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No abstract available

[en] Observations of the transverse component of the Sun's photospheric magnetic field obtained with the MSFC vector magnetograph show where the fields are nonpotential. The correlation was studied between locations of nonpotential fields and sites of flare onset for four different active regions. The details of the active region AR 4711 are outlined. Similar results are presented for three other regions: AR 2372 (April 1980), AR 2776 (November 1980), and AR 4474 (April 1984). For all four regions it is shown that flares initiate at sites on the magnetic neutral line where the local field deviates the most from the potential field. The results of this study suggest that flares are likely to erupt where the shear is equal to or greater than 85 degrees, the field is equal to or greater than 10000 G, and there is strong shear (equal to or greater then 80 degress) extending over a length equal to or greater than 8000 km

[en] The relation between the degree of nonpotentiality of photospheric magnetic fields and the occurrence of gama-ray flares is examined to determine whether there are special signatures of the stressed fields for this type of flare. Observations of the flares in the active region of April 1984 (AR 4474) are analyzed, showing that the big flare initiated at the location on the magnetic neutral line where the field deviated the most from a potential field. The nonpotential signatures of AR 4474 are compared with those of four other regions. The results suggest that gamma-ray flares are associated with strongly nonpotential fields that extend over relatively larger lengths of the magnetic neutral line that the fields associated with flares that do not produce gamma-ray events. 9 refs

[en] The relation between the degree of nonpotentiality of photospheric magnetic fields and the occurrence of gamma ray flares is examined. The parameter delta phi (magnetic shear) and the strength of the magnetic field intensity are used as measures of the degree of nonpotentiality, where delta phi is defined as the angular difference between the observed direction of the transverse component of the photospheric field and the direction of the potential field prescribed by the distribution of measured photospheric flux. An analysis of the great flare of April 24 to 25, 1984 is presented as an example of this technique to quantify the nonpotential characteristics of the pre-flare magnetic field. For this flare, which produced a large gamma ray event, strong shear and high field strengths prevailed over an extended length of the magnetic neutral line where the flare occurred. Moreover, the flare began near the area of strongest measured shear (89 to 90 deg). Four other flaring regions were analyzed; one of these produced a moderate gamma ray event while the other three did not produce detectable gamma rays. For all four regions the flares were located in the area where the field was not nonpotential, regardless of the class of flare. The fields of the gamma ray flares were compared with those associated with the flares without gamma rays, and little distinction was found in the degree of magnetic shear. The major difference is seen in the extent of the sheared field: for gamma ray events, the field is sheared over a longer length of the neutral line

[en] Angiotensin II (ANG) stimulates the hydrolysis of phosphatidylinositol bisphosphate with the consequent formation of inositol trisphosphate and diacylglycerol in cultured smooth muscle cells derived from rat aorta. They have observed the effects of ANG on protein and DNA synthesis by measuring the incorporation of ³H-leucine and ³H-thymidine, respectively, into acid-precipitable material. Aortic muscle cells were grown to confluence in medium containing 10% fetal bovine serum (FBS) and incubated for 24 hours in serum-free medium to arrest growth. Then fresh serum-free medium was added with the following additions: ANG (100 nM), insulin (2 μg/ml), or 10% FBS. After an additional 24 hours the cells were pulse labeled for 30 min with either ³H-leucine or ³H-thymidine. FBS increased ³H-leucine incorporation by -2.5 fold and ³H-thymidine incorporation by 7-10 fold. ANG or insulin increased ³H-leucine incorporation by 40-50%, and the combination of ANG and insulin was nearly as effective as 10% FBS. ANG stimulated ³H-thymidine incorporation by -2.5 fold. Insulin, which was less effective than ANG, increased ³H-thymidine incorporation by about 50%. ANG and insulin added together synergistically increased ³H-thymidine incorporation by 5-6 fold. An ANG antagonist, Sarl,leu8-ANG, at 2 μM markedly decreased ³H-thymidine incorporation in the presence of ANG and insulin

[en] Solar active regions observed during the period of Skylab observations (May 1973-February 1974) were examined for properties that varied systematically with location on the sun, particularly with respect to the location of coronal holes. Approximately 90 percent of the optical and X-ray flare activity occurred in one solar hemisphere (136-315 heliographic degrees longitude). Active regions within 20 heliographic degrees of coronal holes were below average in lifetimes, flare production, and magnetic complexity. Histograms of solar flares as a function of solar longitude were aligned with H alpha synoptic charts on which active region serial numbers and coronal hole boundaries were added

[en] Heparin, when added to citrated platelet-rich plasma (PRP), caused potentiation of platelet aggregation and the release reaction induced by the aggregating agents adenosine diphosphate (ADP), arachidonic acid, collagen, and epinephrine. At low concentrations (4.7 x 10(-5) M) arachidonic acid failed to cause aggregation of platelets in citrated PRP. However, in the presence of heparin, the same concentration of arachidonic acid caused aggregation. Examination of PRP for the presence of thromboxane A2 (TxA2) by use of a bioassay revealed that heparin also stimulated release of TxA2. This finding indicated that platelets released more TxA2 when they were challenged by low concentrations of arachidonic acid in the presence of heparin than in its absence. Platelets were labeled with ³H-arachidonic acid and ¹⁴C-serotonin, and attempts were made to determine whether heparin stimulated the platelet release reaction first with subsequent increased production of TxA2, or alternatively, whether heparin stimulated TxA2 production first with subsequent enhancement of the release reaction. In view of the demonstrated simultaneous release of ¹⁴C-serotonin and ³H-arachidonic acid metabolites, it appeared that either release of ¹⁴C and ³H occurs concurrently or, even if one of these events is dependent on the other, both events take place in rapid succession. Timed sequential studies revealed that in the presence of arachidonic acid, the addition of heparin hastened the apparently simultaneous release of both ¹⁴C and ³H

[en] Previously the authors have shown that uptake and stimulated release of ³H-arachidonate (AA) in human platelets involves mainly 1-acyl-2-arachidonoyl phospholipids. To determine deacylation of molecular species of 1-acyl-2-arachidonoyl phosphatidylcholine (PC) and phosphatidylethanolamine (PE), phospholipid was extracted by the method of Bligh and Dyer from cells (10⁹/ml) stimulated or not by thrombin (THR, 5 U/ml .37⁰C, 5 min). Total PC and PE were isolated by thin-layer chromatography (TLC) and converted to 1-radyl-2-acyl glycerobenzoates. The 1,2 diacyl glycerobenzoates were separated from other subclasses by TLC. Individual molecular species of 1,2 diacyl glycerobenzoates were resolved by reverse phase HPLC. Mass (O.D.₂₃₀) and ³H-AA radioactivity (i.e. specific activity) were determined on-line, and changes in individual molecular species could be deduced. Significant deacylation of all 1-acyl-2-arachidonoyl PC and PE molecular species occurred with no apparent deacylation in any non-AA-containing molecular species of 1,2 diacyl PC/PE. At 5 minutes the net deacylation of 1-acyl-2-arachidonoyl PC and PE was approximately 15 and 5 nanomoles, respectively/10⁹ cells. These results indicate that selective deacylation of arachidonoyl-containing molecular species compared to non-arachidonoyl-containing molecular species of PC/PE occurs in THR-stimulated cells. This suggests certain AA-containing phospholipids are compartmentalized with and susceptible to, the action of phospholipase A₂

[en] Nordhaus (1991), Cline (1992), Fankhauser (1992), and Titus (1992) have published comprehensive estimates of annual climate change damages to the United States in about 2060 that vary from 55 billion dollars to 111 billion dollars (1990). The estimates are comprehensive because they address market and nonmarket impacts. They based their estimates on different assumptions about the rates of climate change and sea level rise, rates of return on investment, and changes in population and income. In addition, many of the damage estimates, although reported for a 2.5-3.0 degree C warming, were based on studies that assumed higher rates of warming. Thus, these studies may have overestimated damages associated with a 2.5-3.0 degree C warming. In this paper, the results of these studies were standardized for a 2.5 degree C warming, a 50-cm sea level rise, 1990 income and population, and a 4% real rate of return on investments. After standardization, the total damage estimates range from 42.3 billion dollars to 52.8 billion dollars, slightly less than 1% of the United States GNP in 1990. Yet, within individual sectors, such as agriculture and electricity, standardized damages differ by more than an order of magnitude. In addition, a significant amount of speculation underlies the damage estimates. Thus, the small range of total standardized damages and apparent agreement about the magnitude of such damages should be interpreted with caution. 37 refs., 3 tabs