12 research outputs found
Thermal width and gluo-dissociation of quarkonium in pNRQCD
The thermal width of heavy-quarkonium bound states in a quark-gluon plasma
has been recently derived in an effective field theory approach. Two phenomena
contribute to the width: the Landau damping phenomenon and the break-up of a
colour-singlet bound state into a colour-octet heavy quark-antiquark pair by
absorption of a thermal gluon. In the paper, we investigate the relation
between the singlet-to-octet thermal break-up and the so-called
gluo-dissociation, a mechanism for quarkonium dissociation widely used in
phenomenological approaches. The gluo-dissociation thermal width is obtained by
convoluting the gluon thermal distribution with the cross section of a gluon
and a 1S quarkonium state to a colour octet quark-antiquark state in vacuum, a
cross section that at leading order, but neglecting colour-octet effects, was
computed long ago by Bhanot and Peskin. We will, first, show that the effective
field theory framework provides a natural derivation of the gluo-dissociation
factorization formula at leading order, which is, indeed, the singlet-to-octet
thermal break-up expression. Second, the singlet-to-octet thermal break-up
expression will allow us to improve the Bhanot--Peskin cross section by
including the contribution of the octet potential, which amounts to include
final-state interactions between the heavy quark and antiquark. Finally, we
will quantify the effects due to final-state interactions on the
gluo-dissociation cross section and on the quarkonium thermal width.Comment: 17 pages, 6 figure
Heavy Quarkonium in a weakly-coupled quark-gluon plasma below the melting temperature
We calculate the heavy quarkonium energy levels and decay widths in a
quark-gluon plasma, whose temperature T and screening mass m_D satisfy the
hierarchy m alpha_s >> T >> m alpha_s^2 >> m_D (m being the heavy-quark mass),
at order m alpha_s^5. We first sequentially integrate out the scales m, m
alpha_s and T, and, next, we carry out the calculations in the resulting
effective theory using techniques of integration by regions. A collinear region
is identified, which contributes at this order. We also discuss the
implications of our results concerning heavy quarkonium suppression in heavy
ion collisions.Comment: 25 pages, 2 figure
The spin-orbit potential and Poincar\'e invariance in finite temperature pNRQCD
Heavy quarkonium at finite temperature has been the subject of intense
theoretical studies, for it provides a potentially clean probe of the
quark-gluon plasma. Recent studies have made use of effective field theories to
exploit in a systematic manner the hierarchy of energy scales that characterize
the system. In the case of a quarkonium in a medium whose temperature is
smaller than the typical momentum transfer in the bound state but larger than
its energy, the suitable effective field theory is pNRQCD_HTL, where degrees of
freedom with energy or momentum larger than the binding energy have been
integrated out. Thermal effects are expected to break Poincar\'e invariance,
which, at zero temperature, manifests itself in a set of exact relations
between the matching coefficients of the effective field theory. In the paper,
we evaluate the leading-order thermal corrections to the spin-orbit potentials
of pNRQCD_HTL and show that Poincar\'e invariance is indeed violated.Comment: 17 page, 4 figures. Version published on JHE
IV Foro Internacional de Ganadería Sustentable: conectividad ecosistémica y articulación territorial hacia la Agenda 2030
En este espacio plural de análisis y reflexiones, buscamos articular conceptos y posibilidades para los territorios de montaña del centro de México, dando importancia a medios de vida vinculados a la ganadería y su interacción ecosistémica, fundamentado en innovaciones, casos de éxito e iniciativas emblemáticas nacionales e internacionales. La socialización de experiencias es uno de los pilares para transitar hacia la sostenibilidad de los sistemas productivos ganaderos: compartir logros e iniciativas, crear sinergias e identificar vulnerabilidades desde distintos enfoques.GIZ, Agencia de Cooperación Aleman
Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries
Abstract
Background
Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres.
Methods
This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries.
Results
In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia.
Conclusion
This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries
Imágenes citológicas de Helicobacter heilmannii (Gastrospirillum hominis), bacteria gástrica no reportada en Cuba
Se observaron 625 citologías gástricas por cepillado tomadas mediante endoscopia a pacientes adultos con gastritis crónica y/o úlcera gástrica, con el objetivo de diagnosticar Helicobacter pylori. En un paciente con úlcera gástrica la prueba de la ureasa fue positiva y la citología resultó negativa de H. pylori. Se observaron otras bacterias espiraladas que solo se habían visto en la literatura, fueron medidas y fotografiadas. Se informó Gastrospirillum hominis. El paciente recibió tratamiento con Q-ulcer, metronidazol, tetraciclina y metoclopramida. A los 2 meses de finalizado se le repitió la endoscopia y había desaparecido la úlcera, se informó entonces gastritis crónica ligeramente agudizada. No existía reflujo biliar. La ureasa fue negativa y las bacterias descritas en la muestra anterior habían desaparecido.632 gastric brush cytologies taken by endoscopy from adult patients with chronic gastritis and/or gastric ulcer in order to diagnose Helicobacter pylori were observed. In a patient with gastric ulcer, the urease test was positive, whereas the H. pylori cytology was negative. Other spiral bacteria that had been only found in literature were detected, measured and photographed. Gastropirillum hominis was reported. The patient received treatment with Q-ulcer, metronidazole, tetracycline and metroclopramide. 2 months later, the endoscopy was repeated and ulcer had disappeared. A slightly more acute chronic gastritis was reported then. There was no biliary reflux. Urease was negative and the bacteria described in the previous sample were not found
Expression of the Biologically Active Insulin Analog SCI-57 in Nicotiana Benthamiana
Diabetes mellitus is a growing problem worldwide; however, only 23% of low-income countries have access to insulin, and ironically it costs higher in such countries than high-income ones. Therefore, new strategies for insulin and insulin analogs production are urgently required to improve low-cost access to therapeutic products, so as to contain the diabetes epidemic. SCI-57 is an insulin analog with a greater affinity for the insulin receptor and lower thermal degradation than native insulin. It also shows native mitogenicity and insulin-like biological activity. In this work, SCI-57 was transiently expressed in the Nicotiana benthamiana (Nb) plant, and we also evaluated some of its relevant biological effects. An expression plasmid was engineered to translate an N-terminal ubiquitin and C-terminal endoplasmic reticulum-targeting signal KDEL, in order to increase protein expression and stability. Likewise, the effect of co-expression of influenza M2 ion channel (M2) on the expression of insulin analog SCI-57 (SCI-57/M2) was evaluated. Although using M2 increases yield, it tends to alter the SCI-57 amino acid sequence, possibly promoting the formation of oligomers. Purification of SCI-57 was achieved by FPLC cation exchange and ultrafiltration of N. benthamiana leaf extract (NLE). SCI-57 exerts its anti-diabetic properties by stimulating glucose uptake in adipocytes, without affecting the lipid accumulation process. Expression of the insulin analog in agroinfiltrated plants was confirmed by SDS-PAGE, RP-HPLC, and MS. Proteome changes related to the expression of heterologous proteins on N. benthamiana were not observed; up-regulated proteins were related to the agroinfiltration process. Our results demonstrate the potential for producing a biologically active insulin analog, SCI-57, by transient expression in Nb