Edge covering with budget constrains

We study two related problems: finding a set of k vertices and minimum number of edges (kmin) and finding a graph with at least m' edges and minimum number of vertices (mvms). Goldschmidt and Hochbaum \cite{GH97} show that the mvms problem is NP-hard and they give a 3-approximation algorithm for the problem. We improve \cite{GH97} by giving a ratio of 2. A 2(1+\epsilon)-approximation for the problem follows from the work of Carnes and Shmoys \cite{CS08}. We improve the approximation ratio to 2. algorithm for the problem. We show that the natural LP for \kmin has an integrality gap of 2-o(1). We improve the NP-completeness of \cite{GH97} by proving the pronlem are APX-hard unless a well-known instance of the dense k-subgraph admits a constant ratio. The best approximation guarantee known for this instance of dense k-subgraph is O(n^{2/9}) \cite{BCCFV}. We show that for any constant \rho>1, an approximation guarantee of \rho for the \kmin problem implies a \rho(1+o(1)) approximation for \mwms. Finally, we define we give an exact algorithm for the density version of kmin.Comment: 17 page

Aplikasi Metode Regresi Logistik Biner Sebagai Model Keberhasilan Belajar

Success or fail in a study at university can be affected by some factors. Entry selectionprocess can be an initial stage in success prediction, up to graduation. Have theentry selection examination detected this appropriately ? Or have other evaluationmechanism within their study set early warning ? These are a focus question in thisarticle.According to academic data of year 1998 through 2006, found that entry selectionexamination give a prediction of success proportion of student finishing theirstudy. Meanwhile their second semester grade point academic gave a significant indicationof the success and failure. And also found that second semester grade pointacademic had a significant contribution for their achievement in first stage evaluationresult at fourth semester

इलाचन्द्र जोशी के उपन्यासों में नायक का मनोविश्लेषणात्मक अनुशीलन

Not availabl

Have we detected the most luminous ULX so far?

We report the XMM-Newton detection of a moderately bright X-ray source superimposed on the outer arms of the inactive spiral galaxy MCG-03-34-63 (z=0.0213). It is clearly offset from the nucleus (by about 19'') but well within the D25 ellipse of the galaxy, just along its bar axis. The field has also been observed with the HST enabling us to compute a lower limit of > 94 on the X-ray to optical flux ratio which, together with the X-ray spectrum of the source, argues against a background AGN. On the other hand, the detection of excess X-ray absorption and the lack of a bright optical counterpart argue against foreground contamination. Short-timescale variability is observed, ruling out the hypothesis of a particularly powerful supernova. If it is associated with the apparent host galaxy, the source is the most powerful ULX detected so far with a peak luminosity of 1.35x10^41 erg/s in the 0.5-7 keV band. If confirmed by future multi-wavelength observations, the inferred bolometric luminosity (about 3x10^41 erg/s) requires a rather extreme beaming factor (larger than 115) to accommodate accretion onto a stellar-mass black hole of 20 solar masses and the source could represent instead one of the best intermediate-mass black hole candidate so far. If beaming is excluded, the Eddington limit implies a mass of >2300 solar masses for the accreting compact object.Comment: MNRAS Letters in press; minor correction at the end of Section

Accretion disc-corona and jet emission from the radio-loud narrow-line Seyfert 1 galaxy RX J1633.3+4719

We perform X-ray/ultraviolet (UV) spectral and X-ray variability studies of the radio-loud narrow-line Seyfert 1 (NLS1) galaxy RX J1633.3+4719 using XMM-Newton and Suzaku observations from 2011 and 2012. The 0.3-10 keV spectra consist of an ultrasoft component described by an accretion disc blackbody (kT_in = 39.6^{+11.2}_{-5.5} eV) and a power law due to the thermal Comptonization ({\Gamma} = 1.96^{+0.24}_{-0.31}) of the disc emission. The disc temperature inferred from the soft excess is at least a factor of 2 lower than that found for the canonical soft excess emission from radio-quiet NLS1s. The UV spectrum is described by a power law with photon index 3.05^{+0.56}_{-0.33}. The observed UV emission is too strong to arise from the accretion disc or the host galaxy, but can be attributed to a jet. The X-ray emission from RX J1633.3+4719 is variable with fractional variability amplitude $F_{\rm var}$=13.5$\pm1.0$ per cent. In contrast to radio-quiet active galactic nuclei (AGN), X-ray emission from the source becomes harder with increasing flux. The fractional rms variability increases with energy and the rms spectrum is well described by a constant disc component and a variable power-law continuum with the normalization and photon index being anticorrelated. Such spectral variability cannot be caused by variations in the absorption and must be intrinsic to the hot corona. Our finding of possible evidence for emission from the inner accretion disc, jet and hot corona from RX J1633.3+4719 in the optical to X-ray bands makes this object an ideal target to probe the disc-jet connection in AGN.Comment: 12 pages, 11 figures, 3 tables, Published in MNRA

Percutaneous transvenous mitral commissurotomy in a case of situs inversus, dextrocardia and rheumatic mitral stenosis

Situs inversus with dextrocardia is a rare congenital disorder. There is rare coincidence of rheumatic severe mitral stenosis in a patient with situs inversus and dextrocardia. Technical difficulties for doing percutaneous transvenous mitral commissurotomy (PTMC) in such patients are well known and there are few reports of PTMC in situs inversus with dextrocardia. Here we report a case of 53 year old female with situs inversus and dextrocardia where PTMC was successfully done with a few modifications of standard Inoue technique. The patient had dyspnea on exertion of NYHA class III with initial mitral valve area of 0.8 cm2 and severe pulmonary arterial hypertension with PA systolic pressure of 106 mmHg. Femoral vein access was performed from the left side to align the septal puncture needle and balloon to the left sided IVC and to facilitate LV entry. Septal descent of the septal puncture needle (Brockenbrough needle) was performed in the AP view with the needle rotated from 12 o’clock to 7 o’clock position instead of 5 o’clock position. The right border of the spine was used as a landmark for trans-septal puncture. The LA pressure fell from 19 mmHg to 9 mmHg with no residual gradient across the valve. PA systolic pressure dropped to 48 mmHg. Echocardiography showed a well-divided anterior commissure with a MVA of 1.8 cm2 and mild mitral regurgitation with mild pulmonary hypertension. In summary, PTMC is feasible in the rare patient with dextrocardia with additional modifications of the Inoue technique and protocols for groin and septal puncture.Keywords: Mitral commissurotomy; Inoue technique; Situs inversus;Dextrocardia; Rheumatic mitral stenosi

Synthesis of bulk, dense, nanocrystalline yttrium aluminum garnet from amorphous powders

Amorphous powders of Al2O3x2014;37.5 mol% Y2O3 (yttrium aluminum garnet (YAG)) were prepared by coprecipitation, decomposed at 800xB0;C, and hot-pressed uniaxally at low temperature (600xB0;C) and a moderate pressure (750 MPa). Optimum conditions yielded microstructures with only 2% porosity and partial crystallization of YAG. Further processing using high quasi-hydrostatic pressure (1 GPa) at 1000xB0;C enabled the production of fully crystallized YAG with gt;96% relative density and a nanocrystalline grain size of x223C;70 nm. 13