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PubMed2004

[High efficiency of L-glutamine production by coupling genetic engineered bacterial glutamine synthetase with yeast alcoholic fermentation system].

Glutamine is an important conditionally necessary amino acid in human body. The effort is to establish a new and high efficient L-glutamine production system instead of traditional fermentaion. In this paper, high efficiency of L-glutamine production is obtained by coupling genetic engineered bacterial glutamine synthetase (GS) with yeast alcoholic fermentation system. Glutamine Synthetase gene (glnA) was amplified from Bacillus subtilis genomic DNA with primers designed according to sequences reported in EMBL data bank, then it was inserted into expression vector PET28b, the sequence of glnA was proved to be the same as that reported in the data bank by DNA sequencing. After transformation of this recombinant plasmid PET28b-glnA into BL-21 (DE3) strain, Lactose and IPTG were used to induce GS expression at 37 degrees C separately. Both of them can induce GS expression efficiently. The induced protein is proved to be soluble and occupies about 80% of the total proteins by SDS-PAGE analysis. The soluble GS was purified by Ni2+ chelating sepharose colum. After purification, the purified enzyme was proved active. Results reveal that the optmum temperature of this enzyme is 60 degrees C and optmum pH is 6.5 in biosynthetic reaction by using glutamate, ammonium choloride and ATP as substrates. After induction, the enzyme activity in crude extract of BL-21/PET28b-glnA is 83 times higher than that of original BL-21 extract. Mn2+ can obviously increase the activity and stability of this enzyme. Experiments show that the transformation efficiency of glutamate to glutamine is more than 95%. Because of the high cost from ATP, a system coupling GS with yeast for ATP regenaration was established. In this system, GS utilizes ATP released by yeast fermentation to synthesize L-glutamine. Yeast was treated by 2% toluence to increase its permeability and a yeast named YC001 with high yield of glutamine by coupling with recombinant GS was obtained. The good efficiency was achieved with the presence of 250 mmol/L glucose and 200 mmol/L phosphate, the transformation efficiency of glutamate to glutamine in this system is more than 80%, the average yield of glutamine is about 22g/L. This provides the basis for future large scale production of L-glutamine.

Bacillus subtilis↗

PubMed2006

Cardiac efficiency and oxygen consumption measured with 11C-acetate PET after long-term cardiac resynchronization therapy.

UNLABELLED: Cardiac resynchronization therapy (CRT) is a treatment option in patients with severe heart failure and left bundle-branch block (LBBB). This study evaluated the effects of 4 and 13 mo of CRT on myocardial oxygen consumption (MVO2) and cardiac efficiency as compared with mild heart failure patients without LBBB. METHODS: Sixteen patients with severe heart failure and LBBB due to idiopathic cardiomyopathy were studied at baseline and after 4 and after 13 mo of therapy. Thirteen patients with mild heart failure without LBBB served as a comparison group. The clearance rate (k2) of 11C-acetate was measured with PET to assess MVO2. Stroke volume was derived from the dynamic PET data according to the Stewart-Hamilton principle and, furthermore, cardiac efficiency using the work metabolic index. RESULTS: After 4 mo of CRT, stroke volume index (SVI) increased by 50% (P = 0.012) and cardiac efficiency increased by 41% (P < 0.001). Global k2 remained unchanged but regional k2 demonstrated a more homogeneous distribution pattern. The parameters showed no significant changes during therapy. Under CRT, cardiac efficiency, SVI, and the distribution pattern of regional k2 did not differ from mild heart failure patients without LBBB. CONCLUSION: CRT improves cardiac efficiency for at least 13 mo, as demonstrated by a higher SVI, whereas MVO2 remains unchanged. Cardiac efficiency, SVI, and the MVO2 distribution pattern reach the level of patients with mild heart failure without LBBB. The unfavorable hemodynamic performance in heart failure with LBBB is effectively restored by long-term CRT to the level of an earlier disease state.

Acetates↗

PubMed2006

[Relationship between several biologic indices and degradation efficiency of bioaugmentation system].

Because of the existence of some unstable factors, the effluent water from a bioaugmentation refinery wastewater treatment system usually exceeds the provided standard. To solve this problem, the relationship between the bacteria number, dehydrogenase, catechol 1,2-dioxygenase(C12O), catechol 2,3-dioxygenase(C23O) and the degradation efficiency of the bioaugmentation and control system is investigated and discussed. Using ERIC-PCR technology, we studied the changes of the microbial populations before and after treatment. The results show addition of microorganisms agent can increase the bacteria number, enzyme efficiency and the efficiency of the reactor. There exists a positive relationship between the bacteria number, C23O and the degradation efficiency in the bioaugmentation reactor. The microbial populations in both the reactors are stable before and after run. C12O is a kind of induction enzyme and its efficiency declines while the degradation efficiency increases.

Bacteria, Anaerobic↗

PubMed1989

[Study on the feeding function and feeding behavior of children. 1. Biting pressure and masticatory efficiency for 3, 4 and 5 years old children].

The purpose of this study was to investigate the biting pressure and masticatory efficiency of 3, 4 and 5 year old children. Some of them had trouble regarding their feeding behavior, either saying that they were not able to bite hard food or that they didn't want to bite hard food. A new method using A.T.P. (Adenosine Triphosphate) granules introduced with rubber finger protectors was used for measurement of the masticatory efficiency. 69 healthy 3, 4 and 5 year old children who had normal occlusion and were caries free were the subject. The results obtained were as follows. 1) The mean of the biting pressure for the 2nd primary molars for 69 children was 21.7 Kg. As for the data of the biting pressure for each age group, it was shown to increase with age (3 to 5 year old). 2) The mean of the masticatory efficiency for 69 children was 0.201 abs. As for the data of the masticatory efficiency for each age, it were shown to increase with age (3 to 5 year old). 3) The coefficient of the correlation of the biting pressure and the masticatory efficiency for 69 children was 0.410 which was considered statistically significant. (P less than 0.05) The coefficient of the correlation of the biting pressure and the masticatory efficiency for 3 year old children was 0.461, the coefficient of the correlation for the same items for 4 year old children was 0.395 and the coefficient of the correlation for 5 year old children was 0.353. All of these were considered statistically significant. (P less than 0.05)

Bite Force↗

PubMed1987

On the efficiency of age-adjusted tests in animal carcinogenicity experiments.

Based on asymptotic relative efficiency calculations, Ryan (1985, Biometrics 41, 525-531) concludes that, in the analysis of animal carcinogenicity experiments, age-adjusted tests of tumor rates should be routinely preferred to simple proportions tests for both lethal and nonlethal tumors. We recalculate the asymptotic efficiencies of the simple proportions test relative to the log-rank test for the lethal tumor case. For a simplified model it is shown that the relative efficiency may be easily computed as a function of the crude tumor rate and the survival rate at the time of terminal sacrifice. More generally, we calculate by numerical quadrature the asymptotic relative efficiency for all models considered by Ryan and, using simulations, examine the relevance of asymptotic efficiencies to typical sample sizes. Contrary to the numerical results of Ryan, we find, for experiments with good survival and typical tumor rates, that the relative efficiencies are greater than 95%, usually about 99%. In the nonlethal tumor case, similar results follow from Ryan for tumor rates and survival rates typically encountered in practice. As it is often difficult to determine whether or not a tumor is lethal, we conclude for equal interim mortality rates, that the simple proportions test is usually adequate in evaluating animal carcinogenicity experiments.

Age Factors↗

PubMed1985

A study of leucocyte labelling efficiencies obtained with 111In-oxine.

The range of leucocyte labelling efficiencies with 111In-oxine for a group of patients extended significantly (P = 0.05) below that obtained for a series of labellings of the same normal blood from a volunteer. A retrospective analysis was made of the results in the two groups to identify the cause of this difference in range. The labelling efficiency for patients did not vary with the volume of 111In-oxine, and was independent of the whole blood leucocyte concentration. The difference between the average labelling efficiencies obtained for a group of patients and the normal series labelled by the same operator was more significant than the difference in average labelling efficiencies obtained by different operators. It was concluded that biological variation in patients' blood, rather than operator technique, must have been a more important cause to the difference in the labelling efficiency range between patients and normal. It was also concluded that variations of contaminant platelet-bound activity and of plasma viscosity were greater in the patient group than the normal series, and contributed to this difference in labelling efficiency range.

Humans↗

PubMed1993

Ventricular perspective on efficiency.

The heart has many efficiencies of different definitions, of which mechanical work efficiency is the most popular and conventional. We have proposed a method to quantify the total mechanical energy generated by ventricular contraction. This energy can be quantified as a specific area called "systolic pressure-volume area" or "PVA" in the ventricular pressure-volume diagram. In the left ventricle of excised, cross-circulated dog heart preparations, we found a closely linear relation between PVA and oxygen consumption (VO2) under various loading conditions in a stable contractile state (Emax). An enhanced contractility was accompanied by an elevation of the load-independent VO2-PVA relation in a parallel manner, where the elevation was proportional to Emax. The slope of the VO2-PVA relation represents the "oxygen cost of mechanical energy (or PVA)" and its reciprocal indicates the "contractile efficiency", i.e., the energy conversion efficiency from PVA-dependent VO2 to PVA. This efficiency was 40% on the average, independent of various inotropic interventions. The slope of the PVA-independent VO2-Emax relation represents the "oxygen cost of contractility (or Emax)". This cost was relatively constant for different inotropic interventions except for myocardial cooling and stunning. We considered the discrepancy between the stable contractile efficiency and the variable thermal economy of force generation and maintenance.

Animals↗

PubMed1994

Detection efficiency of circular gratings and bandpass filtered points with randomized phase spectra.

PURPOSE: In the studies of spatial integration an increase in the spatial extent of the stimulus usually results in a decrease in the spatial frequency bandwidth of the stimulus. The authors investigated separately the effects of these two factors on contrast detectability. METHODS: Efficiencies were measured for a circular grating at 4 c/deg and for bandpass-filtered point stimuli having a constant center frequency at 4 c/deg and bandwidths of 0.25, 0.5, 1, and 2 octaves. The phase range of these two-dimensional stimuli was increased from zero to 90, 180, 270, and 360 degrees by replacing the original zero phase at each spatial frequency component by a random number with zero mean. This procedure left the spatial frequency bandwidth unaffected. RESULTS: The increase in phase range and decrease in spatial frequency bandwidth caused a progressively larger proportion of the contrast energy of the point stimuli to spread into their surroundings. As a result, detection efficiency decreased with increasing bandwidth and phase range for all point stimuli. However, a change in the stimulus bandwidth affected efficiency only when it altered stimulus area. The area of the circular grating and its detection efficiency remained almost constant irrespective of the phase range. When efficiency was plotted in semi-logarithmic coordinates as a function of stimulus area expressed in terms of the spatial spread of contrast energy, the line of least squares explained 85% of the total variance. CONCLUSION: The primary determinant of detection efficiency for stimuli with constant center spatial frequency is not stimulus bandwidth but stimulus area expressed in terms of the spatial spread of contrast energy.

Contrast Sensitivity↗

PubMed1993

Food efficiency in rats following brain lesions which affect target body size: implications on the set point for target size.

Target size, i.e. body size appropriate for age, may be reset by bilateral lesions of several brain areas. The mechanism for control of target body size is unknown, but some of the loci have marked effects on gustatory behavior and/or energy metabolism. We have tested the possibility that a disturbance in energy metabolism may be a common factor in resetting target size. Food efficiency for body weight gain and for metabolic size (the 0.75 power of body weight) was determined in rats that were experimentally stunted by neonatal head-irradiation or by bilateral electrolytic lesions produced soon after weaning in the dorsomedial hypothalamic nuclei (DMH) or the substantia nigra (SN). The irradiations were carried out in males and females; the surgical lesions were produced only in males. Observations were carried out from weaning through early adulthood. Subgroups of irradiated rats and controls were fasted for 48 hours at 40 days of age. Irradiated rats had reduced food efficiency for weight gain and for metabolic size, more marked in males than in females. DMH or SN lesions did not change food efficiency for weight gain. Food efficiency for metabolic size increased after DMH lesions and declined after SN lesions. During refeeding after a fast, irradiated rats showed a normal transient increase in food efficiency for weight gain, but not for metabolic size. The differences in food efficiency following different lesions tend to exclude altered energy metabolism as a common factor in the reset of target body size.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1998

Transcription termination downstream of the Saccharomyces cerevisiae FBP1 [changed from FPB1] poly(A) site does not depend on efficient 3'end processing.

Efficient transcription termination downstream of poly(A) sites has been shown to correlate with the strength of an upstream polyadenylation signal and the presence of a polymerase pause site. To further investigate the mechanism linking termination with 3'-end processing, we analyzed the cis-acting elements that contribute to these events in the Saccharomyces cerevisiae FBP1 gene. FBP1 has a complex polyadenylation signal, and at least three efficiency elements must be present for efficient processing. However, not all combinations of these elements are equally effective. This gene also shows a novel organization of sequence elements. A strong positioning element is located upstream, rather than downstream, of the efficiency elements, and functions to select the cleavage site in vitro and in vivo. Transcription run-on analysis indicated that termination occurs within 61 nt past the poly(A) site. Deletion of two UAUAUA-type efficiency elements greatly reduces polyadenylation in vivo and in vitro, but transcription termination is still efficient, implying that FBP1 termination signals may be distinct from those for polyadenylation. Alternatively, assembly of a partial, but nonfunctional, polyadenylation complex on the nascent transcript may be sufficient to cause termination.

Base Sequence↗

PubMed1998

High-efficiency gene transfer into ex vivo expanded human hematopoietic progenitors and precursor cells by adenovirus vectors.

Replication-deficient adenoviral vectors (AdVec), which infect cycling and noncycling cells with high efficiency, low toxicity, and ease of delivery, provide ideal vehicles to study the expression of regulatory genes controlling different stages of hematopoiesis. To examine the infection efficiency of AdVec in hematopoietic precursor and progenitor cells, we used a replication-deficient adenovector expressing the humanized form of the cDNA for green fluorescent protein (AdGFP), permitting assessment of infection efficiency and kinetics of transgene expression in viable hematopoietic cells using flow cytometry and fluorescence microscopy. Flow-cytometric analysis of ex vivo expanded hematopoietic precursor cells infected with a multiplicity of infection (MOI) of 100 of AdGFP show that 78% of megakaryocytic (CD41a+ and CD42b+) cells, 82% of dendritic (CD1a+) cells, 41% of RBC precursors (glycophorin A+), and 32% of monocytic (CD14(+)) cells expressed GFP. Nineteen percent +/- 1% of freshly isolated CD34(+) cells from peripheral blood leukapheresis products infected under the same conditions expressed GFP. Morphologic evaluation of ex vivo expanded, AdGFP-infected CD34(+) cells showed normal maturation. The functional capacity of AdGFP-infected CD34(+) cells was analyzed by quantifying clonogeneic efficiency and proliferative capacity. Infection of CD34(+) progenitor cells with MOIs of 1 to 100 did not impair clonogeneic efficiency of CD34(+ )cells. However, MOI greater than 100 resulted in a significant inhibition of colony-forming unit-granulocyte/granulocyte-macrophage (CFU-G/GM) formation. In sequential dilution expansion over 3 weeks (Delta assay), the cytokine-driven proliferative potential of CD34(+) cells was not impaired following exposure to AdGFP at MOIs of 1 to 1,000. The GFP+ population expanded 10- to 15-fold at high MOIs (500 to 1,000), indicating multiple copies of the transgene in the initially infected CD34(+) cells, which were expressed in subsequent progenies. These data show that AdVec deliver transgenes with high efficiency and low toxicity to hematopoietic progenitor and precursor cells. Introduction of marker genes such as GFP into hematopoietic cells by AdVec will provide a valuable system for study of development, homing, and trafficking of hematopoietic precursor and progenitor cells in vitro and in vivo. Furthermore, these results provide insights into the design of gene therapy strategies for treatment of hematologic disorders by AdVec.

Adenoviridae↗

PubMed1998

Delayed targeting of cytokine-nonresponsive human bone marrow CD34(+) cells with retrovirus-mediated gene transfer enhances transduction efficiency and long-term expression of transduced genes.

Primitive hematopoietic progenitor cells (HPCs) are potential targets for treatment of numerous hematopoietic diseases using retroviral-mediated gene transfer (RMGT). To achieve high efficiency of gene transfer into primitive HPCs, a delicate balance between cellular activation and proliferation and maintenance of hematopoietic potential must be established. We have demonstrated that a subpopulation of human bone marrow (BM) CD34(+) cells, highly enriched for primitive HPCs, persists in culture in a mitotically quiescent state due to their cytokine-nonresponsive (CNR) nature, a characteristic that may prevent efficient RMGT of these cells. To evaluate and possibly circumvent this, we designed a two-step transduction protocol using neoR-containing vectors coupled with flow cytometric cell sorting to isolate and examine transduction efficiency in different fractions of cultured CD34(+) cells. BM CD34(+) cells stained on day 0 (d0) with the membrane dye PKH2 were prestimulated for 24 hours with stem cell factor (SCF), interleukin-3 (IL-3), and IL-6, and then transduced on fibronectin with the retroviral vector LNL6 on d1. On d5, half of the cultured cells were transduced with the retroviral vector G1Na and sorted on d6 into cytokine-responsive (d6 CR) cells (detected via their loss of PKH2 fluorescence relative to d0 sample) and d6 CNR cells that had not divided since d0. The other half of the cultured cells were first sorted on d5 into d5 CR and d5 CNR cells and then infected separately with G1Na. Both sets of d5 and d6 CR and CNR cells were cultured in secondary long-term cultures (LTCs) and assayed weekly for transduced progenitor cells. Significantly higher numbers of G418-resistant colonies were produced in cultures initiated with d5 and d6 CNR cells compared with respective CR fractions (P < .05). At week 2, transduction efficiency was comparable between d5 and d6 transduced CR and CNR cells (P > .05). However, at weeks 3 and 4, d5 and d6 CNR fractions generated significantly higher numbers of neoR progenitor cells relative to the respective CR fractions (P < .05), while no difference in transduction efficiency between d5 and d6 CNR cells could be demonstrated. Polymerase chain reaction (PCR) analysis of the origin of transduced neoR gene in clonogenic cells demonstrated that mature progenitors (CR fractions) contained predominantly LNL6 sequences, while more primitive progenitor cells (CNR fractions) were transduced with G1Na. These results demonstrate that prolonged stimulation of primitive HPCs is essential for achieving efficient RMGT into cells capable of sustaining long-term in vitro hematopoiesis. These findings may have significant implications for the development of clinical gene therapy protocols.

Adult↗

PubMed1999

Internal markets and health care efficiency: a multiple-output stochastic frontier analysis.

This paper has two purposes. The first purpose is methodological and aims to extend previous work on efficiency analysis by implementing a multiple-output stochastic ray frontier production function model. This model generalizes the single-output stochastic frontier model to multiple-input, multiple-output technologies and allows simultaneous estimation of technical efficiency and analysis of influential variables on efficiency. The second, empirical, purpose is to test for existence and magnitude of the effect of purchaser/provider split combined with new reimbursement schemes on technical efficiency in the Swedish public hospital system. The analysis is carried out with a panel data set covering the total population of 26 Swedish County Councils from 1989 to 1995. Our empirical results support the frontier model specification and indicate that output-based reimbursement improves technical efficiency. The potential saving in costs due to a switch from budget-based allocation to output-based allocation is estimated to be almost 10%.

Adult↗

PubMed2006

East-west: does it make a difference to hospital efficiencies in Ukraine?

Ukraine's history has given it a split personality (e.g. divergent cultural influences on economic and managerial behavior), as was observed in the recent political developments both prior to and following the December 2004 elections. Eastern regions were heavily influenced by Russo-Soviet rule, while western regions have more of a European outlook. This study, which is largely exploratory, compares recent trends in hospital efficiency in Ukraine to see if this split personality manifests itself in differential rates of improvement. Given the inflexibility of Soviet-style planned economies, it is hypothesized that western regions will show greater improvement in economic efficiency that can be attributed to higher levels of managerial and medical entrepreneurship. Data for this study comes from three oblasts (i.e. geopolitical regions), one in the west and two in the east, spanning from 1997 to 2001. Data envelopment analysis (DEA) was used to estimate technical efficiency for the hospitals. After correcting for bias, a second-stage Tobit regression was estimated. Results indicate that hospitals in the west improved efficiencies, while those in the east stayed constant. These western areas of the nation, being more amenable to western management and medical 'business' practice, may be quicker to pick up on new techniques to increase healthcare delivery efficiencies. This may stem from the more limited effects of a shorter history of incorporation into a Soviet-style planned and controlled economy in which individual decision-making and entrepreneurship was suppressed in favor of central decision-making by the state.

Culture↗

PubMed2026

Rapid Agrobacterium-mediated transformation and high-efficiency regeneration of finger millet (Eleusine coracana) for crop improvement.

Finger millet (Eleusine coracana) is a nutritionally important and climate-resilient cereal cultivated in rainfed regions of India and Eastern Africa, yet its genetic improvement has been limited by the lack of efficient and reproducible transformation systems. In this study, we developed a rapid and efficient Agrobacterium tumefaciens-mediated transformation and regeneration system using shoot apical meristem (SAM) explants, enabling direct, callus-free shoot organogenesis. Optimal regeneration and shoot elongation were achieved on Murashige and Skoog (MS) medium supplemented with 3.5 mg L⁻1 6-benzylaminopurine (BAP), 1.5 mg L⁻1 kinetin, 0.1 mg L⁻1 2,4-dichlorophenoxyacetic acid (2,4-D), and 0.2 mg L⁻1 gibberellic acid (GA₃). Genotype-dependent responses were observed, with PR-202 requiring 2 mg L⁻1 AgNO3 to reduce phenolic browning, whereas VL-376 regenerated efficiently without AgNO3. Transformation efficiencies of 30-32% were achieved in PR-202 and VL-376, respectively, by optimising infection and co-cultivation conditions, including reduced MS salt strength and pre-incubation of Agrobacterium. Molecular analyses, including PCR and Southern blot hybridisation, confirmed stable T-DNA integration in independent lines, while segregation analysis of T₁ progenies demonstrated Mendelian inheritance of the transgene. In addition, CRISPR/Cas9 constructs targeting EcCKX2 were successfully introduced via Agrobacterium, demonstrating the suitability of this system for genome engineering applications. Overall, this optimised SAM-based protocol provides a rapid (45-50 days), efficient, and reproducible platform for stable genetic transformation in finger millet and establishes a strong foundation for transgenic research and future genome editing studies in this underutilized crop.

Eleusine↗

PubMed1992

DRGs: the road to hospital efficiency.

In this paper, the effects of using diagnosis-related groups (DRGs) as the basis of a hospital funding mechanism and within a global budgeting mechanism are reviewed. Most forthcoming is the indeterminate effect of DRGs as a funding mechanism. By controlling only the price of hospital care, such systems remain vulnerable to compensatory increases in patient throughout, cost shifting and patient-shifting. Whether the use of DRGs has substantially reduced hospital cost per case is also not clear cut. Effects on patient outcome have not been adequately assessed. At this stage, use of DRGs within a system of global budgeting will simply focus attention on the current average costs of treating cases without consideration of whether such average costs represent efficient clinical practice. Efficient clinical practice is better established through use of less sophisticated techniques, such as clinical budgeting and cost-effectiveness analysis. The failure of more global budgeting in the past has been that patient outcome has not been monitored. Data on outcome are crucial to determining efficiency. Once efficient clinical practice is established through budgeting, DRGs could be calculated according to efficiency criteria rather than current average cost.

Australia↗

PubMed2006

Efficiency of an endoscopy suite in a teaching hospital: delays, prolonged procedures, and hospital waiting times.

BACKGROUND: Increased demand for screening colonoscopy necessitates improved efficiency in endoscopy units, especially more efficient use of existing resources. The purpose of this study was to assess the efficiency of the endoscopy unit of a large tertiary care teaching hospital. OBJECTIVE: To assess the efficiency of the endoscopy unit in a large tertiary care teaching hospital. DESIGN: Prospective study from May 16 to September 5, 2003. SETTING: Endoscopy unit of a 650-bed acute care teaching hospital. PATIENTS: Inpatient and outpatient procedures. MAIN OUTCOME MEASUREMENTS: Time elapsed between endoscopic procedures; the duration of the procedures; procedure delays (>15 minutes between procedures) and the reasons for them. RESULTS: The research assistant observed 675 endoscopic procedures done for 625 patients (207 inpatients [33%]). The most common procedure was colonoscopy (42.1%), followed by EGD (36.0%). Overall, procedures for 193 (30.9%) of the 625 patients were delayed (>15 minutes between procedures), 70.5% (136/193) because the physician was not available to start the procedure. The time elapsed between procedures was longer than 30 minutes for 47 of the 193 delayed procedures (24.4%). The duration of procedures was prolonged for about 22% (130/593) of procedures. CONCLUSIONS: Physician unavailability contributed to considerable delays in endoscopic procedures. Strategies to reduce procedure delays could have a favorable impact on the volume of procedures performed in the unit, thereby improving the use of existing resources. We encourage other groups to assess the efficiency of their hospital-based endoscopy units.

Canada↗

PubMed2004

Efficiency, power, and entropy in event-related FMRI with multiple trial types. Part I: theory.

Experimental designs for functional magnetic resonance imaging (fMRI) experiments can be characterized by their estimation efficiency, which is a measure of the variance in the estimate of the hemodynamic response function (HRF), and their detection power, which is a measure of the variance in the estimate of the amplitude of functional activity. Previous studies have shown that there exists a fundamental trade-off between efficiency and power for experiments with a single trial type of interest. This paper extends the prior work by presenting a theoretical model for the relation between detection power and estimation efficiency in experiments with multiple trial types. It is shown that the trade-off between efficiency and power present in multiple-trial-type experiments is identical in form to that observed for single-trial-type experiments. Departures from the predicted trade-off due to the inclusion of basis function expansions and the assumption of correlated noise are examined. Finally, conditional entropy is introduced as measure for the randomness of a design, and an empirical relation between entropy and estimation efficiency is presented.

Artifacts↗