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At least 361 records · Page 20Linked to original sources

PubMed2000

Recombinant adeno-associated virus vectors efficiently transduce foreign gene into bovine aortic endothelial cells: comparison with adenovirus vectors.

Because the features and kinetics of adeno-associated virus (AAV)-mediated gene transfer to endothelial cells (EC) are yet to be ultimately determined, we tested variables pertinent to the efficiency of AAV-mediated gene transfer to bovine aortic endothelial cells (BAEC). The variables with AAV vectors were compared with the better characterized adenovirus (Ad) vectors. There is a dose-response relationship between multiplicity of infection (moi) of AAV or Ad vectors and transduction efficiency in BAEC. The higher moi of AAV vectors achieved more than 80% of transduction efficiency in cultured BAEC. AAV and Ad vectors showed an incubation-time-dependent increase in transduction efficiency of LacZ gene to the BAEC up to 12 h of vector exposure. Although the similar kinetics of transduction efficiency of LacZ gene to BAEC was found in both vectors, the duration of gene expression was longer in AAV vector than that in Ad vectors in vitro. These results indicate that AAV-vector is efficient for gene transfer to EC, and higher moi of vectors or a longer period exposure of vectors to EC can facilitate efficient transduction of a foreign gene into cultured EC. For the duration of gene expression, the AAV vectors may be better than Ad vectors.

Adenoviridae↗

PubMed2001

Variables pertinent to the efficiency of adeno-associated virus (AAV) vectors mediated gene transfer to human vascular endothelial cells.

Factors influencing adeno-associated virus (AAV) - mediated gene transfer to endothelial cells are not fully determined. We tested the variables pertinent to the efficiency of AAV-mediated gene transfer to human vascular endothelial cells (HUVEC) including: (i) kinetics of transduction efficiency of LacZ gene to HUVEC, (ii) the concentration and volume of vector-containing medium, (iii) the period of incubation time of AAV vectors with HUVEC, (iv) the target cell density/proliferation, (v) the duration of transgene expression. There is a dose-response relationship between moi of vectors and transduction efficiency in HUVEC. The higher moi of AAV vectors achieved more than 80% of transduction efficiency in cultured HUVEC. AAV vectors showed incubation time dependent increase in transduction efficiency of LacZ gene to the HUVEC up to 24 h of vector exposure. The foreign gene of AAV vectors preferably transduces the lower density of cells being proliferated. These results indicate that AAV-vector is efficient for gene transfer to HUVEC, and higher moi of vectors or a longer period exposure of vectors to proliferating HUVEC can facilitate efficient tranduction of foreign gene into human vascular endothelial cells in vitro.

Cell Count↗

PubMed2002

Efficiencies of master, replica, and multilayer gratings for the soft-x-ray-extreme-ultraviolet range: modeling based on the modified integral method and comparisons with measurements.

The near-normal-incidence efficiencies of a 2400-groove/mm holographic master grating, a replica grating, and a multilayer grating are modeled in the soft-x-ray-extreme-ultraviolet (EUV) regions and are compared with efficiencies that are measured with synchrotron radiation. The efficiencies are calculated by the computer program PCGrate, which is based on a rigorous modified integral method. The theory of our integral method is described both for monolayer and multilayer gratings designated for the soft-x-ray-EUV-wavelength range. The calculations account for the groove profile as determined from atomic force microscopy with a depth scaling in the case of the multilayer grating and an average random microroughness (0.7 nm) for the short wavelengths. The refractive indices of the grating substrate and coatings have been taken from different sources because of the wide range of the wavelengths (4.5-50 nm). The measured peak absolute efficiency of 10.4% in the second diffraction order at a wavelength of 11.4 nm is achieved for the multilayer grating and is in good agreement with a computed value of approximately 11.5%. Rigorous modeling of the efficiencies of three similar gratings is in good overall agreement with the measured efficiency over a wide wavelength region. Additional calculations have indicated that relatively high normal incidence efficiency (of at least several percent) and large angular dispersion in the higher orders can be achieved in the 4.5-10.5-nm range by application of various multilayer coatings.

Journal Article↗

PubMed2003

Quantum efficiency of silicon photodiodes in the near-infrared spectral range.

The quantum efficiency of silicon photodiodes and factors that might be responsible for the drop in quantum efficiency in the near-infrared spectral range were analyzed. It was shown that poor reflectivity from the rear surface of the die could account for a decrease in Si photodiode quantum efficiency in near-infrared spectral range by more than 20%. The photodiode quantum efficiency was modeled with an appropriate representation for the carrier-collection efficiency dependence on the die penetration depth. A corrected analytical expression for calculating the photodiode quantum efficiency is given. Some methods to improve the quantum efficiency of silicon photodiodes in near-infrared spectral range are discussed.

Journal Article↗

PubMed2004

Highly efficient continuous-wave operation of a Nd:YAG rod laser that is side pumped by p-polarized diode laser bars.

We report on the performance of highly efficient, high-power continuous-wave (CW) Nd:YAG lasers that are side pumped by p-polarized diode laser beams. In this configuration pump light is directly coupled into the Nd:YAG rod through a threefold symmetric gold-coated flow tube. The polarization direction of our pump diode bars is perpendicular to the rod's axis (p-polarized). In a closed coupled resonator, a maximum output power of 195 W in multimode operation is obtained for a pump power of 423 W, which corresponds to an optical-to-optical efficiency of 46% and an electrical-to-optical efficiency of 23%. This is, to the best of our knowledge, the highest electrical-to-optical efficiency reported for a CW diode side-pumped Nd:YAG laser. By the pump-power leakage analysis method, we measured the pumping efficiency to be approximately 94%. The high efficiency of the system can be attributed to wing pumping, which results in uniform pump-light distribution and better pumping efficiency because of the use of p-polarized pump beams.

Journal Article↗

PubMed1982

Brightness luminous-efficiency functions for 2 degrees and 10 degrees fields.

CIE V lambda is not representative of luminous-efficiency function based on heterochromatic brightness matching. CIE Technical Committee 1.4 Vision (TC 1.4) presented a 2 degrees brightness-matching luminous-efficiency function based on studies of a total of 31 observers to supplement the V lambda. In view of their importance to illuminating engineering and physiological optics, we analyzed the various conditions under which these seven studies were conducted. Data from three of the groups are considered inappropriate, and we revised the TC 1.4 brightness luminous-efficiency function based on the remaining 19 subjects. Data from 18 Japanese subjects, coming from five research groups, are added to the above subjects, and an averaged luminous-efficiency function is derived. The result does not appreciably differ from the revised TC 1.4 function and is considered to represent a brightness-matching standard luminous-efficiency function for a 2 degrees field. A brightness luminous-efficiency function for a 10 degrees field based on nine Japanese subjects is presented. It differs from the 2 degrees function only at short wavelengths when the functions are normalized at 570 nm. A theoretical approach for using the brightness-matching luminous-efficiency function to assess the brightness of 2 degrees broadband sources is introduced, and some numerical examples are given.

Humans↗

PubMed2003

Highly efficient 1063-nm continuous-wave laser emission in Nd:GdVO4.

Highly efficient 1-microm continuous-wave laser emission in 3-mm-thick, 0.5- and 1.0-at. % Nd:GdVO4 crystals longitudinally pumped at 879 nm into the laser emitting level is reported. Under Ti:sapphire pumping, the slope efficiency in absorbed power is approximately 80% for both crystals, while the slope efficiency, the optical-to-optical efficiency (at 1700-mW pump power), and the laser threshold in incident power are 79%, 78%, and 31 mW for 0.5-at. % Nd and 80%, 77%, and 40 mW for 1.0-at. % Nd, respectively. The slope efficiency is close to the quantum defect limit, the difference being fully accounted for by the residual optical losses. Under 879-nm diode laser pumping, the slope efficiency and the optical-to-optical efficiency in absorbed power of the 0.5-at. % Nd:GdVO4 crystal are 60% and 53%, owing to poorer superposition of the pumped and the laser mode volumes.

Journal Article↗

PubMed2005

Relative efficiency of anuran sampling methods in a restinga habitat (Jurubatiba, Rio de Janeiro, Brazil).

Studies on anurans in restinga habitats are few and, as a result, there is little information on which methods are more efficient for sampling them in this environment. Ten methods are usually used for sampling anuran communities in tropical and sub-tropical areas. In this study we evaluate which methods are more appropriate for this purpose in the restinga environment of Parque Nacional da Restinga de Jurubatiba. We analyzed six methods among those usually used for anuran samplings. For each method, we recorded the total amount of time spent (in min.), the number of researchers involved, and the number of species captured. We calculated a capture efficiency index (time necessary for a researcher to capture an individual frog) in order to make comparable the data obtained. Of the methods analyzed, the species inventory (9.7 min/searcher /ind.- MSI; richness = 6; abundance = 23) and the breeding site survey (9.5 MSI; richness = 4; abundance = 22) were the most efficient. The visual encounter inventory (45.0 MSI) and patch sampling (65.0 MSI) methods were of comparatively lower efficiency restinga, whereas the plot sampling and the pit-fall traps with drift-fence methods resulted in no frog capture. We conclude that there is a considerable difference in efficiency of methods used in the restinga environment and that the complete species inventory method is highly efficient for sampling frogs in the restinga studied and may be so in other restinga environments. Methods that are usually efficient in forested areas seem to be of little value in open restinga habitats.

Animals↗

PubMed1991

The effects of response efficiency on functionally equivalent competing behaviors.

Three experiments addressed the role of response efficiency in the application of functional equivalence training. Functional equivalence training includes conducting a functional assessment of the problem behavior. Variables that predict and maintain the problem behavior are defined, and socially appropriate, functionally equivalent skills are identified and taught. The logic is that if the learner has a socially appropriate way to achieve the same function, he or she will be less likely to use problem behaviors. This study examined the role of response efficiency in functional equivalence training. Response efficiency was examined in terms of three variables: (a) physical effort, (b) schedule of reinforcement, and (c) the time delay between presentation of the discriminative stimulus and reinforcer delivery. Each of the three experiments involved a person who performed a set of problem behaviors and a functional assessment of the problem behaviors. A socially appropriate alternative response was taught, but this new response was less efficient than the problem behavior on one of the efficiency variables (effort, schedule, delay in time). The new behaviors did not compete successfully with the problem behaviors until a new, more efficient, alternative behavior was taught. These results are discussed in terms of our understanding of response covariation and the need in applied contexts to include response efficiency in any functional analysis assessment.

Activities of Daily Living↗

PubMed1989

[Clinical study on the prognosis of complete denture wearers covering 10 years. 4. Masticatory efficiency].

The purpose of this study was to estimate masticatory efficiency of complete denture wearers. The subjects were 72 patients, treated before 5-10 years at students' clinic of Tsurumi University, School of Dental Medicine. The masticatory efficiencies with peanuts and Kamaboko were calculated. Results 1. The mean masticatory efficiency with peanuts for 63 patients was 35.8%, and with Kamaboko (steamed fishpast) for 64 patients was 94.5%, in comparison with natural dentition. 2. The mean masticatory efficiency with peanuts was 124.3%, and with Kamaboko was 99.6%, for complete denture wearers. 3. Comparing the measured value of masticatory efficiency with 5 to 10 years wearing period, there was significant difference in the masticatory efficiency between peanuts and Kamaboko. 4. There was significant difference in the masticatory efficiency with peanuts between the group needed new denture and the group not needed but there was not significant difference with Kamaboko.

Denture, Complete↗

PubMed1999

Evaluation of life-cycle herd efficiency in cow-calf systems of beef production.

A deterministic beef efficiency model (BEM) was used to evaluate life-cycle herd efficiency (LCHE) in cow-calf beef production systems using four breed groups of beef cattle. The breed groups were Beef Synthetic #1 (SY1), Beef Synthetic #2 (SY2), Dairy Synthetic (DS), and purebred Hereford (HE). The LCHE was defined over the lifetime of the herd as the ratio of total output (lean meat equivalent) to total input (feed equivalent). Breed differences in LCHE were predicted with the larger/slower maturing DS being most efficient at each age of herd disposal and reproductive rate. This was mainly because, at any average age at culling, the dams of DS breed group were less mature and so had been carrying relatively lower maintenance loads for shorter periods and positively influencing LCHE. Higher LCHE was predicted with improvement in reproductive performance if there were no associated extra costs. However, this declined markedly if there was a delay in marketing of offspring. As average age at culling increased from 4 to 6 yr, efficiency declined sharply, but it began to recover beyond this age in most breed groups. We concluded that the slower maturing DS breed group may be more efficient on a herd basis in cow-calf systems and that improvements in reproductive rate not associated with extra costs improve life-cycle efficiency. Culling cows soon after their replacements are produced seems efficient.

Animal Husbandry↗

PubMed2002

Degree of amino acid restrictions during the grower phase and compensatory growth in pigs selected for lean growth efficiency.

A total of 32 select line (SL) and 32 control line (CL) Duroc pigs were used in two trials to determine the effect of dietary amino acid contents during the grower (G) phase and selection for lean growth efficiency on growth performance, carcass traits, and meat quality. In each trial, pigs weighing 20 kg were assigned to 16 pens with two gilts or two castrated males per pen, and pens were randomly assigned within the genetic line to corn-soybean meal G diets formulated to contain 5.0, 7.0, 9.0, or 11.0 g lysine/kg. After 50 kg, all pigs were fed common finisher 1 (F1) and finisher 2 (F2) diets. Pigs were allowed ad libitum access to feed and water. After the initial statistical analyses, the data sets from the two trials were combined. During the G phase, pigs consumed less feed [linear (Ln), P < 0.001] and more lysine (Ln, P < 0.001), grew faster (Ln, P < 0.05) but utilized feed more and lysine less efficiently (Ln, P < 0.001) for weight gain as the amino acid content of G diets increased. Increasing dietary amino acids resulted in less ultrasound backfat (Ln, P < 0.001) and more serum urea nitrogen [Ln, P < 0.001; quadratic (Qd), P < 0.01] at the end of the G phase. Pigs grew more slowly during the F1 (Ln, P < 0.01 and Qd, P = 0.05) and F2 (Ln, P = 0.07) phases and utilized feed and lysine less efficiently (Ln, P < 0.05) for weight gain during the F1 phase as the amino acid content of G diets increased. The grower diet had no effect on overall weight gain and feed efficiency, carcass traits, or meat quality scores. The efficiency of lysine utilization for overall weight gain (Ln, P < 0.001) and lean accretion (Ln, P < 0.05) improved as the amino acid content of G diets decreased. The SL pigs grew faster (P < 0.05) and had less (P < 0.001) ultrasound backfat throughout the study compared with the CL pigs. The SL pigs had less 10th rib backfat (P < 0.001) and tended to have larger longissimus muscle area (P = 0.09) than the CL pigs, which were reflected in greater rate (P < 0.001) and efficiency (P < 0.05) of lean accretion. Marbling (P < 0.05) and meat color (P = 0.07) scores were lower in the SL pigs. No grower diet x genotype interactions were observed in response criteria of interest. The results indicate that pigs subjected to dietary amino acid restrictions during the G phase (as low as 5.0 g lysine/kg) compensated completely in terms of growth rate and body composition regardless of the genotype. Compensatory growth can have a positive impact not only on the overall efficiency of pig production but also on the environment by reducing excretion of unused nutrients.

Adipose Tissue↗

PubMed1984

Effects of breed and intake level on growth and feed efficiency in ram lambs.

Effects of breed and intake level on growth and feed efficiency in ram lambs were tested with 52 Rambouillet, 46 Dorset and 53 Finnish Landrace (Finn) rams. Rams were individually fed at 100, 85 or 70% of ad libitum or at maintenance. The experimental diet contained 79% digestible dry matter (DM), 3.28% N and 2.95 Mcal metabolizable energy/kg DM. Rams were serially slaughtered every 35 d for 175 d. The efficiency of deposition of body weight, protein, energy and trimmed cuts was determined by breed and intake level over constant time, weight, fat and maturity intervals. Ranking of the breeds for feed efficiency depended upon both the interval and the criterion of evaluation. Efficiency of protein and trimmed cut gain was positively related to mature size in the time and weight intervals, but all differences in efficiency were small in the fat or maturity intervals. Gross energetic efficiency did not differ greatly among breeds in any interval. Dorsets appeared to have a somewhat greater propensity to fatten than the other breeds and to be less able to retain N at a fixed N intake. In the constant time interval, maintenance requirements were estimated to be 115 kcal/kg.75, and the estimated partial efficiencies of energy deposition in fat and protein were .49 and .26, respectively.

Animal Feed↗

PubMed1984

Relationships between traits of cow-calf pairs and a measure of partial efficiency.

Angus cow-calf pairs (N = 114) were individually fed grass silage diets under conditions chosen to approximate nutrient intake under a free grazing, noncreep situation. Postfactum comparison with a subsequently conducted study on pasture indicated that the procedures used produced animal responses similar to those provided by a tall fescue pasture averaging 58% dry matter digestibility. Cow-calf pair efficiency was expressed as the ratio of estimated total digestible nutrient (ETDN) intake of the pair to calf weight at weaning. Initial cow weight per se was unrelated to pair efficiency. When considered jointly with calf weight at weaning, initial cow weight was unfavorably and calf weight was favorably related to pair efficiency. Calf age at weaning and milk production were favorably related to pair efficiency through their relationship with calf weight at weaning. Initial cow fat thickness, estimated ultrasonically, was not related to this measure of efficiency, indicating compensations between the year just completed and the next year in the relationship between cow fat thickness at weaning and pair efficiency. Mating schemes resulting in selection of relatively smaller females and larger males, within the variation available in a straightbred population, would be expected to alter the cow weight-calf weight ratio in a direction favorable to the component of efficiency defined in this study.

Animal Feed↗

PubMed2003

Effects of diet fermentability on efficiency of microbial nitrogen production in lactating dairy cows.

Effect of diet fermentability on efficiency of microbial N production was evaluated. Eight ruminally and duodenally cannulated Holstein cows (55 +/- 15.9 days in milk; mean +/- SD) were used in a duplicated 4 x 4 Latin square design with a 2 x 2 factorial arrangement of treatments. Experimental diets contained either ground high moisture corn (HM) or dry ground corn (DG) at two dietary starch concentrations (32 vs. 21%). All diets were formulated for 18% CP, and the sources of dietary protein were alfalfa silage (50% of forage at DM basis), soybean meal, distillers grain, and blood meal. The amount of OM truly fermented in the rumen varied from 7.7 (DG at 21% dietary starch) to 11.3 kg/d (HM at 32% dietary starch) among treatments, and was greater for high starch diets and HM treatments compared with low starch diets and DG treatments, respectively. Microbial N flow was greater for high starch diets compared with low starch diets, but was not affected by corn grain treatment. Microbial efficiency was lower for HM compared with DG treatment (39.7 vs. 48.4 g of microbial N/kg of true ruminally degraded OM), but was not affected by dietary starch concentration. Microbial efficiency was positively correlated with rate of passage for OM and starch (r = 0.77 and 0.75, respectively). Rapid passage rate may have decreased microbial turnover in the rumen, enhancing microbial efficiency. Microbial efficiency was negatively correlated with rate of starch digestion (r = -0.55), consistent with the energy spilling theory. However, energy spilling did not appear to be from lack of ammonia or low ruminal pH. Microbial efficiency was not related to ruminal ammonia concentration, daily mean ruminal pH, or minimum ruminal pH. Rate of starch availability and rates of passage for starch and OM from the rumen are important determinants of efficiency of microbial protein synthesis in vivo.

Animal Feed↗

PubMed1994

Measuring efficiency and accuracy of detection of estrus.

The ability of management to detect estrus efficiently and accurately in cows and heifers profoundly influences reproductive performance and profitability of dairy herds. Routine estimates of efficiency and accuracy are important to monitor reproduction in a herd and to evaluate management in problem breeding herds. Detection efficiency is usually expressed as the percentage of possible estruses that were observed over a given time period. Eight methods are presented that approximate efficiency using estrus and insemination dates. Efficiency can be estimated from herd summary information using the equation recommended by the Dairy Reproduction Core Parameter Committee or using equations that calculate the breeding interval. Milk progesterone concentrations measured by on-farm tests can be used to approximate efficiency. Seven of the nine Dairy Record Processing Centers calculate an efficiency estimate. Accuracy of detection of estrus is the percentage of estruses observed that are true estruses. Inaccurate detection of estrus results in breeding of cows not in estrus, thus lowering conception rates. Detection accuracy should be evaluated for herds experiencing low conception rates. Comparison of interestrual intervals, results of uterine and ovarian palpation, and progesterone concentrations of cows perceived to be in estrus can be used to estimate the accuracy of detection of estrus.

Animals↗

PubMed1984

Egg characteristics and production efficiency of dwarf (dw) White Leghorn hens divergently selected for body weight.

Egg characteristics, feed efficiency (egg mass/daily feed intake), and performance efficiency (egg mass/body weight) were studied in dwarf White Leghorns after four generations of selection for divergent body weight at 20 weeks of age. Sexual maturity and livability were not significantly different among high (H), low (L), or control (C) lines. Mean 20-week body weights for H, L, and C lines were 1.50 kg, .76 kg, and 1.02 kg, respectively. Daily feed intake, egg mass, egg weight, and yolk, albumen, and shell weights were significantly (P less than .05) different between H and L hens and were directly related to body weight. Percent yolk was greatest and percent yolk mottling and percent albumen were lowest in eggs from L hens. Percent shell was not significantly different among the lines. Albumen quality (Haugh units) was significantly better in eggs from H and L hens than from C hens. Percent hen-day egg production was not significantly different among lines. Feed efficiency was greatest in C hens with both C and L hens significantly more efficient than H hens. Performance efficiencies of C and L hens were significantly better than H hens throughout the experiment, and L hens were significantly more efficient than C hens during peak egg production. These results suggest that there may be minimum body weight requirements for efficient egg production.

Animals↗

PubMed2004

A rapid and efficient method to express target genes in mammalian cells by baculovirus.

AIM: To investigate the modification of baculovirus vector and the feasibility of delivering exogenous genes into mammalian cells with the culture supernatant of Spodoptera frugiperta (Sf9) cells infected by recombinant baculoviruses. METHODS: Two recombinant baculoviruses (BacV-CMV-EGFPA, BacV-CMV-EGFPB) containing CMV-EGFP expression cassette were constructed. HepG2 cells were directly incubated with the culture supernatant of Sf9 cells infected by recombinant baculoviruses, and reporter gene transfer and expression efficiencies were analyzed by flow cytometry (FCM). The optimal transduction conditions were investigated by FCM assay in HepG2 cells. Gene-transfer and expression efficiencies in HepG2 or CV1 cells by baculovirus vectors were compared with lipofectAMINE, recombinant retrovirus and vaccinia virus expression systems. Twenty different mammalian cell lines were used to investigate the feasibility of delivering exogenous genes into different mammalian cells with the culture supernatant of infected Sf9 cells. RESULTS: CMV promoter could directly express reporter genes in Sf9 cells with a relatively low efficiency. Target cells incubated with the 1:1 diluted culture supernatant (moi=50) for 12 h at 37 degrees C could achieve the highest transduction and expression efficiencies with least impairment to cell viability. Under similar conditions the baculovirus vector could achieve the highest gene-transfer and expression efficiency than lipofectAMINE, recombinant retrovirus and vaccinia virus expression systems. Most mammalian cell lines could be transduced with recombinant baculovirus. In primate adherent culture cells the recombinant baculovirus could arrive the highest infection and expression efficiencies, but it was not very satisfactory in the cell lines from mice and suspended culture cells. CONCLUSION: Mammalian cells incubated with the culture supernatant of infected Sf9 cells could serve as a very convenient way for rapid and efficient expression of foreign genes in mammalian cells, but it might be more suitable for primate adherent culture cells.

Animals↗