3,958 research outputs found
Restriction on the energy and luminosity of e+e- storage rings due to beamstrahlung
The role of beamstrahlung in high-energy e+e- storage-ring colliders (SRCs)
is examined. Particle loss due to the emission of single energetic
beamstrahlung photons is shown to impose a fundamental limit on SRC
luminosities at energies 2E_0 >~ 140 GeV for head-on collisions and 2E_0 >~ 40
GeV for crab-waist collisions. With beamstrahlung taken into account, we
explore the viability of SRCs in the E_0=240-500 GeV range, which is of
interest in the precision study of the Higgs boson. At 2E_0=240 GeV, SRCs are
found to be competitive with linear colliders; however, at 2E_0=400-500 GeV,
the attainable SRC luminosity would be a factor 15-25 smaller than desired.Comment: Latex, 5 pages. v2 differs only by minor changes is abstract and
introduction, one reference is added. v3 corresponds to the paper published
in PR
Soil and Phyllosphere Microorganisms of the Rapeseed (Brassica napus L.) Holobiont Involved in Chloromethane Emissions
Brassica napus, or rapeseed, is one major oilseed crop in Europe and Germany and is used for food, feed, and Biodiesel production. Chloromethane (CH3Cl) is the most abundant halogenated organic compound in the atmosphere and triggers the chlorine-mediated destruction of the ozone layer. Anthropogenic sources became negligible because of taken measures according to the Montreal Protocol (1987) and therefore natural sources such as plants became more relevant for the global chloromethane budget. The actual global budget is imbalanced through missing sinks, which may be activities of soil and phyllosphere microbiomes which together with the plant is considered as the holobiont. The amount of CH3Cl from crops has not been addressed and might even increase under stresses such as elevated soil salinization and temperature. We proved that B. napus (rapeseed) plants emit CH3Cl. Certain methylotrophs (microorganisms that utilize one-carbon compounds) degrade CH3Cl and can gain a selective advantage while colonizing plants. Moreover, methylotrophs thrive in the rhizosphere of grassland plants. The rapeseed associated microbiome likely harbours methylotrophs that degrade CH3Cl. Therefore, we addressed in this study the rapeseed holobiont to resolve its response to stressors such as salt and temperature in regard to CH3Cl emission. We addressed in our project the following objectives: (i) To measure CH3Cl emission rates from single B. napus holobionts under different NaCl and temperature stress levels in pot experiments, (ii) to assess the B. napus microbiome and its CH3Cl degradation ability through amplicon sequencing of bacterial 16S rRNA genes and functional gene markers. The summer cultivar MAKRO was used as a model organism. We identified methylotrophs that responded to salt and temperature stress conditions in the phyllo- and rhizosphere of rapeseed and correlated those to the observed net emission rates
Modification of Kawai model about the mixing of the pseudoscalar mesons
The Kawai model describing the glueball-quarkonia mixing is modified. The
mixing of , and is re-investigated based on
the modified Kawai model. The glueball-quarkonia content of the three states is
determined from a fit to the data of the electromagnetic decays involving
, . Some predictions about the electromagnetic decays
involving are presented.Comment: revtex 8 page
Quark-Resonance model
We construct an effective Lagrangian for low energy hadronic interactions
through an infinite expansion in inverse powers of the low energy cutoff
of all possible chiral invariant non-renormalizable interactions
between quarks and mesons degrees of freedom. We restrict our analysis to the
leading terms in the expansion. The effective expansion is in
(\mu^2/\cutoff^2 )^P \ln (\cutoff^2/\mu^2 )^Q. Concerning the next-to-leading
order, we show that, while the pure \mu^2/\cutoff^2 corrections cannot be
traced back to a finite number of non renormalizable interactions, those of
order (\mu^2/\cutoff^2 ) \ln (\cutoff^2/\mu^2 ) receive contributions from a
finite set of 1/\cutoff^2 terms. Their presence modifies the behaviour of
observable quantities in the intermediate region. We explicitely discuss
their relevance for the two point vector currents Green's function.Comment: 41 pages, 11 figures, preprint ROM2F 93/3
Magnetism in Semiconducting Molybdenum Dichalcogenides
Transition metal dichalcogenides (TMDs) are interesting for understanding
fundamental physics of two-dimensional materials (2D) as well as for many
emerging technologies, including spin electronics. Here, we report the
discovery of long-range magnetic order below TM = 40 K and 100 K in bulk
semiconducting TMDs 2H-MoTe2 and 2H-MoSe2, respectively, by means of muon
spin-rotation (muSR), scanning tunneling microscopy (STM), as well as density
functional theory (DFT) calculations. The muon spin rotation measurements show
the presence of a large and homogeneous internal magnetic fields at low
temperatures in both compounds indicative of long-range magnetic order. DFT
calculations show that this magnetism is promoted by the presence of defects in
the crystal. The STM measurements show that the vast majority of defects in
these materials are metal vacancies and chalcogen-metal antisites which are
randomly distributed in the lattice at the sub-percent level. DFT indicates
that the antisite defects are magnetic with a magnetic moment in the range of
0.9-2.8 mu_B. Further, we find that the magnetic order stabilized in 2H-MoTe2
and 2H-MoSe2 is highly sensitive to hydrostatic pressure. These observations
establish 2H-MoTe2 and 2H-MoSe2 as a new class of magnetic semiconductors and
opens a path to studying the interplay of 2D physics and magnetism in these
interesting semiconductors.Comment: 13 pages, 10 Figure
Comportamento de linhagens e cultivares de aspargo introduzidas de New Jersey, E.U.A., no municĂpio de Pelotas, RS.
Acentuadas reduções nas produções de aspargo no Rio Grande do Sul, na Ăşltima dĂ©cada, justificaram a necessidade da introdução de novas cultivares. Em levantamento efetuado em 1979/80 pela EMBRAPA/UEPAE de Cascata e EMATER/RS, em lavouras do MunicĂpio de Pelotas, RS, constatou-se que as cultivares mais usadas sĂŁo "Comum" (41%), "Washington" (31%), "Gigante" (15%), "Crioulo" (1%) e, em 12% dos casos, de material desconhecido. As sementes sĂŁo colhidas em lavouras comerciais e semeadas sem inspeção, portadoras de doenças e com baixo poder germinativo. Portanto, o que vulgarmente se denomina de cultivar, nĂŁo passa de uma população de plantas com grande heterogeneidade entre seus indivĂduos
Detecting Gluino-Containing Hadrons
When SUSY breaking produces only dimension-2 operators, gluino and photino
masses are of order 1 GeV or less. The gluon-gluino bound state has mass
1.3-2.2 GeV and lifetime > 10^{-5} - 10^{-10} s. This range of mass and
lifetime is largely unconstrained because missing energy and beam dump
techniques are ineffective. With only small modifications, upcoming K^0 decay
experiments can study most of the interesting range. The lightest
gluino-containing baryon (uds-gluino) is long-lived or stable; experiments to
find it and the uud-gluino are also discussed.Comment: 13 pp, 1 figure (uuencoded). Descendant of hep-ph/9504295,
hep-ph/9508291, and hep-ph/9508292, focused on experimental search
techniques. To be published in Phys Rev Let
Unquenching the scalar glueball
Computations in the quenched approximation on the lattice predict the
lightest glueball to be a scalar in the 1.5-1.8 GeV region. Here we calculate
the dynamical effect the coupling to two pseudoscalars has on the mass, width
and decay pattern of such a scalar glueball. These hadronic interactions allow
mixing with the scalar nonet, which is largely fixed by the
well-established K_0^*(1430). This non-perturbative mixing means that, if the
pure gluestate has a width to two pseudoscalar channels of ~100 MeV as
predicted on the lattice, the resulting hadron has a width to these channels of
only ~30 MeV with a large eta-eta component. Experimental results need to be
reanalyzed in the light of these predictions to decide if either the f_0(1500)
or an f_0(1710) coincides with this dressed glueball.Comment: 12 pages, LaTex, 3 Postscript figure
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“Provide care for everyone please”: Engaging Community Leaders as Sexual and Reproductive Health Advocates in North and South Kivu, Democratic Republic of Congo
Background: Inadequate infrastructure, security threats from ongoing armed conflict, and conservative socio-cultural and gender norms that favour large families and patriarchal power structures contribute to poor sexual and reproductive health (SRH) outcomes in North and South Kivu provinces, Democratic Republic of the Congo (DRC). In order to expand contraceptive and post-abortion care (PAC) access in North and South Kivu, CARE, the International Rescue Committee and Save the Children provided technical support to the Ministry of Health and health facilities in these regions. Partners acknowledged that community leaders, given their power to influence local customs, could play a critical role as agents of change in addressing inequitable gender norms, stigma surrounding SRH service utilization, and topics traditionally considered taboo within Congolese society. As such, partners actively engaged with community leaders through a variety of activities such as community mapping exercises, values clarification and transformation (VCAT) activities, situational analyses, and education.
Methods: This manuscript presents findings from 12 key informant interviews (KIIs) with male political and non-political community leaders conducted in six rural health zones of North and South Kivu, DRC. Transcripts were analysed thematically to explore community leaders’ perceptions of their role in addressing the issue of unintended pregnancy in their communities.
Results: While community leaders in this study expressed overall positive impressions of contraception and strong support for ensuring access to PAC services following spontaneous and induced abortions, the vast majority held negative beliefs concerning women who had induced abortion. Contrasting with their professed opposition to induced abortion, leaders’ commitment to mediating interpersonal conflict arising between community members and women who had abortions was overwhelming.
Conclusion: Results from this study suggest that when thoughtfully engaged by health interventions, community leaders can be empowered to become advocates for SRH. While study participants were strong supporters of contraception and PAC, they expressed negative perceptions of induced abortion. Given the hypothesized link between the presence of induced abortion stigma and care-avoidance behavior, further engagement and values clarification exercises with leaders must be integrated into community mobilization and engagement activities in order to increase PAC utilization
Sensitivity analysis and model order reduction for random linear dynamical systems
Abstract We consider linear dynamical systems defined by differential algebraic equations. The associated input-output behaviour is given by a transfer function in the frequency domain. Physical parameters of the dynamical system are replaced by random variables to quantify uncertainties. We analyse the sensitivity of the transfer function with respect to the random variables. Total sensitivity coefficients are computed by a nonintrusive and by an intrusive method based on the expansions in series of the polynomial chaos. In addition, a reduction of the state space is applied in the intrusive method. Due to the sensitivities, we perform a model order reduction within the random space by changing unessential random variables back to constants. The error of this reduction is analysed. We present numerical simulations of a test example modelling a linear electric network
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