Seasonal and diurnal variations of greenhouse gases in Florence (Italy): Inferring sources and sinks from carbon isotopic ratios.

In this study, the results of a continuous monitoring of (i) CO2 fluxes, and (ii) CO2 and CH4 concentrations and carbon isotopic ratios (δ13C-CO2 and δ13C-CH4) in air, carried out from 7 to 21 July 2017 and from October 10 to December 15, 2017 in the city centre of Florence, are presented. The measurements were performed from the roof of the historical building of the Ximenes Observatory. CO2 flux data revealed that the metropolitan area acted as a net source of CO2 during the whole observation period. According to the Keeling plot analysis, anthropogenic contributions to atmospheric CO2 were mainly represented by vehicular traffic (about 30%) and natural gas combustion (about 70%), the latter contributing 7 times more in December than in July. Moreover, the measured CO2 fluxes were about 80% higher in fall than in summer, confirming that domestic heating based on natural gas is the dominant CO2 emitting source in the municipality of Florence. Even though the continuous monitoring revealed a shift in the δ13C-CO2 values related to photosynthetic uptake of atmospheric CO2, the isotopic effect induced by plant activity was restricted to few hours in October and, to a lesser extent, in November. This suggests that urban planning policies should be devoted to massively increase green infrastructures in the metropolitan area in order to counterbalance anthropogenic emissions. During fall, the atmospheric CH4 concentrations were sensibly higher with respect to those recorded in summer, whilst the δ13C-CH4 values shifted towards heavier values. The Keeling plot analysis suggested that urban CH4 emissions were largely related to fugitive emissions from the natural gas distribution pipeline network. On the other hand, δ13C-CH4 monitoring allowed to recognize vehicular traffic as a minor CH4 emitting source.

Morphological and functional modifications of the aneurysm-endograft complex following endoluminal treatment of abdominal aortic aneurysms.

PURPOSE: The aim of the study was to evaluate quantitatively the main morphological changes of the abdominal aortic aneurysm (AAA)-endograft (EG) complex following endovascular repair of infrarenal AAA and to evaluate the functional consequences of these changes in terms of rate of complications (endoleaks and thrombosis). We also assessed whether these morphological and functional changes were related to the size of the AAA and to the type of EG used. MATERIALS AND METHODS: Eighty-five patients (M/F=82/3; mean age at time of operation 70.5+/-3.5 years, range 49.9-89.6 years) who underwent endovascular treatment of infrarenal AAA between April 1997 and October 2004 with a follow-up of at least 1 month were considered. All images of 408 preoperative and postoperative computed tomography (CT) studies were reviewed. Statistical analysis was performed with log-rank test on the 85 patients grouped according to AAA diameter <50 mm or < or =50 mm, and on 75 patients grouped according to EG device used (AneuRx, Talent or Excluder). RESULTS: Morphological and dimensional changes involved the diameter (six cases) and length (14 cases) of AAA proximal neck, diameter (36 cases) and length (51 cases) of the aneurysm sac and shape of the stent-graft (47 cases). The prevalence of endoleaks was 37.6% whereas endoluminal thrombosis was observed in 27.1% of patients. AAA growth was significantly correlated (p=0.002) with the preprocedural diameter of the aneurysm sac whereas shrinkage was significantly correlated (p=0.0005) with the EG used. CONCLUSIONS: AAA growth was correlated with the diameter of the aneurysm sac while shrinkage was correlated with the EG used. During follow-up after endovascular repair, patients require careful evaluation of the morphological and dimensional features of the AAA and EG to promptly identify any changes that can anticipate major complications and even conversion to conventional surgery.

[Endovascular treatment for recurrent carotid stenosis]. / Il trattamento endovascolare della restenosi carotidea.

PURPOSE: Surgery of recurrent carotid stenosis (RCS) has higher complication rates than primary carotid endoarterectomy (CEA). Percutaneous transluminal angioplasty (PTA) and stent placement were evaluated retrospectively with a view to proposing then as alternative procedures for RCS. METHODS: In the last 10 years, 19 patients underwent 20 endovascular procedures for RCS at our Department. The mean interval between CEA and PTA was 21 months (range 4-96): 14 patients had PTA within 2 years, 3 patients within 2 and 3 years,and 2 after 3 years. The mean degree of stenosis was 92% (range 80-95%). PTA was performed by balloon catheters (size 4-7 mm) without using cerebral protection device; one self-expanding stent was used to treat RCS after PTA. All patients underwent physical examination and carotid color-coded Doppler sonography in autumn 1999 RESULTS: The procedure was technically successful, with residual stenosis lower than 50%, in 17 of 19 patients; 10 patients showed residual stenosis lower than 30%. Carotid PTA was stopped due to transient neurological deficit in one case. One RCS proved uncompliant even though high-pressure balloon catheters were used. The mean follow-up period in 16 patients was 37.4 months (range 3-99 months). Carotid restenosis after PTA developed in 3 patients, respectively after 29,18 and 7 months. In the last case RCS was successfully treated by stent placement (Wallstent). The primary patency rate was 81%, the secondary patency rate was 88% and the late clinical success rate was of 94%. CONCLUSIONS: In selected cases, PTA without the use of cerebral protection devices and stent placement proved to be a safe and effective alternative treatment for early RCS. When an atherosclerotic lesion is suspected surgery or endovascular treatment with cerebral protection devices are recommended.

[A new conservative approach in the treatment of postoperative digestive-tract fistulas. Mechanical closure by a balloon-catheter]. / Nuova metodica conservativa nel trattamento delle fistole digestive postoperatorie. Chiusura meccanica con catetere con palloncino.

BACKGROUND: Digestive fistulas represent troublesome complication in patients operated in modern surgical wards where the improved surgical procedures and better intensive care enhance the surgeon to perform more aggressive approaches with a high surgical risk index. The management of a patient presenting a digestive-tract fistula is never easy, being its approach either conservative (TPN) or surgical. We applied an alternative surgical procedure consisting in a mechanical closure of the fistula using a balloon-catheter so as to improve outcome in those patients in whom medical tratment did not show satisfactory RESULTS. METHODS: We treated 7 patients presenting a postoperative fistula following several surgical procedures for neoplasms of the digestive system. These fistulas were closed using a Foley or Fogarthy balloon catheter preceeded by radiological and/or endoscopy controls. Once the catheter was placed, oral nutrition was started and some patients were discharged. A progressive deflation of the balloon was performed until complete removal of the catheter upon approx 10 days. RESULTS: We obtained a complete healing of the fistula in 6 patients, within 10 days since catheter placement. Only one patient required another operation. CONCLUSIONS: Our case-series may seem statistically not significant, but varied concerning location and type of fistulas. We observed an excellent outcome using this procedure which allows very short healing period thanks to an early oral nutrition uptake and a decrease in costs mainly due to a short hospital stay and a minor use of expensive drugs (TPN).

Design of efficient all-optical code-division multiplexing systems supporting multiple-bit-rate and equal-bit-rate transmissions.

We present the design of efficient all-optical code-division multiplexing (AOCDM) systems that can transmit multiple-bit-rate (MBR) data signals over a common optical fiber. This is achieved when the proposed strict optical orthogonal code (OOC) of autocorrelation and cross-correlation constraints of 1 are used but without performance degradation compared with the use of conventional OOC. We describe the design of various strict OOC's by employing the useful concept of slot distances, and methods of code construction are also presented. Moreover, we give the principle of MBR data transmissions in an AOCDM system. It is shown that AOCDM systems using the proposed OOC can effectively transmit multiuser MBR and equal-bit-rate (EBR) data with no increase of system complexity. In principle, optimal strict OOC's need the same or a slightly larger system bandwidth compared with optimal conventional OOC's for EBR operation, whereas the former can require a smaller system bandwidth and have a better system performance than the latter for MBR transmissions. A new, to our knowledge, family of strict OOC's is also introduced, whose code words can have nonconstant weights to support multiuser communications with different transmission quality. Furthermore, we design low-cost AOCDM transmitters that are based on an efficient gain-switching scheme that does not require an electro-optic intensity modulator to on-off modulate an optical clock pulse stream at each transmitter. The basic operation principle is also experimentally demonstrated.

[Congenital cysts of the liver. Their instrumental diagnosis and the indications for surgical treatment]. / Cisti congenite del fegato. Diagnosi strumentale e indicazioni al trattamento chirurgico.

The authors report their experience of 8 cases of congenital cysts of the liver describing instrumental examinations used for diagnosis and different surgical operation performed. The Authors believe that the choice of surgical procedure, performed in symptomatic patients and large cysts, has to be according to different parameters as morphology and localization of the cysts and coexisting pathologies. Being non-malignant pathology, conservative surgery often avoids the complications of liver resection.

Ruptured aneurysms of the abdominal aorta.

The experience with ruptured aneurysms of the abdominal aorta is reported. Out of 395 aneurysms observed, 78 were ruptured. A review of case histories and an analysis of the causes of death demonstrate the importance of prompt diagnosis and early operation: delay and the use of complicated (TC) or invasive (angiography) instrumental examinations does not appear justified since clinical symptoms, plain standard abdominal films and ultrasound almost always lead to prompt diagnosis. Notwithstanding the improvements in resuscitation and intensive care procedures, a significant difference persists between the mortality rate of elective surgery (3 to 8%) and that of emergency surgery. There were 28 deaths (36%) for emergency surgery as against 3.4% for operations performed for non-ruptured aneurysms. This confirms the need for preventive treatment of aneurysmal lesions of the abdominal aorta, since even aneurysms smaller than 5 cm may rupture.

Surgery of carotid stenoses associated with contralateral obstruction.

Surgical correction of stenosing lesions of the extracranial cerebral arteries, responsible for reduced encephalic perfusion, may prevent neurological damage, even when there is bilateral involvement of carotid arteries (stenosis + obstruction). Moreover in these patients poor haemodynamical conditions are thought to be responsible for high perioperatory neurological morbidity and mortality. From case histories with no mortality and low neurological morbidity, other authors state that revascularization of a stenotic carotid artery may be carried out with a reasonable safety margin, even when there is an obstructive lesion of the contralateral carotid artery. On the basis of the 64 cases of revascularization carried out in patients with obstructions of an internal carotid artery associated with a stenotic lesion of the contralateral, we have made a survey of the results, indications and possibilities of treatment in these patients.

Vascular access for hemodialysis: Thomas' shunt.

The immediate and long-term results obtained by the use of a Thomas' shunt as a vascular access through which periodical hemodialysis can be performed, are reported. The lower incidence of septic and thrombotic complications due to the iliac instead of the femoral implantation of the shunt, is stressed.

[Importance of combined surgical and heparin treatment of peripheral embolism]. / Importanza del trattamento chirurgico ed eparinico combinato nell'embolia periferica.

The authors dwell upon the physiopathologic and diagnostical aspects of the peripheral embolism, and emphasize the effectiveness of the surgical treatment if associated to the anticoagulative one: the valid results obtained should be ascribed to a prompt diagnosis, a stronger surgical aggressiveness and a constant combination of heparinic and surgical therapy.

Effect of portacaval shunt on circulating free fatty acids and ketone bodies in rats.

To ascertain whether portal diversion affects ketone body (KB) metabolism, fasting circulating levels of free fatty acids (FFA), acetoacetate (AcAc) and B-hydroxybutyrate (3-OH-B) were measured in portacaval shunted (PCS), sham-operated (S-O) and unoperated control (C) rats. In PCS animals blood KB concentration was clearly reduced when compared with S-O and C rats. Beta-hydroxybutyrate level was significantly lower in PCS rats, whereas AcAc concentration did not appear significantly modified in these animals. The hypothesis is proposed that hypoketonemia induced by portal diversion is due to reduced hepatic availability of fatty acids.

[Experimental arterialization of the portal vein in the rat]. / L'arterializzazione sperimentale della vena porta nel ratto.

The article reports an original technique of arterialisation of the portal vein in the rat, after porto-cava shunt, with termino-latreal anastomosis between the proximal stump of the portal vein and the aorta; compared with other techniques, this method has the advantage of avoiding right nephrectomy.