Multidimensional en-face OCT imaging of the retina.

Fast T-scanning (transverse scanning, en-face) was used to build B-scan or C-scan optical coherence tomography (OCT) images of the retina. Several unique signature patterns of en-face (coronal) are reviewed in conjunction with associated confocal images of the fundus and B-scan OCT images. Benefits in combining T-scan OCT with confocal imaging to generate pairs of OCT and confocal images similar to those generated by scanning laser ophthalmoscopy (SLO) are discussed in comparison with the spectral OCT systems. The multichannel potential of the OCT/SLO system is demonstrated with the addition of a third hardware channel which acquires and generates indocyanine green (ICG) fluorescence images. The OCT, confocal SLO and ICG fluorescence images are simultaneously presented in a two or a three screen format. A fourth channel which displays a live mix of frames of the ICG sequence superimposed on the corresponding coronal OCT slices for immediate multidimensional comparison, is also included. OSA ISP software is employed to illustrate the synergy between the simultaneously provided perspectives. This synergy promotes interpretation of information by enhancing diagnostic comparisons and facilitates internal correction of movement artifacts within C-scan and B-scan OCT images using information provided by the SLO channel

Finite temperature calculations for the bulk properties of strange star using a many-body approach

We have considered a hot strange star matter, just after the collapse of a supernova, as a composition of strange, up and down quarks to calculate the bulk properties of this system at finite temperature with the density dependent bag constant. To parameterize the density dependent bag constant, we use our results for the lowest order constrained variational (LOCV) calculations of asymmetric nuclear matter. Our calculations for the structure properties of the strange star at different temperatures indicate that its maximum mass decreases by increasing the temperature. We have also compared our results with those of a fixed value of the bag constant. It can be seen that the density dependent bag constant leads to higher values of the maximum mass and radius for the strange star.Comment: 21 pages, 2 tables, 12 figures Astrophys. (2011) accepte

Death is not a success: reflections on business exit

This article is a critical evaluation of claims that business exits should not be seen as failures, on the grounds that may constitute voluntary liquidation, or because they are learning opportunities. This can be seen as further evidence of bias affecting entrepreneurship research, where failures are repackaged as successes. This article reiterates that the majority of business exits are unsuccessful. Drawing on ideas from the organisational life course, it is suggested that business ‘death’ is a suitable term for describing business closure. Even cases of voluntary ‘harvest liquidation’ such as retirement can be meaningfully described as business deaths

Class of invariants for the 2D time-dependent Landau problem and harmonic oscillator in a magnetic field

We consider an isotropic two dimensional harmonic oscillator with arbitrarily time-dependent mass $M(t)$ and frequency $\Omega(t)$ in an arbitrarily time-dependent magnetic field $B(t)$. We determine two commuting invariant observables (in the sense of Lewis and Riesenfeld) $L,I$ in terms of some solution of an auxiliary ordinary differential equation and an orthonormal basis of the Hilbert space consisting of joint eigenvectors $\phi_\lambda$ of $L,I$. We then determine time-dependent phases $\alpha_\lambda(t)$ such that the $\psi_\lambda(t)=e^{i\alpha_\lambda}\phi_\lambda$ are solutions of the time-dependent Schr\"odinger equation and make up an orthonormal basis of the Hilbert space. These results apply, in particular to a two dimensional Landau problem with time-dependent $M,B$, which is obtained from the above just by setting $\Omega(t) \equiv 0$. By a mere redefinition of the parameters, these results can be applied also to the analogous models on the canonical non-commutative plane.Comment: 13 pages, 3 references adde

Effects of Lateral Diffusion on the Dynamics of Desorption

The adsorbate dynamics during simultaneous action of desorption and lateral adsorbate diffusion is studied in a simple lattice-gas model by kinetic Monte Carlo simulations. It is found that the action of the coverage-conserving diffusion process during the course of the desorption has two distinct, competing effects: a general acceleration of the desorption process, and a coarsening of the adsorbate configuration through Ostwald ripening. The balance between these two effects is governed by the structure of the adsorbate layer at the beginning of the desorption process

Aspects on the risk factors of laparoscopic cholecystectomy conversion in patients with acute calculous colecystitis

Materiale şi metode. S-au studiat 114 bolnavi operaţi laparoscopic sau prin conversie pentru CA. CA a fost stabilită conform criteriilor Tokyo Guidelines. Bolnavii au fost stratificaţi în 2 loturi: I- CEL fără conversie şi II- CEL cu conversie. S-au analizat vîrstă, sexul, rezultatele examinărilor clinico- paraclinice, inclusiv a raportului neutrofile/limfocite (RNL) ca marker al inflamaţiei. Dificultatea intraoperatorie a CEL a fost apreciată conform scalei Parkland. Rezultate. Rata de conversie a constituit 7,9% cazuri. În lotul cu conversie au predominat bărbaţii- 66,7%, în lotul fără conversie - femeile (61,9%). Vârsta pacienţilor a fost semnificativ mai înaltă în cazul conversiei. În lotul cu conversie în 55,6% cazuri s-a iniţiat CEL în termeni > de 72 ore de la debutul primelor manifestări clinice, în lotul fără conversie acest indice a constituit 27,6 %. În lotul I a predominat gr.III de severitate intraoperatorie conform Parkland, în cazul conversiei gr.IV şi V. Cauzele conversiei: plastron inflamator perivezicular şi al ligamentului hepato-duodenal (n=4), hemoragie intraoperatorie incontrolabilă laparoscopic (n=3), CA gangrenoasă cu perforare şi abces perivezicular (n=2). RNL a fost semnificativ mai mare în lotul cu conversie (8,6), comparativ cu lotul fără conversie (3,9). Concluzii. Conversia CEL constituie o etapă raţională a tratamentului CA complicate. Factori predictivi ai conversiei au constituit sexul masculin, vîrsta înaintată, adresarea tardivă. RNL poate fi util ca factor de pronostic în ce priveşte gradul de severitate al CA.Aim of study. To study the risk factors of laparoscopic cholecystectomy (LC) conversion in patients with acute calculous cholecystitis (AC). Materials and methods. The 114 patients operated laparoscopically or by conversion for CA were studied. AC was established according to Tokyo Guidelines criteria. The patients were stratified into 2 groups: I- LC without conversion and II- LC with conversion. Age, sex, the results of clinical-paraclinical examinations, including the neutrophil/lymphocyte ratio (NLR) as a marker of inflammation, were analyzed. The intraoperative difficulty of LC was assessed according to the Parkland scale. Results. The conversion rate constituted 7.9% of cases. In the group with conversion, men predominated - 66.7%, in the group without conversion - women (61.9%). The age of the patients was significantly higher in the case of conversion. In the group with conversion in 55.6% of cases, LC was initiated within > 72 hours from the onset of the first clinical manifestations, in the group without conversion this index was 27.6%. In group I, grade III of intraoperative severity according to Parkland prevailed, in the case of conversion prevailed grade IV and V. The causes of conversion were: perivesicular inflammatory and hepato-duodenal ligament plastron (n=4), laparoscopic uncontrollable intraoperative hemorrhage (n=3), gangrenous AC with perforation and perivesicular abscess (n=2). NLR was significantly higher in the conversion group (8.6) compared to the non-conversion group (3.9). Conclusions. LC conversion is a rational step in the treatment of complicated AC. Predictive factors of conversion were male sex, advanced age, late addressing. NLR may be useful as a prognostic factor regarding the severity of AC