3,147 research outputs found
Independence of Odor Quality and Absolute Sensitivity in a Study of Aging
Young, middle-aged, and senior subjects performed tasks designed to examine whether odor quality discrimination varies independently of sensitivity. One task entailed detection of 2-heptanone and the others AB-X discrimination of quality for sets of 2-heptanone and homologues or 2-heptanone and non-ketones. Subjects sought to discriminate either at intensity-matched concentrations far above threshold, but fixed across subjects, or at levels adjusted to neutralize differences in sensitivity. The young and middle-aged groups manifested the same absolute sensitivity, but the senior group poorer sensitivity. Performance in quality discrimination, however, declined progressively. Performance lacked an association with absolute sensitivity, no matter how examined. These data, in conjunction with converging findings from patients with neurological damage, studies of brain imaging, and the relation between concentration and quality discrimination in younger persons, suggest largely independent processing of odor quality and intensity
The room temperature phosphine-free synthesis of near-infrared emitting HgSe quantum dots
Luminescent mercury selenide (HgSe) quantum dots have been synthesised by a phosphine-free method using oleic acid as a capping agent. The modification of experimental conditions such as temperature resulted in particles of various sizes (15–100 nm) and morphologies not previously seen in HgSe, with emission tuneable between 1000 nm and 1350 nm
Amalan pengurusan keselamatan bengkel kemahiran hidup (KHB) Sekolah Menengah Harian Daerah Batu Pahat
Kajian ini dijalankan untuk mengkaji sejauhmanakah persepsi pelajar terhadap amalan pengurusan keselamatan dari aspek keselamatan alatan dan bahan, diri dan rakan serta keselamatan am di bengkel Kemahiran Hidup sekolah menengah harian daerah Batu Pahat. Kajian berbentuk kuantitatif dilaksanakan di empat buah sekolah menengah harian daerah Batu Pahat iaitu SMK Datin Onn Jaafar, SMK Banang Jaya, SMK Dato Onn dan SMK Seri Gading. Sampel kajian terdiri daripada 350 orang pelajar tingkatan dua yang mengambil matapelajaran KHB dan data dikumpul menggunakan instrumen borang soal selidik. Dapatan kajian dianalisis menggunakan perisian Winsteps Version 3.69.1.11 dengan pendekatan Model Pengukuran Rasch sepenuhnya. Data dianalisis menggunakan teknik analisis diskriptif dan analisis inferensi iaitu ujian-t bagi menguji hipotesis kajian. Dapatan kajian menunjukkan bahawa amalan pengurusan keselamatan di bengkel diamalkan secara sederhana bagi ketiga-tiga aspek tersebut. Terdapat perbezaan yang signifikan di antara pelajar di bandar dan luar bandar iaitu t=-4.08 dan p=0.000 di mana nilai min ukuranya pula ialah -.19. Beberapa cadangan telah dikemukakan bagi penambahbaikkan seperti mengadakan kempen kesedaran dan menyediakan sudut standard operasi amalan pengurusan keselamatan agar pelajar sentiasa mematuhi peraturan semasa berada di bengkel Kemahiran Hidup
The effect of filler loading and silane coupling agent on properties of rice husk powder filled natural rubber compounds / Razif Nordin, Said C. S. and Ismail H.
The effect of silane coupling agent, bis(triethoxysilyl propyl) tetrasulphide, Si69 on cure characteristics and mechanical properties of rice husk powder, RHP filled natural rubber, NR compounds were studied. Scorch time t2 and cure time t90 of the compounds decrease with increasing filler loading and with presence of a silane coupling agent, Si69. However, minimum torque increases with increasing filler loading but at a similar filler loading shows lower value with the presence of Si69. The mechanical properties of compounds viz tensile strength, tensile modulus and hardness were also increased while resilience decreases with additional of Si6
The universe dynamics in the tachyon cosmology with non-minimal coupling to matter
Recently, the tachyon cosmology has been represented as dark energy model to
support the current acceleration of the universe without phantom crossing. In
this paper, we study the dynamics of the tachyon cosmology in which the field
plays the role of tachyon field and also non--minimally coupled to the matter
lagrangian. The model shows current universe acceleration and also phantom
crossing in the future. Two cosmological tests are also performed to validate
the model; the difference in the distance modulus and the model independent
Cosmological Redshift Drift (CRD) test.Comment: 14 pages, 11 figure
Antibacterial agents produced by lactic acid bacteria isolated from threadfin salmon and grass shrimp
Lactic acid bacteria (LAB) are non-pathogenic bacteria that have an important role in human daily life. LAB produce antimicrobial agents, such as bacteriocins, diacetyl and hydrogen peroxide which help to extend the shelf life of food products. In this study, LAB were isolated from selected seafood; threadfin salmon and grass shrimp. Antibacterial activity of LAB extracts against Salmonella typhimurium, Listeria monocytogenes, Bacillus cereus and Escherichia coli were determined using the disc diffusion method. Three strains of LAB were selected for the characterization of antibacterial agents produced by LAB. The parameters such as pH, heat, incubation period and medium, were analyzed in this experiment. Changes in environmental parameters affected the activity of antibacterial agents. The antibacterial agents produced by LAB were generally heat stable and stable in a wide range of pH levels. However, the inhibition activity of LAB was destroyed with a heat treatment of 121°C, and the antibacterial effect was reduced at a pH of 12, which occurs in most strains. The medium containing NaCl enhanced the antibacterial activity of P1S1 and P3S3 strains against S. typhimurium, L. monocytogenes and E. coli. Moreover, the antibacterial agents exhibited the greatest inhibition activity at incubation times between 24 and 72 h. The antibacterial activity was reduced after an incubation time of 96 h. The characterization of antibacterial agents aids in the improvement of food products safety
Does knowledge based psychological ownership matter? Transformational leadership and knowledge hiding: A proposed framework
The prevalent and negative impact of knowledge hiding behaviour among employees has called the attention of both practitioners and researchers to begin investigations on its causes, and other factors that influence it on both the targets and perpetrators. Some of the possible suggested antecedents of knowledge hiding studied include trust, job characteristic, organisational culture, and workplace environment. Despite these studies, few have attempted to investigate the influence of leadership, particularly, transformational leadership on knowledge hiding. Previous studies also indicated conflicting results, and the mechanisms through which transformational leadership influences knowledge hiding are not adequately addressed. Therefore, mediator variable is suggested. Hence, this paper proposes knowledge psychological ownership as a potential mediator on the relationship between transformational leadership and knowledge hiding behaviour of an employee in the organization. We hereby argue that transformational leadership through knowledge psychological ownership will influence employees to refrain from the knowledge hiding behaviour that may negatively affect the organisation and encourage knowledge sharing to improve the performance of the organization
Foundations of uncertainty in evaluation of nominal properties
Measurement uncertainty is a key component of metrology but, as it is defined, it does not apply to nominal properties. The possibility to define, evaluate, and express the uncertainty in the examination of nominal properties is then a critical prerequisite for a harmonized treatment of nominal properties in metrology. The assumption at the basis of this paper is that examination uncertainty can be understood in analogy with and as a generalization of measurement uncertainty. To this aim a foundational framework is introduced, grounded on a generic concept of evaluation uncertainty that applies equally to quantitative and non-quantitative evaluations. Based on this, a concept of examination uncertainty is presented and some examples of mathematical functions of examination uncertainty are proposed
Morphologies of Nanostuctured ZnO prepared by matrix-assisted method and its effects on photocatalytic activity
Zinc oxide nanoparticles have been successfully synthesized by matrix-assisted method using activated carbon as a matrix and zinc nitrate and zinc acetate as ZnO precursors. Different weight percentages (10-40 wt %) of Zn precursor were loaded onto activated carbon and calcined in air at 500 and 600 ºC, producing highly crystallined ZnO particles with a wurtzite structure. Nanospherical ZnO and a mixture of nanosphere and nanorod ZnO were produced from zinc nitrate and zinc acetate, respectively. The efficiency study of the synthesized ZnO in the photodegradation of rhodamine 6G indicated that ZnO produced from zinc acetate is more effective than that from zinc nitrate, possibly due to the differences in the morphology of the synthesized ZnO
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