2,335 research outputs found
Application of ERTS-1 data to the protection and management of New Jersey's coastal environment
ERTS-1 imagery is being used by the New Jersey Department of Environmental Protection (NJDEP) to develop information products that will assist the state in optimally managing its coastal resources and in allocating funds. Interviews with NJDEP personnel have identified significant problem areas in the coastal zone, and the types of remote sensor derived information products that can be used in real-time decision making. Initial analyses of imagery from several successive ERTS-1 orbits have shown the extent, predominant drift, and dispersion characteristics of waste disposal in coastal New Jersey waters. Imagery (MSS Bands 4 and 5) for several orbits, shows that New-York Harbor tidal discharge extending as far south as Long Branch, New Jersey
Quantitative uniqueness for elliptic equations with singular lower order terms
We use a Carleman type inequality of Koch and Tataru to obtain quantitative
estimates of unique continuation for solutions of second order elliptic
equations with singular lower order terms. First we prove a three sphere
inequality and then describe two methods of propagation of smallness from sets
of positive measure.Comment: 23 pages, v2 small changes are done and some mistakes are correcte
Trapping of magnetic flux by the plunge region of a black hole accretion disk
The existence of the radius of marginal stability means that accretion flows
around black holes invariably undergo a transition from a MHD turbulent
disk-like flow to an inward plunging flow. We argue that the plunging inflow
can greatly enhance the trapping of large scale magnetic field on the black
hole, and therefore may increase the importance of the Blandford-Znajek (BZ)
effect relative to previous estimates that ignore the plunge region. We support
this hypothesis by constructing and analyzing a toy-model of the dragging and
trapping of a large scale field by a black hole disk, revealing a strong
dependence of this effect on the effective magnetic Prandtl number of the MHD
turbulent disk. Furthermore, we show that the enhancement of the BZ effect
depends on the geometric thickness of the accretion disk. This may be, at least
in part, the physical underpinnings of the empirical relation between the
inferred geometric thickness of a black hole disk and the presence of a radio
jet.Comment: 18 pages, 3 figures, accepted for publication in the Astrophysical
Journal. See
http://www.astro.umd.edu/~chris/publications/movies/flux_trapping.html for
animation
Do radiolucent lines and stress shielding of the humeral shaft really matter in shoulder arthroplasty?
The purpose of this study is to evaluate at a mid-term follow up, the radiological survival of an
uncemented humeral stem in shoulder arthroplasty. One hundred and twenty-six replacements
including hemi (HA), total (TSA) and reverse (RSA) implanted from 1999 to 2008 were reviewed at
a mean follow up of 7.2 years (48-144 months). The same uncemented triconical stem (SMR, Lima
Corporate) was implanted. There were: 23 HSA, 43 TSA, 60 RSA. An independent observer evaluated
all the patients with Constant Score. A radiologic analysis by an expert radiologist and an orthopaedic
surgeon was performed: humeral component-bone interface was divided in seven zones. They judged
a mobilisation if a migration or tilt of the humeral implant or if≥ 2 mm radiolucent line in at least
three zones was present. Chi-squared test, Fisher test and analysis of variance were performed and
a p<0.05 was considered statistically significant. No major radiological signs of loosening and no tilt
or migration of the humeral component were found. Only 23 (18.2%) patients had no RL around the
humeral implant. In the remaining 103 (81.7%) implants: 96 (76.1%) presented RL less than 2 mm,
particularly 75 (59.5%) in less than 3 zones and 21 (16.6%) in more than 3 zones. Of the remaining 7
(5.5%) implants the presence of RL of 2 mm or greater in only one zone was seen. Apart from sepsis
no revision was performed for humeral component loosening. Although a high rate of RL, uncemented
humeral stem has an excellent survivorship at a mid-term follow up. Relationship between presence,
position and depth of RL and internal stress shielding is commonly observed but does not appear t
The encaged lung: rapidly progressive idiopathic pleurisy.
Here we present a case of an idiopathic fibrinous pleurisy affecting a 56-year old non-smoker male that has shown a rapidly progressive course. With a brief review of the literature we discuss the absence of any identified cause of pleurisy as a relatively common condition, requiring attention and clinical awareness
Nonlinear diffusion & thermo-electric coupling in a two-variable model of cardiac action potential
This work reports the results of the theoretical investigation of nonlinear
dynamics and spiral wave breakup in a generalized two-variable model of cardiac
action potential accounting for thermo-electric coupling and diffusion
nonlinearities. As customary in excitable media, the common Q10 and Moore
factors are used to describe thermo-electric feedback in a 10-degrees range.
Motivated by the porous nature of the cardiac tissue, in this study we also
propose a nonlinear Fickian flux formulated by Taylor expanding the voltage
dependent diffusion coefficient up to quadratic terms. A fine tuning of the
diffusive parameters is performed a priori to match the conduction velocity of
the equivalent cable model. The resulting combined effects are then studied by
numerically simulating different stimulation protocols on a one-dimensional
cable. Model features are compared in terms of action potential morphology,
restitution curves, frequency spectra and spatio-temporal phase differences.
Two-dimensional long-run simulations are finally performed to characterize
spiral breakup during sustained fibrillation at different thermal states.
Temperature and nonlinear diffusion effects are found to impact the
repolarization phase of the action potential wave with non-monotone patterns
and to increase the propensity of arrhythmogenesis
Local behavior of p-harmonic Green's functions in metric spaces
We describe the behavior of p-harmonic Green's functions near a singularity
in metric measure spaces equipped with a doubling measure and supporting a
Poincar\'e inequality
Laparoscopic versus Open Surgery in Complicated Appendicitis in Children Less Than 5 Years Old: A Six-Year Single-Centre Experience
Introduction. Acute appendicitis is the most common surgical emergency in the pediatric population. The peak incidence occurs in the first decade of life, while it is uncommon to face appendicitis in children younger than 5 years of age. Laparoscopy is now demonstrated to be the optimal approach also to treat complicated appendicitis, but in very young children this standardized operation is not always easy to perform. Material and Methods. From January 2009 to December 2015 we operated on 525 acute appendicitis, with 120 patients less than 5 years of age. Results. 90 children had a complicated appendicitis (localized or diffuse peritonitis): 43 (48%) were operated on by open approach and 47 (52%) by laparoscopy. The overall incidence of postoperative complications was greater in the open appendectomy group (63% versus 26%) and all severe complications requiring reintervention (6% of cases: 3 postoperative abscesses resolved with ultrasound guided percutaneous abscess drainage; 1 tubal surgery for salpingitis; 1 adhesion-related ileus requiring relaparotomy) were mostly associated with open surgery. Conclusions. Laparoscopic surgery resulted as the best approach for treating complicated appendicitis also in younger children, with minor and less severe postoperative complications compared to open surgery
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