627 research outputs found
Fire performance of heavyweight self-compacting concrete and heavyweight high strength concrete
In this study, the fresh and hardened state properties of heavyweight self-compacting concrete (HWSCC) and heavyweight high strength concrete (HWHSC) containing heavyweight magnetite aggregate with 50, 75, and 100% replacement ratio, and their performance at elevated temperatures were explored experimentally. For fresh-state properties, the flowability and passing ability of HWSCCs were assessed by using slump flow, T500 mm, and J-ring tests. Hardened-state properties including hardened density, compressive strength, and modulus of elasticity were evaluated after 28 days of mixing. High-temperature tests were also performed to study the mass loss, spalling of HWSCC and HWHSC, and residual mechanical properties at 100, 300, 600 and 900 °C with a heating rate of 5 °C/min. Ultimately, by using the experimental data, rational numerical models were established to predict the compressive strength and modulus of elasticity of HWSCC at elevated temperatures. The results of the flowability and passing ability revealed that the addition of magnetite aggregate would not deteriorate the workability of HWSCCs and they retained their self-compacting characteristics. Based on the hardened densities, only self-compacting concrete (SCC) with 100% magnetite content, and high strength concrete (HSC) with 75 and 100% magnetite aggregate can be considered as HWC. For both the compressive strength and elastic modulus, decreasing trends were observed by introducing magnetite aggregate to SCC and HSC at an ambient temperature. Mass loss and spalling evaluations showed severe crack propagation for SCC without magnetite aggregate while SCCs containing magnetite aggregate preserved up to 900 °C. Nevertheless, the mass loss of SCCs containing 75 and 100% magnetite content were higher than that of SCC without magnetite. Due to the pressure build-up, HSCs with and without magnetite showed explosive spalling at high temperatures. The residual mechanical properties analysis indicated that the highest retention of the compressive strength and modulus of elasticity after exposure to elevated temperatures belonged to HWSCC with 100% magnetite content
Constraints on Finite Soft Supersymmetry-Breaking Terms
Requiring the soft supersymmetry-breaking (SSB) parameters in finite
gauge-Yukawa unified models to be finite up to and including two-loop order, we
derive a two-loop sum rule for the soft scalar-masses. It is shown that this
sum rule coincides with that of a certain class of string models in which the
massive string states are organized into N=4 supermultiplets. We investigate
the SSB sector of two finite SU(5) models. Using the sum rule which allows the
non-universality of the SSB terms and requiring that the lightest superparticle
particleis neutral, we constrain the parameter space of the SSB sector in each
model.Comment: 34 page
Dermanyssus gallinae in layer farms in Kosovo: a high risk for salmonella prevalence
Background
The poultry red mite (PRM), Dermanyssus gallinae (D.g.) is a serious ectoparasitic pest of poultry and potential pathogen vector. The prevalence of D. g. and the prevalence of Salmonella spp. within mites on infested laying poultry farms were investigated in Kosovo.
Findings
In total, 14 populated layer farms located in the Southern Kosovo were assessed for D. g. presence. Another two farms in this region were investigated 6 months after depopulation. Investigated flocks were all maintained in cages, a common housing system in Kosovo. A total of eight farms were found to be infested with D. g. (50%) at varying levels, including the two depopulated farms. The detection of Salmonella spp. from D. g. was carried out using PCR. Out of the eight layer farms infested with D. g., Salmonella spp. was present in mites on three farms (37.5%).
Conclusions
This study confirms the high prevalence of D. g. in layer flocks in Kosovo and demonstrates the link between this mite and the presence of Salmonella spp. on infested farms
Finite Grand Unified Theories and the Quark Mixing Matrix
In N = 1 super Yang-Mills theories, under certain conditions satisfied by the
spectrum and the Yukawa couplings, the beta functions will vanish to all orders
in perturbation theory. We address the generation of realistic quark mixing
angles and masses in such finite Grand Unified Theories. Working in the context
of finite SUSY SU(5), we present several examples with realistic quark mixing
matrices. Non-Abelian discrete symmetries are found to be important in
satisfying the conditions for finiteness. Our realistic examples are based on
permutation symmetries and the tetrahedral symmetry . These examples
enable us to address questions such as the decay rate of the proton in finite
GUTs.Comment: 16 pages, LaTeX, typos correcte
Stringy origin of non-Abelian discrete flavor symmetries
We study the origin of non-Abelian discrete flavor symmetries in superstring
theory. We classify all possible non-Abelian discrete flavor symmetries which
can appear in heterotic orbifold models. These symmetries include D_4 and
Delta(54). We find that the symmetries of the couplings are always larger than
the symmetries of the compact space. This is because they are a consequence of
the geometry of the orbifold combined with the space group selection rules of
the string. We also study possible breaking patterns. Our analysis yields a
simple geometric understanding of the realization of non-Abelian flavor
symmetries.Comment: 27 pages, 4 figures, v2: matches version published in Nuclear Physics
Reduction of Couplings and Finiteness in Realistic Supersymmetric GUTs
Reduction of couplings in supersymmetric GUTs is achieved by searching for
renormalization group invariant (RGI) relations among couplings which hold
beyond the unification scale. Finiteness is due to the fact that there exist
RGI relations among couplings that guarantee the vanishing of the
beta-functions of a N=1 supersymmetric GUT even to all orders in perturbation
theory. Of particular interest are the relations among gauge and Yukawa
couplings which lead to very interesting predictions of the top quark massComment: 25 pages, 1 figure. To appear in the proceedings of the Buckow
Symposium 199
Virtual histological staining of unlabeled autopsy tissue
Histological examination is a crucial step in an autopsy; however, the
traditional histochemical staining of post-mortem samples faces multiple
challenges, including the inferior staining quality due to autolysis caused by
delayed fixation of cadaver tissue, as well as the resource-intensive nature of
chemical staining procedures covering large tissue areas, which demand
substantial labor, cost, and time. These challenges can become more pronounced
during global health crises when the availability of histopathology services is
limited, resulting in further delays in tissue fixation and more severe
staining artifacts. Here, we report the first demonstration of virtual staining
of autopsy tissue and show that a trained neural network can rapidly transform
autofluorescence images of label-free autopsy tissue sections into brightfield
equivalent images that match hematoxylin and eosin (H&E) stained versions of
the same samples, eliminating autolysis-induced severe staining artifacts
inherent in traditional histochemical staining of autopsied tissue. Our virtual
H&E model was trained using >0.7 TB of image data and a data-efficient
collaboration scheme that integrates the virtual staining network with an image
registration network. The trained model effectively accentuated nuclear,
cytoplasmic and extracellular features in new autopsy tissue samples that
experienced severe autolysis, such as COVID-19 samples never seen before, where
the traditional histochemical staining failed to provide consistent staining
quality. This virtual autopsy staining technique can also be extended to
necrotic tissue, and can rapidly and cost-effectively generate artifact-free
H&E stains despite severe autolysis and cell death, also reducing labor, cost
and infrastructure requirements associated with the standard histochemical
staining.Comment: 24 Pages, 7 Figure
Limits of minimal models and continuous orbifolds
The lambda=0 't Hooft limit of the 2d W_N minimal models is shown to be
equivalent to the singlet sector of a free boson theory, thus paralleling
exactly the structure of the free theory in the Klebanov-Polyakov proposal. In
2d, the singlet sector does not describe a consistent theory by itself since
the corresponding partition function is not modular invariant. However, it can
be interpreted as the untwisted sector of a continuous orbifold, and this point
of view suggests that it can be made consistent by adding in the appropriate
twisted sectors. We show that these twisted sectors account for the `light
states' that were not included in the original 't Hooft limit. We also show
that, for the Virasoro minimal models (N=2), the twisted sector of our orbifold
agrees precisely with the limit theory of Runkel & Watts. In particular, this
implies that our construction satisfies crossing symmetry.Comment: 33 pages; v2: minor improvements and references added, published
versio
All-order Finiteness in N=1 SYM Theories: Criteria and Applications
As a motivation, we first recall the possible connection of electric-magnetic
duality to finiteness in N=1 super-Yang-Mills theories (SYM). Then, we present
the criterion for all-order finiteness (i.e., vanishing of the beta-functions
at all orders) in N=1 SYM. Finally, we apply this finiteness criterion to an
SU(5) SGUT. The latter turns out to be all-order finite if one imposes
additional symmetries.Comment: 17 pages, plain LaTex, no figures. Some typos corrected, references
update
Finite Theories and the SUSY Flavor Problem
We study a finite SU(5) grand unified model based on the non-Abelian discrete
symmetry A_4. This model leads to the democratic structure of the mass matrices
for the quarks and leptons. In the soft supersymmetry breaking sector, the
scalar trilinear couplings are aligned and the soft scalar masses are
degenerate, thus solving the SUSY flavor problem.Comment: 17 pages, LaTeX, 1 figur
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