The Minimum Rank Problem: a counterexample

We provide a counterexample to a recent conjecture that the minimum rank of every sign pattern matrix can be realized by a rational matrix. We use one of the equivalences of the conjecture and some results from projective geometry. As a consequence of the counterexample, we show that there is a graph for which the minimum rank over the reals is strictly smaller than the minimum rank over the rationals. We also make some comments on the minimum rank of sign pattern matrices over different subfields of $\mathbb R$.Comment: 4 pages, 1 figur

KNOWLEDGE, ATTITUDE & PRACTICE PATTERN OF DIABETIC RETINOPATHY AMONG DIABETOLOGISTS OF VISAKHAPATNAM DISTRICT -A STUDY

Background: Diabetic Retinopathy (DR) is the major cause of blindness in working age adults. Because of its asymptomatic nature, most of these patients do not seek ophthalmologists care till the advent of visual loss. Patients who do not receive any form of educational intervention regarding Diabetes and DR, has a fourfold increased risk of developing Diabetic Retinopathy and its delayed recognition. Patients with Diabetes Mellitus (DM) look to their Diabetologists guidance in managing all aspects of their disease including their eye care. According to ICMR guidelines, Diabetologists should discuss visual health with their patients and insist upon annual dilated eye examinations. Present study was undertaken to assess Diabetologists self reported knowledge, awareness and practice patterns of DR relative to the published ICMR guidelines. Methods: A pre tested, semi structured questionnaire was given to 126 Diabetologists practicing in Visakhapatnam district with >5 years of experience in managing DM patients. Results: Study population consisted of 78 General practitioners, 44 General physicians and 4 Endocrinologists. Among 126 Diabetologists, 93.65% (n=118/126) had knowledge about DR. Only 32.53% (n=41/126) had knowledge about recent management modalities of DR. 81.74% (n=103/126) knew about the necessity of annual, fundus examination in DM pts. Only 20.33% (n=26/126) were imparting this knowledge to their patients. Only 6.34% (n=8/126) were advising Ophthalmologist\u27s evaluation at the time of diagnosis of DM. Conclusion: DR related practice patterns of Diabetologists of Visakhapatnam district  significantly differ from recommended strategies for  Diabetes eye care . Based upon the results of our study, we suggest the need of certain measures and regulations. KEYWORDS: Diabetes; Diabetic Retinopathy; Diabetes eye care; ICMR guidelines; Physician\u27s role

Wind and Solar Cell-Based Distribution System for Different Load Variations Using Fuzzy Logic Controller

The proposed system presents power-control strategies of a grid-connected hybrid generation system with versatile power transfer. This hybrid system allows maximum utilization of freely available renewable energy sources like wind and photovoltaic energies . For this, an adaptive MPPT algorithm along with standard perturb and observe method will be used for the system.Also, this configuration allows the two sources to supply the load separately or simultaneously depending on the availability of the energy sources. The turbine rotor speed is the main determinant of mechanical output from wind energy and Solar cell operating voltage in the case of output power from solar energy. Permanent Magnet Synchronous Generator is coupled with wind turbine for attaining wind energy conversion system . The inverter converts the DC output from non-conventional energy into useful AC power for the connected load . This hybrid system operates under normal conditions which include normal room temperature in the case of solar energy and normal wind speed at plain area in the case of wind energy. A fuzzy based PWM system will be designed to reduce the harmonic ripples. The simulation results are presented to illustrate  the operating principle, feasibility and reliability of this proposed system. Keywords: smart grid, solar cell, fuzzy logic controlle

KNOWLEDGE, ATTITUDE & PRACTICE PATTERN OF DIABETIC RETINOPATHY AMONG DIABETOLOGISTS OF VISAKHAPATNAM DISTRICT -A STUDY

Background: Diabetic Retinopathy (DR) is the major cause of blindness in working age adults. Because of its asymptomatic nature, most of these patients do not seek ophthalmologists care till the advent of visual loss. Patients who do not receive any form of educational intervention regarding Diabetes and DR, has a fourfold increased risk of developing Diabetic Retinopathy and its delayed recognition. Patients with Diabetes Mellitus (DM) look to their Diabetologists guidance in managing all aspects of their disease including their eye care. According to ICMR guidelines, Diabetologists should discuss visual health with their patients and insist upon annual dilated eye examinations. Present study was undertaken to assess Diabetologists self reported knowledge, awareness and practice patterns of DR relative to the published ICMR guidelines. Methods: A pre tested, semi structured questionnaire was given to 126 Diabetologists practicing in Visakhapatnam district with >5 years of experience in managing DM patients. Results: Study population consisted of 78 General practitioners, 44 General physicians and 4 Endocrinologists. Among 126 Diabetologists, 93.65% (n=118/126) had knowledge about DR. Only 32.53% (n=41/126) had knowledge about recent management modalities of DR. 81.74% (n=103/126) knew about the necessity of annual, fundus examination in DM pts. Only 20.33% (n=26/126) were imparting this knowledge to their patients. Only 6.34% (n=8/126) were advising Ophthalmologist's evaluation at the time of diagnosis of DM. Conclusion: DR related practice patterns of Diabetologists of Visakhapatnam district  significantly differ from recommended strategies for  Diabetes eye care . Based upon the results of our study, we suggest the need of certain measures and regulations. KEYWORDS: Diabetes; Diabetic Retinopathy; Diabetes eye care; ICMR guidelines; Physician's role

Geometry of good sets in n-fold Cartesian product

We propose here a multidimensional generalisation of the notion of link introduced in our previous papers and we discuss some consequences for simplicial measures and sums of function algebras.Comment: 17 pages, no figures, no table