Hasil untuk "gr-qc"

Li Yang, Jianhua Huang, X. Ren et al.

Aberrant TGFbeta signaling is common in human cancers and contributes to tumor metastasis. Here, we demonstrate that Gr-1+CD11b+ myeloid cells are recruited into mammary carcinomas with type II TGF beta receptor gene (Tgfbr2) deletion and directly promote tumor metastasis. Gr-1+CD11b+ cells infiltrate into the invasive front of tumor tissues and facilitate tumor cell invasion and metastasis through a process involving metalloproteinase activity. This infiltration of Gr-1+CD11b+ cells also results in increased abundance of TGF beta 1 in tumors with Tgfbr2 deletion. The recruitment of Gr-1+CD11b+ cells into tumors with Tgfbr2 deletion involves two chemokine receptor axes, the SDF-1/CXCR4 and CXCL5/CXCR2 axes. Together, these data indicate that Gr-1+CD11b+ cells contribute to TGFbeta-mediated metastasis through enhancing tumor cell invasion and metastasis.

Bo-Yang Huang, P. Pan, Qingsheng Li et al.

Li Yang, L. Debusk, Koari Fukuda et al.

We demonstrate a novel tumor-promoting role of myeloid immune suppressor Gr+CD11b+ cells, which are evident in cancer patients and tumor-bearing animals. These cells constitute approximately 5% of total cells in tumors. Tumors coinjected with Gr+CD11b+ cells exhibited increased vascular density, vascular maturation, and decreased necrosis. These immune cells produce high levels of MMP9. Deletion of MMP9 in these cells completely abolishes their tumor-promoting ability. Gr+CD11b+ cells were also found to directly incorporate into tumor endothelium. Consistent with this observation, Gr+CD11b+ cells acquire endothelial cell (EC) properties in tumor microenvironment and proangiogenic culture conditions. Our data provide evidence that Gr+CD11b+ cells of immune origin induced by tumors directly contribute to tumor growth and vascularization by producing MMP9 and differentiating into ECs.

Ghani Imadouchene

We construct and analyze a symmetric bimetric cosmological model connecting Anti-de Sitter (AdS) and de Sitter (dS) regimes through a coupled scalar field. Starting from a Lagrangian with Einstein-Hilbert terms for two FLRW metrics and an inter-metric potential, we derive modified Friedmann and Klein-Gordon equations governing their evolution. In the symmetric effective-fluid limit, the model reproduces the main phenomenology of the $Λ$CDM cosmology with a small dynamical correction proportional to $(1+z)^{-3}$, and naturally satisfies local-gravity constraints through Vainshtein screening. This article outlines the theoretical structure and calibration of the model within a dual-geometry cosmological setting.

D. Mitri, A. Toso, Jing jing Chen et al.

Yu Han, Long Chen

In Ref. [1], it was claimed that in the spatially flat cosmological case there exists a unique conserved measure (up to normalization) on the $(φ,\dotφ)$ phase space for scalar field with $m^2φ^2$ potential by finding a unique solution to the differential equation (44) (in Ref. [1]) in the low-energy regime. In Ref. [2], it was also claimed that a unique solution to the same differential equation was found in the high-energy regime and using this solution the authors calculated the expected total number of e-folds of inflation. In this comment, we reanalyze the differential equation (44) and obtain general solutions both in the low-energy and high-energy regime, which can include the solution in Ref. [1] and the solution in Ref. [2] as a special case in the corresponding energy regime. In this way, we find that following the constructions in Ref. [1] there actually exist infinitely many nonequivalent conserved measures for the scalar-field cosmology with $m^2φ^2$ potential on the $(φ,\dotφ)$ phase space. Moreover, through specific calculations, we also show that different choices of measures can lead to quite different predictions of the expected total number of e-folds of inflation.

M. -N. Célérier

In a recent series of papers new exact analytical solutions of Einstein equations representing interior spacetimes sourced by stationary rigidly rotating cylinders of fluids have been displayed. We have first considered a fluid with an axially directed pressure Célérier, Phys. Rev. D 104, 064040 (2021), J. Math. Phys. 64, 032501 (2023), then a perfect fluid, J. Math. Phys. 64, 022501 (2023), followed by a fluid with an azimuthally directed pressure, J. Math. Phys. 64, 042501 (2023), and finally a fluid where the anisotropic pressure is radially oriented, J. Math. Phys. 64, 052502 (2023). This work is being currently extended to the cases of differentially rotating irrotational fluids. The results are presented in a new series of papers considering, in turn, a perfect fluid source, arXiv:2305.11565 [gr-qc], and the same three anisotropic pressure cases. Here, fluids with an axially directed pressure are considered. A general method for generating new mathematical solutions to the field equations is displayed and three classes are presented so as to exemplify this recipe. Their mathematical and physical properties are analyzed. The first class, named class A, whose other mathematical and physical properties determine a standard configuration, is shown to exhibit a singular axis of symmetry which can be considered as an awkward drawback. The second class, class B, is free from such a singularity but appears to exhibit a negative energy density which characterizes a rather exotic kind of matter. The third class, class C, is the best behaved since it possesses the main properties expected from spacetimes sourced by rather standard fluids. The three classes are matched to an exterior Lewis-Weyl vacuum and the conditions for avoiding an angular deficit are discussed. A comparison with the rigidly rotating fluid case is provided.

Eleftherios-Ermis Tselentis, Ämin Baumeler

We derive multiparty games that, if the winning chance exceeds a certain limit, prove the incompatibility of the parties' causal relations with any partial order. This, in turn, means that the parties exert a back-action on the causal relations; the causal relations are dynamical. The games turn out to be representable by directed graphs, for instance by an orientation of the Möbius ladder. We discuss these games as device-independent tests of spacetime's dynamical nature in general relativity. To do so, we design relativistic settings where, in the Minkowski spacetime, the winning chance is bound to the limits. In contrast, we find otherwise tame processes with classical control of causal order that win the games deterministically. These suggest a violation of the bounds in gravitational implementations. We obtain these games by uncovering a "pairwise central symmetry" of the correlations in question. This symmetry allows us to recycle the facets of the acyclic subgraph polytope studied by Grötschel, Jünger, and Reinelt in the mid-80s for combinatorial optimization. In addition, we derive multiparty games in a scenario where the polytope dimension grows only linearly in the number of parties. Here, exceeding the limits not only proves the dynamical nature of the causal relations, but also that the correlations are incompatible with any global causal order.

Carlos Silva

In this paper, we address the nature of spacetime in quantum gravity in light of a new version of the holographic principle that has established a relationship between string theory and polymer holonomy structures similar to Loop Quantum Cosmology spin networks. In front of the results found out, it is possible to argue that, for such a relationship to work, spacetime must be seen as emergent from a fundamental structure whose degrees of freedom correspond to quantum correlations only.

Shailesh Kumar

Gravitational memory effect has emerged as a new window and opened up several intriguing avenues in the field of gravitational wave astronomy together with its inter-connection to asymptotic symmetries (AS). The recent developments in this direction have drawn considerable attention from theoretical as well as observational perspectives. It has been shown that such effects can also be recovered near the horizon of black holes which might play a crucial role in understanding the information paradox. With this motivation, we have studied the gravitational memory effect near the horizon of black holes analogous to the one obtained at asymptotic null infinity. We first study how the AS emerge near the horizon of black holes and how they can be detected via some ideal detectors as some permanent change of configurations (Memory) once GW passes through the setup. The emergence of AS is studied from two different perspectives. First, how AS emerge as soldering freedoms when two black holes are being glued along a common null surface. Secondly, in the form of AS that preserve the asymptotic form of the near horizon metric of a black hole. We have established an analogous form of the displacement memory near the horizon of non-extreme and extreme black holes for both these perspectives. We also discuss the detection prospects of the supertranslation memory or hair. In this direction, other than the memory effect, we have explored the possibility of detecting a supertranslated black hole through standard tests of General Relativity. We propose a scenario in which such a configuration may be distinguished from ordinary black holes by examining the photon trajectories near the horizon. As we know that the gravitational memory has not been detected yet, in this direction, our study might serve as a useful contribution towards investigation of the signatures of AS in the future.

Joanna Godzień, V. Alonso‐Herranz, C. Barbas et al.

Hee-Woong Lim, N. H. Uhlenhaut, Alexander Rauch et al.

Glucocorticoids (GCs) are commonly prescribed drugs, but their anti-inflammatory benefits are mitigated by metabolic side effects. Their transcriptional effects, including tissue-specific gene activation and repression, are mediated by the glucocorticoid receptor (GR), which is known to bind as a homodimer to a palindromic DNA sequence. Using ChIP-exo in mouse liver under endogenous corticosterone exposure, we report here that monomeric GR interaction with a half-site motif is more prevalent than homodimer binding. Monomers colocalize with lineage-determining transcription factors in both liver and primary macrophages, and the GR half-site motif drives transcription, suggesting that monomeric binding is fundamental to GR's tissue-specific functions. In response to exogenous GC in vivo, GR dimers assemble on chromatin near ligand-activated genes, concomitant with monomer evacuation of sites near repressed genes. Thus, pharmacological GCs mediate gene expression by favoring GR homodimer occupancy at classic palindromic sites at the expense of monomeric binding. The findings have important implications for improving therapies that target GR.

S. K. Bansal, D. Jaiswal, Nishi Gupta et al.

We analyzed the AZFc region of the Y-chromosome for complete (b2/b4) and distinct partial deletions (gr/gr, b1/b3, b2/b3) in 822 infertile and 225 proven fertile men. We observed complete AZFc deletions in 0.97% and partial deletions in 6.20% of the cases. Among partial deletions, the frequency of gr/gr deletions was the highest (5.84%). The comparison of partial deletion data between cases and controls suggested a significant association of the gr/gr deletions with infertility (P = 0.0004); however, the other partial deletions did not correlate with infertility. In cohort analysis, men with gr/gr deletions had a relatively poor sperm count (54.20 ± 57.45 million/ml) in comparison to those without deletions (72.49 ± 60.06), though the difference was not statistically significant (p = 0.071). Meta-analysis also suggested that gr/gr deletions are significantly associated with male infertility risk (OR = 1.821, 95% CI = 1.39–2.37, p = 0.000). We also performed trial sequential analyses that strengthened the evidence for an overall significant association of gr/gr deletions with the risk of male infertility. Another meta-analysis suggested a significant association of the gr/gr deletions with low sperm count. In conclusion, the gr/gr deletions show a strong correlation with male infertility risk and low sperm count, particularly in the Caucasian populations.

Dr. Gina P. Nilo, Maribel R. Jalalon, Lady Rachelle M. Casareno et al.

It is apparent that agriculture is the food source of the nation, and in the Philippines, the agricultural sector accounts for about two-thirds of the country’s employment. Agriculture significantly contributes to the increase of its economic status by 1.47% during the first quarter of 2018. Pre-husked rice and corn production primarily contributes to the increased by 4.61% and 4.66% respectively, and followed by other major crops like coconut, banana, pineapple, tobacco, abaca and rubber. However, this significant increase in crop production cannot be achieved without examining the nutrient status of the soil. As the nationally-mandated agency on sustainable management of soil and water resources for agriculture, the Bureau of Soils and Water Management Laboratory Services Division having been assessed and found conforming to the requirements of PNS ISO/IEC 17025:2005 and the Philippine Accreditation Bureau in the field of Chemical Testing was issued certification from June 15, 2016 and valid until June 14, 2021. Significant activities include chemical testing of soil, plant tissues, fertilizers and water samples. This is done by licensed chemists and chemical technicians. QA/QC implementation is a must in the entire test being undertaken including physical, biological and rapid soil test. It also participates in a number of local and international Proficiency Tests. These international institutions include: Agricultural Laboratory Proficiency (ALP) in soil and water from Cycle 27 in 2015 to Cycle 35 to date; Australasian Soil and Plant Analysis Council (ASPAC) in New Zealand six cycles from June 2016 to June 2018 for soil and most recently, the Food and Fertilizer Technology Center (FFTC) for the Asian and Pacific Region and the Taiwan Agricultural Research Institute (TARI) for soil and plant tissues samples. Thus BSWM-LSD was granted certification in soil testing from The Minnesota Department of Agriculture and ASPAC. At the local level, participation in plant tissue proficiency test for corn based snack food was provided by the Department of Science and Technology – Food and Nutrition Research Institute (DOST-FNRI). As member country of the Food and Agriculture Organization to the Global Soil Productivity Network, the BSWM also participated in the Inter-laboratory exchange for the South-East Soil Laboratory Network (SEALNET). The BSWM-LSD is also mandated to provide soil nutrient recommendations on the basis of the results of soil analysis which is performed by licensed agriculturist. Thus to operate soil and plant tissue analytical laboratory would require team efforts among agriculture experts in soils, biologist, chemists and technicians. The BSWM-LSD is overall responsible to supervise, regulate and control the establishment and operation of all soil laboratories in the Philippines. Through the ongoing project for the implementation of Presidential Decree 1435, the BSWM–LSD takes the lead role in strengthening the capacities of Regional Soils Laboratories under the Department of Agriculture (DA) and to prepare these laboratories for ISO Accreditation. The BSWM-LSD also provides technical assistance and guidance for these DA Laboratories to comply with the requirements of regulatory agencies in the country such as the Professional Regulatory Commission for the authority to operate chemical laboratories; the Department of Environment and Natural Resources (DENR) for the Hazardous waste disposal, the Philippine Drug Enforcement Authority and the Philippine National Police for the purchase of high risk controlled chemicals. Networking with other agencies to comply with regulatory requirements can be both a challenge and opportunity to improve laboratory services. With due consideration on the activities and operations of soil and plant analytical laboratory it can be concluded that soil laboratories in the Philippines play a significant role in providing quality data for improved agricultural production, and food safety; clean and healthy environment for the well-being and improved quality of life of the Filipino people.

J. Kuligowski, Á. Sánchez-Illana, Daniel Sanjuán-Herráez et al.

Ingo von Maurich, Tobias Oder, T. Güneysu

Hassan Khodaiemehr, Mohammad-Reza Sadeghi, A. Sakzad

LDPC lattices were the first family of lattices that equipped with iterative decoding algorithms under which they perform very well in high dimensions. In this paper, we introduce quasi cyclic low density parity check (QC-LDPC) lattices as a special case of LDPC lattices with one binary QC-LDPC code as their underlying code. These lattices are obtained from Construction A of lattices providing us to encode them efficiently using shift registers. To benefit from an encoder with linear complexity in dimension of the lattice, we obtain the generator matrix of these lattices in "quasi cyclic" form. We provide a low-complexity decoding algorithm of QC-LDPC lattices based on sum product algorithm. To design lattice codes, QC-LDPC lattices are combined with nested lattice shaping that uses the Voronoi region of a sublattice for code shaping. The shaping gain and shaping loss of our lattice codes with dimensions $40$, $50$ and $60$ using an optimal quantizer, are presented. Consequently, we establish a family of lattice codes that perform practically close to the sphere bound.

Varsha M. Magar, V. Shinde

Carleton Coffrin, H. Hijazi, Pascal Van Hentenryck

Convex relaxations of the power flow equations and, in particular, the Semi-Definite Programming (SDP) and Second-Order Cone (SOC) relaxations, have attracted significant interest in recent years. The Quadratic Convex (QC) relaxation is a departure from these relaxations in the sense that it imposes constraints to preserve stronger links between the voltage variables through convex envelopes of the polar representation. This paper is a systematic study of the QC relaxation for AC Optimal Power Flow with realistic side constraints. The main theoretical result shows that the QC relaxation is stronger than the SOC relaxation and neither dominates nor is dominated by the SDP relaxation. In addition, comprehensive computational results show that the QC relaxation may produce significant improvements in accuracy over the SOC relaxation at a reasonable computational cost, especially for networks with tight bounds on phase angle differences. The QC and SOC relaxations are also shown to be significantly faster and reliable compared to the SDP relaxation given the current state of the respective solvers.

Ingo von Maurich, T. Güneysu