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Hepatic mesenchymal hamartoma is the third most common liver neoplasm of the pediatric age group, rarely diagnosed in adults, with under 50 cases having been reported so far. Mesenchymal hamartoma of the spleen is a very rare vascular lesion, documented in less than 200 cases since 1861 when it was first described by Karl von Rokitansky. 1.1. Aim: The aim of this paper is to discuss the differential diagnosis of these tumour-like lesions and the association between them, especially considering their rarity. 1.2. Methods: We present a case of multifocal mesenchymal hamartoma of the liver and spleen in a 51-year-old female patient. The hepatic tumour appears as a macro nodular lesion involving the interface between segments V and VIII [30x28mm], showing central scarring upon MRI imaging and suggesting the diagnosis of focal nodular hyperplasia. Moreover, a sub capsular splenic cystic mass was also revealed, involving the sub diaphragmatic surface of the organ [15x10mm]. 1.3. Results: The histological examination of the hepatic tumour revealed a myxoid stromal proliferation, composed of stellate and fibroblastoid cells, bile ducts with inconspicuous lumina, small vascular structures and chronic non-specific inflammatory infiltrate. On microscopic examination, the splenic lesion exhibited nodular collagenous fibrosis, radial septa and large hyalinized areas. 1.4. Conclusion: A key aspect in the effective treatment of patients diagnosed with mesenchymal hamartomas is surgery with negative margins. The peculiarity of this case consisted of the incidental finding of multiple liver tumours, the incidental finding of the splenic mass, and the rarity of this particular association in adults.

The focus of this thesis is Ultra Wideband (UWB) Impulse Radio (UWB-IR) transmitters and non-coherent receivers. The aim of the thesis is to investigate, analyze and design UWB-IR transmitter and receiver structures both from a theoretical and circuit design viewpoint. An UWB-IR transmitter structure is proposed and is the subject of a detailed investigation. The transmitter generates a Gaussian monocycle and can be modified to generate a family of Gaussian waveforms. The Gaussian monocycle is easy to generate while providing good bit-error-rate (BER) performance. The Gaussian monocycle has a wide -10 dB bandwidth and a zero-DC component which does not decrease antenna efficiency. The transmitter design includes a delay locked loop (DLL) based frequency synthesis approach. The advantage of using a frequency synthesis approach based on a DLL is based on the fact that a DLL generates less noise than a phase locked loop (PLL) and is inherently stable. The generated pulse has a width of less than 350 ps and a -10 dB bandwidth of 4.7 GHz. The power consumption of the designed UWBIR transmitter is 20 mW at a voltage supply of 3.3 V. Compared with other integrated UWB-IR transmitters, the transmitter presented in this thesis has the lowest pulse width for comparable integrated processes, one of the lower power consumptions and a low die area. The BER performance of several UWB-IR non-coherent receiver structures is presented. The energy detection (ED) receiver offers the same BER performance as the transmitted reference scheme with binary pulse amplitude modulation (BPAM) but has a lower implementation complexity since it does not require an analogue delay line in its structure. Circuit performance of several blocks of the ED receiver is presented. The radio frequency (RF) front-end and analogue baseband sections of the receiver have been designed as an integrated circuit (IC) in a 0.35 μm bipolar complementary metal oxide semiconductor (BiCMOS) process. The RF front-end section includes a low noise amplifier (LNA), a variable gain amplifier (VGA) and a Gilbert cell. The LNA has a noise figure (NF) of less than 3 dB, a gain of 18 dB in the interest bandwidth and less than 20 mW of power consumption. The NF of the LNA can be reduced even further at the expense of a higher power consumption or by using input pads with lower capacitance values. The noise figure can be also lowered by using a process which provides transistors with higher transit frequency (fT). Trading-off power consumption for noise is still a key design issue in the design of integrated UWB-IR receivers. The analogue baseband section includes a bank of integrators and a 4-bit analogue to digital converter (ADC). The ADC is running at a sampling rate equal to the symbol rate and takes only 2 mW of power at 3.3 V supply. The power consumption of the designed integrated front-end and analogue baseband receiver sections is 117 mW at a power supply of 3.3 V. The digital baseband of the receiver have been implemented on a field programmable gate array (FPGA) technology. The power consumption of the baseband is 450 mW with a power supply of 1.2 V and a maximum supply of 3.3 V for input-output pins. The total power consumption of the designed transceiver is 587 mW. When compared with other UWB receiver architectures, the energy detection receiver has the lowest power consumption due to the low power consumption of the LNA, simple synchronization architecture and low sampling rate of the ADC.

Pulmonary atresia with ventricular septal defect (PAVSD) is a complex cardiopathy represented by a complete obstruction between the right ventricle outflow and the pulmonary trunk associated with a ventricular septal defect (VSD) and major aortopulmonary collaterals (MAPCA). The goal of the unifocalization in the PAVSD is to prepare the pulmonary tree for the complete repair by connecting the MAPCAs to the central pulmonary arteries that should be enlarged. After that we can made the VSD or other intracardiac repair. This is a retrospective study on 31 patients. We report our results discussing the PAVSD classification and the strategy of the complete repair in comparison with other reported results.

We consider a second order semi-elliptic differential operator L with measurable coefficients, in divergence form, and the semilinear parabolic PDE \begin{eqnarray*} (_t+L)u(t,x)+f(t,x,u,u) &=&0,0tT u(T,x) &=&(x) \end{eqna- rray*} and employ the symmetric Markov process of infinitesimal operator L in order to give a probabilistic interpretation for the solution u, i.e. we solve the corresponding BSDE. We obtain also a representation theorem for martingales which represents a generalization of the representation theorem given by Fukushima for additive functional martingales. This permits us to solve general (non-Markov) BSDE's with semi-linear terms. The nonlinear term f satisfies a monotonicity condition with respect to u and a Lipschitz condition with respect to u. Finally we prove a comparison theorem and use it in order to solve a stochastic control problem.