Compilación de Proyectos de Investigación desde el año 2003 al 2012

Listado de Proyectos de investigación de UPIICSA desde 2003 a 201

Prompt and non-prompt J/ψ\hbox {J}/\psi production and nuclear modification at mid-rapidity in p–Pb collisions at sNN=5.02\mathbf{\sqrt{{ s}_{\text {NN}}}= 5.02} TeV

A measurement of beauty hadron production at mid-rapidity in proton-lead collisions at a nucleon–nucleon centre-of-mass energy $\sqrt{s_\text {NN}}=5.02$ TeV is presented. The semi-inclusive decay channel of beauty hadrons into $\hbox {J}/\psi$ is considered, where the $\hbox {J}/\psi$ mesons are reconstructed in the dielectron decay channel at mid-rapidity down to transverse momenta of 1.3 GeV/c. The $\hbox {b}\bar{\hbox {b}}$ production cross section at mid-rapidity, $\hbox {d}\sigma _{\hbox {b}\bar{\hbox {b}}}/\hbox {d}y$ , and the total cross section extrapolated over full phase space, $\sigma _{\text {b}\bar{\text {b}}}$ , are obtained. This measurement is combined with results on inclusive $\hbox {J}/\psi$ production to determine the prompt $\hbox {J}/\psi$ cross sections. The results in p–Pb collisions are then scaled to expectations from pp collisions at the same centre-of-mass energy to derive the nuclear modification factor $R_{\text {pPb}}$ , and compared to models to study possible nuclear modifications of the production induced by cold nuclear matter effects. $R_{\text {pPb}}$ is found to be smaller than unity at low $p_{\mathrm{T}}$ for both $\hbox {J}/\psi$ coming from beauty hadron decays and prompt $\hbox {J}/\psi$

Constraints on jet quenching in p-Pb collisions at sNN\mathbf{\sqrt{s_{NN}}} = 5.02 TeV measured by the event-activity dependence of semi-inclusive hadron-jet distributions

The ALICE Collaboration reports the measurement of semi-inclusive distributions of charged-particle jets recoiling from a high-transverse momentum trigger hadron in p–Pb collisions at sNN=5.02 TeV. Jets are reconstructed from charged-particle tracks using the anti- kT algorithm with resolution parameter R=0.2 and 0.4. A data-driven statistical approach is used to correct the uncorrelated background jet yield. Recoil jet distributions are reported for jet transverse momentum 15<pT,jetch<50GeV/c and are compared in various intervals of p–Pb event activity, based on charged-particle multiplicity and zero-degree neutral energy in the forward (Pb-going) direction. The semi-inclusive observable is self-normalized and such comparisons do not require the interpretation of p–Pb event activity in terms of collision geometry, in contrast to inclusive jet observables. These measurements provide new constraints on the magnitude of jet quenching in small systems at the LHC. In p–Pb collisions with high event activity, the average medium-induced out-of-cone energy transport for jets with R=0.4 and 15<pT,jetch<50GeV/c is measured to be less than 0.4 GeV/c at 90% confidence, which is over an order of magnitude smaller than a similar measurement for central Pb–Pb collisions at sNN=2.76TeV . Comparison is made to theoretical calculations of jet quenching in small systems, and to inclusive jet measurements in p–Pb collisions selected by event activity at the LHC and in d–Au collisions at RHIC

ϕ\phi meson production at forward rapidity in Pb-Pb collisions at sNN=2.76\sqrt{s_\mathrm{NN}}=2.76 TeV

$\phi$ meson measurements provide insight into strangeness production, which is one of the key observables for the hot medium formed in high-energy heavy-ion collisions. ALICE measured $\phi$ production through its decay in muon pairs in Pb–Pb collisions at $\sqrt{s_\mathrm {NN}} = 2.76$ TeV in the intermediate transverse momentum range $2< p_\mathrm {T}< 5$  GeV/c and in the rapidity interval $2.5<y<4$ . The $\phi$ yield was measured as a function of the transverse momentum and collision centrality. The nuclear modification factor was obtained as a function of the average number of participating nucleons. Results were compared with the ones obtained via the kaon decay channel in the same $p_\mathrm {T}$ range at midrapidity. The values of the nuclear modification factor in the two rapidity regions are in agreement within uncertainties

Neutral pion and η\eta meson production in p-Pb collisions at sNN=5.02\sqrt{s_\mathrm{NN}} = 5.02 TeV

Neutral pion and $\eta$ meson invariant differential yields were measured in non-single diffractive p–Pb collisions at $\sqrt{s_{\mathrm{NN}}}$  = 5.02 TeV with the ALICE experiment at the CERN LHC. The analysis combines results from three complementary photon measurements, utilizing the PHOS and EMCal calorimeters and the Photon Conversion Method. The invariant differential yields of $\pi ^{0}$ and $\eta$ meson inclusive production are measured near mid-rapidity in a broad transverse momentum range of $0.3 4$\hbox {GeV}/c$at$0.483 \pm 0.015_{\mathrm{stat}} \pm 0.015_{\mathrm{sys}}$. A deviation from$m_{\mathrm{T}}$scaling is observed for$p_{\mathrm{T}}<$2$\hbox {GeV}/c$. The measured$\eta /\pi ^{0}$ratio is consistent with previous measurements from proton-nucleus and pp collisions over the full$p_{\mathrm{T}}$range. The measured$\eta /\pi ^{0}$ratio at high$p_{\mathrm{T}}$also agrees within uncertainties with measurements from nucleus–nucleus collisions. The$\pi ^{0}$and$\eta $yields in p–Pb relative to the scaled pp interpolated reference,$R_{{\mathrm{pPb}}}$, are presented for$0.3 < p_{\mathrm{T}}<$20$\hbox {GeV}/c$and$0.7 < p_{\mathrm{T}}<$20$\hbox {GeV}/c$, respectively. The results are compared with theoretical model calculations. The values of$R_{{\mathrm{pPb}}}$are consistent with unity for transverse momenta above 2$\hbox {GeV}/c$ . These results support the interpretation that the suppressed yield of neutral mesons measured in Pb–Pb collisions at LHC energies is due to parton energy loss in the hot QCD medium

Λc+\Lambda_{\rm c}^+ production in pp collisions at s=7\sqrt{s} = 7 TeV and in p-Pb collisions at sNN=5.02\sqrt{s_{\rm NN}} = 5.02 TeV

The p$_{T}$-differential production cross section of prompt Λ$_{c}^{+}$ charmed baryons was measured with the ALICE detector at the Large Hadron Collider (LHC) in pp collisions at $\sqrt{s}=7$ TeV and in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV at midrapidity. The Λ$_{c}^{+}$ and ${\overline{\varLambda}}_{\overline{\mathrm{c}}}$ were reconstructed in the hadronic decay modes Λ$_{c}^{+}$ → pK$^{−}$π$^{+}$, Λ$_{c}^{+}$ → pK$_{S}^{0}$ and in the semileptonic channel Λ$_{c}^{+}$ → e$^{+}$ν$_{e}$Λ (and charge conjugates). The measured values of the Λ$_{c}^{+}$ /D$^{0}$ ratio, which is sensitive to the c-quark hadronisation mechanism, and in particular to the production of baryons, are presented and are larger than those measured previously in different colliding systems, centre-of-mass energies, rapidity and p$_{T}$ intervals, where the Λ$_{c}^{+}$ production process may differ. The results are compared with the expectations obtained from perturbative Quantum Chromodynamics calculations and Monte Carlo event generators. Neither perturbative QCD calculations nor Monte Carlo models reproduce the data, indicating that the fragmentation of heavy-flavour baryons is not well understood. The first measurement at the LHC of the Λ$_{c}^{+}$ nuclear modification factor, R$_{pPb}$, is also presented. The R$_{pPb}$ is found to be consistent with unity and with that of D mesons within the uncertainties, and consistent with a theoretical calculation that includes cold nuclear matter effects and a calculation that includes charm quark interactions with a deconfined medium

Neutral pion and η\eta meson production at mid-rapidity in Pb-Pb collisions at sNN\sqrt{s_{NN}} = 2.76 TeV

International audienceNeutral pion and η meson production in the transverse momentum range 1 <pT< 20 GeV/c have been measured at midrapidity by the ALICE experiment at the Large Hadron Collider (LHC) in central and semicentral Pb-Pb collisions at sNN  = 2.76 TeV. These results were obtained using the photon conversion method as well as the Photon Spectrometer (PHOS) and Electromagnetic Calorimeter detectors. The results extend the upper pT reach of the previous ALICE π0 measurements from 12 to 20 GeV/c and present the first measurement of η meson production in heavy-ion collisions at the LHC. The η/π0 ratio is similar for the two centralities and reaches at high pT a plateau value of 0.457 ± 0.013stat ± 0.018syst. A suppression of similar magnitude for π0 and η meson production is observed in Pb-Pb collisions with respect to their production in pp collisions scaled by the number of binary nucleon-nucleon collisions. We discuss the results in terms of Next to Leading Order (NLO) pQCD predictions and hydrodynamic models. The measurements show a stronger suppression than observed at lower center-of-mass energies in the pT range 6 <pT< 10 GeV/c. For pT< 3 GeV/c, hadronization models describe the π0 results while for the η some tension is observed

Global variation in postoperative mortality and complications after cancer surgery: a multicentre, prospective cohort study in 82 countries

© 2021 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 licenseBackground: 80% of individuals with cancer will require a surgical procedure, yet little comparative data exist on early outcomes in low-income and middle-income countries (LMICs). We compared postoperative outcomes in breast, colorectal, and gastric cancer surgery in hospitals worldwide, focusing on the effect of disease stage and complications on postoperative mortality. Methods: This was a multicentre, international prospective cohort study of consecutive adult patients undergoing surgery for primary breast, colorectal, or gastric cancer requiring a skin incision done under general or neuraxial anaesthesia. The primary outcome was death or major complication within 30 days of surgery. Multilevel logistic regression determined relationships within three-level nested models of patients within hospitals and countries. Hospital-level infrastructure effects were explored with three-way mediation analyses. This study was registered with ClinicalTrials.gov, NCT03471494. Findings: Between April 1, 2018, and Jan 31, 2019, we enrolled 15 958 patients from 428 hospitals in 82 countries (high income 9106 patients, 31 countries; upper-middle income 2721 patients, 23 countries; or lower-middle income 4131 patients, 28 countries). Patients in LMICs presented with more advanced disease compared with patients in high-income countries. 30-day mortality was higher for gastric cancer in low-income or lower-middle-income countries (adjusted odds ratio 3·72, 95% CI 1·70–8·16) and for colorectal cancer in low-income or lower-middle-income countries (4·59, 2·39–8·80) and upper-middle-income countries (2·06, 1·11–3·83). No difference in 30-day mortality was seen in breast cancer. The proportion of patients who died after a major complication was greatest in low-income or lower-middle-income countries (6·15, 3·26–11·59) and upper-middle-income countries (3·89, 2·08–7·29). Postoperative death after complications was partly explained by patient factors (60%) and partly by hospital or country (40%). The absence of consistently available postoperative care facilities was associated with seven to 10 more deaths per 100 major complications in LMICs. Cancer stage alone explained little of the early variation in mortality or postoperative complications. Interpretation: Higher levels of mortality after cancer surgery in LMICs was not fully explained by later presentation of disease. The capacity to rescue patients from surgical complications is a tangible opportunity for meaningful intervention. Early death after cancer surgery might be reduced by policies focusing on strengthening perioperative care systems to detect and intervene in common complications. Funding: National Institute for Health Research Global Health Research Unit

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

© 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licenseBackground: Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide. Methods: A multimethods analysis was performed as part of the GlobalSurg 3 study—a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital. Findings: Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3·85 [95% CI 2·58–5·75]; p<0·0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63·0% vs 82·7%; OR 0·35 [0·23–0·53]; p<0·0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer. Interpretation: Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised. Funding: National Institute for Health and Care Research

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially