Tunneling with the Lorentz Force and the Friction

We present a semiclassical study of a transport process, the tunneling, in the presence of a magnetic field and a dissipative environment. We have found that the problem can be mapped onto an effective one-dimensional one, and the tunneling rate is strongly affected by the magnetic field, such as a complete suppression by a large parallel magnetic field, an example of the dynamical localization. In such case a small perpendicular component of the field, or the dissipation, can enhance the tunneling rate. In the small parallel field and finite temperatures the tunneling rate is finite. Explicit expressions will be presented in those cases. If viewing the tunneling in the presence of a magnetic field as a dissipative tunneling process, by varying the magnetic field and the potential one can obtain the dissipative spectral function between the subohmic $s =0$ and the superohmic $s = \infty$. In combination with a real dissipative spectral function, the effect of the magnetic field can map the spectral function from $s$ to $2-s$, with $s>2$ mapping to $s = 0$, revealing a dual symmetry between the friction and the Lorentz force. Two cases relevant to experiments, the edge state tunneling in a Hall bar and the tunneling near the dynamical localization will be discussed in detail.Comment: Late

Invalidity of Classes of Approximated Hall Effect Calculations

In this comment, I point out a number of approximated derivations for the effective equation of motion, now been applied to d-wave superconductors by Kopnin and Volovik are invalid. The major error in those approximated derivations is the inappropriate use of the relaxation time approximation in force-force correlation functions, or in force balance equations, or in similar variations. This approximation is wrong and unnecessary.Comment: final version, minor changes, to appear in Phys. Rev. Let

Dissipative Tunneling in 2 DEG: Effect of Magnetic Field, Impurity and Temperature

We have studied the transport process in the two dimensional electron gas (2DEG) in presence of a magnetic field and a dissipative environment at temperature T. By means of imaginary time series functional integral method we calculate the decay rates at finite temperature and in the presence of dissipation. We have studied decay rates for wide range of temperatures -- from the thermally activated region to very low temperature region where the system decays by quantum tunneling. We have shown that dissipation and impurity helps the tunneling. We have also shown that tunneling is strongly affected by the magnetic field. We have demonstrated analytical results for all the cases mentioned above.Comment: 8 pages, 2 figure

Reply to Comment "Invalidity of classes of approximate Hall effect calculations."

We reply to the criticism raised by Ao in his Comment (cond-mat/9801180). Being unable to properly treat the Hall conductivity in a mixed state of superconductors, Ao is looking for possible mistakes in microscopic and phenomenological calculations, as well as in the corresponding experiments. The errors in his treatment of the problem (cond-mat/9704247) are analized. We indicate where the approach advocated by him fails to properly account for the interaction with impurities and other sources of relaxation.Comment: reply to Comment by Ao (cond-mat/9801180) on our paper in PRL, 79, 1377 (1997), revtex file, 1 page, no figure

Magnus Force in High Temperature Superconductivity and Berry Phase

In the topological framework of high temperature superconductivity we have discussed the Magnus force acting on its vortices

Magnus Force on Quantum Hall Skyrmions and Vortices

We have discussed here the Magnus force acting on the vortices and skyrmions in the quantum Hall systems. We have found that it is generated by the chirality of the system which is associated with the Berry phase and is same for both the cases.Comment: 5 page

The Royal Free Hospital score: a calibrated prognostic model for patients with cirrhosis admitted to intensive care unit. Comparison with current models and CLIF-SOFA score

Prognosis for patients with cirrhosis admitted to intensive care unit (ICU) is poor. ICU prognostic models are more accurate than liver-specific models. We identified predictors of mortality, developed a novel prognostic score (Royal Free Hospital (RFH) score), and tested it against established prognostic models and the yet unvalidated Chronic Liver Failure-Sequential Organ Failure Assessment (CLIF-SOFA) model

Bilateral Spontaneous Hyphaema in Juvenile Xanthogranuloma: A case report and literature review

Background: A four-month-old Nigerian male was presented with spontaneous hyphaema in both eyes initially thought to be due to trauma or possibly non accidental injury. There was associated secondary glaucoma and skin lesions typical of juvenile xanthogranuloma. This condition, to the best of our knowledge, has not yet been reported in Nigeria. Case report: There was redness in the right eye with no associated tearing or photophobia. On examination, there was visually directed reaching in both eyes, with central, steady and maintained fixation, corneal haze and 15% hyphaema. The left eye, which appeared normal, later also developed 10% hyphaema, upon which an impression of juvenile xanthogranuloma was entertained. Laboratory investigations, including a clotting profile, were all within normal limits. Examination under anaesthesia showed progressively increasing buphthalmos and vitreous haemorrhage in the left eye with high intraocular pressure and large cup disc ratios. Histology showed irregularly disposed spindle-shaped cells in the dermis that were intimately associated with small capillaries containing red blood cells. Occasional tuton-like giant cells were seen with hyperkeratosis and papillomatosis of the epidermis which is consistent with juvenile xanthogranuloma. Conclusion: Ocular complications provide the primary concern in this condition and could eventually lead to blindness. Therefore, a high index of suspicion is the key to the prevention of blindness. Keywords: juvenile xanthogranuloma, hyphaema, glaucomaNigerian Journal of Opthalmology Vol. 15 (2) 2007: pp. 61-6

Palatal rugae as a tool for human identification

Objective: This study was conducted to assess the accuracy of palatal rugae as a tool for human identification and to determine factors that may limit accuracy. This will serve as a potential basis for advising national health policy formulation on human identification as forensic rugoscopy is unexplored in sub.Saharan Africa.Materials and Methods: One hundred consenting participants were  recruited; impressions of the upper jaws were taken and cast with dental stone. All the teeth on the models were trimmed off to prevent  identification by tooth morphology and the models were coded. Five uncalibrated dentists independently pair.matched the models based on the pattern of the palatal rugae.Results: The overall accuracy for all 50 paired models ranged from 72 to 96%, while the percentage correct match for each of the 50 paired models range from 40-100%. All the examiners properly matched 60% of the models. Conclusion: Rugoscopy is a useful technique for human identification due to the unique rugae pattern in every individual. However, without the aid of ancillary aids, visual inspection alone can be challenging. Clinical relevance: This study provides useful information on an additional clinical technique relevant for human identification.Key words: Forensic, human, identification, palatal rugae, rugoscopy, Ibadan, Nigeri

Serum Uric Acid Levels in Oral Cancer Patients Seen at Tertiary Institution in Nigeria

Introduction: Toxicity by oxygen radicals has been considered as an important cause of cancer. It is proposed that the antioxidant properties of uric acid may act to prevent formation of oxygen radicals and thereby protect against carcinogenesis. This study aims to assess the role of uricacid in the aetiology of oral cancer.Materials and Methods: Thirty one oral cancer patients and thirty normal patients had serum uric acid measured using spectophotometer. The data obtained was analyzed using the Statistical Package for the Social Sciences, version 19.0 (SPSS19). Statistical significance was determined at P < 0.05. Results: The mean serum uric acid level in oral cancer patientswas 5.18 mg/dl (SD±1.96) while the mean was 7.09 mg/dl (SD±1.84) for the control group and this difference was statistically significant (p=0.000, t= -3.914, C.I. = - 2.885 to - 0.933). The risk of oral cancer was 3.98 times more in patients who had low serum uric acid.Conclusion: This study showed that serum uric acid was lower in oral cancer patients compared with healthy volunteers and low serum uric acid was associated with increased risk of oral cancer development. However, further prospective cohort studies are suggested to better understand the role of serum uric acid in aetiology of oral cancer