experience with two young patients who
were hospitalized for low grade gliomas and had a positive
anamnesis for ALL and consequent radiotherapy
Synchrotron x-ray scattering analysis of nylon-12 crystallisation variation depending on 3D printing conditions
7Nylon-12 is an important structural polymer in wide use in the form of fibres and bulk structures. Fused filament fabrication (FFF) is an extrusion-based additive manufacturing (AM) method for rapid prototyping and final product manufacturing of thermoplastic polymer objects. The resultant microstructure of FFF-produced samples is strongly affected by the cooling rates and thermal gradients experienced across the part. The crystallisation behaviour during cooling and solidification influences the micro- and nano-structure, and deserves detailed investigation. A commercial Nylon-12 filament and FFF-produced Nylon-12 parts were studied by differential scanning calorimetry (DSC) and wide-angle X-ray scattering (WAXS) to examine the effect of cooling rates under non-isothermal crystallisation conditions on the microstructure and properties. Slower cooling rates caused more perfect crystallite formation, as well as alteration to the thermal properties.openopende Jager B.; Moxham T.; Besnard C.; Salvati E.; Chen J.; Dolbnya I.P.; Korsunsky A.M.de Jager, B.; Moxham, T.; Besnard, C.; Salvati, E.; Chen, J.; Dolbnya, I. P.; Korsunsky, A. M
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