The moore idempotents of a matrix

AbstractLet R be a commutative ring with 1 and with an involution -, and let MR be the category of finite matrices over R with the involution (aij) → (aij)∗=(āji). If A is in MR, then there exists a unique list (e0, …, es) of pairwise orthogonal symmetric idempotents of R that are characterized by several properties involving the rank and squared volume of the eiA. In particular, A has a Moore-Penrose inverse in MR iff esA=0

On the existence of generalized inverses

AbstractConditions are given for the existence of a generalized inverse of a ring morphism, and the results are related to the theory of semi-simple Artinian rings. Necessary and sufficient conditions are also given for the existence of a generalized inverse of a morphism on real inner product spaces

Categories of matrices with only obvious Moore-Penrose inverses

AbstractLet R be an associative ring with 1 and with an involution a → ā, and let MR be the category of finite matrices over R with the involution (aij) → (aij)∗ = (āji). Then the following two statements are equivalent: (i) If A in MR has a Moore-Penrose inverse with respect to ∗, then A is permutationally equivalent to a matrix of the form B000 with B invertible. (ii) If 1 = ∑aā in R, then at most one of the a's is not zero

Homocysteine and coronary atherosclerosis

AbstractHomocysteine is increasingly recognized as a risk factor for coronary artery disease. An understanding of its metabolism and of the importance of vitamins B6and B12and folate as well as enzyme levels in its regulation will aid the development of therapeutic strategies that, by lowering circulating concentrations, may also lower risk. Possible mechanisms by which elevated homocysteine levels lead to the development and progression of vascular disease include effects on platelets, clotting factors and endothelium. This review presents the clinical and basic scientific evidence supporting the risk and mechanisms of vascular disease associated with elevated homocysteine concentrations as well as the results of preliminary therapeutic trials

Surface Brightness of Starbursts at Low and High Redshifts

Observations in the rest frame ultraviolet from various space missions are used to define the nearby starburst regions having the highest surface brightness on scales of several hundred pc. The bright limit is found to be 6x10^-16 ergs/cm^2-s-A-arcsec^2 for rest frame wavelength of 1830 A. Surface brightness in the brightest pixel is measured for 18 galaxies in the Hubble Deep Field having z > 2.2. After correcting for cosmological dimming, we find that the high redshift starbursts have intrinsic ultraviolet surface brightness that is typically four times brighter than low redshift starbursts. It is not possible to conclude whether this difference is caused by decreased dust obscuration in the high redshift starburst regions or by intrinsically more intense star formation. Surface brightness enhancement of starburst regions may be the primary factor for explaining the observed increase with redshift of the ultraviolet luminosity arising from star formation.Comment: accepted for publication in AJ; 11 pages text, 3 tables, 3 figures (embedded

Analisa Pasar Proyek Mini Market

Usaha mini market telah menggeser posisi pasar-pasar tradisional sebagai tempat perbelanjaan kebutuhan bahan pokok sehari-hari, sehingga USAha pendiriannya akan memberikan prospek yang lebih baik pada masa sekarang dan yang akan datang. Berdasarkan Analisa Persediaan (Supply Analysis), Analisa Permintaan (Demand Analysis) dan Analisa Persaingan Pasar, USAha pendirian mini market di kelurahan Keputih Kecamatan Sukolilo Surabaya dengan jumlah pertumbuhan penduduk 2,11 % pertahun dan jumlah penduduk miskin sekitar 10,77 % masih memiliki potensi yang sangat besar untuk didirikan. Tujuan Penulisan adalah untuk mengetahui analisa pasar proyek USAha mini market yang masih memiliki peluang besar untuk didirikan seiring dengan kebutuhan masyarakat yang terus meningkat

1015-72 Elevated Plasma Homocysteine: An Important Independent Risk Factor for Coronary Artery Disease in the Elderly

BackgroundHigh plasma homocysteine (HCY) concentration is an established risk factor for premature vascular disease which can be reduced using vitamin therapy. The role of increased homocysteine as a coronary risk factor in the elderly, however, remains uncertain.MethodsWe studied 228 patients with angiographically documented coronary disease (≥ 70% stenosis in at least one major epicardial vessel). These included 136 patients less than, and 92 greater than 65 years old. Patients were compared to 223 healthy controls 199 (<65) and 24 (> 65). The presence of traditional risk factors including hypertension, smoking, hypercholesterolemia and diabetes mellitus were noted. Total fasting plasma homocysteine was measured in all subjects. A gender-adjusted threshold for a high homocysteine level was defined as the 80th percentile for healthy controls (corresponding to a level of 11.7 μmol/L in women and 13.6 μmo1/L in men).ResultsAge<65Age>65PatientsControlsPatientsControlsHomocysteine12.2±4.0*11.0±3.414.2±4.6*11.9±3.6High HCY(%)33*2050†25Odds Ratios2.0*NA2.9*NAConfidence Interval1.2–3.2NA1.0–8.3NA*p<am vs controls†p<0.03ConclusionsHomocysteine concentrations are elevated in patients with coronary artery disease older than 65 years in age. A high value confers an independent three-fold risk for coronary disease in this patient group. Accordingly, intervention studies designed to reduce plasma homocysteine levels should not exclude the elderly

Directly Measured Denitrification Reveals Oyster Aquaculture and Restored Oyster Reefs Remove Nitrogen at Comparable High Rates

Coastal systems are increasingly impacted by over-enrichment of nutrients, which has cascading effects for ecosystem functioning. Oyster restoration and aquaculture are both hypothesized to mitigate excessive nitrogen (N) loads via benthic denitrification. The degree to which these management activities perform similar functions for removing N, however, has not been extensively examined in New England, a place where nutrient runoff is high and increasing oyster (Crassostrea virginica) restoration and aquaculture activity is taking place. Here, we use a novel in situ methodology to directly measure net N2 and O2 fluxes across the sediment-water interface in a shallow (~1 m) coastal pond in southern Rhode Island. We collected data seasonally during 2013 and 2014 at restored oyster reefs, oyster aquaculture, oyster cultch (shell), and bare sediment. Restored oyster reefs and aquaculture had the highest mean (±SE) denitrification rates, 581.9 (±164.2) and 346 (±168.6) μmol N2−N m−2 h−1, respectively, and are among the highest recorded for oyster-dominated environments. Denitrification rates at sites with oyster cultch were 60.9 (±44.3) μmol N2−N m−2 h−1, which is substantially less than the sites with active oysters but still more than 50% higher than denitrification rates measured in bare sediment (24.4 ± 10.1 μmol N2–N m−2 h−1). The increase in denitrification rates at treatments, however, varied by season and the greatest rates for restored reefs were in the fall. Overall, the greatest aggregate denitrification rates occurred in the fall. Sediment oxygen demand (SOD) followed similar patterns but with greater overall rates in the summer, and displayed a strong linear relationship with denitrification (R2 = 0.93). Our results demonstrate that habitats associated with live oysters have higher net denitrification rates and that oyster reef restoration and oyster aquaculture may provide similar benefits to the ecosystem in terms of N removal. However, gas fluxes may also be affected where three-dimensional structure is introduced via oyster shell cultch and this appears to be seasonally-dependent. These data will be important for managers as they incorporate oysters into nutrient reduction strategies and consider system-level trade-offs in services provided by oyster reef restoration and aquaculture activities

Directly Measured Denitrification Reveals Oyster Aquaculture and Restored Oyster Reefs Remove Nitrogen at Comparable High Rates

Coastal systems are increasingly impacted by over-enrichment of nutrients, which has cascading effects for ecosystem functioning. Oyster restoration and aquaculture are both hypothesized to mitigate excessive nitrogen (N) loads via benthic denitrification. The degree to which these management activities perform similar functions for removing N, however, has not been extensively examined in New England, a place where nutrient runoff is high and increasing oyster (Crassostrea virginica) restoration and aquaculture activity is taking place. Here, we use a novel in situ methodology to directly measure net N2 and O2 fluxes across the sediment-water interface in a shallow (~1 m) coastal pond in southern Rhode Island. We collected data seasonally during 2013 and 2014 at restored oyster reefs, oyster aquaculture, oyster cultch (shell), and bare sediment. Restored oyster reefs and aquaculture had the highest mean (±SE) denitrification rates, 581.9 (±164.2) and 346 (±168.6) μmol N2−N m−2 h−1, respectively, and are among the highest recorded for oyster-dominated environments. Denitrification rates at sites with oyster cultch were 60.9 (±44.3) μmol N2−N m−2 h−1, which is substantially less than the sites with active oysters but still more than 50% higher than denitrification rates measured in bare sediment (24.4 ± 10.1 μmol N2–N m−2 h−1). The increase in denitrification rates at treatments, however, varied by season and the greatest rates for restored reefs were in the fall. Overall, the greatest aggregate denitrification rates occurred in the fall. Sediment oxygen demand (SOD) followed similar patterns but with greater overall rates in the summer, and displayed a strong linear relationship with denitrification (R2 = 0.93). Our results demonstrate that habitats associated with live oysters have higher net denitrification rates and that oyster reef restoration and oyster aquaculture may provide similar benefits to the ecosystem in terms of N removal. However, gas fluxes may also be affected where three-dimensional structure is introduced via oyster shell cultch and this appears to be seasonally-dependent. These data will be important for managers as they incorporate oysters into nutrient reduction strategies and consider system-level trade-offs in services provided by oyster reef restoration and aquaculture activities