The Resolution of the Ideal of 2×2 Minors of a 2×nMatrix of Linear Forms

AbstractLetkbe an algebraically closed field and letS=k[x1,…,xm]. LetMbe a 2×nmatrix of linear forms ofSand letI2(M) denote the ideal generated by the determinants of the 2×2 minors ofM. We study in this paper the minimal finite free resolution ofS/I2(M) as anS-module.Mcorresponds to a certain 2-dimensional vector spaceLofm×nmatrices, that is, to a matrix pencil. The Kronecker–Weierstrass theory of such matrix pencils provides a normal form forL, and we characterize the resolution ofS/I2(M) in terms of this normal form. In particular, if the general element ofLis injective, we explicitly construct the minimal resolution ofS/I2(M) by repeated application of the horseshoe lemma. For anyM, we express the regularity ofS/I2(M) as a function of the invariants ofL

The Stromal and Immune Landscape of Colorectal Cancer Progression during Anti-EGFR Therapy

The EGFR antibodies cetuximab and panitumumab are used in patients with EGFR-expressing, KRAS, or NRAS wild-type metastatic colorectal cancer (mCRC) either in combination with standard chemotherapy, for first-line treatment, or as single agents when tumors become resistant to prior cytotoxic regimens. However, only 20% of individuals experience tumor regressions, and only an additional 30% have some extent of clinical benefit in terms of disease stabilization (Douillard et al., 2013). This relatively low response rate is compounded by the dismal reality that subjects who initially respond typically become refractory to treatment in a period of months. In this issue of Cancer Cell, Woolston et al., 2019 offer a comprehensive picture of the identifying traits of primary and acquired resistance to cetuximab in a cohort of 35 mCRC patients (Figure 1). In a difference from previous studies, mostly conducted in a retrospective manner and focused on a small number of candidate biomarkers, here the authors embarked on a prospective trial whereby biopsies collected before initiation of single-agent cetuximab and at the time of disease progression were subjected to whole-exome and RNA-sequencing analyses and immunophenotyping

Night-time shift work and related stress responses: A study on security guards

Work-related stress can induce a break in homeostasis by placing demands on the body that are met by the activation of two different systems, the hypothalamic\u2013pituitary\u2013adrenal axis and the sympathetic nervous system. Night-shift work alters the body\u2019s exposure to the natural light\u2013 dark schedule and disrupts circadian (daily) rhythms. The greatest effect of night-shift work is the disruption of circadian rhythms. The impact that these disruptions may have on the pathogenesis of many diseases, including cancer, is unknown. This study aims to discover the relationship among three different job activities of security guards and their stress-related responses by evaluating salivary cortisol levels and blood pressure. Methods: Ninety security guards, including night-time workers and night-time and daily-shift workers, were recruited for this study. Each security guard provided two saliva samples before and after three scheduled time points: (i) at 22:00, (ii) at 06:30, and (iii) at 14:00. Results: The results of the study showed a significant alteration in cortisol levels. Night-time shift cortisol levels significantly increased before and after the work shifts. A physiological prevalence of the vagal tone on the cardiocirculatory activity was found during night-shift work. Conclusions: This study indicates that cortisol levels and blood pressure are sensitive markers of biological responses to severe work stress. Shift-change consequences may occur at the end of the night shift when there is a significant increase in the cortisol level and a significant variation in cardiovascular parameters

Determinants associated with obesity and physical activity in the public and private schools of the city of palermo

Introduction: Obesity is a medical condition associated with premature death and it is a risk factor for many chronic diseases. In this context, performing a regular physical activity promotes a healthy lifestyle, with significant health benefits. The aim of the study was to investigate behaviors that increase the risk of obesity and the determinants that encourage physical activity among adolescents. Materials and methods: The HBSC (Health Behavior in School-aged Children) questionnaire was administered to students in Palermo's private and public schools. For the sampling of public schools the protocol of the HBSC Surveillance System was followed; for the private ones it was opportunistic. Results: Private school students are more likely to exercise more than 3 days per week (OR 1.58) and are more likely to exercise more than 2 times a week (OR 2.08). Obese students in private schools in Palermo are more likely to perform physical activity for less than 3 days a week (OR 3.52) and a higher risk of not having breakfast (OR 10.11) and a snack between main meals (OR 3.82) every day. For all the schools examined, it emerged that obese subjects are more likely not to consume fruit (OR 3.13), to stay more than 6 hours a day in front of PCs and video games (OR 3.24) and more than 2 hours a day in front of TV (OR 3.79). Male students are more likely to perform physical activity for more than 3 days per week (OR 1.48) and intense physical activity at least 2 times per week (OR 1.76) Conclusions: It is necessary to intervene early with training on school and family in order to promote correct and responsible food choices and increase the level of physical activity among students. Therefore prevention interventions must be an integral part of coherent strategies based on tests of agreed effectiveness in order to minimize the risk linked to the development of diseases

Immunogenomics of Colorectal Tumors: Facts and Hypotheses on an Evolving Saga

Different mutational burden only partially explains the different response of MSI and MSS CRCs to immunotherapy. Neoantigen load, as measured using available prediction algorithms, is not sufficiently accurate for implementation into clinical decision making. Abundant immune infiltration in the tumor tissue is likely to have high prognostic value, but not an equally high predictive value in terms of response to immunotherapy. The intrinsic characteristics of MSI and MSS CRCs determine differences in their evolutionary paths, which inevitably influence the way the immune system sculpts tumor clonal and subclonal dynamics. Immunotherapy with immune checkpoint inhibitors is an approved treatment option for a subpopulation of patients with colorectal cancers that display microsatellite instability. However, not all individuals within this subgroup respond to immunotherapy, and molecular biomarkers for effective patient stratification are still lacking. In this opinion article, we provide an overview of the different biological parameters that contribute to rendering colorectal cancers with microsatellite instability potentially sensitive to immunotherapy. We critically discuss the reasons why such parameters have limited predictive value and the implications therein. We also consider that a more informed knowledge of response determinants in this tumor subtype could help understand the mechanisms of immunotherapy resistance in microsatellite stable tumors. We conclude that the dynamic nature of the interactions between cancer and immune cells complicates conventional biomarker development and argue that a new generation of adaptive metrics, borrowed from evolutionary genetics, may improve the effectiveness and reliability of clinical decision making

PG 1613+426: a new sdB pulsator

We report the detection of short period oscillations in the hot subdwarf B (sdB) star PG 1613+426 from time-series photometry carried out with the 91-cm Cassegrain telescope of the Catania Astrophysical Observatory. This star, which is brighter than the average of the presently known sdB pulsators, with B = 14.14 mag, has $T_{\rm eff}=34 400 {\rm K}$ and $\log g = 5.97$, its position is near the hot end of the sdB instability strip, and it is a pulsator with a well observed peak in the power spectrum at $144.18\pm 0.06 \rm s$. This star seems to be well suited for high precision measurements, which could detect a possible multi-mode pulsation behaviourComment: 3 pages, 4 figures. to appear on A&