1,984 research outputs found
Exciton-phonon scattering and photo-excitation dynamics in J-aggregate microcavities
We have developed a model accounting for the photo-excitation dynamics and
the photoluminescence of strongly coupled J-aggregate microcavities. Our model
is based on a description of the J-aggregate film as a disordered Frenkel
exciton system in which relaxation occurs due to the presence of a thermal bath
of molecular vibrations. In a strongly coupled microcavity exciton-polaritons
are formed, mixing superradiant excitons and cavity photons. The calculation of
the microcavity steady-state photoluminescence, following a CW non resonant
pumping, is carried out. The experimental photoluminescence intensity ratio
between upper and lower polariton branches is accurately reproduced. In
particular both thermal activation of the photoluminescence intensity ratio and
its Rabi splitting dependence are a consequence of the bottleneck in the
relaxation, occurring at the bottom of the excitonic reservoir. The effects due
to radiative channels of decay of excitons and to the presence of a
paritticular set of discrete optical molecular vibrations active in relaxation
processes are investigared.Comment: 8 pages, 6 figure
What is a Gene? A Two Sided View
The need to account for all currently available experimental observations
concerning the gene nature, has reshaped the concept of gene turning it from the
essentially mechanistic unit, predominant during the '70s, into a quite abstract
open and generalized entity, whose contour appears less defined as compared to the
past. Here we propose the essence of the gene to be considered double faced. In
this respect genotypic and phenotypic entities of a gene would coexist and mix
reciprocally. This harmonizes present knowledge with current definitions and
predisposes for remodelling of our thinking as a consequence of future discoveries.
A two sided view of the gene also allows to combine the genetic and epigenetic
aspects in a unique solution, being structural and functional at the same time and
simultaneously able to include the different levels in an overlapping unicum
Border Collision Bifurcations in a Generalized Model of Population Dynamics
We analyze the dynamics of a generalized discrete time population model of a two-stage species with recruitment and capture. This generalization, which is inspired by other approaches and real data that one can find in literature, consists in considering no restriction for the value of the two key parameters appearing in the model, that is, the natural death rate and the mortality rate due to fishing activity. In the more general case the feasibility of the system has been preserved by posing opportune formulas for the piecewise map defining the model. The resulting two-dimensional nonlinear map is not smooth, though continuous, as its definition changes as any border is crossed in the phase plane. Hence, techniques from the mathematical theory of piecewise smooth dynamical systems must be applied to show that, due to the existence of borders, abrupt changes in the dynamic behavior of population sizes and multistability emerge. The main novelty of the present contribution with respect to the previous ones is that, while using real data, richer dynamics are produced, such as fluctuations and multistability. Such new evidences are of great interest in biology since new strategies to preserve the survival of the species can be suggested
La messa in sicurezza dell'area industriale di Priolo-Augusta rispetto ai rischi da terremoto e maremoto
I recenti forti terremoti che hanno interessato zone particolarmente industrializzate in
Turchia ed in India (terremoto del 17.8.1999, Kocaeli, Turchia, Mw = 7.4; e terremoto
di Guyarat, India, del 26.01.2001, Mw =7.7) hanno messo in evidenza che al
danno prodotto dal terremoto si pu\uf2 aggiungere quello dovuto alle conseguenze di
incidenti e/o rotture negli impianti, cosiddetti, \u201ca rischio di incidente rilevante\u201d. Il rischio
totale nell\u2019area pu\uf2 quindi assumere valori estremamente elevati in termini economici,
ambientali, e talvolta con perdita di vite umane. Ad esempio, nel caso del terremoto turco,
il danneggiamento della raffineria Tupras di IZMIT ha provocato l\u2019incendio della stessa
e la fuoriuscita di una quantit\ue0 rilevante di olio (Foto 1). Sulla base di quanto sopra e di quanto conosciuto, il presente studio si propone come
elemento di base per l\u2019impostazione di interventi strutturali sugli impianti e sul territorio
con l\u2019obiettivo di mettere il tutto in condizioni di sicurezza a fronte del terremoto
(ed eventuale maremoto associato) atteso nell\u2019area.
A questo scopo \ue8 stata realizzata un\u2019analisi per mettere in evidenza l\u2019entit\ue0 e la frequenza
dei fenomeni naturali (terremoti e maremoti) che possono determinare significativi
impatti sia sull\u2019ambiente fisico che su quello antropizzato (infrastrutture) nell\u2019area
di Priolo-Augusta. Il progetto ha avuto come obiettivo iniziale la valutazione dei carichi
dovuti a fenomeni naturali che, trasformati in termini ingegneristici, devono essere utilizzati per la verifica della idoneit\ue0 progettuale degli impianti industriali presenti
nelle aree studiate. In particolare \ue8 stato valutato, dapprima, il terremoto di riferimento
per la progettazione, in termini di picco massimo di accelerazione e spettro di risposta
associato. In tale fase si \ue8 anche provveduto alla costruzione di scenari associati ad
un eventuale maremoto. I siti prescelti sono esposti ad un elevato rischio sismico la cui
definizione ha richiesto l\u2019adozione delle metodologie pi\uf9 avanzate disponibili. A tale
scopo sono stati applicati diversi approcci innovativi sia di tipo sismologico che ingegneristico
Ground effects induced by the 2012 seismic sequence in Emilia: implications for seismic hazard assessment in the Po Plain
Since May 16, 2012, a seismic sequence has affected a wide portion of the Emilia Region (northern Italy), chiefly for the Modena and Ferrara Provinces. The first mainshock (Ml 5.9; focal depth, ca. 6 km) occurred on May 20, 2012, with the epicenter located a few kilometers north of Finale Emilia. A second main shock (Ml 5.8; focal depth, ca. 10 km) occurred on May 29, 2012, about 12 km west of the first earthquake, with the epicenter near Medolla. The seismic sequence has been characterized by five other Ml 655 events, and more than 2,300 aftershocks of lower magnitude, until the end July 2012. The distribution of the aftershocks identifies a WNW-ESE-trending zone ca. 40 km long that is characterized by NNE-SSW nearly pure compression, as indicated by the focal mechanisms. This report focuses on the many ground effects that were induced by this seismic sequence, as mainly cracks, liquefaction-type phenomena, and hydrological anomalies. The aim is to provide a complete representation of such effects, to: illustrate their type, size and areal distribution; identify the zones in the affected area that were most prone to the occurrence of ground effects (i.e., more susceptible to local geological instability in the case of earthquake occurrence); carry out an independent assessment of the intensities of the earthquakes through the ESI 2007 intensity scale, which is based only on coseismic effects on the natural environment
Return of the cadaver: Key role of anatomic dissection for plastic surgery resident training.
Successful Plastic Surgery Residency training is subjected to evolving society pressure of lower hourly work weeks imposed by external committees, labor laws, and increased public awareness of patient care quality. Although innovative measures for simulation training of surgery are appearing, there is also the realization that basic anatomy training should be re-enforced and cadaver dissection is of utmost importance for surgical techniques.In the development of new technology for implantable neurostimulatory electrodes for the management of phantom limb pain in amputee patients, a design of a cadaveric model has been developed with detailed steps for innovative transfascicular insertion of electrodes. Overall design for electrode and cable implantation transcutaneous was established and an operating protocol devised.Microsurgery of the nerves of the upper extremities for interfascicular electrode implantation is described for the first time. Design of electrode implantation in cadaver specimens was adapted with a trocar delivery of cables and electrodes transcutaneous and stabilization of the electrode by suturing along the nerve. In addition, the overall operating arena environment with specific positions of the multidisciplinary team necessary for implantable electrodes was elaborated to assure optimal operating conditions and procedures during the organization of a first-in-man implantation study.Overall importance of plastic surgery training for new and highly technical procedures is of importance and particularly there is a real need to continue actual cadaveric training due to patient variability for nerve anatomic structures
Diagnostic Accuracy of S100B Urinary Testing at Birth in Full-Term Asphyxiated Newborns to Predict Neonatal Death
BACKGROUND: Neonatal death in full-term infants who suffer from perinatal asphyxia (PA) is a major subject of investigation, since few tools exist to predict patients at risk of ominous outcome. We studied the possibility that urine S100B measurement may identify which PA-affected infants are at risk of early postnatal death. METHODOLOGY/PRINCIPAL FINDINGS: In a cross-sectional study between January 1, 2001 and December 1, 2006 we measured S100B protein in urine collected from term infants (n = 132), 60 of whom suffered PA. According to their outcome at 7 days, infants with PA were subsequently classified either as asphyxiated infants complicated by hypoxic ischemic encephalopathy with no ominous outcome (HIE Group; n = 48), or as newborns who died within the first post-natal week (Ominous Outcome Group; n = 12). Routine laboratory variables, cerebral ultrasound, neurological patterns and urine concentrations of S100B protein were determined at first urination and after 24, 48 and 96 hours. The severity of illness in the first 24 hours after birth was measured using the Score for Neonatal Acute Physiology-Perinatal Extension (SNAP-PE). Urine S100B levels were higher from the first urination in the ominous outcome group than in healthy or HIE Groups (p<0.001 for all), and progressively increased. Multiple logistic regression analysis showed a significant correlation between S100B concentrations and the occurrence of neonatal death. At a cut-off >1.0 microg/L S100B had a sensitivity/specificity of 100% for predicting neonatal death. CONCLUSIONS/SIGNIFICANCE: Increased S100B protein urine levels in term newborns suffering PA seem to suggest a higher risk of neonatal death for these infants
Quaternary capable folds and seismic hazard in Lombardia (Northern Italy): the Castenedolo structure near Brescia.
We identify evidence of late Quaternary compressive tectonics
in the Northern sector of the Central Po Plain through a systematic
revision of the literature, new field mapping, and a new study of
seismic reflection data obtained by ENI E&P. In particular, the reinterpretation
of ca. 18.000 km of seismic profiles clearly shows a belt
of segmented, 10 to 20 km long, fault propagation folds, controlled
by the Plio-Quaternary growth of several out-of-sequence thrusts. As
an example of this active structural style, in this paper we focus on a
buried fold located just south of the Castenedolo Hill, a few km SE
of Brescia. Although the Castenedolo anticline has long ago been
described as a young compressional structure (e.g., DESIO, 1965), no
detailed structural analysis of this feature has been performed until
now. We calculated the uplift rates of this fold through the analysis
of its syntectonic sedimentary record as imaged by the extremely
high quality ENI E&P subsurface data available in the area. The evolution
of this anticline was a discontinuous process characterized by
several tectonic uplift pulses (with rates of ca. 0.1 mm/yr) of different
duration, separated by periods of variable extent in which no
fold growth occurred. The Quaternary growth history of this anticline
and the presence of faulted and folded late Pleistocene to
Holocene deposits at nearby sites (Ciliverghe and Monte Netto)
demonstrate that the significant seismicity of this area (e.g., the
December 25, 1222, Io = IX MCS Brescia earthquake, MAGRI &
MOLIN, 1986; GUIDOBONI, 1986) must be related to active compressional
structures within the Brescia piedmont belt. Our
regional investigations show that the structural and paleoseismic
setting illustrated near Castenedolo is typical of the whole Lombardia
domain of the Southern Alps. This implies that the currently
accepted seismotectonic model for this region, and related
seismic hazard assessment, should be thoroughly and carefully
re-evaluated
Effectiveness of direct egfr mutations research at time of diagnostic biopsy for lung cancer: a single institution outcome research
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