1,943 research outputs found

    New X-ray detections of magnetic period-bounce cataclysmic variables from XMM-Newton and SRG/eROSITA

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    A great portion of the cataclysmic variable population, between 40% and 70%, is predicted to be made up of period-bouncers, systems with degenerate donors that have evolved past the period minimum. However, due to their intrinsic faintness, only a few of these systems have been observed and confidently identified so far. We have searched for X-ray emission as a proof of accretion in order to confirm period-bounce cataclysmic variables. In a dedicated XMM-Newton observation of the period-bounce candidate SDSS J151415.65+074446.5 we discovered X-ray modulation at the binary orbital period confirming it as an accreting system. The X-ray light curve and the X-ray spectrum display characteristics of magnetic Polar-type systems allowing for the first time the determination of the X-ray luminosity and mass accretion rate for this system. Catalog data from eROSITA on the SRG satellite for V379 Vir and SDSS J125044.42+154957.4 allowed a first look into the X-ray behavior of period-bounce candidates with this new all-sky instrument. From the eROSITA measurements the X-ray luminosity and mass accretion rate were determined for the first time for SDSS J125044.42+154957.4, and the earlier result for V379 Vir from XMM-Newton was confirmed. All three cataclysmic variables with a magnetic white dwarf and very low-mass donor studied in this work present evidence for X-ray emission at a similar level of Lx[erg/s]1029L_{\rm x}\,{\rm [erg/s]} \approx 10^{29}, which, together with the detection of X-ray orbital modulation in two of them, V379 Vir and SDSS J151415.65+074446.5, unambiguously proves the presence of accretion in these systems. The detection of these period-bouncers at faint X-ray luminosity levels with the all-sky X-ray survey eROSITA offers new prospects for the identification of additional period-bouncers, providing impetus for theoretical studies of binary evolution.Comment: 8 pages, 4 figures. Accepted for publication in A&

    Aspetti igienico-sanitari in ambito urbanistico: conflittualità nelle norme urbanistiche nazionali e locali in tema di sanità pubblica [Hygienic and sanitary aspects in urban planning: contradiction in national and local urban legislation regarding public health]

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    Nowadays, the majority of world population lives in urban areas and this portion is going to increase in the coming decades. The health impact of urban areas is well established and described in scientific literature. Italian health and hygiene legislation dealing with urban health is fragmented and not coordinated with the regulation about environment and city planning. The overlapping of legal competences between different authorities and the conflict of attribution between the Central State and Regional Governments deeply contributed to generate uncertainty. The authors here analyse the Italian regulatory framework and depict its lacks in terms of public health protection

    Diencephalic Syndrome Due to Optic Pathway Gliomas in Pediatric Patients: An Italian Multicenter Study

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    : Diencephalic syndrome (DS) is a rare pediatric condition associated with optic pathway gliomas (OPGs). Since they are slow-growing tumors, their diagnosis might be delayed, with consequences on long-term outcomes. We present a multicenter case series of nine children with DS associated with OPG, with the aim of providing relevant details about mortality and long-term sequelae. We retrospectively identified nine children (6 M) with DS (median age 14 months, range 3-26 months). Four patients had NF1-related OPGs. Children with NF1 were significantly older than sporadic cases (median (range) age in months: 21.2 (14-26) versus 10 (3-17); p = 0.015). Seven tumors were histologically confirmed as low-grade astrocytomas. All patients received upfront chemotherapy and nutritional support. Although no patient died, all of them experienced tumor progression within 5.67 years since diagnosis and were treated with several lines of chemotherapy and/or surgery. Long-term sequelae included visual, pituitary and neurological dysfunction. Despite an excellent overall survival, PFS rates are poor in OPGs with DS. These patients invariably present visual, neurological or endocrine sequelae. Therefore, functional outcomes and quality-of-life measures should be considered in prospective trials involving patients with OPGs, aiming to identify "high-risk" patients and to better individualize treatment

    ICD patients with elevated defibrillation threshold: clinical behavior and therapeutic alternatives

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    FUNDAMENTO: A programação ideal da energia de choque do CDI deve ser pelo menos 10 J acima do limiar de desfibrilação (LDF), necessitando de técnicas alternativas quando o LDF é elevado. OBJETIVO: Avaliar o comportamento clínico dos portadores de CDI com LDF>25 J e a eficácia da terapêutica escolhida. MÉTODOS: Foram selecionados portadores de CDI, entre janeiro de 2000 e agosto de 2004 (banco de dados prospectivo), com LDF>25 J intra-operatório, e analisaram-se: características clínicas, FEVE, resgate de eventos arrítmicos pelo CDI e óbitos. RESULTADOS: dentre 476 pacientes, 16 (3,36%) apresentaram LDF>25J. Idade média de 56,5 anos, sendo 13 pacientes (81%) do sexo masculino. Quanto à cardiopatia de base 09 eram chagásicos, 04 isquêmicos e 03 com etiologia idiopática. A FEVE média dos pacientes foi 37% e 94% utilizavam amiodarona. O seguimento médio foi de 25,3 meses. Em 02 pacientes com LDF > Choque Máximo (CM), foi necessário implante de eletrodo de choque adicional (array), sendo mantido programação com CM em zona de FV (>182bpm) nos demais. Durante o seguimento 03 pacientes apresentaram 67 terapias de choque apropriadas (TCA) com sucesso. Ocorreram 07 óbitos sendo 5 por causas não cardíacas e 2 por insuficiência cardíaca avançada. Os pacientes que foram a óbito apresentaram níveis de LDF maiores (p=0,0446), entretanto sem relação com a causa dos mesmos tendo em vista que não ocorreram TCA sem sucesso. CONCLUSÃO: Nessa coorte de pacientes com CDI, a ocorrência de LDF elevado foi baixa, implicando terapêuticas alternativas. Houve associação com disfunção ventricular grave, entretanto sem correlação com as causas de óbito.BACKGROUND: The ideal programming of the implantable cardioverter defibrillator (ICD) shock energy should be at least 10J above the defibrillation threshold (DFT), requiring alternative techniques when the DFT is elevated. OBJECTIVE: To assess the clinical behavior of ICD patients with DFT>25J and the efficacy of the chosen therapy. METHODS: Patients who had undergone ICD implantation between Jan/00 and Aug/04 (prospective database) and presented intraoperative DFT>25J were selected. The analyzed variables were: clinical characteristics, LVEF, rescue of arrhythmic events from ICD and causes of deaths. RESULTS: among 476 patients, 16 (3.36%) presented DFT>25J. The mean age was 56.5 years, and 13 patients (81%) were men. According to the baseline cardiomyopathy, 09 patients had Chagas' disease, 04 had ischemic cardiomyopathy and 03 had idiopathic cardiomyopathy. Mean LVEF was 0.37 and amiodarone was used by 94% of the patients. Mean follow-up (FU) period was 25.3 months. DFT was higher than maximum energy shock (MES) in 2 patients and it was necessary to implant an additional shock electrode (array). It was programmed MES in ventricular fibrillation zone of ICD therapy in the other patients. In the FU, 03 patients had 67 successful appropriate shock therapies (AST). There were 05 noncardiac and 02 heart failure deaths. The patients who died showed higher DFT levels (p=0.044) without correlation with death because there wasn't unsuccessful AST. CONCLUSION: In this cohort of ICD patients, the occurrence of elevated DFT (>25J) was low, leading to alternative therapies. There was an association with severe ventricular dysfunction, although without correlation to the causes of death

    Functional behavior of patients with conventional pacemakers undergoing cardiac resynchronization

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    FUNDAMENTO: A terapia de ressincronização cardíaca (TRC) é eficiente no tratamento de pacientes com insuficiência cardíaca (IC), disfunção ventricular grave e bloqueio intraventricular. O marcapasso convencional (MPC) em região apical de ventrículo direito provoca alterações da seqüência de ativação normal do coração semelhante às do BRE. Nesse sentido, pacientes com MPC e IC avançada poderiam ser candidatos a TRC, mas reduzidas casuísticas foram avaliadas e não há conclusões definitivas. OBJETIVO: Analisar o comportamento clínico-funcional da terapia de ressincronização cardíaca (TRC) nos portadores de marcapasso convencional. MÉTODOS: Pacientes com MPC, IC-CF(NYHA) III/IV refratária a terapêutica medicamentosa, fração de ejeção do ventrículo esquerdo (FEVE) <35%, foram submetidos a TRC. O comportamento clínico-funcional foi avaliado prospectivamente após seis meses. A redução de uma CF-IC foi estabelecida como resposta efetiva ao procedimento. Foram analisados: duração do QRS (ECG), diâmetro diastólico (DDVE), diâmetro sistólico do ventrículo esquerdo (DSVE) e FEVE ao ECO. A análise estatística utilizou os testes t de Student pareado e a correlação de Spearman. RESULTADOS: Vinte e nove pacientes com idade média de 61,5 anos foram estudados. Seis eram do sexo feminino e houve predomínio da cardiomiopatia chagásica. Em seguimento clínico de 22,7±13 meses, 86,2% dos pacientes melhoraram com a TRC. Nesse grupo, a FEVE média aumentou em 18% (p=0,013); houve redução da duração do QRS em 11,8% (p=0,002) e não houve redução significativa dos diâmetros intracavitários do ventrículo esquerdo. CONCLUSÃO: A TRC é efetiva para pacientes com MPC e IC avançada porque proporciona taxa elevada de responsivos (86,2%), melhora significativa da FEVE e redução da duração do QRS.BACKGROUND: Cardiac resynchronization therapy (CRT) is an efficient treatment for patients with heart failure (HF), severe ventricular dysfunction and intraventricular block. Conventional pacemakers (CPM) implanted in the right ventricular apical area cause alterations in the normal sequence of cardiac activation similar to those induced by LBBB (left bundle-branch block). Therefore, patients with CPM and advanced HF could be candidates to undergo CRT, but as only small numbers of patients have been evaluated so far, definitive conclusions are lacking. OBJECTIVE: To assess the clinical and functional outcome of cardiac resynchronization therapy (CRT) in patients with conventional pacemakers. METHODS: Patients with CPM, who were in NYHA HF functional class III/IV class refractory to drug therapy, and left ventricular ejection fraction (LVEF) ) <35% underwent CRT. Patients’ clinical-functional behavior was assessed prospectively six months after the procedure. The improvement of one HF-functional class was set as an effective response to the procedure. The following was assessed: QRS duration (ECG), diastolic diameter (LVDd), left ventricular systolic diameter (LVSd) and LVEF seen on the echocardiogram. For the statistical analysis, Student’s paired t test and Spearman’s correlation were used. RESULTS: Twenty-nine patients (mean age 61.5) were evaluated. Of these, six were females, and chagasic cardiomyopathy was predominant. During the clinical follow-up of 22.7±13 months, 86.2% of the patients benefited from CRT. Within this group, the mean LVEF increased by 18% (p=0.013), QRS duration dropped by 11.8% (p=0.002) and no significant reduction in left ventricular intracavitary diameters was observed. CONCLUSION: CRT is effective for patients with CPM and advanced HF as it yields a high rate of response (86.2%), significantly improves LVEF and reduces QRS duration

    FLASH radiotherapy with electrons: issues related to the production, monitoring, and dosimetric characterization of the beam

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    Various in vivo experimental works carried out on different animals and organs have shown that it is possible to reduce the damage caused to healthy tissue still preserving the therapeutic efficacy on the tumor tissue, by drastically reducing the total time of dose delivery (&lt;200 ms). This effect, called the FLASH effect, immediately attracted considerable attention within the radiotherapy community, due to the possibility of widening the therapeutic window and treating effectively tumors which appear radioresistant to conventional techniques. Despite the experimental evidence, the radiobiological mechanisms underlying the FLASH effect and the beam parameters contributing to its optimization are not yet known in details. In order to fully understand the FLASH effect, it might be worthy to investigate some alternatives which can further improve the tools adopted so far, in terms of both linac technology and dosimetric systems. This work investigates the problems and solutions concerning the realization of an electron accelerator dedicated to FLASH therapy and optimized for in vivo experiments. Moreover, the work discusses the saturation problems of the most common radiotherapy dosimeters when used in the very high dose-per-pulse FLASH conditions and provides some preliminary experimental data on their behavior
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