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Biomedical subjects

R N Mohapatra

Publications and source records attributed to R N Mohapatra.

9 recordsLinked to original sources
PubMed2006

Postsphaleron baryogenesis.

We present a new mechanism for generating the baryon asymmetry of the Universe directly in the decay of a singlet scalar field S(r) with a weak scale mass and a high dimensional baryon number-violating coupling. Unlike most currently popular models, this mechanism, which becomes effective after the electroweak phase transition, does not rely on the sphalerons for inducing a nonzero baryon number. CP asymmetry in S(r) decay arises through loop diagrams involving the exchange of W+/- gauge bosons and is suppressed by light quark masses, leading naturally to a value of eta(B) approximately 10(-10). The simplest realization of this idea which uses a six quark DeltaB=2 operator predicts colored scalars accessible to the CERN Large Hadron Collider and neutron-antineutron oscillation within reach of the next-generation experiments.

Journal Article↗
PubMed2006

Observable N-N oscillation in high scale seesaw models.

We discuss a realistic high scale (nu(B-L) approximately 10(12) GeV) supersymmetric seesaw model based on the gauge group SU(2)L x SU(2)R x SU(4)c where neutron-antineutron oscillation can be in the observable range. This is contrary to the naive dimensional arguments which say that tau(N-N) is proportional to nu(B-L)5 and should therefore be unobservable for seesaw scale nu(B-L) > or = 10(5) GeV. Two reasons for this enhancement are (i) accidental symmetries which keep some of the diquark Higgs masses at the weak scale and (ii) a new supersymmetric contribution from a lower dimensional operator. The net result is that tau(N-N) is proportional to nu(B-L)2 nu(wk)3 rather than nu(B-L)5. The model also can explain the origin of matter via the leptogenesis mechanism and predicts light diquark states which can be produced at LHC.

Journal Article↗
PubMed2005

Suppressing proton decay in the minimal SO(10) model.

We show that in a class of minimal supersymmetric SO(10) models which have been found to be quite successful in predicting neutrino mixings, all proton decay modes can be suppressed by a particular choice of Yukawa textures. The required texture not only fits all lepton and quark masses as well as Cabibbo-Kobayashi-Maskawa parameters, but it also predicts neutrino mixing parameter U(e3) and Dirac CP phase sin(/delta(MNS)/ to be 0.07-0.09 and 0.3-0.7, respectively.

Journal Article↗
PubMed2001

Geometric CP violation with extra dimensions.

We discuss how CP symmetry can be broken geometrically through orbifold projections in hidden extra dimensions in the context of brane-bulk models for particle unifications. The CP violation arises from a crash between the geometry of the compactification and the original higher dimensional CP definition. We present toy models to illustrate the idea and suggest ways to incorporate it into more realistic models.

Journal Article↗
PubMed2001

Large extra dimensions, sterile neutrinos and solar neutrino data.

Solar, atmospheric, and LSND neutrino oscillation results require a light sterile neutrino, nu(B), which can exist in the bulk of extra dimensions. Solar nu(e), confined to the brane, can oscillate in the vacuum to the zero mode of nu(B) and via successive Mikheyev-Smirnov-Wolfenstein transitions to Kaluza-Klein states of nu(B). This new way to fit solar data is provided by both low and intermediate string scale models. From average rates seen in the three types of solar experiments, the Super-Kamiokande spectrum is predicted with 73% probability, but dips characteristic of the 0.06 mm extra dimension should be seen in the SNO spectrum.

Journal Article↗
PubMed1979

The role of intraoperative angiography in salvaging bovine grafts for hemodialysis.

Bovine grafts used in hemodialysis frequently need declotting. Success of the declotting procedure usually is dependent upon relieving outflow obstruction. Intraoperative angiography was done during 22 declotting procedures and outflow obstructions were detected in 14 grafts. Of these 5 grafts had clinically unsuspected clots, residual to the initial declotting attempt. Four grafts had stenotic areas at the site of the venous anastomosis, which were corrected subsequently by patch grafts. Two grafts had stenotic areas in the graft owing to an infolding of the intima covered with an organized blood clot. In 2 grafts the veins draining the grafts were stenotic for a considerable length and needed revision. In 1 graft there was stenotic change at the site of the arterial anastomosis, which required revision. Of the 14 grafts 11 have remained functioning for an additional 6 to 18 months after relief of obstruction.

Adult↗
PubMed1976

Serum lactic dehydrogenase and irreversible renal allograft rejection.

The relationship between serum lactic dehydrogenase (SLDH) values and renal allograft rejection was examined in the dog and in man. Nine dogs with renal allografts and four with autografts had similar maximal elevations of SLDH during the first five postoperative days (mean, 420 +/- 213 and 433 +/- 80 I.U. per liter, respectively). During rejection of the allografts between days 7 and 14 the maximum SLDH was 810 +/- 285 I.U. per liter, and in autografts the peak SLDH was 233 +/- 22 I.U. per liter (p less than 0.01). The isoenzyme pattern of maximum SLDH during rejection was prominent in LDH5 and corresponded with renal tissue LDH isoenzyme composition. In 93 episodes of initial acute human renal allograft rejection reactions, the SLDH peaked above 500 I.U. per liter in 23 cases and remained below 500 I.U. per liter in 70 cases. SLDH levels above 500 I.U. per liter were associated with complete rejection of the kidney in 91 percent of patients and SLDH levels persistently below 500 I.U. per liter corresponded with reversal of rejection reaction in 99 percent of patients (p less than 0.01). Marked SLDH elevation is associated with severe, usually complete renal allograft rejection and may be useful in identifying patients with irreversible rejection reactions.

Animals↗