308 research outputs found
Microlocal spectrum condition and Hadamard form for vector-valued quantum fields in curved spacetime
Some years ago, Radzikowski has found a characterization of Hadamard states
for scalar quantum fields on a four-dimensional globally hyperbolic spacetime
in terms of a specific form of the wavefront set of their two-point functions
(termed `wavefront set spectrum condition'), thereby initiating a major
progress in the understanding of Hadamard states and the further development of
quantum field theory in curved spacetime. In the present work, we extend this
important result on the equivalence of the wavefront set spectrum condition
with the Hadamard condition from scalar fields to vector fields (sections in a
vector bundle) which are subject to a wave-equation and are quantized so as to
fulfill the covariant canonical commutation relations, or which obey a Dirac
equation and are quantized according to the covariant anti-commutation
relations, in any globally hyperbolic spacetime having dimension three or
higher. In proving this result, a gap which is present in the published proof
for the scalar field case will be removed. Moreover we determine the
short-distance scaling limits of Hadamard states for vector-bundle valued
fields, finding them to coincide with the corresponding flat-space, massless
vacuum states.Comment: latex2e, 41 page
Effect of enriched rotifer (Brachionus plicatilis) with probiotic lactobacilli on growth, survival and resistance indicators of western white shrimp (Litopenaeus vannamei) larvae
This study examined the effects of a commercial Lactobacillus probiotic on growth, survival and resistance of western white shrimp (Litopenaeus vannamei) larvae against salinity and formalin stresses in the Persian Gulf and Oman Sea Ecology Research Center. In this experiment, larvae were fed 6 times a day from mysis I (M1) step to post larvae 5 over 3 treatments including a control treatment C (without probiotic) and 2 experimental treatments namely A (having probiotic enriched rotifer) and B (having probiotic enriched rotifer and adding probiotic powder directly to the water). Larvae were stocked in 9 plastic tanks (20-liter) containing 10 L of seawater at a density of 50 larvae per liter. Three replicates were used for each treatment. At the end of the experimental period biometric larvae were studied under salinity and formalin stresses. Results showed that using probiotic bacteria had significant and positive effects on shrimp resistance, survival and growth (p0.05). According to the results we may conclude that the use of probiotic powder is effective in increasing growth, survival and resistance rate of western white shrimp in the larval and post larval stages
Continuity of symplectically adjoint maps and the algebraic structure of Hadamard vacuum representations for quantum fields on curved spacetime
We derive for a pair of operators on a symplectic space which are adjoints of
each other with respect to the symplectic form (that is, they are sympletically
adjoint) that, if they are bounded for some scalar product on the symplectic
space dominating the symplectic form, then they are bounded with respect to a
one-parametric family of scalar products canonically associated with the
initially given one, among them being its ``purification''. As a typical
example we consider a scalar field on a globally hyperbolic spacetime governed
by the Klein-Gordon equation; the classical system is described by a symplectic
space and the temporal evolution by symplectomorphisms (which are
symplectically adjoint to their inverses). A natural scalar product is that
inducing the classical energy norm, and an application of the above result
yields that its ``purification'' induces on the one-particle space of the
quantized system a topology which coincides with that given by the two-point
functions of quasifree Hadamard states. These findings will be shown to lead to
new results concerning the structure of the local (von Neumann)
observable-algebras in representations of quasifree Hadamard states of the
Klein-Gordon field in an arbitrary globally hyperbolic spacetime, such as local
definiteness, local primarity and Haag-duality (and also split- and type
III_1-properties). A brief review of this circle of notions, as well as of
properties of Hadamard states, forms part of the article.Comment: 42 pages, LaTeX. The Def. 3.3 was incomplete and this has been
corrected. Several misprints have been removed. All results and proofs remain
unchange
Pengaruh Pengeluaran Pemerintah, Tenaga Kerja dan Investasi Terhadap Pertumbuhan Ekonomi di Provinsi Aceh
Penelitian ini bertujuan untuk menganalisis dan mengetahui seberapa besar pengaruh secara parsial maupun simultan variabel pengeluaran pemerintah, tenaga kerja dan investasi terhadap pertumbuhan ekonomi dengan menggunakan data tahun 1990 – 2020. Penelitian ini merupakan penelitian kuantitatif dengan menggunakan data runtun waktu sekunder, data diperoleh dari BPS dan NSWI. Metode yang digunakan adalah linier berganda (OLS) dengan uji asumsi klasik. Hasil penelitian menunjukkan bahwa secara parsial belanja pemerintah memiliki nilai prob 0,000 < 0,05 dan dibuktikan dengan nilai thitung > ttabel dimana 7,10265 > 1,70329 artinya belanja pemerintah berpengaruh positif dan signifikan terhadap pertumbuhan ekonomi dan investasi memiliki nilai -0,02 < 0,05 yang berarti berpengaruh negatif dan signifikan terhadap pertumbuhan ekonomi. pertumbuhan ekonomi dibuktikan dengan thitung dan ttabel dimana -2,401442 > 1,70329. Sedangkan angkatan kerja dengan nilai 0,30 > 0,05 bahwa tenaga kerja tidak berpengaruh signifikan dan signifikan terhadap pertumbuhan ekonomi thitung > ttabel dimana 1,0427 > 1,70329. Secara simultan nilai ketiga variabel tersebut ditunjukkan dengan nilai F prob sebesar 0,000 < 0,05 yang berarti ketiga variabel tersebut secara bersama-sama mempunyai pengaruh yang signifikan terhadap pertumbuhan ekonomi
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Exploring the Impact on Self-regulated Learning: a Comparative Analysis of Learner Experiences Using Problem-based Learning, Game Play, and Computer-based Instruction
The ability to transfer what you know to new and different contexts is a sign of successful learning. While students often graduate from college with the required number of courses many lack the skills necessary to apply appropriate strategies to solve problems in different contexts, to reason, and think critically. More than a decade ago the Boyer Report (1995) pointed to this fact as a sign that Universities were falling short in adequately supporting their undergraduate populations. As a result, it is not uncommon to see educational institutions introducing new courses and programs geared towards helping students learn better. This study explores learner experiences and the impact on self-regulated learning within a distributed learning setting when motivated by problem-based learning, game play, and computer-based instruction. In this study the instructional design of the course introduced undergraduate students to authentic learning experiences in which students engaged in collaborative problem solving and learning activities framed within the narrative of an alternate reality game. Fifteen self-regulated learning constructs were examined. The comparison group engaged with problem solving tasks and computer-based instruction. Additionally, the study used the theory Learning and Teaching as Communicative Action and its four communicative actions as a lens to understand the full range of student interactions and how they constructed knowledge. The research design employed computer-mediated discourse analysis to examine qualitative data. Data was triangulated through constant-comparative coding of student communication in the form of web logs, emails, student assignments, and semi-structured interviews. Review and consensus building was embedded in the process of identifying emerging codes and categories, and used to support emergent inferences before the final themes were identified and mutually agreed upon. Finally, to evaluate the outcome of the instructional design, pre and posttest measures were used among groups using a two-sample t-test. Statistical significance was used to determine changes in learning outcomes while select qualitative codes were examined and reviewed to gauge student satisfaction with the instructional approach. Results indicated substantial qualitative and quantitative differences among the three versions of the course related to self-regulated learning practices and communicative action in particular in terms of student interaction, and knowledge construction. Additional, findings revealed differences in epistemic beliefs about learning, which in turn influenced how students chose to learn. These outcomes are presented and discussed along with the implications for instructional design
Gall-inducing Aphids (Hemiptera: Aphidoidea: Eriosomatinae) Associated with Salicaceae and Ulmaceae in Razavi Khorasan Province, with New Records for Fauna of Iran
A survey of gall-inducing aphids on elm and poplar trees was carried out during
2017 in Razavi Khorasan province, NE Iran. As a result, 15 species of
gall-inducing aphids from 5 genera, all belonging to the subfamily
Eriosomatinae, were recorded on 6 host plant species. The collected species
included the genera Eriosoma, Kaltenbachiella,
Pemphigus, Tetraneura and
Thecabius. Pemphigus passeki Börner
(Hemiptera: Aphididae) and Pemphigus populinigrae (Schrank)
(Hemiptera: Aphididae) on Populus nigra var.
italica (Salicaceae) were new records for the Iranian aphid
fauna. Both new recorded species belong to the tribe Pem-phigini, subfamily
Eriosomatinae. Among the identified species, 8 aphid species were new records
for Razavi Khorasan province
A Study on the Second Year Students' Ability of SMP As-shofa Pekanbaru in Constructing Yes/no Questions
This research was about the ability of the students in constructing yes/no questions. The aim of this research was to find out the ability of the second year students of SMP As-Shofa Pekanbaru in constructing yes/no questions. The population was 138 students. The sample was chosen through cluster random sampling and lottery technique. The analysis was based on giving test to the students. It was found that 20 out of 138 students were 1 student (5%) in excellent level, 5 students (25%)in good level, 10 students (50%) in mediocre level, 2 students (10%) in poor level and 2 students (10%) in very poor level. The mean score of the students was 51,81. It implies that the students' ability falls into mediocre ability level. Based on the result, it is recommended that teachers should pay attention more on material yes/no questions escpecially in using did
Simulations of ionospheric turbulence produced by HF heating near the upper hybrid layer
Heating of the ionosphere by high-frequency (HF), ordinary (O) mode electromagnetic waves can excite magnetic field aligned density striations (FAS), associated with upper and lower hybrid turbulence and electron heating. We have used Vlasov simulations in one spatial and two velocity dimensions to study the induced turbulence in the presence of striations when the O-mode pump is mode converted to large amplitude upper hybrid oscillations trapped in a striation. Parametric processes give rise to upper and lower hybrid turbulence, as well as to large amplitude, short wavelength electron Bernstein waves. The latter excite stochastic electron heating when their amplitudes exceed a threshold for stochasticity, leading to a rapid increase of the electron temperature by several thousands of Kelvin. The results have relevance for high latitude heating experiments
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