98 research outputs found
Resource recovery and low carbon transitions: The hidden impacts of substituting cement with imported âwasteâ materials from coal and steel production
Here we investigate the increasingly complex relationship between the resource recovery practices of the UK concrete industryandongoing low-carbontransitions takingplaceinelectricityandsteel.ReductionsinUKcoalbased electricity and primary steel production are reducing domestic availability of residues â coal ash and steel slag â that are used to replace cement in concrete; for decarbonisation purposes and to increase concrete quality. This is leading to an unusual mass-transportation of âwastesâ from the Global South to Global North. Focusing closely upon the mitigation pathways of concrete producers, we develop an inter-industry model of material ïŹows, and a diversity of scenarios and sensitivity tests, to consider how resource recovery practices and carbon emissions of the three sectors may evolve. A continuation of domestic shortages in waste-derived cement substitutes appears inevitable and future international shortages possible. But even if foreign producers supplied enough cement substitutes to meet UK demand, the broader carbon implications of such trade may be far from benign. Using a revenue-based approach to allocate emissions to coal ash leads to a wide range of embodied carbon estimates â from relatively low (0.15t.CO2/t.ash) to exceeding that of traditional Portland cement (1t.CO2/t.ash). However, the carbonassociated withinternationally traded recovered resources currently stands behindaâdouble-blindâsystemofaccounting: emissionsdonotregisterintheconventionalterritorialaccountsof theimportingcountry andtheymaybehiddenfromitsconsumption-based accountsaswell.Theimpactsofsuch trade and related carbon accounting conventions are unclear and we emphasise the need for further investigation. To this end, our results demonstrate the importance of incorporating highly interconnected sectors and international trade into analyses of low-carbon transitions, and highlight the challenges this presents for designing appropriate policies, accounting frameworks, and interdisciplinary impact assessment methods that look beyond sectorial and national horizons.The UK Natural Environment Research Council (NERC), UK Economic and Social Research Council (ESRC) and Department for Environment, Food & Rural AïŹairs (DEFRA
Type-IIA flux compactifications and N=4 gauged supergravities
We establish the precise correspondence between Type-IIA flux
compactifications preserving an exact or spontaneously broken N=4 supersymmetry
in four dimensions, and gaugings of their effective N=4 supergravities. We
exhibit the explicit map between fluxes and Bianchi identities in the
higher-dimensional theory and generalized structure constants and Jacobi
identities in the reduced theory, also detailing the origin of gauge groups
embedded at angles in the duality group. We present AdS4 solutions of the
massive Type-IIA theory with spontaneous breaking to N=1, at small string
coupling and large volume, and discuss their dual CFT3.Comment: 43 pages, 1 figure. v2: refs added, v3: minor additions. Final
version to appear on JHE
On general flux backgrounds with localized sources
We derive new consistency conditions for string compactifications with
generic fluxes (RR, NSNS, geometrical) and localized sources (D-branes,
NS-branes, KK-monopoles). The constraints are all related by string dualities
and share a common origin in M-theory. We also find new sources of
instabilities. We discuss the importance of these conditions for the
consistency of the effective action and for the study of interpolating
solutions between vacua.Comment: 29 pages, 2 figures, v2: published versio
Non-universal minimal Z' models: present bounds and early LHC reach
We consider non-universal 'minimal' Z' models, whose additional U(1) charge
is a non-anomalous linear combination of the weak hypercharge Y, the baryon
number B and the partial lepton numbers (L_e, L_mu, L_tau), with no exotic
fermions beyond three standard families with right-handed neutrinos. We show
that the observed pattern of neutrino masses and mixing can be fully reproduced
by a gauge-invariant renormalizable Lagrangian, and flavor-changing neutral
currents in the charged lepton sector are suppressed by a GIM mechanism. We
then discuss the phenomenology of some benchmark models. The electrophilic
B-3L_e model is significantly constrained by electroweak precision tests, but
still allows to fit the hint of an excess observed by CDF in dielectrons but
not in dimuons. The muonphilic B-3L_mu model is very mildly constrained by
electroweak precision tests, so that even the very early phase of the LHC can
explore significant areas of parameter space. We also discuss the hadrophobic
L_mu-L_tau model, which has recently attracted interest in connection with some
puzzling features of cosmic ray spectra.Comment: 29 pages, 13 figure
MSSM in view of PAMELA and Fermi-LAT
We take the MSSM as a complete theory of low energy phenomena, including
neutrino masses and mixings. This immediately implies that the gravitino is the
only possible dark matter candidate. We study the implications of the
astrophysical experiments such as PAMELA and Fermi-LAT, on this scenario. The
theory can account for both the realistic neutrino masses and mixings, and the
PAMELA data as long as the slepton masses lie in the TeV range. The
squarks can be either light or heavy, depending on their contribution to
radiative neutrino masses. On the other hand, the Fermi-LAT data imply heavy
superpartners, all out of LHC reach, simply on the grounds of the energy scale
involved, for the gravitino must weigh more than 2 TeV. The perturbativity of
the theory also implies an upper bound on its mass, approximately TeV.Comment: Published version, figures update
Impact of R-Parity Violation on Supersymmetry Searches at the Tevatron
We evaluate cross sections for \eslt, 1 and various dilepton and
multilepton event topologies that result from the simultaneous production of
all sparticles at the Tevatron collider, both within the minimal model
framework as well as in two different -parity violating scenarios. Our
analysis assumes that these -violating couplings are small, and that their
sole effect is to cause the lightest supersymmetric particle to decay inside
the detector. We reassess future strategies for sparticle searches at the
Tevatron, and quantify by how much the various signals for supersymmetry could
differ from their minimal model expectations, if -parity is not conserved
due to either baryon number or lepton number violating operators. We also
evaluate the Tevatron reach in for the various models, and find that
rate-limited multilepton signals ultimately provide the largest reach for both
-parity conserving and -parity violating cases.Comment: preprint nos. FSU-HEP-941001, UR-1387, ER-40685-836 and
UH-511-807-94, 13 pages (REVTEX) plus 3 uuencoded figures attache
D terms from D-branes, gauge invariance and moduli stabilization in flux compactifications
We elucidate the structure of D terms in N=1 orientifold compactifications
with fluxes. As a case study, we consider a simple orbifold of the type-IIA
theory with D6-branes at angles, O6-planes and general NSNS, RR and
Scherk-Schwarz geometrical fluxes. We examine in detail the emergence of D
terms, in their standard supergravity form, from an appropriate limit of the
D-brane action. We derive the consistency conditions on gauged symmetries and
general fluxes coming from brane-localized Bianchi identities, and their
relation with the Freed-Witten anomaly. We extend our results to other N=1
compactifications and to non-geometrical fluxes. Finally, we discuss the
possible role of U(1) D terms in the stabilization of the untwisted moduli from
the closed string sector.Comment: 1+31 pages, 1 figur
Reversal of gastrointestinal carcinoma-induced immunosuppression and induction of antitumoural immunity by a combination of cyclophosphamide and gene transfer of IL-12
Immunotherapy-based strategies for gastrointestinal carcinomas (GIC) have been exploited so far, but these approaches have to face strong mechanisms of immune escape induced by tumours. We previously demonstrated that sub-therapeutic doses of an adenovirus expressing IL-12 genes (AdIL-12) mediated a potent antitumour effect against subcutaneous (s.c.) colorectal carcinomas (CRC) in mice pre-treated with low doses of cyclophosphamide (Cy). In our study we used this combination to assess its impact on the immunosuppressive microenvironment. In s.c. CRC model we demonstrated that non-responder mice failed to decrease Tregs in tumour, spleen and peripheral blood. Reconstitution of Tregs into tumour-bearing mice treated with combined therapy abolished the antitumoural effect. In addition, Cy + AdIL-12 modified Tregs functionality by inhibiting the in vitro secretion of IL-10 and TGF-ÎČ and their ability to inhibit dendritic cells activation. Combined treatment decreased the number of myeloid-derived suppressor cells (MDSCs) in comparison to non-treated mice and, interestingly, administration of Tregs restored splenic MDSCs population. Furthermore, combined therapy potently generated specific cytotoxic IFN-Îł-secreting CD4+ T cells able to eradicate established CRC tumours after adoptive transfer. Finally, we evaluated the combination on disseminated CRC and pancreatic carcinoma (PC). Cy + AdIL-12 were able to eradicate liver metastatic CRC (47%) and PC tumour nodules (40%) and to prolong animal survival. The results of this study support the hypothesis that Cy + AdIL-12 might be a valid immunotherapeutic strategy for advanced GIC.Fil: Malvicini, Mariana. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Austral; ArgentinaFil: Ingolotti, Mariana. Universidad Austral; ArgentinaFil: Piccioni, Flavia Valeria. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Austral; ArgentinaFil: GarcĂa, Mariana Gabriela. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Austral; ArgentinaFil: Bayo Fina, Juan Miguel. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Austral; ArgentinaFil: Atorrasagasti, MarĂa Catalina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Austral; ArgentinaFil: Alaniz, Laura Daniela. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Austral; ArgentinaFil: Aquino, Jorge Benjamin. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Austral; ArgentinaFil: Espinoza, Jaime A.. Universidad Adolfo Ibañez; Chile. Universidad de La Frontera; ChileFil: Gidekel, Manuel. Universidad Adolfo Ibañez; ChileFil: Scharovsky, Olga Graciela. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Medicas. Instituto de Genetica Experimental; ArgentinaFil: Matar, Pablo. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Medicas. Instituto de Genetica Experimental; ArgentinaFil: Mazzolini Rizzo, Guillermo Daniel. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Austral; Argentin
Hypercharge and the Cosmological Baryon Asymmetry
Stringent bounds on baryon and lepton number violating interactions have been
derived from the requirement that such interactions, together with electroweak
instantons, do not destroy a cosmological baryon asymmetry produced at an
extremely high temperature in the big bang. While these bounds apply in
specific models, we find that they are generically evaded. In particular, the
only requirement for a theory to avoid these bounds is that it contain charged
particles which, during a certain cosmological epoch, carry a non-zero
hypercharge asymmetry. Hypercharge neutrality of the universe then dictates
that the remaining particles must carry a compensating hypercharge density,
which is necessarily shared amongst them so as to give a baryon asymmetry.
Hence the generation of a hypercharge density in a sector of the theory forces
the universe to have a baryon asymmetry.Comment: 12 pages plus 1 Postscript figure available upon request. LBL 3482
Lepton number violating interactions and their effects on neutrino oscillation experiments
Mixing between bosons that transform differently under the standard model
gauge group, but identically under its unbroken subgroup, can induce
interactions that violate the total lepton number. We discuss four-fermion
operators that mediate lepton number violating neutrino interactions both in a
model-independent framework and within supersymmetry (SUSY) without R-parity.
The effective couplings of such operators are constrained by: i) the upper
bounds on the relevant elementary couplings between the bosons and the
fermions, ii) by the limit on universality violation in pion decays, iii) by
the data on neutrinoless double beta decay and, iv) by loop-induced neutrino
masses. We find that the present bounds imply that lepton number violating
neutrino interactions are not relevant for the solar and atmospheric neutrino
problems. Within SUSY without R-parity also the LSND anomaly cannot be
explained by such interactions, but one cannot rule out an effect
model-independently. Possible consequences for future terrestrial neutrino
oscillation experiments and for neutrinos from a supernova are discussed.Comment: 28 pages, 2 figures, Late
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