Application of manure to no-till soils: phosphorus losses by sub-surface and surface pathways

The acceleration of surface water eutrophication attributed to agricultural runoff has focused attention on manure management in no-till. We evaluated losses of phosphorus (P) in sub-surface and surface flow as a function of dairy manure application to no-till soils in north-central Pennsylvania. Monitoring of a perennial spring over 36 months revealed that dissolved reactive P (DRP) concentrations increased 3- to 28-fold above background levels whenever manure was broadcast to nearby field soils. A study conducted with 30-cm deep intact soil cores indicated that incorporation of manure by tillage lowered P loss in leachate relative to broadcast application, presumably due to the destruction of preferential flow pathways. More P was leached from a sandy loam than a clay loam soil, although differences between soils were not as great as differences between application methods. In contrast, rainfall simulations on 2-m² field runoff plots showed that total P (TP) losses in surface runoff differed significantly by soil but not by application method. Forms of P in surface runoff did change with application method, with DRP accounting for 87 and 24% of TP from broadcast and tilled treatments, respectively. Losses of TP in leachate from manured columns over 7 weeks (0.22–0.38 kg P ha⁻¹) were considerably lower than losses in surface runoff from manured plots subjected to a single simulated rainfall event (0.31–2.07 kg TP ha⁻¹). Results confirm the near-term benefits of incorporating manure by tillage to protect groundwater quality, but suggest that for surface water quality, avoiding soils prone to runoff is more important.

Adrenergic control of pineal N-acetyltransferase activity: developmental aspects

The activity of pineal N-acetyltransferase in the neonatal rat does not exhibit the large daily rhythm seen in the adult and is intermediate between the low day and high night adult values. These intermediate values appear to result from adrenergic stimulation. Blockade of adrenergic receptors or of catecholamine synthesis results in a decrease in enzyme activity in vivo. In vitro studies provide additional evidence of a completely developed postsynaptic adrenergic control system for pineal N-acetyltransferase activity at birth. Our observations indicate that the appearance of a circadian rhythm in pineal N-acetyltransferase at the end of the first week of life reflects the development of presynaptic mechanisms and structures necessary for the control of catecholamine release and uptake. These events follow the developmental appearance of the postsynaptic mechanisms required to mediate the adrenergic-cycle AMP regulation of pineal N-acetyltransferase activity, which can be detected prior to birth.     

带端面齿的连接盘加工工艺设计

对带端面齿的连接盘加工工艺和检测方法的优化设计进行了分析总结。在加工工艺优化设计中,为保证端面齿的加工精度,采用了以连接盘花键内孔和端面齿所在端面互为基准进行加工的方法;在检测工序的优化设计中,为提高检测精度和生产率,采用了以特制综合量规来检测端面齿部几何公差的方法。本设计方法的应用不仅可保证零部件的加工质量,而且还提高了加工效率,对同类零部件加工提供了可借鉴的工艺和检验技术。     

Fish erythrocytes as a tool to study temperature-induced responses in plasma membranes

The dorsal aorta of carp (Cyprinus carpio L.) was cannulated, and the fish were kept in thermostated aquaria at 5°C for 24h. The water temperature was then gradually increased to 25°C at a rate of 0.5°C/h, and then decreased to 5°C at the same rate. Blood was withdrawn at five-degree intervals to determine the fluidity of erythrocyte plasma membranes uponex vivo incorporation of the fluorescent dye, 3-[p-(6-phenyl-1,3,5-hexatrienyl)phenyl] propionic acid. Steady-state anisotropy (R_ss) of the plasma membranes increased and decreased with the increase and decrease in water temperature, respectively. The sterol-to-phospholipid ratio remained unchanged throughout the thermal shifts. The fatty acid compositions of the total phospholipids, of phosphatidylcholine and of phosphatidylethanolamine remained virtually unchanged, except for the level of arachidonic acid, which increased in erythrocytes from fish at the higher temperature (25°C). The molecular species compositions of phosphatidylcholines and phosphatidylethanolamines also remained unaffected throughout the thermal shifts. The erythrocyte plasma membranes were more responsive to temperature shiftsin vivo thanin vitro when percent efficacy was compared. Thus, factors other than lipid changes are conceivably involved in the adaptation of erythrocyte plasma membranes to short-term thermal changes.     

Effect of prior performance information on ratings of present performance: Contrast versus assimilation revisited.

Examined the effects of knowledge of a ratee's prior performance on evaluations of present performance. Subjects received knowledge of either good or poor prior performances and then viewed and rated a videotape depicting average performance. In Study 1, some subjects received knowledge of the ratee's prior performance by directly viewing videotapes of good or poor ratee behavior, whereas others only reviewed written performance ratings completed by those subjects who had actually viewed the ratee. A contrast effect occurred when knowledge of prior performance was obtained by observing ratee behavior, but an assimilation effect occurred when knowledge of prior performance was obtained by reviewing performance ratings. In Study 2, subjects viewed videotapes of good or poor performances prior to viewing an average performance by the same ratee. However, the separate ratee performances were observed over a more realistic time interval than that used in Study 1 (3 weeks vs. 1 h). No significant contrast effects were observed. In Study 3, subjects reviewed written ratings of prior performances before viewing an average videotape. Subjects who reviewed extremely good (or poor) prior performance ratings provided more extreme ratings of the "average" performance than did subjects who reviewed less extreme ratings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characteristics of MOCVD-grown thin p-clad InGaAs quantum-dot lasers

Thin p-clad quantum-dot lasers grown by metal-organic chemical vapor deposition are fabricated and shown to lase in ground state for device lengths greater than 2.5 mm. The device characteristics are presented and the modal behavior is investigated. The threshold current density is found to be much larger for narrow (4 /spl mu/m) stripe width devices than expected from the wider (50 /spl mu/m) stripe width devices. This is attributed to gain saturation within the devices.     

The porosity and morphology of mesoporous silica agglomerates

The synthesis of mesoporous MCM-41 silica materials was investigated at various conditions. A series of ordered mesopores MCM-41 silica materials was synthesized in concentrated reaction mixtures. The influence of water concentration at the constant ratio of the remaining reagents on the morphology and structural parameters of MCM-41 was studied. Hexadecyltrimethylammonium bromide CTAB was used as a structure-directing agent. The pore size, the wall thickness and cylindrical pores array were characterized by powder X-ray diffraction and nitrogen adsorption. The presented results show that in concentrated reaction mixtures, the pore size and the thickness of the pore walls remain practically constant. However, the dimensions of silica particles depend strongly on the water concentration. A high regularity of pore structure for large MCM-41 particles synthesized in concentrated solution was supported by independent AFM technique.     

A two-stage sequential demodulator for the Gosset lattice

A construction of the Gosset lattice is considered that has practical advantages over other constructions of the same lattice. Codes derived from this construction have been shown to exhibit a null at DC in their baseband spectrum. A two-stage approach to the demodulation of this construction of the Gosset lattice is discussed. This demodulator consists of an initial stage which may declare erasures and a secondary stage designed to correct erasures. A study of erasure events is made and then used to reduce the number of steps in the second-stage correction algorithm. While the overall demodulator is somewhat more complex than a straight forward maximum-likelihood demodulator designed for this construction, the present structure has the advantage of greater speed     

A method for a fully automatic definition of coronary arterial edges from cineangiograms

The authors describe a novel algorithm, known as sequential edge linking (SEL), for the automatic definition of coronary arterial edges in cineangiograms. This algorithm is based on sequential tree searching of possible coronary artery boundary locations. Using a coronary artery phantom, the authors compared the results obtained using SEL with hand-traced boundaries. Using a magnification of 2x, the results are generally good, with the average error being 1.7% of the diameter. Actual coronary artery images were also processed and a similar comparison indicated that total areas were comparable but the hand-drawn stenoses were, on average, 7% greater than the unobstructed diameter. Based on these data it is concluded that the SEL algorithm is an accurate method for fully automatic definition of coronary artery dimensions.