The wind profile in the atmospheric stable boundary layer over complex terrain and heterogeneous surfaces: limitations of local similarity theory

L'indagine ha riguardato il profilo del vento nei primi 30 metri dello strato limite atmosferico stabile nell'ambito della teoria di similarità locale. Ad oggi, diversi esperimenti hanno confermato la validità della teoria per strati-limite su terreni livellati e superfici omogenee. Tali condizioni ideali sono però infrequenti nella realtà ed è perciò importante capire quali siano i limiti della similarità locale per strati-limite su terreni complessi e superfici disomogenee. Entrambe le condizioni sono presenti a Ny-Alesund (Svalbard, Norvegia) dove il Consiglio Nazionale delle Ricerche (CNR), nel 2009, ha installato una torre di 30 m, la Amudsen-Nobile Climate Change Tower (CCT), per lo studio dello strato-limite artico. Il lavoro di tesi ha riguardato misure di vento e turbolenza acquisite sulla CCT da maggio 2012 a maggio 2014. Il confronto tra le velocità del vento misurate dagli anemometri installati sulla CCT, ha rivelato criticità nel dato sonico manifestatesi con sovrastime sistematiche e maggiore erraticità rispetto alle misure provenienti dagli anemometri a elica. Un test condotto fra diversi metodi per il calcolo dei gradienti verticali della velocità del vento ha rivelato scarsa sensibilità dei risultati ottenuti al particolare metodo utilizzato. Lo studio ha riguardato i gradienti verticali adimensionali della velocità del vento nei primi 30-m dello strato limite stabile. Deviazioni significative tra i tra le osservazioni e i valori predetti dalla similarità locale sono state osservate in particolare per i livelli più distanti dal suolo e per valori crescenti del parametro di stabilità z/L (L, lunghezza di Obukhov locale). In particolare, si sono osservati gradienti adimensionali inferiori a quelli predetti dalle più usate relazioni di flusso-gradiente. Tali deviazioni, presenti perlopiù per z/L>0.1, sono state associate ad un effetto di accentuazione della turbolenza da parte delle irregolarità del terreno. Per condizioni meno stabili, z/L<0.1, scarti positivi tra i gradienti osservati e quelli attesi sono stati attribuiti alla formazione di strati limite interni in condizioni di vento dal mare verso la costa. Sono stati proposti diversi metodi per la stima dell'effetto della self-correlazione nella derivazione delle relazioni di flusso-gradiente, dovuta alla condivisione della variabile u*. La formula per il coefficiente lineare di self correlazione e le sue distribuzioni di probabilità empiriche sono state derivate e hanno permesso di stimare il livello di self-correlazione presente nel dataset considerato.

Micromass co-culture of human articular chondrocytes and human bone marrow mesenchymal stem cells to investigate stable neocartilage tissue formation in vitro

Cell therapies for articular cartilage defects rely on expanded chondrocytes. Mesenchymal stem cells (MSC) represent an alternative cell source should their hypertrophic differentiation pathway be prevented. Possible cellular instruction between human articular chondrocytes (HAC) and human bone marrow MSC was investigated in micromass pellets. HAC and MSC were mixed in different percentages or incubated individually in pellets for 3 or 6 weeks with and without TGF-beta1 and dexamethasone (±T±D) as chondrogenic factors. Collagen II, collagen X and S100 protein expression were assessed using immunohistochemistry. Proteoglycan synthesis was evaluated applying the Bern score and quantified using dimethylmethylene blue dye binding assay. Alkaline phosphatase activity (ALP) was detected on cryosections and soluble ALP measured in pellet supernatants. HAC alone generated hyaline-like discs, while MSC formed spheroid pellets in ±T±D. Co-cultured pellets changed from disc to spheroid shape with decreasing number of HAC, and displayed random cell distribution. In -T-D, HAC expressed S100, produced GAG and collagen II, and formed lacunae, while MSC did not produce any cartilage-specific proteins. Based on GAG, collagen type II and S100 expression chondrogenic differentiation occurred in -T-D MSC co-cultures. However, quantitative experimental GAG and DNA values did not differ from predicted values, suggesting only HAC contribution to GAG production. MSC produced cartilage-specific matrix only in +T+D but underwent hypertrophy in all pellet cultures. In summary, influence of HAC on MSC was restricted to early signs of neochondrogenesis. However, MSC did not contribute to the proteoglycan deposition, and HAC could not prevent hypertrophy of MSC induced by chondrogenic stimuli.

Heart rate variability and biomarkers of systemic inflammation in patients with stable coronary heart disease: findings from the Heart and Soul Study

Chronic low-grade systemic inflammation is a key component in atherogenesis. Decreased heart rate variability (HRV), a strong predictor of cardiovascular events, has been associated with elevations in circulating levels of C-reactive protein (CRP), interleukin (IL)-6, and fibrinogen in apparently healthy individuals. We investigated whether decreased HRV is associated with inflammatory markers in patients with coronary heart disease (CHD).

Catheter ablation of stable ventricular tachycardia before defibrillator implantation in patients with coronary heart disease (VTACH): a multicentre randomised controlled trial

In patients with ventricular tachycardia (VT) and a history of myocardial infarction, intervention with an implantable cardioverter defibrillator (ICD) can prevent sudden cardiac death and thereby reduce total mortality. However, ICD shocks are painful and do not provide complete protection against sudden cardiac death. We assessed the potential benefit of catheter ablation before implantation of a cardioverter defibrillator.

Controversies in cardiovascular medicine: Chronic stable coronary artery disease: drugs vs. revascularization

Coronary artery disease remains the leading cause of mortality in most industrialized countries, although age-standardized mortality related to coronary artery disease (CAD) has decreased by more than 40% during the last two decades. Coronary atherosclerosis may cause angina pectoris, myocardial infarction, heart failure, arrhythmia, and sudden death. Medical management of atherosclerosis and its manifestation aims at retardation of progression of plaque formation, prevention of plaque rupture, and subsequent events and treatment of symptoms, when these occur as well as treatment of the sequelae of the disease. Revascularization by either percutaneous coronary intervention (PCI) or coronary artery bypass surgery (CABG) is performed as treatment of flow-limiting coronary stenosis to reduce myocardial ischaemia. In high-risk patients with acute coronary syndromes (ACS), a routine invasive strategy with revascularization in most patients provides the best outcome with a significant reduction in death and myocardial infarction compared with an initial conservative strategy. Conversely, the benefit of revascularization among patients with chronic stable CAD has been called into question. This review will provide information that revascularization exerts favourable effects on symptoms, quality of life, exercise capacity, and survival, particularly in those with extensive CAD and documented moderate-to-severe ischaemia. Accordingly, CABG and PCI should be considered a valuable adjunct rather than an alternative to medical therapy.

Fatal Left Ventricular Rupture and Pericardial Tamponade Following a Horse Kick to the Chest

ABSTRACT: Horse kicks are rare incidents-especially, if they end in fatality. In this case, a 13-year-old girl collapsed 3 minutes after sustaining a kick to the chest from a pony. Resuscitation attempts were unsuccessful. Postmortem computed tomography and magnetic resonance imaging were performed before autopsy.Imaging revealed a 3-cm long laceration of the left ventricle and a large pericardial effusion. Using segmentation techniques, the amount of blood inside the pericardium was determined. These findings correlated well with the autopsy findings. Pericardial tamponade was determined at autopsy to be the cause of death.Postmortem imaging may prove useful for the diagnosis of these types of injury, but further studies are needed to document accuracy.

Generation and characterization of stable, highly concentrated titanium dioxide nanoparticle aerosols for rodent inhalation studies

The intensive use of nano-sized titanium dioxide (TiO2) particles in many different applications necessitates studies on their risk assessment as there are still open questions on their safe handling and utilization. For reliable risk assessment, the interaction of TiO2 nanoparticles (NP) with biological systems ideally needs to be investigated using physico-chemically uniform and well-characterized NP. In this article, we describe the reproducible production of TiO2 NP aerosols using spark ignition technology. Because currently no data are available on inhaled NP in the 10–50 nm diameter range, the emphasis was to generate NP as small as 20 nm for inhalation studies in rodents. For anticipated in vivo dosimetry analyses, TiO2 NP were radiolabeled with 48V by proton irradiation of the titanium electrodes of the spark generator. The dissolution rate of the 48V label was about 1% within the first day. The highly concentrated, polydisperse TiO2 NP aerosol (3–6 × 106 cm−3) proved to be constant over several hours in terms of its count median mobility diameter, its geometric standard deviation, and number concentration. Extensive characterization of NP chemical composition, physical structure, morphology, and specific surface area was performed. The originally generated amorphous TiO2 NP were converted into crystalline anatase TiO2 NP by thermal annealing at 950 °C. Both crystalline and amorphous 20-nm TiO2 NP were chain agglomerated/aggregated, consisting of primary particles in the range of 5 nm. Disintegration of the deposited TiO2 NP in lung tissue was not detectable within 24 h.

Impact of non-steroidal anti-inflammatory drugs (NSAIDs) on cardiovascular outcomes in patients with stable atherothrombosis or multiple risk factors

We aimed to assess whether the use of non-steroidal anti-inflammatory drugs (NSAIDs) is associated with an increased risk of cardiovascular (CV) events in stable patients with established atherothrombosis or multiple risk factors.

Swiss warmblood horse with symptoms of hereditary equine regional dermal asthenia without mutation in the cyclophylin B gene (PPIB)

Hereditary equine dermal asthenia (HERDA) is an autosomal recessive skin disease that affects predominantly Quarter Horses and related breeds. Typical symptoms are easy bruising and hyperextensible skin on the back. The prognosis is guarded, as affected horses cannot be ridden normally and are often euthanised. In the Quarter Horse, HERDA is associated with a mutation in cyclophilin B (PPIB), an enzyme involved in triple helix formation of collagen. Here we describe the case of a Swiss Warmblood filly with symptoms of HERDA without PPIB-mutation and in which we also could exclude Ehlers-Danlos syndrome Type IV, VI, VIIA, VIIB and VIIC (dermatosparaxis type) as etiological diseases.