Search results for " dar"

Degradation of dimeric lignin model compounds by aerobic bacteria isolated from the hindgut of xylophagous termites.

1997

The capability of the intestinal flora from the gut of xylophagous termites of degrading lignin model compounds was investigated. Different dimeric lignin model compounds-degrading bacteria were obtained from the hindgut flora of Mastotermes darwiniensis FROGGATT, Reticulitermes santonensis FEYTAUD, Nasutitermes nigriceps HALDEMAN and Zootermopsis angusticollis HAGEN. In the presence of oxygen dimeric model compounds were degraded by all isolates. This indicates that the hindgut flora of termites is basically able to produce substrate for their host from aromatic extractives of wood.

Influence of bundle porosity on shell-side hydrodynamics and mass transfer in regular fiber arrays: A computational study

2023

CFD predictions of the effects of a fiber bundle porosity on shell-side hydrodynamics and mass transfer under conditions of steady laminar flow were obtained. Fluid was assumed to flow around regular hexag-onal or square arrays of cylindrical fibers of different pitch to diameter ratios, yielding bundle porosities ranging from the theoretical minimum up to similar to 1. A large number of axial, transverse and mixed flow combinations were simulated by letting the axial and transverse flow Reynolds numbers and the trans-verse flow attack angle vary. Both fully developed and developing conditions (entrance effects) were con-sidered. The continuity and momentum equations, along with a transport…

2016. gada veiksmes

2017

Rakstā izklāstīti Latvijas Universitātes nozīmīgākie notikumi 2016.gadā. Tajā pieminēti ar dažādām nominācijām godinātie Latvijas Universitātes darbinieki.

Main Sequence Stars with Asymmetric Dark Matter

2012

We study the effects of feebly or non-annihilating weakly interacting Dark Matter (DM) particles on stars that live in DM environments denser than that of our Sun. We find that the energy transport mechanism induced by DM particles can produce unusual conditions in the core of Main Sequence stars, with effects which can potentially be used to probe DM properties. We find that solar mass stars placed in DM densities of rhochi>= e2 GeV/cm3 are sensitive to Spin-Dependent scattering cross-section sigmsd >= e-37 cm2 and a DM particle mass as low as mchi=5 GeV, accessing a parameter range weakly constrained by current direct detection experiments.

Valoda: nozīme un forma, 10: Latvijas gramatiskā doma gadsimta gaitā

2019

Kompetenču pieeja kombinēto darbu apguvē 7.-9. klasē

2018

Bakalaura darbs „ Kompetenču pieeja kombinēto darbu apguvē 7.-9. klasē” sastāv no ievada, teorētiskās, empīriskās daļas, kā arī no izstrādātiem mācību nodarbību plāniem, mācību nodarbību norises aprakstiem Mājturībā un tehnoloģijās 7.-9. klasei, apgūstot darba instrumentu izgatavošanu grafikas nodarbībām. Ievadā tiek atspoguļota tēmas aktualitāte un izvirzīti pētījuma uzdevumi: izpētīt speciālo un pedagoģisko literatūru; apkopot un analizēt informāciju par grafiku kā praktiskas darbības veidu; izstrādāt mācību uzskates līdzekļus; izstrādāt tematisko plānu nodarbībām 7.-9. klašu grupai; izveidot mācību uzdevumus un izstrādāt vērtēšanas kritērijus; izveidoto tematisko plānu, mācību uzdevumus …

Physics beyond colliders at CERN: beyond the Standard Model working group report

2019

The Physics Beyond Colliders initiative is an exploratory study aimed at exploiting the full scientific potential of the CERN's accelerator complex and scientific infrastructures through projects complementary to the LHC and other possible future colliders. These projects will target fundamental physics questions in modern particle physics. This document presents the status of the proposals presented in the framework of the Beyond Standard Model physics working group, and explore their physics reach and the impact that CERN could have in the next 10–20 years on the international landscape.

Search for gamma-ray spectral lines with the DArk Matter Particle Explorer

2021

The DArk Matter Particle Explorer (DAMPE) is well suitable for searching for monochromatic and sharp $\gamma$-ray structures in the GeV$-$TeV range thanks to its unprecedented high energy resolution. In this work, we search for $\gamma$-ray line structures using five years of DAMPE data. To improve the sensitivity, we develop two types of dedicated data sets (including the BgoOnly data which is the first time to be used in the data analysis for the calorimeter-based gamma-ray observatories) and adopt the signal-to-noise ratio optimized regions of interest (ROIs) for different DM density profiles. No line signals or candidates are found between 10 and 300 GeV in the Galaxy. The constraints o…

Dark gamma-ray bursts

2016

Many theories of dark matter (DM) predict that DM particles can be captured by stars via scattering on ordinary matter. They subsequently condense into a DM core close to the center of the star and eventually annihilate. In this work, we trace DM capture and annihilation rates throughout the life of a massive star and show that this evolution culminates in an intense annihilation burst coincident with the death of the star in a core collapse supernova. The reason is that, along with the stellar interior, also its DM core heats up and contracts, so that the DM density increases rapidly during the final stages of stellar evolution. We argue that, counterintuitively, the annihilation burst is …

Impeded Dark Matter

2016

We consider dark matter models in which the mass splitting between the dark matter particles and their annihilation products is tiny. Compared to the previously proposed Forbidden Dark Matter scenario, the mass splittings we consider are much smaller, and are allowed to be either positive or negative. To emphasize this modification, we dub our scenario "Impeded Dark Matter". We demonstrate that Impeded Dark Matter can be easily realized without requiring tuning of model parameters. For negative mass splitting, we demonstrate that the annihilation cross-section for Impeded Dark Matter depends linearly on the dark matter velocity or may even be kinematically forbidden, making this scenario al…