On the stability of high-speed milling with spindle speed variation

Spindle speed variation is a well-known technique to suppress regenerative machine tool vibrations, but it is usually considered to be effective only for low spindle speeds. In this paper, the effect of spindle speed variation is analyzed in the high-speed domain for spindle speeds corresponding to the first flip (period doubling) and to the first Hopf lobes. The optimal amplitudes and frequencies of the speed modulations are computed using the semidiscre- tization method. It is shown that period doubling chatter can effectively be suppressed by spindle speed variation, although, the technique is not effective for the quasiperiodic chatter above the Hopf lobe. The results are verified by cutting tests. Some special cases are also discussed where the practical behavior of the system differs from the predicted one in some ways. For these cases, it is pointed out that the concept of stability is understood on the scale of the principal period of the system—that is, the speed modulation period for variable spindle speed machining and the tooth passing period for constant spindle speed machining

COVID-19 infection in patients on long-term home parenteral nutrition for chronic intestinal failure

To investigate the incidence and the severity of COVID-19 infection in patients enrolled in the database for home parenteral nutrition (HPN) for chronic intestinal failure (CIF) of the European Society for Clinical Nutrition and Metabolism (ESPEN).Period of observation: March 1st, 2020 March 1st, 2021.patients included in the database since 2015 and still receiving HPN on March 1st, 2020 as well as new patients included in the database during the period of observation. Data related to the previous 12 months and recorded on March 1st 2021: 1) occurrence of COVID-19 infection since the beginning of the pandemic (yes, no, unknown); 2) infection severity (asymptomatic; mild, no-hospitalization; moderate, hospitalization no-ICU; severe, hospitalization in ICU); 3) vaccinated against COVID-19 (yes, no, unknown); 4) patient outcome on March 1st 2021: still on HPN, weaned off HPN, deceased, lost to follow up.Sixty-eight centres from 23 countries included 4680 patients. Data on COVID-19 were available for 55.1% of patients. The cumulative incidence of infection was 9.6% in the total group and ranged from 0% to 21.9% in the cohorts of individual countries. Infection severity was reported as: asymptomatic 26.7%, mild 32.0%, moderate 36.0%, severe 5.3%. Vaccination status was unknown in 62.0% of patients, non-vaccinated 25.2%, vaccinated 12.8%. Patient outcome was reported as: still on HPN 78.6%, weaned off HPN 10.6%, deceased 9.7%, lost to follow up 1.1%. A higher incidence of infection (p = 0.04), greater severity of infection (p < 0.001) and a lower vaccination percentage (p = 0.01) were observed in deceased patients. In COVID-19 infected patients, deaths due to infection accounted for 42.8% of total deaths.In patients on HPN for CIF, the incidence of COVID-19 infection differed greatly among countries. Although the majority of cases were reported to be asymptomatic or have mild symptoms only, COVID-19 was reported to be fatal in a significant proportion of infected patients. Lack of vaccination was associated with a higher risk of death

Increased Mucosal Thrombin is Associated with Crohn's Disease and Causes Inflammatory Damage through Protease-activated Receptors Activation

Background and Aims: Thrombin levels in the colon of Crohn's disease patients have recently been found to be elevated 100-fold compared with healthy controls. Our aim was to determine whether and how dysregulated thrombin activity could contribute to local tissue malfunctions associated with Crohn's disease. Methods: Thrombin activity was studied in tissues from Crohn's disease patients and healthy controls. Intracolonic administration of thrombin to wild-type or protease-activated receptor-deficient mice was used to assess the effects and mechanisms of local thrombin upregulation. Colitis was induced in rats and mice by the intracolonic administration of trinitrobenzene sulphonic acid. Results: Active forms of thrombin were increased in Crohn's disease patient tissues. Elevated thrombin expression and activity were associated with intestinal epithelial cells. Increased thrombin activity and expression were also a feature of experimental colitis in rats. Colonic exposure to doses of active thrombin comparable to what is found in inflammatory bowel disease tissues caused mucosal damage and tissue dysfunctions in mice, through a mechanism involving both protease-activated receptors -1 and -4. Intracolonic administration of the thrombin inhibitor dabigatran, as well as inhibition of protease-activated receptor-1, prevented trinitrobenzene sulphonic acid-induced colitis in rodent models. Conclusions: Our data demonstrated that increased local thrombin activity, as it occurs in the colon of patients with inflammatory bowel disease, causes mucosal damage and inflammation. Colonic thrombin and protease-activated receptor-1 appear as possible mechanisms involved in mucosal damage and loss of function and therefore represent potential therapeutic targets for treating inflammatory bowel disease

COVID-19 infection in patients on long-term home parenteral nutrition for chronic intestinal failure

Background and aims: To investigate the incidence and the severity of COVID-19 infection in patients enrolled in the database for home parenteral nutrition (HPN) for chronic intestinal failure (CIF) of the European Society for Clinical Nutrition and Metabolism (ESPEN). Methods: Period of observation: March 1st, 2020 March 1st, 2021. Inclusion criteria: patients included in the database since 2015 and still receiving HPN on March 1st, 2020 as well as new patients included in the database during the period of observation. Data related to the previous 12 months and recorded on March 1st 2021: 1) occurrence of COVID-19 infection since the beginning of the pandemic (yes, no, unknown); 2) infection severity (asymptomatic; mild, no-hospitalization; moderate, hospitalization no-ICU; severe, hospitalization in ICU); 3) vaccinated against COVID-19 (yes, no, unknown); 4) patient outcome on March 1st 2021: still on HPN, weaned off HPN, deceased, lost to follow up. Results: Sixty-eight centres from 23 countries included 4680 patients. Data on COVID-19 were available for 55.1% of patients. The cumulative incidence of infection was 9.6% in the total group and ranged from 0% to 21.9% in the cohorts of individual countries. Infection severity was reported as: asymptomatic 26.7%, mild 32.0%, moderate 36.0%, severe 5.3%. Vaccination status was unknown in 62.0% of patients, non-vaccinated 25.2%, vaccinated 12.8%. Patient outcome was reported as: still on HPN 78.6%, weaned off HPN 10.6%, deceased 9.7%, lost to follow up 1.1%. A higher incidence of infection (p = 0.04), greater severity of infection (p &lt; 0.001) and a lower vaccination percentage (p = 0.01) were observed in deceased patients. In COVID-19 infected patients, deaths due to infection accounted for 42.8% of total deaths. Conclusions: In patients on HPN for CIF, the incidence of COVID-19 infection differed greatly among countries. Although the majority of cases were reported to be asymptomatic or have mild symptoms only, COVID-19 was reported to be fatal in a significant proportion of infected patients. Lack of vaccination was associated with a higher risk of death

The effects of long-term total parenteral nutrition on gut mucosal immunity in children with short bowel syndrome: a systematic review

BACKGROUND: Short bowel syndrome (SBS) is defined as the malabsorptive state that often follows massive resection of the small intestine. Most cases originate in the newborn period and result from congenital anomalies. It is associated with a high morbidity, is potentially lethal and often requires months, sometimes years, in the hospital and home on total parenteral nutrition (TPN). Long-term survival without parenteral nutrition depends upon establishing enteral nutrition and the process of intestinal adaptation through which the remaining small bowel gradually increases its absorptive capacity. The purpose of this article is to perform a descriptive systematic review of the published articles on the effects of TPN on the intestinal immune system investigating whether long-term TPN induces bacterial translocation, decreases secretory immunoglobulin A (S-IgA), impairs intestinal immunity, and changes mucosal architecture in children with SBS. METHODS: The databases of OVID, such as MEDLINE and CINAHL, Cochran Library, and Evidence-Based Medicine were searched for articles published from 1990 to 2001. Search terms were total parenteral nutrition, children, bacterial translocation, small bowel syndrome, short gut syndrome, intestinal immunity, gut permeability, sepsis, hyperglycemia, immunonutrition, glutamine, enteral tube feeding, and systematic reviews. The goal was to include all clinical studies conducted in children directly addressing the effects of TPN on gut immunity. RESULTS: A total of 13 studies were identified. These 13 studies included a total of 414 infants and children between the ages approximately 4 months to 17 years old, and 16 healthy adults as controls; and they varied in design and were conducted in several disciplines. The results were integrated into common themes. Five themes were identified: 1) sepsis, 2) impaired immune functions: In vitro studies, 3) mortality, 4) villous atrophy, 5) duration of dependency on TPN after bowel resection. CONCLUSION: Based on this exhaustive literature review, there is no direct evidence suggesting that TPN promotes bacterial overgrowth, impairs neutrophil functions, inhibits blood's bactericidal effect, causes villous atrophy, or causes to death in human model. The hypothesis relating negative effects of TPN on gut immunity remains attractive, but unproven. Enteral nutrition is cheaper, but no safer than TPN. Based on the current evidence, TPN seems to be safe and a life saving solution

Lessons learned from the first European project on the integration of infectious diseases in testing services, data collection and country responses.

Despite the progress in effective treatments for HIV, viral hepatitis, tuberculosis and sexually transmitted infections (STIs), these infections remain major public health concerns across Europe. Recurring challenges of late presentation and unprioritized prevention programmes need to be effectively addressed in order to control and prevent transmission and ensure that people are diagnosed early and rapidly enter the care system. The prevalence of co-infections is high due to the social context of key populations and the shared modes of transmission, varying with local epidemiology, which underlines the need to combine efforts throughout the continuum of care