Nonlinearities in Fringe-Counting Compact Michelson Interferometers

Compact Michelson interferometers are well positioned to replace existing displacement sensors in the readout of seismometers and suspension systems, such as those used in contemporary gravitational-wave detectors. Here, we continue our previous investigation of a customised compact displacement sensor built by SmarAct that operates on the principle of deep frequency modulation. The focus of this paper is the linearity of this device and its subsequent impact on sensitivity. We show the three primary sources of nonlinearity that arise in the sensor: residual ellipticity, intrinsic distortion of the Lissajous figure, and distortion caused by exceeding the velocity limit imposed by the demodulation algorithm. We verify the theoretical models through an experimental demonstration, where we show the detrimental impact that these nonlinear effects have on device sensitivity. Finally, we simulate the effect that these nonlinearities are likely to have if implemented in the readout of the Advanced LIGO suspensions and show that the noise from nonlinearities should not dominate across the key sub-10 Hz frequency band

La dieta ipolipidica nei pazienti con emicrania: effetti sulla frequenza e sulla gravità degli episodi di emicrania e sulla disfunzione vascolare periferica

Abbiamo stabilito di proporci nel corso di questo Dottorato di Ricerca di fare luce su diversi aspetti della relazione tra emicrania, arteriosclerosi ed alimentazione, rivolgendo in particolare la nostra attenzione al ruolo dei grassi, quelli saturi in particolare, nel determinismo di tale associazione. Pertanto gli scopi della ricerca sono stati: a) valutare se una moderata riduzione dell’introito lipidico, con una restrizione del contenuto di grassi giornalieri non così drastica come quella precedentemente praticata in altri studi che rende impossibile seguire tale dieta a medio e lungo termine, sia in grado di avere effetto sulla severità e sulla frequenza delle crisi di emicrania; b) verificare, con metodica non invasiva, se i pazienti affetti da emicrania presentano disfunzione vascolare; c) investigare se l’ intervento dietetico mediante riduzione moderata del contenuto lipidico della dieta sia in grado di migliorare tale eventuale disfunzione. Lo studio è stato condotto su 128 pazienti afferenti all'ambulatorio di cefalea. i risultati del nostro trial indicano che i pazienti emicranici di base hanno abitudini alimentari in eccesso rispetto ai limiti consentiti seguendo diete ricche di lipidi e calorie, soprattutto di acidi grassi saturi e che la riduzione del contenuto calorico e lipidico giornaliero migliora intensità e frequenza degli attacchi. Inoltre nei pazienti emicranici la funzione endoteliale non risulta alterata e la dieta ipolipidica esercita i suoi effetti benefici su frequenza ed intensità delle crisi emicraniche indipendentemente da qualsiasi azione sulla funzione endoteliale

Innovative perspectives for seismic isolation of gravitational-wave detectors

The discovery of gravitational waves opened a new way to look at the Universe and offered new opportunities to shed light on the still unknown aspects of physical sciences. The work presented in this thesis wants to give a contribution to the development of this new type of research: the author chose to focus on the improvement of the instruments able to detect the gravitational waves. This field is important to make the detectors more sensitive, in order to see more gravitational-wave sources and help to complete the mosaic of the astrophysical science. In particular, the detectors currently in use are interferometers, which are especially blind in a range of frequency below 30 Hz: this affects the chance to detect sources emitting in this frequency band. This lack of sensitivity is mainly due to seismic motion, and the work presented in this thesis focussed on new techniques to lower the noise sources and allow the instruments to be sensitive below 30 Hz. During the studies, the development and test of devices capable of potentially reducing the seismic motion have been performed, such as optical levers for tilt motion reduction and laser stabilization for low frequency readout; a new concept of the seismic system on one of the interferometers (LIGO) has also been proposed. The optical levers can in principle reduce tilt motion below 1 Hz; the use of capacitive position sensors in a new software configuration for LIGO can help to suppress ground motion by a factor of 3 in order of magnitude below 0.1 Hz. A competitive frequency stabilization to 3.6 times 10$^{3}$ $Hz\sqrt{Hz}$ at 1 Hz for readout at low frequency is possible with a compact and easy to handle setup. These results are promising to provide suppression of the seismic motion in the bandwidth of interest and show that it is possible for a ground-based instrument to be seismically more stable and capable of detecting gravitational waves where it is now forbidden

Przełom hiperkalcemiczny z powodu pierwotnej nadczynności przytarczyc — przegląd piśmiennictwa i opis przypadku

Hypercalcaemic crisis is an uncommon and potentially life-threatening manifestation of primary hyperparathyroidism, and it is associated with rapid deterioration of the central nervous system, and cardiac, gastrointestinal, and renal function. We present the case of a 76 year-old man in a sudden coma due to hypercalcaemic crisis as a first manifestation of primary hyperparathyroidism. At first, the patient was treated conservatively, his mental status gradually improved in the next three days. On the ninth day after the initiation of therapy, a minimally invasive radio-guided parathyroidectomy was performed. Histologically, the tumour consisted of densely arranged chief cells immunohistochemically positive for PTH antigens, suggesting adenoma. Calcaemia level and PTH were normalised in the immediate postoperative period. A systematic review was performed by consulting PubMed MEDLINE for publications from 1958 to 2011. This review found a total of 499 reported cases of hypercalcaemic crisis due to primary hyperparathyroidism. Manifestations are neurological alterations, and cardiac, renal and gastrointestinal dysfunctions associated with markedly elevated serum calcium and parathyroid hormone levels. The most frequent histology is the parathyroid adenoma. In untreated cases, mortality is 100%. Despite advances in its management, the mortality rate is still 93.5% in patients treated only conservatively. Medical therapy followed by expeditious parathyroidectomy should be considered as the treatment of choice for patients affected by hypercalcaemic crisis due to a primary hyperparathyroidism. (Endokrynol Pol 2012; 63 (6): 494–502)Przełom hiperkalcemiczny jest rzadkim choć potencjalnie zagrażającym życiu objawem pierwotnej nadczynności przytarczyc i jest skojarzony z gwałtownym pogorszeniem funkcji ośrodkowego układu nerwowego, serca, przewodu pokarmowego i funkcji nerek. W pracy zaprezentowano przypadek 76-letniego mężczyzny, u którego pierwszym objawem pierwotnej nadczynności przytarczyc był przełom hiperkalemiczny w postaci nagłej śpiączki. Na początku pacjent był leczony zachowawczo i jego stan psychiczny zaczął ulegać stopniowej poprawie w ciągu pierwszych 3 dni. Dziewiątego dnia terapii wykonano u niego mini inwazyjny zabieg usunięcia przytarczyc pod kontrolą RTG. Histologicznie guz składał się z gęsto ułożonych dużych komórek pozytywnych badaniem imunohistologiczno-chemicznym dla antygenów PTH, sugerując gruczolak. Stężenie wapnia i PTH znormalizowano w bezpośrednim okresie pooperacyjnym. Dokonano systematycznego przeglądu publikacji PubMed MEDLINE w latach 1958–2011. Przegląd zawiera łącznie 499 odnotowanych przypadków przełomu hiperkalcemicznego jako objawu pierwotnej nadczynności przytarczyc. Przejawy to zmiany neurologiczne, dysfunkcja nerek, przewodu pokarmowego i serca związanych ze znacznie podwyższonym stężeniem wapnia i parathormonu w surowicy. W badaniu histologicznym najczęściej diagnozowany jest gruczolak przytarczycowy. W przypadkach nieleczonych odnotowuje się 100-procentową śmiertelność. Mimo postępów w leczeniu, przy terapii tylko zachowawczej, śmiertelność jest nadal wysoka — 93,5%. Leczenie zachowawcze plus szybkie usuniecie przytarczyc powinny być uważane za leczenie z wyboru u pacjentów dotkniętych przełomem hiperkalcemicznym z powodu pierwotnej nadczynności przytarczyc. (Endokrynol Pol 2012; 63 (6): 494–502