1,228 research outputs found
Severe portal and systemic acidosis during CO2-laparoscopy compared to helium or gasless laparoscopy and laparotomy in a rodent model: an experimental study
Background and aims: This experimental study assesses the influence of different gases and insufflation pressures on the portal, central-venous and peripheral-arterial pH during experimental laparoscopy.
Methods: Firstly, 36 male WAG/Rij rats were randomized into six groups (n = 6) spontaneously breathing during anaesthesia: laparoscopy using carbon dioxide or helium at 6 and 12 mmHg, gasless laparoscopy and laparotomy. 45 and 90 min after setup, blood was sampled from the portal vein, vena cava and the common femoral artery with immediate blood gas analysis. Secondly, 12 animals were mechanically ventilated at physiological arterial pH during 90 min of laparotomy (n = 6) or carbon dioxide laparoscopy at 12 mmHg (n = 6) with respective blood gas analyses.
Results: Over time, in spontaneously breathing rats, carbon dioxide laparoscopy caused significant insufflation pressure-dependent portal acidosis (pH at 6 mmHg, 6.99 [6.95-7.04] at 45 min and 6.95 [6.94-6.96] at 90 min, pH at 12 mmHg, 6.89 [6.82-6.90] at 45 min and 6.84 [6.81-6.87] at 90 min; p 0.05). Central-venous and peripheral-arterial acidosis was significant but less severely reduced during carbon dioxide laparoscopy. Laparotomy, helium laparoscopy and gasless laparoscopy showed no comparable acidosis in all vessels. Portal and central-venous acidosis during carbon dioxide laparoscopy at 12 mmHg was not reversible by mechanical hyperventilation maintaining a physiological arterial pH (pH portal 6.85 [6.84-6.90] (p = 0.004), central-venous 6.93 [6.90-6.99] (p = 0.004), peripheral-arterial 7.29 [7.29-7.31] (p = 0.220) at 90 min; Wilcoxon-Mann-Whitney test).
Conclusion: Carbon dioxide laparoscopy led to insufflation pressure-dependent severe portal and less severe central-venous acidosis not reversible by mechanical hyperventilation.
Keywords: Acidosis; Blood gases; Insufflation gas; Insufflation pressure; Laparoscop
Superfield Approach to 5D Conformal SUGRA and the Radion
We propose that the radion chiral supermultiplet of five dimensional
compactified supergravity is obtained by reduction of the graviphoton gauge
multiplet to N=1 superfields in the off shell 5D superconformal gravity
formalism of Fujita, Kugo and Ohashi. We present a superfield Lagrangian of
Chern-Simons type (similar to global SUSY), which reproduces all component
couplings of gauge fields and the radion. A hypermultiplet superspace action is
also proposed which correctly accounts for the coupling of matter multiplets
with gauge and radion superfields. 4D supergravity enters by the coupling to
the 4D Weyl multiplet, an even orbifold parity multiplet embedded in the 5D
Weyl multiplet. We apply this formalism to a discussion of Fayet-Iliopolous
terms, and the gauging of orbifold SUGRA to obtain warped solutions.Comment: Typos correcte
Mildly sequestered supergravity models and their realization in string theory
We elaborate on the idea that five-dimensional models where sequestering is
spoiled due to contact interactions induced by vector multiplets may still be
mildly sequestered if a global version of the gauge symmetry associated to the
latter survives in the hidden sector. Interestingly, it has been argued that
although in such a situation non-trivial current-current contact interactions
are induced by the heavy vector modes, these do not induce soft scalar masses,
as a consequence of the global symmetry. We perform a detailed study of how
this hybrid mechanism can be implemented in supergravity and string models,
focusing on the prototypical case of heterotic M-theory orbifolds. We emphasize
that in general the mechanism works only up to subleading effects suppressed by
the ratio between the global symmetry breaking scale in the hidden sector and
the vector mass scale or the Planck scale. We also argue that this mild
sequestering mechanism allows to rehabilitate the scenario of dilaton
domination of supersymmetry breaking, which is incompatible with dilaton
stabilization in its original version, by exploiting the fact that hidden brane
fields do contribute to the cosmological constant but not to soft terms, thanks
to the global symmetry.Comment: 31 pages, LaTex, no figure
Sequestering by global symmetries in Calabi-Yau string models
We study the possibility of realizing an effective sequestering between
visible and hidden sectors in generic heterotic string models, generalizing
previous work on orbifold constructions to smooth Calabi-Yau compactifications.
In these theories, genuine sequestering is spoiled by interactions mixing
chiral multiplets of the two sectors in the effective Kahler potential. These
effective interactions however have a specific current-current-like structure
and can be interpreted from an M-theory viewpoint as coming from the exchange
of heavy vector multiplets. One may then attempt to inhibit the emergence of
generic soft scalar masses in the visible sector by postulating a suitable
global symmetry in the dynamics of the hidden sector. This mechanism is however
not straightforward to implement, because the structure of the effective
contact terms and the possible global symmetries is a priori model dependent.
To assess whether there is any robust and generic option, we study the full
dependence of the Kahler potential on the moduli and the matter fields. This is
well known for orbifold models, where it always leads to a symmetric scalar
manifold, but much less understood for Calabi-Yau models, where it generically
leads to a non-symmetric scalar manifold. We then examine the possibility of an
effective sequestering by global symmetries, and argue that whereas for
orbifold models this can be put at work rather naturally, for Calabi-Yau models
it can only be implemented in rather peculiar circumstances.Comment: 47 pages, no figure
Symmetry Breaking for Bosonic Systems on Orbifolds
We discuss a general class of boundary conditions for bosons living in an
extra spatial dimension compactified on S^1/Z_2. Discontinuities for both
fields and their first derivatives are allowed at the orbifold fixed points. We
analyze examples with free scalar fields and interacting gauge vector bosons,
deriving the mass spectrum, that depends on a combination of the twist and the
jumps. We discuss how the same physical system can be characterized by
different boundary conditions, related by local field redefinitions that turn a
twist into a jump or vice-versa. When the description is in term of
discontinuous fields, appropriate lagrangian terms should be localized at the
orbifold fixed points.Comment: 21 pages, 2 figure
Better survival in right-sided versus left-sided stage I - III colon cancer patients
Background: The distinction between right-sided and left-sided colon cancer has recently received considerable attention due to differences regarding underlying genetic mutations. There is an ongoing debate if right- versus left-sided tumor location itself represents an independent prognostic factor. We aimed to investigate this question by using propensity score matching. Methods: Patients with resected, stage I - III colon cancer were identified from the Surveillance, Epidemiology, and End Results (SEER) database (2004–2012). Both univariable and multivariable Cox regression as well as propensity score matching were used. Results: Overall, 91,416 patients (51,937 [56.8%] with right-sided, 39,479 [43.2%] with left-sided colon cancer; median follow-up 38 months) were eligible. In univariable analysis, patients with right-sided cancer had worse overall (hazard ratio [HR] = 1.32, 95% CI:1.29–1.36, P < 0.001) and cancer-specific survival (HR = 1.26, 95% CI:1.21–1.30, P < 0.001) compared to patients with left-sided cancer. After propensity score matching, the prognosis of right-sided carcinomas was better regarding overall (HR = 0.92, 95% CI: 0.89 − 0.94, P < 0.001) and cancer-specific survival (HR = 0.90, 95% CI:0.87 − 0.93, P < 0.001). In stage I and II, the prognosis of right-sided cancer was better for overall (HR = 0.89, 95% CI:0.84–0.94 and HR = 0.85, 95% CI:0.81–0.89) and cancer-specific survival (HR = 0.71, 95% CI:0.64 − 0.79 and HR = 0.75, 95% CI:0.70–0.80). Right- and left-sided colon cancer had a similar prognosis for stage III (overall: HR = 0.99, 95% CI:0.95–1.03 and cancer-specific: HR = 1.04, 95% CI:0.99–1.09). Conclusions: This population-based analysis on stage I - III colon cancer provides evidence that the prognosis of localized right-sided colon cancer is better compared to left-sided colon cancer. This questions the paradigm from previous research claiming a worse survival in right-sided colon cancer patients
SUSY flavor structure of generic 5D supergravity models
We perform a comprehensive and systematic analysis of the SUSY flavor
structure of generic 5D supergravity models on with multiple
-odd vector multiplets that generate multiple moduli. The SUSY flavor
problem can be avoided due to contact terms in the 4D effective K\"ahler
potential peculiar to the multi-moduli case. A detailed phenomenological
analysis is provided based on an illustrative model.Comment: 37 pages, 7 figures, Sec.4 is modifie
Search for Direct Top Squark Pair Production in Final States with One Isolated Lepton, Jets, and Missing Transverse Momentum in √s = 7 TeV pp Collisions Using 4.7 fb^(-1) of ATLAS Data
Impact of the COVID-19 pandemic on TB services at ART programmes in low- and middle-income countries: a multi-cohort survey.
INTRODUCTION
COVID-19 stretched healthcare systems to their limits, particularly in settings with a pre-existing high burden of infectious diseases, including HIV and tuberculosis (TB). We studied the impact of COVID-19 on TB services at antiretroviral therapy (ART) clinics in low- and middle-income countries.
METHODS
We surveyed ART clinics providing TB services in the International Epidemiology Databases to Evaluate AIDS (IeDEA) consortium in Africa and the Asia-Pacific until July 2021 (TB diagnoses until the end of 2021). We collected site-level data using standardized questionnaires.
RESULTS
Of 46 participating ART clinics, 32 (70%) were in Africa and 14 (30%) in the Asia-Pacific; 52% provided tertiary care. Most clinics (85%) reported disrupted routine HIV care services during the pandemic, both in Africa (84%) and the Asia-Pacific (86%). The most frequently reported impacts were on staff (52%) and resource shortages (37%; protective clothing, face masks and disinfectants). Restrictions in TB health services were observed in 12 clinics (26%), mainly reduced access to TB diagnosis and postponed follow-up visits (6/12, 50% each), and restrictions in TB laboratory services (22%). Restrictions of TB services were addressed by dispensing TB drugs for longer periods than usual (7/12, 58%), providing telehealth services (3/12, 25%) and with changes in directly observed therapy (DOT) (e.g. virtual DOT, 3/12). The number of TB diagnoses at participating clinics decreased by 21% in 2020 compared to 2019; the decline was more pronounced in tertiary than primary/secondary clinics (24% vs. 12%) and in sites from the Asia-Pacific compared to Africa (46% vs. 14%). In 2021, TB diagnoses continued to decline in Africa (-8%) but not in the Asia-Pacific (+62%) compared to 2020. During the pandemic, new infection control measures were introduced or intensified at the clinics, including wearing face masks, hand sanitation and patient triage.
CONCLUSIONS
The COVID-19 pandemic led to staff shortages, reduced access to TB care and delays in follow-up visits for people with TB across IeDEA sites in Africa and the Asia-Pacific. Increased efforts are needed to restore and secure ongoing access to essential TB services in these contexts
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