Development of a phase-sensitive pulse measurement technique for semiconductor mode-locked lasers

The ultrashort pulses emitted by passive semiconductor mode-locked lasers (PSMLLs) can be applied to a wide range of applications, including modern optical communication systems, optical sampling, security, imaging or sensing. For most of these applications, it is of critical importance to gather detailed information on the mode-locked laser (MLL) dynamics as well as on the temporal intensity and phase profiles of the pulses. The pulse formation in a PSMLL is in fact a very complex mechanism that is governed by the close interplay between a number of linear and nonlinear phenomena, influenced by various semiconductor parameters. The complete characterisation of the devices as a function of the laser driving parameters, geometry and semiconductor material structure has therefore the potential to provide a deeper understanding of the PSMLL behaviour. As the available detectors are usually incapable of resolving the temporal structures of ultrashort pulses from the high repetition rate MLLs, a number of indirect measurement solutions have been developed for full pulse characterisation. However, these methods are designed for lasers with high-energy optical pulses or require pulse synchronisation or ultrafast modulation. This obviously restricts their suitability for the unsynchronised, low energy and high repetition rate pulses as those emitted by the mode-locked laser diodes. In this work, an extensive study of various dynamical regimes, such as mode-locking, self-pulsation and continuous-wave operations of the monolithically integrated AlGaInAs/InP MLLs is reported. The devices operate around 1.55 µm and emit optical pulses with sub-40 GHz repetition frequencies. The influence of the biasing conditions, laser geometry and semiconductor material on the lasers performance is analysed in detail. The complete characterisation includes the evaluation of both the phase and time profiles of pulses, using a sonogram system developed as part of this thesis. It is based on a self-referenced method, capable of ambiguity-free measurements of low power and sub-picosecond pulses. A sensitivity as low as 5mW on the pulse peak power has been achieved through the design and fabrication of a two-photon absorption (TPA) detector, optimised for polarisation insensitivity and high nonlinear response. The travelling-wave operation enables the characterisation of high-repetition rate pulses and minimises the amount of introduced dispersion. The sonogram system has been successfully employed to study the evolution of the temporal intensity and group delay profiles as a function of the laser biasing conditions and for different device geometries. The obtained results indicate a prevailing positive chirp present in the pulses, which can be reduced by a careful adjustment of the device biasing. The minimum pulse width emitted from the investigated MLLs and measured with the sonogram technique was ~500 fs

Zapalenie przyzębia a ryzyko przedwczesnych porodów i niskiej masy urodzeniowej – metaanaliza

Introduction: Periodontitis and prematurity are social diseases with common risk factors. In 1996 periodontitis was proven to be a possible significant and independent risk factor of preterm birth of newborns with low body weight. Numerous studies on the influence of periodontitis on the time of birth and/or birth weight of newborns have been conducted throughout the world since, including several ones in Poland, but their results have been inconsistent. Work objective: A meta-analysis of case-control, prospective and cohort studies on the influence of periodontitis on preterm birth and low birth weight. Methods: The international and Polish bibliography bases were searched for essays on the relationship between periodontitis and preterm birth and/or low birth weight published between 1996 and 2010. All essays qualified for the meta-analysis were subjected to qualitative evaluation. The calculation of the overall odds ratio used both, fixed-effects and random-effects models (DerSimonian-Liard method). The heterogeneity of the included studies and effect of publication bias were also subjected to evaluation. Results: The meta-analysis included 15 case-control studies, 1 cross-sectional study, and 6 cohort studies. The essays came from 4 continents: 8 from Europe (including 2 from Poland), 7 from South America, 4 from North America, and 3 from Asia. The total analysis covered 12047 pregnant women. The overall odds ratio of giving premature birth to a child with low weight for mothers with periodontitis in the model of random effects amounted to 2.35 (1.88-2.93, pWprowadzenie: Zapalenie przyzębia i wcześniactwo to choroby społeczne o wspólnych czynnikach ryzyka. W 1996 roku wskazano, że zapalenie przyzębia mogłoby być istotnym i niezależnym czynnikiem ryzyka przedwczesnego porodu noworodka o niskiej masie ciała. Od tego czasu przeprowadzono wiele badań na świecie i kilka w Polsce nad wpływem zapalenia przyzębia na termin porodu i/lub masę urodzeniową noworodka. Ich wyniki były sprzeczne. Cel pracy: Metaanaliza badań kliniczno-kontrolnych, przekrojowych i kohortowych dotyczących wpływu zapalenia przyzębia na przedwczesny poród noworodka o niskiej masie urodzeniowej. Metody: W międzynarodowych i polskiej bazie bibliograficznej poszukiwano prac opublikowanych w latach od 1996 do 2010 na temat związków pomiędzy zapaleniem przyzębia z przedwczesnym porodem i/lub niską masą urodzeniową noworodka. Wszystkie prace zakwalifikowane do metaanalizy były poddane ocenie jakościowej. Dla wyliczenia skumulowanego ilorazu szans zastosowano model efektów stałych i model efektów losowych w metodzie DerSimonian-Liard. Oceniano także jednorodność włączonych badań i efekt obciążenia publikacyjnego. Wyniki: W metaanalizie uwzględniono 15 badań kliniczno-kontrolnych, 1 przekrojową oraz 6 kohortowych. Prace pochodziły z 4 kontynentów: 8 z Europy (w tym dwie polskie), 7 z Ameryki Południowej, 4 z Ameryki Północnej i 3 z Azji. Analizie łącznej poddano 12047 kobiet w ciąży. Skumulowany iloraz szans przedwczesnego urodzenia dziecka o niskiej masie dla matek z zapaleniem przyzębia w modelu efektów losowych wynosił 2,35 (1,88-2,93,

Gambling: Sometimes Unseemly; Not What It Seems

Gambling offers opportunities for basic research and theory, and has hugely important applied implications. As Fantino (2008) said recently, “The current view of pathological gambling as an addiction cries out for a functional analysis of the controlling variables and for strategies of behavioral intervention.” This view echoed that of Dixon (2007) who called out for behavior analysts to apply their very relevant skills to discovering the causes of gambling disorders. To understand the behavior of gambling, one must understand the basic processes and variables involved in making the decisions gamblers make. Behavior ana-lysts, those experimental psychologists who approach psychological phenomena from a behavioral (or functional) perspective, have long concentrated on the choices organisms make. Thus, they should be in a strong position to contribute to our appreciation of the factors controlling gambling. In this paper we will examine some of the advances already made, and also propose some directions for future research

Podwójna lewa żyła ramienno-głowowa, rzadka anomalia żył systemowych i potencjalne ryzyko powikłań procedur CIED

Abnormal systemic vein embryogenesis results in the development of anomalies which, in the case of the left brachiocephalic vein (LBCV), can manifest as a significant and morphometric deviation from the normal anatomy of the vessel. One rare example of such an anatomical variation is the presence of a double LBCV. Depending on its nature and extent, this anomalous LBCV variation, which may be incidentally detected during an invasive procedure, can not only pose difficulties in terms of the successful completion of the procedure, but can also result in injuries to the vessel itself as well as to adjacent structures. We here present a case featuring such a congenital LBCV anomaly, which was discovered during a cardiac pacemaker implantation procedure.Zaburzenie embriogenezy żył systemowych skutkuje powstaniem wad, które w przypadkach dotyczących lewej żyły ramienno-głowowej (LBCV) cechuje znaczna odmienność topograficzna i morfometryczna w odniesieniu do budowy anatomicznej typowej dla tego naczynia. Przykładem jest sporadyczne występowanie obserwowanej podwójnej LBCV. Charakter i zakres tak zaistniałej rozwojowej odmienności LBCV, doraźnie wykryty podczas wykonywania inwazyjnej procedury, niezależnie od trudności jej w realizacji, może sprzyjać traumatyzacji zarówno samego naczynia, jak i przyległych struktur. W opracowaniu zaprezentowano postać tej żylnej anomalii rozwojowej wykrytą podczas procedury implantacji stymulatora serca

Ultrashort Q-switched pulses from a passively mode-locked distributed Bragg reflector semiconductor laser

A compact semiconductor mode-locked laser (MLL) is presented that demonstrates strong passive Q-switched mode-locking over a wide range of drive conditions. The Q-switched frequency is tunable between 1 and 4 GHz for mode-locked pulses widths around 3.5 ps. The maximum ratio of peak to average power of the pulse-train is >120, greatly exceeding that of similarly sized passively MLLs

Receptory glutaminianu u roślin

Badania prowadzone na pobudliwych plechach wątrobowca Conocephalum conicum wykazały, że podanie 5 mM roztworu glutaminianu (Glu) bądź glicyny (Gly) wywołuje serie potencjałów czynnościowych (AP), którym towarzyszy napływ wapnia do cytoplazmy pobudzonej komórki. Otrzymane wyniki są zgodne z istniejącą hipotezą że międzykomórkowy signalling oparty na aminokwasach jest obecny w królestwie roślin i zwierząt. Jak dotąd opublikowane dane eksperymentalne z równoległych pomiarów wewnątrzkom órkowego stężenia Ca"+ i poziomu potencjału transmem branowego izolowanych komórek liści (M eyerhoff et al. 2004, 2005) lub korzenia (Dennison i Spalding 2000) dotyczą głownie A rabidopsis thaliana, u której to rośliny zlokalizowano i sklonowano geny receptora kwasu glutaminowego (GLR). Nasze badania po raz pierwszy wykazały istnienie zależności między podaniem Glu a pobudzeniem u roślin niższych.Zadanie pt. „Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki” nr 885/P-DUN/2014 dofinansowane zostało ze środków MNiSW w ramach działalności upowszechniającej naukę

Types of left brachiocephalic vein aberrations detected during cardiac implantable electronic device implantation procedures

Background: Cardiac implantable electronic device (CIED) implantation procedures with transvenous lead placement afford an opportunity to observe vascular anatomic variations. The course of CIED implantation depends largely on morphometric and topographic characteristics of the relevant brachiocephalic vein (BCV), which is the left BCV in the case of lead insertion via the left clavipectoral triangle. This study aims to present left BCV anomalies arising from abnormal systemic vein embryogenesis and encountered during CIED implantation. Materials and methods: Venograms obtained during CIED implantation procedures and illustrating left BCV topography/morphometry were analysed retrospectively for two types of anomalies: anomalies of the left BCV itself (data from the period 2014–2018) and a combination of left BCV variations with a persistent left superior vena cava (PLSVC); since the latter instances are rare, the analysed period was longer (2003–2018). Results: Analysis of data from the first, 5-year-long, period included data from a group of 1812 patients and revealed 5 (0.3%) cases of developmental left-BCV anomalies (3 double left BCV and 2 cases of a single subaortic left BCV). The 16-year-long analysed period included 6110 CIED implantation procedures, which showed 12 (0.2%) cases of PLSVC including 4 (33%) cases of left BCV agenesis. Conclusions: The analysed venograms rarely showed isolated left-BCV aberrations (0.3%), with the combination of left-BCV agenesis and PLSVC being much more common (33%). The morphometry and/or topography of aberrant left-BCV may result in difficulties during cardiac lead insertion