49 resultados para Estimador de Horvitz-Thompson


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Pay roll voucher #20 from the Engineer Department of Port Dalhousie and Thorold Railway Extension, for the Northern Division approved by F. Shanly, chief engineer and W.G. Thompson, assistant engineer (copy) June 1857.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Voucher from the Engineer Department of Port Dalhousie and Thorold Railway Extension to W.G. Thompson regarding horse hire (copy), Jul. 30, 1857.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Pay roll voucher #25 from the Engineer Department of Port Dalhousie and Thorold Railway Extension, for the Northern Division, for the month of July, 1857 approved by F. Shanly, chief engineer and W. G. Thompson (copy), July 30, 1857.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Letter to S.D. Woodruff from Archibald Thompson regarding funds, Dec. 13, 1855.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Letter to Henry Nelles from T. Thompson requesting him to certify the time that he was employed by the regiment. Included with this letter is a copy of the letter to T.H. Thompson from H.N., Lieutenant Colonel of the 4th Lincoln Militia regarding the certificates and saying that he will comply. An envelope is included with this letter, Sept. 21, 1838.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Receipt to John Thompson from Lieutenant Nelles for a gold ring and white ribbon, June 5, 1788.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Pictured here from left to right are: R. Nairn, W. Jolly, M. Miller, C. Shaver, C. Slemon, O. Loberg, W. Thompson.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Pictured here from left to right are: W. Thompson, M. Williams, M. Stevens, C. McMillan.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

At the time the language lab at the Glenridge Campus was state of the art. It was equiped with 18 individual student cubicles and a main console. In this photograph Mr. Guy Gauthier, Instructor in French, demonstrates the equipment manufactured by Thompson-Ramo-Wooldridge Corp. to one of his French classes. Mr. Gauthier was one of the original Brock faculty members.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

From left to right. Top: Sean Dowd, Dave Muirhead, Mike Thompson, Rick Cicchine, Mark Thomas, John Ahlstedt, Mark Reynolds, Tom Kent, and Tony Biernacki (Coach). Bottom: Bob Nguyen (Coxie).

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Back Row: J.B. Owens, Ross Smith (Head Coach), Adam Frost, Derrick Harwood, Dave DeRose, Bill Arniel, Danny Mazor, Alan Ross, Randy McKeller, Pete McDougall, Ray D'Archi, Kelvin Oda, Mark Pelletier, Eric Thompson, Marty Houston, Ken White (Asst. Coach) Front Row: Peter Love, Chris Peskett, Duff Porteous, Bart Ward, Dave Sohmer, Gary Gautier, Ken Murray, Dave Tamowski, Steve Shaughnessy, Jeff Wood Absent: Alfred Esmaily, Luc Gignac, Fred Kovacs, Andrew Norman

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Fifty kHz rat vocalizations are theorized to reflect a positive affective state, and index the reward value of stimuli (Knutson, Burgdorf & Panksepp, 2002; Panksepp & Burgdorf, 2003; Brudzynski,2005). Previous studies have identified the neurochemical substrate of this behaviour to be dependent on dopaminergic activity at the nucleus accumbens shell (Burgdorf, Knutson, Panksepp & Ikemoto, 2001; Thompson, Leonard & Brudzynski, 2006). The utilization of d-amphetamine (a non-selective dopamine agonist) in these studies does not address the specific dopamine receptor types involved. The present study aims to identify the role of the D2- like family of receptors in the nucleus accumbens shell in the production of 50 kHz vocalizations in adult rats. Single injections of quinpirole in a saline vehicle were administered to the nucleus accumbens shell of 57 rats, and the number of 50 kHz vocalizations were recorded. An inverted V-shaped relationship was found between quinpirole dose (0.5 ~g, 3 ~g, 6 ~g, 1 0 ~g and 20 ~g, all in 0.2~1 saline) and the mean number of 50 kHz calls produced. Quinpirole successfully elicited significantly more 50 kHz calls than did a saline control at the 6 ~g dose, as did 7 ~g/0.2 ~l of d-amphetamine injections into the same brain site. To test whether a selective D2 antagonist could reverse elicited 50 kHz calling, double injections were given that used either saline or raclopride as a pretreatment before quinpirole injections. Saline followed by 6 ~g/0.2 ~l of quinpirole elicited significantly more 50 kHz vocalizations than did a double injection of saline, while pretreatment with an equimolar dose of raclopride reduced elicited calls to control levels. Raclopride was also used as a pretreatment of 7 ~g/0.2 ~l d-amphetamine, which elicited significantly fewer 50 kHz vocalizations than saline followed by amphetamine, replicating the finding of Thompson, Leonard & Brudzynski (2006).Subcutaneous injections of 0.5 mg/kg and 1.5 mg/kg of quinpirole produced a similar number of 50 kHz vocalizations as subcutaneous injection of saline. Wider dose ranges may be explored in fiiture research. Thus, direct activation of the Da-like receptors in the nucleus accumbens shell was sufficient to elicit 50 kHz vocalizations in adult rats, an effect which was reversed with selective local antagonism of Da-like receptors. The Da-like receptor family also appears necessary for pharmacological activation of 50 kHz calling, as d-amphetamine was no longer able to effectively elicit these vocalizations from the nucleus accumbens shell when the Da-receptor family was antagonized with raclopride. The acoustic parameters of elicited vocalizations remained typical of rat 50 kHz calls. Detailed analyses of the acoustic characteristics of elicited calls indicated significant increases in call duration and peak frequency across drug injection groups, particularly among quinpirole dose groups. The implications of these findings are not yet clear, but may represent an important direction for future research into the coding of semiotic content into affective signals in rats.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Higher plants have evolved a well-conserved set of photoprotective mechanisms, collectively designated Non-Photochemical Quenching of chlorophyll fluorescence (qN), to deal with the inhibitory absorption of excess light energy by the photosystems. Their main contribution originates from safe thermal deactivation of excited states promoted by a highly-energized thylakoid membrane, detected via lumen acidification. The precise origins of this energy- or LlpH-dependent quenching (qE), arising from either decreased energy transfer efficiency in PSII antennae (~ Young & Frank, 1996; Gilmore & Yamamoto, 1992; Ruban et aI., 1992), from alternative electron transfer pathways in PSII reaction centres (~ Schreiber & Neubauer, 1990; Thompson &Brudvig, 1988; Klimov et aI., 1977), or from both (Wagner et aI., 1996; Walters & Horton, 1993), are a source of considerable controversy. In this study, the origins of qE were investigated in spinach thylakoids using a combination of fluorescence spectroscopic techniques: Pulse Amplitude Modulated (PAM) fluorimetry, pump-probe fluorimetry for the measurement of PSII absorption crosssections, and picosecond fluorescence decay curves fit to a kinetic model for PSII. Quenching by qE (,..,600/0 of maximal fluorescence, Fm) was light-induced in circulating samples and the resulting pH gradient maintained during a dark delay by the lumenacidifying capabilities of thylakoid membrane H+ ATPases. Results for qE were compared to those for the addition of a known antenna quencher, 5-hydroxy-1,4naphthoquinone (5-0H-NQ), titrated to achieve the same degree of Fm quenching as for qE. Quenching of the minimal fluorescence yield, F0' was clear (8 to 130/0) during formation of qE, indicative of classical antenna quenching (Butler, 1984), although the degree was significantly less than that achieved by addition of 5-0H-NQ. Although qE induction resulted in an overall increase in absorption cross-section, unlike the decrease expected for antenna quenchers like the quinone, a larger increase in crosssection was observed when qE induction was attempted in thylakoids with collapsed pH gradients (uncoupled by nigericin), in the absence of xanthophyll cycle operation (inhibited by DTT), or in the absence of quenching (LlpH not maintained in the dark due to omission of ATP). Fluorescence decay curves exhibited a similar disparity between qE-quenched and 5-0H-NQ-quenched thylakoids, although both sets showed accelerated kinetics in the fastest decay components at both F0 and Fm. In addition, the kinetics of dark-adapted thylakoids were nearly identical to those in qEquenched samples at F0' both accelerated in comparison with thylakoids in which the redox poise of the Oxygen-Evolving Complex was randomized by exposure to low levels of background light (which allowed appropriate comparison with F0 yields from quenched samples). When modelled with the Reversible Radical Pair model for PSII (Schatz et aI., 1988), quinone quenching could be sufficiently described by increasing only the rate constant for decay in the antenna (as in Vasil'ev et aI., 1998), whereas modelling of data from qE-quenched thylakoids required changes in both the antenna rate constant and in rate constants for the reaction centre. The clear differences between qE and 5-0H-NQ quenching demonstrated that qE could not have its origins in the antenna alone, but is rather accompanied by reaction centre quenching. Defined mechanisms of reaction centre quenching are discussed, also in relation to the observed post-quenching depression in Fm associated with photoinhibition.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This study investigated the effectiveness of a computer program, PERSONAL CAREER DIRECTIONS (PC DIRECTIONS) (Anderson, Welborn, & Wright, 1983) on career planning and exploration for twenty-four Brock University students (18 women and 6 men) who requested career planning assistance at the Career/Placement Services of the Counselling Centre. A one-group pretest/posttest design was used in the study_ Progress in career planning and exploration was measured by Career Planning (CP) and Career Exploration (CE) scales of the Career Development Inventory (College and University Form) (Super, Thompson, Lindeman, Jordaan, & Myers, 1981). A paired samples 2-tailed t test for Career Development Attitudes (CDA) , the combined CP and CE scales, revealed the posttest scores were significantly higher than the pretest scores, t(23) = 3.74, 2 < .001. Student progress was also assessed by self-report lists of job titles which reflected positive changes after students used PC DIRECTIONS. In response to several questions, students' attitudes were more positive than negative toward the program. Implications are that PC DIRECTIONS is an effective component in promoting career planning for university students. Further studies may reveal that different types of students may benefit from different interventions in the career planning process.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The purpose of this study was to investigate the relationship between learning styles and academic achievement in postsecondary education. It was the intent of the study to establish if there was a relationship between student learning style, teacher style, learner/teacher matching and/or mismatching, student gender and age, to the academic grades of students. This study was basically a replication of a study completed by Mary J. Thompson and Terrance P. O'Brien in 1991 on two campuses of a southeast community college in the United States. In the present study, 243 students and 18 teachers from two different campuses of a community college in the Province of Ontario participated in the research. All participants were administered the Gregorc Style Delineator and students identified by program, age and gender. Data were tested by two analysis of variance (ANOVA) models. In the first ANOVA model considered in this study, significant main effects were manifested in regard to the teaching style, age group and gender. With the exception of gender, these findings were very similiar to those of the original study. Duncan's multiple range test revealed that Concrete Sequential (CS) teachers assigned significantly lower grades than did teachers dominant in any of the other three learning styles. Post hoc testing revealed that students 25 years of age and older received significantly higher grades than did younger students. Female students also received significantly higher grades than did male students. In the second ANOVA model student/teacher learning style match/mismatch did emerge as a significant main effect. However, Duncan's multiple range test and Chi square analysis did not substantiate the relationship. Forty-eight references are cited.