Energetic photoionization of neutral and ionic metal clusters

We show, with an example of Na_92, that for jellium metal clusters the interference of fast electron-waves emitted from equivalent sites on the cluster edge produces monochromatic oscillations in all photoionization observables as a function of the photoelectron momentum; the effect is equivalent to the usual dispersion phenomenon. In dealing with formalisms, a serious consequence of the inadequacy of self-interaction corrected local density-functional theory in correctly accounting for the exchange interaction is identified. We also briefly discuss the influence of the ionicity of the residual core on photospectra by considering the neutral member with N=58 and and the ionic member with N=52 of the Na_58 iso-jellium series, where N is the number of valence electrons. A few final remarks on possible implications of these results on other quantum systems of delocalized electrons are made.Comment: 4 pages, 5 figures, for XIII-NCAMP (IACS-Calcutta, India) proceeding

Solutions to a system of Yang-Baxter matrix equations

In this article, we take a system, $XAX=BXB$, $XBX=AXA$, of Yang-Baxter type matrix equations that ``generalizes" the matrix Yang-Baxter equation. We completely characterize the case when $A,B$ are orthogonal idempotents

The extrinsic proteins of Photosystem II

Years of genetic, biochemical, and structural work have provided a number of insights into the oxygen evolving complex (OEC) of Photosystem II (PSII) for a variety of photosynthetic organisms. However, questions still remain about the functions and interactions among the various subunits that make up the OEC. After a brief introduction to the individual subunits Psb27, PsbP, PsbQ, PsbR, PsbU, and PsbV, a current picture of the OEC as a whole in cyanobacteria, red algae, green algae, and higher plants will be presented. Additionally, the role that these proteins play in the dynamic life cycle of PSII will be discussed. © 2006 Springer Science+Business Media B.V

A study of evaluation of unhealthy cervix by various diagnostic modalities

Background: This study was carried out to evaluate cases of unhealthy cervix by using Pap (Papanicolaou) smear, colposcopy and cervical biopsy and to arrive at a definitive diagnosis. It correlated the findings of Pap smear, colposcopy and histopathology. It is important to strictly implement the screening program and spread awareness of the disease symptoms and its management to reduce the overall incidence of morbidity and mortality reported due to cervical cancer.Methods: A total 120 patients satisfying the inclusion/exclusion criteria were recruited for the study and informed consent was taken from all the participants. Pap smear was taken for all the cases. Then cases were subjected to colposcopy followed by biopsy. All the findings were correlated and analyzed. The findings of Pap smear and colposcopy were correlated with the gold standard of histopathology.Results: The sensitivity and specificity of Pap smear and colposcopy with respect to cervical biopsy were 53.1% and 98.7%, 87.87% and 72.72% respectively. Colposcopy had higher sensitivity and lower specificity than Pap smear for screening of cancer cervix.Conclusions: Cervical cancer is one of the preventable and highly curable conditions when diagnosed in the precancerous stage. The incidence of deaths resulting from cervical cancer can be brought down with adequate cervical cancer screening. Colposcopy and colposcopy directed biopsy should be done along with Pap smear in screening for early detection of cervical cancer since the accuracy of detection of cervical abnormalities is higher when these two methods are used complementarily

Nonclassical properties of states engineered by superpositions of quantum operations on classical states

We consider an experimentally realizable scheme for manipulating quantum states using a general superposition of products of field annihilation ($\hat{a}$) and creation ($\hat{a}^\dag$) operators of the type ($s \hat{a}\hat{a}^\dag+ t \hat{a}^\dag \hat{a}$), with $s^2 + t^2 = 1$. Such an operation, when applied on states with classical features, is shown to introduce strong nonclassicality. We quantify the generated degree of nonclassicality by the negative volume of Wigner distribution in the phase space and investigate two other observable nonclassical features, sub-Poissonian statistics and squeezing. We find that the operation introduces negativity in the Wigner distribution of an input coherent state and changes the Gaussianity of an input thermal state. This provides the possibility of engineering quantum states with specific nonclassical features.Comment: 19 pages, IOPclass(iopart.cls

Cyanobacterial Alkanes Modulate Photosynthetic Cyclic Electron Flow to Assist Growth under Cold Stress

All cyanobacterial membranes contain diesel-range C15-C19 hydrocarbons at concentrations similar to chlorophyll. Recently, two universal but mutually exclusive hydrocarbon production pathways in cyanobacteria were discovered. We engineered a mutant of Synechocystis sp. PCC 6803 that produces no alkanes, which grew poorly at low temperatures. We analyzed this defect by assessing the redox kinetics of PSI. The mutant exhibited enhanced cyclic electron flow (CEF), especially at low temperature. CEF raises the ATP:NADPH ratio from photosynthesis and balances reductant requirements of biosynthesis with maintaining the redox poise of the electron transport chain. We conducted in silico flux balance analysis and showed that growth rate reaches a distinct maximum for an intermediate value of CEF equivalent to recycling 1 electron in 4 from PSI to the plastoquinone pool. Based on this analysis, we conclude that the lack of membrane alkanes causes higher CEF, perhaps for maintenance of redox poise. In turn, increased CEF reduces growth by forcing the cell to use less energy-efficient pathways, lowering the quantum efficiency of photosynthesis. This study highlights the unique and universal role of medium-chain hydrocarbons in cyanobacterial thylakoid membranes: they regulate redox balance and reductant partitioning in these oxygenic photosynthetic cells under stress