NLO Renormalization in the Hamiltonian Truncation

Hamiltonian Truncation (a.k.a. Truncated Spectrum Approach) is a numerical technique for solving strongly coupled QFTs, in which the full Hilbert space is truncated to a finite-dimensional low-energy subspace. The accuracy of the method is limited only by the available computational resources. The renormalization program improves the accuracy by carefully integrating out the high-energy states, instead of truncating them away. In this paper we develop the most accurate ever variant of Hamiltonian Truncation, which implements renormalization at the cubic order in the interaction strength. The novel idea is to interpret the renormalization procedure as a result of integrating out exactly a certain class of high-energy "tail states". We demonstrate the power of the method with high-accuracy computations in the strongly coupled two-dimensional quartic scalar theory, and benchmark it against other existing approaches. Our work will also be useful for the future goal of extending Hamiltonian Truncation to higher spacetime dimensions.Comment: 28pp + appendices, detailed version of arXiv:1706.0612

High-Precision Calculations in Strongly Coupled Quantum Field Theory with Next-to-Leading-Order Renormalized Hamiltonian Truncation

Hamiltonian Truncation (a.k.a. Truncated Spectrum Approach) is an efficient numerical technique to solve strongly coupled QFTs in d=2 spacetime dimensions. Further theoretical developments are needed to increase its accuracy and the range of applicability. With this goal in mind, here we present a new variant of Hamiltonian Truncation which exhibits smaller dependence on the UV cutoff than other existing implementations, and yields more accurate spectra. The key idea for achieving this consists in integrating out exactly a certain class of high energy states, which corresponds to performing renormalization at the cubic order in the interaction strength. We test the new method on the strongly coupled two-dimensional quartic scalar theory. Our work will also be useful for the future goal of extending Hamiltonian Truncation to higher dimensions d >= 3.Comment: 8 pages, 4 figures; v2: published versio

Immunopathology of Leishmaniasis: an update.

Leishmaniasis represents a severe, increasing, public health problem. The perspective of its control is highly dependent on research progress, on therapeutic manipulations of the immune system, and on vaccine development. There is a correlation between the clinical outcome of Leishmania infection and the cytokine response profile. While a protective immune response against Leishmania has been clearly identified to be related to the influence of a type-1 response and IFN-gamma production, the precise role of T helper (TH) 2 cytokines in non-healing infections requires further exploration. IL-4 and IL-13 (TH2 cytokines) can promote disease progression in cutaneous leishmaniasis, whereas IL-4 would appear to enhance protective type-1 responses in visceral leishmaniasis. Thus, the TH1/TH2 paradigm of resistance/susceptibility to intracellular parasites is probably an oversimplification of a more complicated network of regulatory/counter regulatory interactions. Moreover, the presence of antigen specific regulatory T cell subsets may provide an environment that contributes to the balance between TH1 and TH2 cells. Finally, the involvement of CD8 positive T cells has been described, but the modality of their function in this kind of infection has not been so far elucidated

Immunology of human rickettsial diseases.

Among human rickettsial diseases caused by micro-organisms of the genus Rickettsia (Order Rickettsiales; Family Rickettsiaceae), transmitted to human hosts through arthropod vectors, Mediterranean Spotted Fever, or Boutonneuse Fever, and Rocky Mountain Spotted Fever are considered to be important infectious diseases due to continued prevalence in the developed world, and potentially fatal outcome in severe cases. Proliferation of rickettsiae, at the site of the tick bite, results in focal epidermal and dermal necrosis (tache noire). Rickettsiae then spread via lymphatic vessels to the regional lymph nodes, and, via the bloodstream, to skin, brain, lungs, heart, liver, spleen and kidneys. The pathogen invades and proliferates in the endothelial cells of small vessels, target cells of rickettsial infection, destroying them, and spreading the infection to the endothelia of the vascular tree. The damage of the endothelium, and the subsequent endothelia dysfunction, is followed by the activation of acute phase responses, with alteration in the coagulation and in the cytokine network, together with a transient immune dysregulation, characterized by the reduction in peripheral CD4+ T lymphocytes

How does climate change affect a fishable resource? The case of the royal sea cucumber (Parastichopus regalis) in the central Mediterranean Sea

Holothurians or sea cucumbers are key organisms in marine ecosystems that, by ingesting large quantities of sediments, provide important ecosystem services. Among them, Parastichopus regalis (Cuvier, 1817) is one of the living sea cucumbers in the Mediterranean actively fished for human consumption mainly in Spain, where it is considered a gastronomic delicacy. In the Strait of Sicily (central Mediterranean Sea), this species is not exploited for commercial use even if it is used as bait by longline fishery. P. regalis is frequently caught by bottom trawling and discarded at sea by fishers after catch, and because of its capacity to resist air exposition (at least in cold months), it is reasonable to consider that it is not affected by fishing mortality. Having observed a significant decrease in abundance since 2018, the possible effects of some ecological factors related to current climate change (i.e., temperature and pH) were sought. Generalized additive models (GAMs) were applied to investigate the relationship among the abundance of P. regalis and environmental variables and fishing effort. Long time series of P. regalis densities (2008-2021) were extracted from the MEDITS bottom trawling survey and modeled as function of environmental parameters (i.e., salinity, dissolved oxygen, ammonium, pH, and chlorophyll alpha) and fishing effort (i.e., total number of fishing days per gross tonnage). Our results showed that this species prefers the soft bottoms (50-200 m) of the Adventure Bank and Malta Plateau, and its distribution changed over time with a slight deepening and a rarefaction of spatial distribution starting from 2011 and 2017, respectively. In addition, a positive relationship with pH concentration in surface waters during the larval dispersal phase (3-year lag before the survey) and nutrient concentration at sea bottom (1-year lag) has been found, suggesting that this species is sensitive to climate change and food availability. This study adds new knowledge about the population dynamics of an unexploited stock of P. regalis under fishing impact and environmental under climate change in fisheries management

The IMPACT study: early loss of skeletal muscle mass in advanced pancreatic cancer patients

Abstract Background Pancreatic cancer (PC) patients have multiple risk factors for sarcopenia and loss of skeletal muscle mass (LSMM), which may cause greater treatment toxicities, reduced response to cancer therapy, prolonged hospitalization, impaired quality of life, and worse prognosis. Methods This is a retrospective study on advanced PC patients treated at the Department of Oncology of Udine, Italy, from January 2012 to November 2017. Among 162 patients who received chemotherapy, 94 consecutive patients with an available computed tomography (CT) scan were retrospectively analyzed. The primary objective of our study was to explore if an early LSMM ≥ 10% (measured at first radiological evaluation and compared with baseline) and/or baseline sarcopenia may impact prognosis. Baseline sarcopenia was defined according to Prado's criteria. Skeletal muscle area was measured as cross‐sectional areas (cm2) using CT scan data through the Picture archiving and communication system (PACS) image system. Results In the whole cohort, 48% of patients were ≤70 years old, and 50% had metastatic disease. At baseline, 73% of patients had sarcopenia, and 16% presented a visceral fat area ≥ 44 cm2/m2. Overall, 21% experienced an early LSMM ≥ 10%. Approximately 33% of sarcopenic patients at baseline and ~35% of patients with early LSMM ≥ 10% had a body mass index > 25 kg/m2. Of note, 71% of patients were evaluated by a nutritionist, and 56% received a dietary supplementation (oral and/or parenteral). After a median follow‐up of 30.44 months, median overall survival (OS) was 11.28 months, whereas median progression‐free survival (PFS) was 5.72 months. By multivariate analysis, early LSMM ≥ 10% was significantly associated with worse OS [hazard ratio (HR): 2.16; 95% confidence interval (CI) 1.23–3.78; P = 0.007] and PFS (HR: 2.31; 95% CI 1.30–4.09; P = 0.004). Moreover, an exploratory analysis showed that inflammatory indexes, such as neutrophil–lymphocyte ratio variation, impact early LSMM ≥ 10% (odds ratio 1.31, 95% CI 1.06–1.61, P = 0.010). Conclusions Early LSMM ≥ 10% has a negative prognostic role in advanced PC patients. Further prospective investigations are needed to confirm these preliminary data