873 research outputs found
Confirmatory Factor Analysis using Amos, LISREL, Mplus, SAS/STAT CALIS
Factor analysis is a statistical method used to find a small set of unobserved variables (also called latent variables, or factors) which can account for the covariance among a larger set of observed variables (also called manifest variables). A factor is an unobservable variable that is assumed to influence observed variables. Scores on multiple tests may be indicators of intelligence (Spearman, 1904); political liberties and popular sovereignty may measure the quality of a country’s democracy (Bollen, 1980); or issue emphases in election manifestos may signify a political party’s underlying ideology (Gabel & Huber, 2000). Factor analysis is also used to assess the reliability and validity of measurement scales (Carmines & Zeller, 1979)
Cholesteryl isobutylcarbonate
Cholesteryl isobutylcarbonate, C 32H 54O 3, contains two molecules (A and B) in the asymmetric unit. The isobutylcarbonate chain of molecule A and the isoprenoid tail of molecule B are each conformationally disordered over two positions. The two distinct molecules form separate stacks along the screw axes so that they are arranged in an antiparallel array, forming monolayers with a thickness of d 001 = 19.412 A. The central regions of the monolayers are characterized by efficient molecular packing and are separated by interface regions, which are more loosely packed.open4
Application of Nondestructive Measurement to Improve Soybean Quality by Near Infrared Reflectance Spectroscopy
Directly pumped 10 GHz microcomb modules from low-power diode lasers
Soliton microcombs offer the prospect of advanced optical metrology and timing systems in compact form factors. In these applications, the pumping of microcombs directly from a semiconductor laser without amplification or triggering components is desirable to reduce system power and to simplify system design. At the same time, low-repetition-rate microcombs are required in many comb applications as an interface to detectors and electronics, but their increased mode volume makes them challenging to pump at low power. Here 10 GHz repetition rate soliton microcombs are directly pumped by low-power (<20 mW) diode lasers. High-Q silica microresonators are used for this low-power operation and are packaged into fiber-connectorized modules that feature temperature control for improved long-term frequency stability
Ultralow noise optical pulse generation in an actively mode-locked quantum-dot semiconductor laser
We report excellent noise performance of an external-cavity actively mode-locked laser based on quantum-dot gain medium. Optical pulse trains with less than 7.5 fs residual timing jitter (1 Hz to 10 MHz) for a 12.8 GHz harmonically mode-locked ring laser were obtained. This result represents, to our knowledge, the lowest residual jitter reported from actively mode-locked semiconductor lasers, and shows that quantum-dot mode-locked lasers are promising as sources of ultralow noise optical pulse trains
Spontaneous Symmetry Breaking of Population between Two Dynamic Attractors in a Driven Atomic Trap: Ising-class Phase Transition
We have observed spontaneous symmetry breaking of atomic populations in the
dynamic phase-space double-potential system, which is produced in the
parametrically driven magneto-optical trap of atoms. We find that the system
exhibits similar characteristics of the Ising-class phase transition and the
critical value of the control parameter, which is the total atomic number, can
be calculated. In particular, the collective effect of the laser shadow becomes
dominant at large atomic number, which is responsible for the population
asymmetry of the dynamic two-state system. This study may be useful for
investigation of dynamic phase transition and temporal behaviour of critical
phenomena.Comment: 4 pages, 4 figure
Criterion for transformation of transverse domain wall to vortex or antivortex wall in soft magnetic thin-film nanostripes
We report on the criterion for the dynamic transformation of the internal
structure of moving domain walls (DWs) in soft magnetic thin-film nanostripes
above the Walker threshold field, Hw. In order for the process of
transformation from transverse wall (TW) to vortex wall (VW) or antivortex wall
(AVW) occurs, the edge-soliton core of the TW-type DW should grow sufficiently
to the full width at half maximum of the out-of-plane magnetizations of the
core area of the stabilized vortex (or antivortex) by moving inward along the
transverse (width) direction. Upon completion of the nucleation of the vortex
(antivortex) core, the VW (AVW) is stabilized, and then its core accompanies
the gyrotropic motion in a potential well (hill) of a given nanostripe. Field
strengths exceeding the Hw, which is the onset field of DW velocity breakdown,
are not sufficient but necessary conditions for dynamic DW transformation
Effects of diabetes and hypertension on glomerular transforming growth factor-β receptor expression
Effects of diabetes and hypertension on glomerular transforming growth factor-β receptor expression.BackgroundSeveral studies have suggested that transforming growth factor-β1 (TGF-β1) is an important determinant of diabetic glomerular injury. TGF-β1 forms a heteromeric complex with two cellular receptor subtypes, designated TGF-β RII and TGF-β RI, but the effects of diabetes mellitus on glomerular TGF-β receptor expression have not been completely elucidated. We first compared the effect of experimental type I diabetes mellitus and uninephrectomy on glomerular TGF-β receptor expression in spontaneously hypertensive rats (SHRs), and then sought to determine whether changes in TGF-β receptor expression were strain specific by studying normotensive Wistar-Kyoto (WKY) rats.MethodsFive groups of male SHRs were studied. The first group received streptozotocin (60 mg/kg IV) and was studied after one week. The second group received streptozotocin and was studied after two weeks. The third group received streptozotocin (60 mg/kg IV) but received insulin to maintain euglycemia. The fourth group of age-matched SHRs served as the control group, while a fifth group of SHRs underwent uninephrectomy. Four groups of male WKY rats were also studied. The first group of WKY rats served as the age-matched control group. The second group of WKY rats received streptozotocin, while a third group of WKY rats underwent uninephrectomy. The fourth group underwent uninephrectomy and received streptozotocin. At each time point, glomeruli were isolated for protein extraction, and the protein was subjected to Western blot analysis of TGF-β RII and TGF-β RI expression.ResultsBasal expression of both TGF-β receptors per microgram of glomerular protein was similar in normotensive WKY rats and hypertensive SHRs. Hyperglycemia (blood glucose level, 17.8 ± 2.9 mmol/L) led to an early twofold increase in TGF-β RII protein expression and a fourfold increase in TGF-β RI protein expression in the glomeruli of hypertensive diabetic SHRs compared with euglycemic SHRs (blood glucose level, 5.8 ± 0.8 mmol/L), which was sustained after two weeks. Insulin treatment (blood glucose level, 5.2 ± 0.9 mmol/L) normalized both TGF-β RII and TGF-β RI expression in the glomeruli of SHRs that received streptozotocin. Glomerular capillary hypertension in the uninephrectomized SHRs led to a twofold increase in glomerular TGF-β RII protein expression, but did not reproduce the effect of diabetes mellitus on TGF-β RI expression. In contrast to the findings in SHRs, neither hyperglycemia (blood glucose level, 15.5 ± 2.1 mmol/L), uninephrectomy, nor hyperglycemia (blood glucose level, 16.8 ± 3.0 mmol/L) and uninephrectomy altered TGF-β receptor expression in the glomeruli of normotensive WKY rats.ConclusionThese studies support the hypothesis that hemodynamic factors and metabolic factors influence glomerular TGF-β receptor in vivo in the SHRs
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