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Performance of Smallholder Dairy Farming in Nakuru County, Kenya

Journal of Agricultural Science and Technology(A) 2012年第4期2卷 481-488页

作者： dennis kinambuga Benjamin K. Mutai George Owuor Aquilars M. Kalio Emmanuel K. Kinuthia Department of Agricultural Economics and Agribusiness Management University of Egerton Njoro 536-20115 Kenya International Livestock Research Institute （ILRI） Market Opportunities Nairobi 30709-00100 Kenya

The Kenya dairy sub-sector has been undergoing developments since the 1980s in the areas of adoption of intensive dairy farming, especially zero grazing. There have been concerted efforts by the government and other development partners to commercialize the sub-sector so as to make it more profitable to farmers, especially smallholder farmers, but the profitability in the sector continues to be variable with some smallholder farmers making losses. The causes of the varying profits have not been empirically established, with the influence of institutional arrangements and financial factors contributing to this inconsistency not fully established. This study dwelt on establishing the critical institutional arrangements and financial factors that constrain the profitability of smallholder dairy farmers in Nakuru County. A multi-stage sampling procedure was used to select respondents. Data were collected by structured interviews at the farm level. Data Envelopment Analysis （DEA） was used to come up with profit efficiency rankings among the farmers, and the Frontier Model was used to establish the factors that constrain profit efficiency. The mean efficiency according to the results was 86%. The farm and farmer characteristics that were significant in explaining profitability efficiency according to the frontier results were： feeding system, breed type, and gender. The financial characteristics included debt amount and debt asset ratio. Additionally, issues of trust were also found to have an effect on profitability, and they included trust in local buyer price, trust in unit of measurement of institutional buyer, and trust in unit of measurement of middlemen.

关键词： Profitability data envelopment analysis dairy farming smallholder

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Neural Regeneration Research 2025年第2期20卷 366-377页

作者： Samuel Abokyi dennis Yan-yin Tse School of Optometry The Hong Kong Polytechnic UniversityKowloonHong Kong Special Administrative RegionChina Research Center for SHARP Vision The Hong Kong Polytechnic UniversityKowloonHong Kong Special Administrative RegionChina Center for Eye and Vision Research Sha TinHong Kong Special Administrative RegionChina

Retinal aging has been recognized as a significant risk factor for various retinal disorders,including diabetic retinopathy,age-related macular degeneration,and glaucoma,following a growing understanding of the molecular underpinnings of their *** comprehensive review explores the mechanisms of retinal aging and investigates potential neuroprotective approaches,focusing on the activation of transcription factor *** meta-analyses have demonstrated promising outcomes of transcription factor EB-targeted strategies,such as exercise,calorie restriction,rapamycin,and metformin,in patients and animal models of these common retinal *** review critically assesses the role of transcription factor EB in retinal biology during aging,its neuroprotective effects,and its therapeutic potential for retinal *** impact of transcription factor EB on retinal aging is cell-specific,influencing metabolic reprogramming and energy homeostasis in retinal neurons through the regulation of mitochondrial quality control and nutrient-sensing *** vascular endothelial cells,transcription factor EB controls important processes,including endothelial cell proliferation,endothelial tube formation,and nitric oxide levels,thereby influencing the inner blood-retinal barrier,angiogenesis,and retinal ***,transcription factor EB affects vascular smooth muscle cells,inhibiting vascular calcification and *** retinal pigment epithelial cells,transcription factor EB modulates functions such as autophagy,lysosomal dynamics,and clearance of the aging pigment lipofuscin,thereby promoting photoreceptor survival and regulating vascular endothelial growth factor A expression involved in *** cell-specific functions of transcription factor EB significantly impact retinal aging mechanisms encompassing proteostasis,neuronal synapse plasticity,energy metabolism,microvasculature,and inflammation,ultimately offering pro

关键词： age-related macular degeneration anti-aging interventions autophagy calorie restriction diabetic retinopathy exercise glaucoma neuromodulation phagocytosis photoreceptor outer segment degradation retinal aging transcription factor EB

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Asymptotic false discovery control of the Benjamini-Hochberg procedure for pairwise comparisons

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Science China Mathematics 2025年第1期 223-252页

作者： Weidong Liu dennis Leung Qi-Man Shao School of Mathematical Sciences Shanghai Jiao Tong University School of Mathematics and Statistics University of Melbourne Department of Statistics and Data Science SICMSouthern University of Science and Technology

In a one-way analysis-of-variance(ANOVA) model,the number of pairwise comparisons can become large even with a moderate number of *** by this,we consider a regime with a growing number of groups and prove that,when testing pairwise comparisons,the Benjamini-Hochberg(BH) procedure can asymptotically control false discoveries,despite the fact that the involved t-statistics do not exhibit the wellknown positive dependence structure required for exact false discovery rate(FDR) *** Tukey's perspective that the difference between the means of any two groups cannot be exactly zero,our main result provides control over the directional false discovery rate and directional false discovery proportion.A key technical contribution of our work is demonstrating that the dependence among the t-statistics is sufficiently weak to establish the convergence result typically required for asymptotic FDR *** analysis does not rely on conventional assumptions such as normality,variance homogeneity,or a balanced design,thereby offering a theoretical foundation for applications in more general settings.

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Principles to Support Modular Software Construction

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Journal of Computer Science & Technology 2017年第1期32卷 3-10页

作者： Jack B. dennis Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA 02139 U.S.A.

The construction of large software systems is always achieved through assembly of independently written components -- program modules. For these software components to work together, they must share a common set of data types and principles for representing structured data such as arrays of values and files. This common set of tools for creating and operating on data objects is provided by the infrastructure of the computer system： the hardware, operating system and runtime code. Because the nature and properties of these tools are crucial for correct operation of software components and their inter-operation, it is essential to have a precise specification that may be used for verifying correctness of application software on one hand, and to verify correctness of system behavior on the other. We call such a specification a program execution model （PXM）. It is evident that the properties of the PXM implemented by a computer system can have serious impact on the ability of application programmers to practice modular software construction. This paper discusses the concept of program execution models and presents a set of principles that a PXM must satisfy to provide a sound basis for modular software construction. Because parallel program execution on computer systems with many processing units is an essential part of contemporary computing environments, the expression of parallelism and modular software construction using components involving parallel operations is included in this treatment. The conclusion is that it is possible to build computer systems that implement a PXM within which any parallel program may be used, unmodified, as a component for building more substantial parallel programs.

关键词： program execution model data flow model codelet abstract architecture parallel computing

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Review of current method to determine outburst threshold limits in Australian underground coal mines

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International Journal of Mining Science and Technology 2019年第6期29卷 859-865页

作者： dennis J.Black CoalGAS Department of Civil Mining and Environmental Engineering University of Wollongong

Desorption rate index(DRI)was presented to the Australian underground coal industry in 1995 as a means for determining outburst threshold limits for Australian coal *** is a measure of the gas volume released from a coal sample in the first 30 s of crushing during the Q3 stage of gas content testing,multiplied by the ratio between measured Q3 and *** were identified between QM and DRI for both CO2 and CH4 rich coal samples collected from the Bulli Seam at West Cliff Colliery and that identified relationship was referred to as the Bulli Seam *** outburst mining gas content threshold limit values specified for the Bulli Seam at that time,when applied to the QM-DRI Bulli Seam benchmark,was shown to closely align with a DRI value of 900(DRI900),for both CO2 and CH4 rich seam gas *** Australian coal industry adopted the DRI900 as the basis for determining outburst gas content TLV for Australian coal *** mining experience in Australia has shown that gas content is not the only significant factor that impacts outburst risk,as all significant outburst events have been associated with abnormal geological conditions,such as faults and ***,assessing the potential application of additional outburst risk factors,to accurately define outburst risk zones,set safe mining threshold levels,and determine appropriate mining controls,warrants further *** Australian coal mines have implemented mining procedures enabling mining to continue in areas with gas content greater than the TLV determined using the DRI900 approach,without inducing an *** is a broad lack of understanding among Australian coal mine operators as to the procedure and calculations used to determine ***,there has been growing concern regarding the accuracy and validity of the DRI900 method for determining outburst TLV.A comprehensive set of gas data has been collected from Australian coal seams,including the Bulli Seam,and t

关键词： Outburst Desorption rate DRI Threshold limit

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Review of coal and gas outburst in Australian underground coal mines

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International Journal of Mining Science and Technology 2019年第6期29卷 815-824页

作者： dennis J.Black CoalGAS Department of Civil Mining and Environmental Engineering University of Wollongong

Outburst of coal and gas represents a significant risk to the health and safety of mine personnel working in development and longwall production face *** have been over 878 outburst events recorded in twenty-two Australian underground coal *** outburst incidents have been associated with abnormal geological *** of Australian outburst incidents and mining experience in conditions where gas content was above current threshold levels are presented and *** experience suggests that for gas con-tent below 9.0 m^3/t,mining in carbon dioxide(CO2)rich seam gas conditions does not pose a greater risk of outburst than mining in CH4 rich seam gas *** experience also suggests that where no abnormal geological structures are present that mining in areas with gas content greater than the current accepted threshold levels can be undertaken with no discernible increase in outburst *** current approach to determining gas content threshold limits in Australian mines has been effective in prevent-ing injury from outburst,however operational experience suggests the current method is overly conser-vative and in some cases the threshold limits are low to the point that they provide no significant reduction in outburst *** factors that affect outburst risk,such as gas pressure,coal toughness and stress and geological structures are presently not incorporated into outburst threshold limits adopted in Australian *** factors and the development of an outburst risk index applicable to Australian underground coal mining conditions are the subject of ongoing research.

关键词： Outburst Desorption rate DRI Threshold limit

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Ethene／norbornene copolymerization by[Me2Si（3—^tertBuCp）（N^tertBu）]TiCl2／MAO—catalyst

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Journal of Zhejiang University Science 2003年第2期4卷 121-130页

作者： TRANPhu-dennis KAMINSKYWalter InstituteofTechnicalandMacromolecularChemistry UniversityofHamburgGermany

?Ethene/norbornene copolymerization by the catalyst system [Me_2Si( 3- tertBuCp)(N tertBu)]TiCl_2/MAO was investigated in detail at 30 ℃, 60℃, and 90℃. A mass flow controller was used in this work to obtain kine tic data and investigate tempera ture's effects on activity, norbornene incorporation, copolymerization parameter , microstructure, glass transition temperature, and molar masses were described. H igh copolymerization values r_E and high alternation are determined. The n umber of isotactic alternating sequences is much higher than that of the syndiot actic alter nating sequences.

关键词： Polymerization Ethene/norbornene copolymers Const rained geometry catalyst Temperature effects.

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Investigations into the identification and control of outburst risk in Australian underground coal mines

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International Journal of Mining Science and Technology 2017年第5期27卷 749-753页

作者： dennis J.Black PacificMGM Bulli 2516Australia Department of Civil Mining and Environmental EngineeringUniversity of WollongongWollongong 2500Australia

Australian coal mines currently use gas content to assess outburst risk. The gas content threshold values for each mine are indirectly determined from measurement of gas volume liberated from 150 g coal samples during Q_3 residual gas content testing. It has been more than twenty years since this method, known as desorption rate index(DRI), was presented to the Australian coal industry, and in that time, there have been significant changes in mining conditions and the outburst threshold limits used at the benchmark Bulli seam mines. NSW Regulations list matters to be considered in developing control measures to manage the risk of gas outburst, and specifies that gas content, or DRI method, is used as the basis for determining outburst control zone. Whilst Queensland Regulations state that a coal or rock outburst is a high potential incident, there is no guidance provided to assist mine operators to define outburst prone conditions. A research project is planned at UOW to investigate the application of the DRI method and other potentially significant factors, such as gas pressure, coal toughness and permeability, which can be utilised by mine operators to assess outburst risk and determine appropriate outburst threshold limits and controls.

关键词： Outburst Desorption rate DRI Threshold limit

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Chemical biology: a toolbox to unlock neurochemical epigenetics?

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Neural Regeneration Research 2021年第2期16卷 298-299页

作者： dennis Ozcelik Center for Biopharmaceuticals Department of Drug Design and PharmacologyUniversity of CopenhagenCopenhagenDenmark Department of Chemistry and Biomolecular Sciences University of OttawaOttawaOntarioCanada

The complex challenges of studying neurochemistry: Neurochemistry comprises the molecular and biochemical roles of a vast variety of chemical compounds, including amino acids, peptides, gaseous molecules, and small mo... 详细信息

关键词： chemical chemistry gaseous

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A theoretical study of the mechanism of the nucleotidyl transfer reaction catalyzed by yeast RNA polymerase Ⅱ

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Science China Chemistry 2012年第9期55卷 1887-1894页

作者： ZHANG Yue SALAHUB dennis Key Laboratory for Macromolecular Science of Shaanxi Province School of Chemistry&Materials Shaanxi Normal UniversityXi’an 710062China Institute for Biocomplexity and Informatics University of CalgaryCalgary T2N 1N4Canada Department of Chemistry University of CalgaryCalgary T2N 1N4Canada

The mechanism of the nucleotidyl transfer reaction catalyzed by yeast RNA polymerase I1 has been investigated using molec- ular mechanics and quantum mechanics methods. Molecular dynamics （MD） simulations were carried out using the TIP3 water model and generalized solvent boundary potential （GSBP） by CHARMM based on the X-ray crystal structure. Two models of the ternary elongation complex were constructed based on CHARMM MD calculations. All the species including reactants, transition states, intermediates, and products were optimized using the DFT-PBE method coupled with the basis set DZVP and the auxiliary basis set GEN-A2. Three pathways were explored using the DFT method. The most favorable reaction pathway involves indirect proton migration from the RNA primer 3＇-OH to the oxygen atom of a-phosphate via a solvent water mole- cule, proton rotation from the oxygen atom of a-phosphate to the 13-phosphate side, the RNA primer 3＇-O nucleophilic attack on the a-phosphorus atom, and P-O bond breakage. The corresponding reaction potential profile was obtained. The rate limit- ing step, with a barrier height of 21.5 kcal/mol, is the RNA primer 3＇-0 nucleophilic attack, rather than the commonly consid- ered proton transfer process. A high-resolution crystal structure including crystallographic water molecules is required for fur- ther studies.

关键词： yeast RNA polymerase II nucleotidyl transfer reaction two-metal-ion mechanism two-proton-transfer active center

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