41 research outputs found
Is soil organic carbon underestimated in the largest mangrove forest ecosystems? Evidence from the Bangladesh Sundarbans
Globally, mangroves sequester a large amount of carbon into the sediments, although spatial heterogeneity exists owing to a wide variety of local, regional, and global controls. Rapid environmental and climate change, including increasing sea-level rise, global warming, reduced upstream discharge and anthropogenic activities, are predicted to increase salinity in the mangroves, especially in the Bangladesh Sundarbans, thereby disrupting this blue carbon reservoir. Nevertheless, it remains unclear how salinity affects the belowground soil carbon despite the recognised effect on above ground productivity. To address this gap, research was undertaken in the Bangladesh Sundarbans to compare total soil organic carbon (SOC) across three salinity zones and to explore any potential predictive relationships with other physical, chemical properties and vegetation characteristics. Total SOC was significantly higher in the oligohaline zone (74.8 ± 14.9 Mg ha-1 23 ), followed by the mesohaline (59.3 ± 15.8 Mg ha-1), and polyhaline zone (48.3 ± 10.3 Mg ha-1 24 ) (ANOVA, F2, 500 = 118.9, p <0.001). At all sites, the topmost 10 cm of soil contained higher SOC density than the bottom depths (ANOVA, F3, 500= 30.1, p <0.001). On average, Bruguiera sp. stand holds the maximum SOC measured, followed by two pioneer species Sonneratia apetala and Avicennia sp. Multiple regression results indicated that soil salinity, organic C: N and tree diameter were the best predictor for the variability of the SOC in the Sundarbans (R2 = 0.62). Despite lower carbon in the soil, the study highlights that the conservation priorities and low deforestation have led to less CO2 emissions than most sediment carbon-rich mangroves in the world. The study also emphasised the importance of spatial conservation planning to safeguard the soil carbon-rich zones in the Bangladesh Sundarbans from anthropogenic tourism and development activities to support climate change adaptation and mitigation strategies
Higher Resonance Contamination of pi NN Couplings Obtained Via the Three-Point Function Method in QCD Sum Rules
We investigate the size of potential higher pseudoscalar resonance
contaminations of the estimates of isospin-conserving and isospin-violating
couplings obtained using the 3-point function method in QCD sum rules.
For the isospin-conserving case it is shown that conventional models of the
isovector pseudoscalar spectral function imply resonance decay constants large
enough to create significant contaminations, and that assuming these models are
incorrect, and that the decay constants are actually much smaller, implies
physically implausible values for the flavor-breaking quark condensate ratios.
For the isospin-violating case it is shown explicitly that such resonance
contamination is unavoidably present and precludes using the 3-point function
method as a means of estimating the at present unmeasured isospin-violating
couplings.Comment: 8 page
CP asymmetries in neutralino production in e+e- collisions
We study two CP sensitive triple-product asymmetries for neutralino
production e+e- \to\tilde\chi^0_i \tilde\chi^0_j and the subsequent leptonic
two-body decay \tilde\chi^0_i \to \tilde l l, \tilde l \to \tilde\chi^0_1 l,
for \l= e,\mu,\tau. We calculate the asymmetries, cross sections and branching
ratios in the Minimal Supersymmetric Standard Model with complex parameters \mu
and M_1. We present numerical results for the asymmetries to be expected at a
linear electron-positron collider in the 500 GeV range. The asymmetries can go
up to 25 %. We estimate the event rates which are necessary to observe the
asymmetries. Polarized electron and positron beams can significantly enhance
the asymmetries and cross sections. In addition, we show how the two decay
leptons can be distinguished by making use of their energy distributions.Comment: 22 pages, 7 figures; typos corrected, version to appear in Phys. Rev.
The Effects of Quantum Entropy on the Bag Constant
The effects of quantum entropy on the bag constant are studied at low
temperatures and small chemical potentials. The inclusion of the quantum
entropy of the quarks in the equation of state provides the hadronic bag with
an additional heat which causes a decrease in the effective latent heat inside
the bag. We have considered two types of baryonic bags, and
. In both cases we have found that the bag constant without the
quantum entropy almost does not change with the temperature and the quark
chemical potential. The contribution from the quantum entropy to the equation
of state clearly decreases the value of the bag constant.Comment: 7 pages, 2 figures (two parts each
Flavor Alignment Solutions to the Strong CP Problem in Supersymmetry
An approach to solving the Strong CP Problem in supersymmetric theories is
discussed which uses abelian family symmetries to align the mass matrices of
the quarks and squarks. In this way both the Strong CP Problem and the
characteristic flavor and CP problems of supersymmetry can be solved in a
single way.Comment: 13 pages, LaTe
Identification of trans protein QTL for secreted airway mucins in mice and a causal role for Bpifb1
Mucus hyper-secretion is a hallmark feature of asthma and other muco-obstructive airway diseases. The mucin proteins MUC5AC and MUC5B are the major glycoprotein components of mucus and have critical roles in airway defense. Despite the biomedical importance of these two proteins, the loci that regulate them in the context of natural genetic variation have not been studied. To identify genes that underlie variation in airway mucin levels, we performed genetic analyses in founder strains and incipient lines of the Collaborative Cross (CC) in a house dust mite mouse model of asthma. CC founder strains exhibited significant differences in MUC5AC and MUC5B, providing evidence of heritability. Analysis of gene and protein expression of Muc5ac and Muc5b in incipient CC lines (n = 154) suggested that post-transcriptional events were important regulators of mucin protein content in the airways. Quantitative trait locus (QTL) mapping identified distinct, trans protein QTL for MUC5AC (chromosome 13) and MUC5B (chromosome 2). These two QTL explained 18 and 20% of phenotypic variance, respectively. Examination of the MUC5B QTL allele effects and subsequent phylogenetic analysis allowed us to narrow the MUC5B QTL and identify Bpifb1 as a candidate gene. Bpifb1 mRNA and protein expression were upregulated in parallel to MUC5B after allergen challenge, and Bpifb1 knockout mice exhibited higher MUC5B expression. Thus, BPIFB1 is a novel regulator of MUC5B
Stability of the Scalar Potential and Symmetry Breaking in the Economical 3-3-1 Model
A detailed study of the criteria for stability of the scalar potential and
the proper electroweak symmetry breaking pattern in the economical 3-3-1 model,
is presented. For the analysis we use, and improve, a method previously
developed to study the scalar potential in the two-Higgs-doublet extension of
the standard model. A new theorem related to the stability of the potential is
stated. As a consequence of this study, the consistency of the economical 3-3-1
model emerges.Comment: to be published in EPJ C, 13 page
Gluino Contribution to Radiative B Decays: Organization of QCD Corrections and Leading Order Results
The gluino-induced contributions to the decay b-> s gamma are investigated in
supersymmetric frameworks with generic sources of flavour violation. It is
shown that, when QCD corrections are taken into account, the relevant operator
basis of the Standard Model effective Hamiltonian gets enlarged to contain: i)
magnetic and chromomagnetic operators with a factor of alpha_s and weighted by
a quark mass m_b or m_c; ii) magnetic and chromomagnetic operators of lower
dimensionality, also containing alpha_s; iii) four-quark operators weighted by
a factor alpha_s^2. Numerical results are given, showing the effects of the
leading order QCD corrections on the inclusive branching ratio for b-> s gamma.
Constraints on supersymmetric sources of flavour violation are derived.Comment: 36 pages including 16 postscript figures; uses epsf; journal version:
one ref. added; rephrasing of a couple of paragraph
Phenomenology of non-standard Z couplings in exclusive semileptonic b -> s transitions
The rare decays , and
are analyzed in a generic scenario where New Physics effects
enter predominantly via penguin contributions. We show that this
possibility is well motivated on theoretical grounds, as the vertex
is particularly susceptible to non-standard dynamics. In addition, such a
framework is also interesting phenomenologically since the coupling
is rather poorly constrained by present data. The characteristic features of
this scenario for the relevant decay rates and distributions are investigated.
We emphasize that both sign and magnitude of the forward-backward asymmetry of
the decay leptons in , , carry sensitive information on New Physics. The observable is proposed as a useful probe of
non-standard CP violation in couplings.Comment: Minor modifications; version to appear in Phys. Rev.
b -> s gamma in the left-right supersymmetric model
The rare decay is studied in the left-right supersymmetric
model. We give explicit expressions for all the amplitudes associated with the
supersymmetric contributions coming from gluinos, charginos and neutralinos in
the model to one-loop level. The branching ratio is enhanced significantly
compared to the standard model and minimal supersymmetric standard model values
by contributions from the right-handed gaugino and squark sector. We give
numerical results coming from the leading order contributions. If the only
source of flavor violation comes from the CKM matrix, we constrain the scalar
fermion-gaugino sector. If intergenerational mixings are allowed in the squark
mass matrix, we constrain such supersymmetric sources of flavor violation. The
decay sets constraints on the parameters of the model and
provides distinguishing signs from other supersymmetric scenarios.Comment: 12 figure