Muon `Depth -- Intensity' Relation Measured by LVD Underground Experiment and Cosmic-Ray Muon Spectrum at Sea Level

We present the analysis of the muon events with all muon multiplicities collected during 21804 hours of operation of the first LVD tower. The measured angular distribution of muon intensity has been converted to the `depth -- vertical intensity' relation in the depth range from 3 to 12 km w.e.. The analysis of this relation allowed to derive the power index, $\gamma$, of the primary all-nucleon spectrum: $\gamma=2.78 \pm 0.05$. The `depth -- vertical intensity' relation has been converted to standard rock and the comparison with the data of other experiments has been done. We present also the derived vertical muon spectrum at sea level.Comment: 7 pages, 3 figures, to be published on Phys. Rev.

Upper Limit on the Prompt Muon Flux Derived from the LVD Underground Experiment

We present the analysis of the muon events with all muon multiplicities collected during 21804 hours of operation of the first LVD tower. The measured depth-angular distribution of muon intensities has been used to obtain the normalization factor, A, the power index, gamma, of the primary all-nucleon spectrum and the ratio, R_c, of prompt muon flux to that of pi-mesons - the main parameters which determine the spectrum of cosmic ray muons at the sea level. The value of gamma = 2.77 +/- 0.05 (68% C.L.) and R_c < 2.0 x 10^-3 (95% C.L.) have been obtained. The upper limit to the prompt muon flux favours the models of charm production based on QGSM and the dual parton model.Comment: 10 pages, 4 figures, RevTex. To appear in Phys. Rev.

Global overview of the management of acute cholecystitis during the COVID-19 pandemic (CHOLECOVID study)

Background: This study provides a global overview of the management of patients with acute cholecystitis during the initial phase of the COVID-19 pandemic. Methods: CHOLECOVID is an international, multicentre, observational comparative study of patients admitted to hospital with acute cholecystitis during the COVID-19 pandemic. Data on management were collected for a 2-month study interval coincident with the WHO declaration of the SARS-CoV-2 pandemic and compared with an equivalent pre-pandemic time interval. Mediation analysis examined the influence of SARS-COV-2 infection on 30-day mortality. Results: This study collected data on 9783 patients with acute cholecystitis admitted to 247 hospitals across the world. The pandemic was associated with reduced availability of surgical workforce and operating facilities globally, a significant shift to worse severity of disease, and increased use of conservative management. There was a reduction (both absolute and proportionate) in the number of patients undergoing cholecystectomy from 3095 patients (56.2 per cent) pre-pandemic to 1998 patients (46.2 per cent) during the pandemic but there was no difference in 30-day all-cause mortality after cholecystectomy comparing the pre-pandemic interval with the pandemic (13 patients (0.4 per cent) pre-pandemic to 13 patients (0.6 per cent) pandemic; P = 0.355). In mediation analysis, an admission with acute cholecystitis during the pandemic was associated with a non-significant increased risk of death (OR 1.29, 95 per cent c.i. 0.93 to 1.79, P = 0.121). Conclusion: CHOLECOVID provides a unique overview of the treatment of patients with cholecystitis across the globe during the first months of the SARS-CoV-2 pandemic. The study highlights the need for system resilience in retention of elective surgical activity. Cholecystectomy was associated with a low risk of mortality and deferral of treatment results in an increase in avoidable morbidity that represents the non-COVID cost of this pandemic

Understanding the effect of MPEG-PCE's microstructure on the adsorption and hydration of OPC

Polycarboxylic ethers or polycarboxylate (PCEs) are one of the most employed superplasticizers in construction. However, the understanding of their microstructure–property relationship is still incomplete. Recently, a theoretical model was proposed that relates the microstructure–conformation of the PCE to its effect on the adsorption onto cement particles and cement hydration time. In this work, the effects of a wide range of PCEs with different side chain lengths (P = 5, Group 1; P = 20, Group 2; and P = 45 and 113, Group 3) having flexible backbone worm conformation except one which has stretch backbone worm conformation (P = 113) were experimentally investigated for their effect on adsorption and cement hydration. It is found that PCEs from Group 1 show electrostatic repulsion as dispersing mechanism, unlike PCEs from Groups 2 and 3. Furthermore, the prediction of the theoretical model is also assessed for all the studied PCEs. Only Group 1 PCEs (shortest side chains) showed deviation from the theoretical predictions, and it was attributed to their different behaviors from the standard PCEs for which the theoretical model was developed.The authors thank the financial support received from EUSKAMPUS Fundazioa, POLYMAT (UPV/EHU), and Tecnalia to carry out the project. The work was carried out under the umbrella of the LTC “Green Concrete”. The authors would like to acknowledge the funding from Misiones Euskampus 1.0 (project “HEMEN”). J. R. Leiza and I. Emaldi also acknowledge the funding from Basque Government (Project IT-1512-22) and MINECO (PID2021-123146OB-I00), and J. S. Dolado acknowledges the funding from the Gobierno Vasco UPV/EHU (Project No. IT-1246-19).Peer reviewe

Characterization of comb shaped MAA‐co‐PEGMA copolymers synthesized by free‐radical polymerization

Methacrylic acid‐co‐polyethylene glycol methacrylate (MAA‐co‐PEGMA) copolymers (also known as MPEG‐type polycarboxylate ether (PCE) superplasticizers) present comb‐shaped microstructure and they are generally used as dispersants of inorganic particles in cementitious formulations. Application properties of the PCEs strongly depend on the molecular structure and therefore accurate characterization of the microstructure is necessary to fully understand the structure–property relationship. In this work, MAA‐co‐PEGMA copolymers with various lateral size chain lengths and homogeneous copolymer compositions are synthesized by starved‐feed semibatch copolymerization. Molar mass and radius of gyration distributions and monomer sequence distribution are measured using size exclusion chromatography coupled with multi angle light scattering (SEC/MALS/refractive index, RI) and 1H and 13C NMR, respectively. Furthermore, it is proved that the experimental radius of gyration compares well with the prediction of a theoretical model for the radius of gyration that uses characteristic parameters of the microstructure of the PCEs (e.g., average molar masses). This confirms the accuracy of the measurements of the absolute molar masses for the MPEG‐type PCEs synthesized by free‐radical (co)polymerization.The authors thank the financial support received from EUSKAMPUS Fundazioa, POLYMAT (UPV/EHU) and Tecnalia Research & Innovation to carry out this research. Financial support from the Basque Government (GV‐IT‐999‐16, PI2017‐11) and MINECO (CTQ2017‐87841‐R) is gratefully acknowledged.Peer reviewe

Modelling and control of the microstructure of comb-like poly(MAA-: Co-PEGMA) water-soluble copolymers

Water-soluble copolymers of methacrylic acid and poly(ethylene glycol) methacrylate (poly(MAA-co-PEGMA)) present a comb like structure. These macromolecules under alkaline conditions present an anionic backbone and uncharged side chains. The control of their microstructure is of paramount importance for application as cementitious admixtures. With this in mind, open-loop control strategies including monomer starved and optimal addition policies were employed to obtain homogeneous composition copolymers. A detailed mathematical model was developed for the copolymerization of MAA and PEGMA5 and was used to develop optimal feeding strategies. The mathematical model provides a good representation of the experimental data sets and copolymers with desired homogeneous copolymer compositions were synthesized within the shortest possible reaction times.The authors thank the financial support received from EUSKAMPUS Fundazioa, POLYMAT (UPV/EHU) and Tecnalia Research & Innovation to carry out the project. The SGIker J. I. Miranda is gratefully acknowledged for his help with the NMR analysis and Dr Amaia Agirre for molar mass analysis. S. Hamzehlou acknowledges the University of the Basque Country (UPV/EHU) for the “Contratación para la especialización de personal investigador doctor” postdoctoral grant