Digital electronic predistortion for optical communications

The distortion of optical signals has long been an issue limiting the performance of communication systems. With the increase of transmission speeds the effects of distortion are becoming more prominent. Because of this, the use of methods known from digital signal processing (DSP) are being introduced to compensate for them. Applying DSP to improve optical signals has been limited by a discrepancy in digital signal processing speeds and optical transmission speeds. However high speed Field Programmable Gate Arrays (FPGA) which are sufficiently fast have now become available making DSP experiments without costly ASIC implementation possible for optical transmission experiments. This thesis focuses on Look Up Table (LUT) based digital Electronic Predistortion (EPD) for optical transmission. Because it is only one out of many possible implementations of EPD, it has to be placed in context with other EPD techniques and other distortion combating techniques in general, especially since it is possible to combine the different techniques. Building an actual transmitter means that compromises and decisions have to be made in the design and implementation of an EPD based system. These are based on balancing the desire to achieve optimal performance with technological and economic limitations. This is partly done using optical simulations to asses the performance. This thesis describes a novel experimental transmitter that has been built as part of this research applying LUT based EPD to an optical signal. The experimental transmitter consists of a digital design (using a hardware description language) for a pair of FPGAs and an analogue optical/electronic setup including two standard DAC integrated circuits. The DSP in the transmitter compensated for both chromatic dispersion and self phase modulation. We achieved transmission of 10.7 Gb/s non-return-to-zero (NRZ) signals with a +4 dBm launch power over 450 km keeping the required optical-signal-to-noise-ratio (OSNR) for a bit-error-rate of 2x10^{-3} below 11 dB. In doing so we showed experimentally, for the first time, that nonlinear effects can be compensated with this approach and that the combination of FPGA-DAC is a viable approach for an experimental setup

Travelogues about Nicholas I’s Russia: Belgian Monarchists versus Astolphe Marquis de Custine

The article was submitted on 10.09.2015.Translated by Dutch Irina Bassina.The article focuses on the account of Belgian traveller Jan Nolet of his trip to Russia published in 1843 and known as A Trip to the North. In 1842 two Belgians went on a trip to Russia, a far-away country, still rarely visited by Europeans. They were Jean-Baptist David, a renowned representative of Flemish culture and a canon, and his younger fellow traveller, Dutchman Jan Nolet de Brauwere van Steeland. They both were opposed to the Belgian revolution of 1830 which led to the establishment of constitutional monarchy in the country with it later becoming a model to follow for the leading European countries. In Russia under Nicholas I they found the kind of rule that complied with their views, i. e. that characterized by discipline but also justice, absolute rule combined with trust in a beneficent tsar that rules the country without a conflicting opposition or insolent parliament. They visited Moscow and Saint Petersburg and saw things unfamiliar to them, and were amazed by what they discovered. They write respectfully and with a deep understanding about Russia and Russians, and they appreciate the majestic ruler Nicholas I. It is all the more noteworthy, because after the suppression of the Polish uprising of 1831, the West’s favourable attitude to Russia (after Peter the Great’s reforms and Catherine II’s regime, after Alexander I’s victory over Napoleon) was exhausted. It is this event that marks the start of constant criticism of Russia’s ways and actions by western journalists and travellers which continued until as long as 1917. The perception of Russia expressed by the Belgian travellers is also interesting because the same period is marked by the publication of a book by Astolphe de Custine, a French publicist, who criticised many sides of the Russian reality.Основной предмет исследования автора составляет отчет бельгийского путешественника Яна Нолета де Браувере ван Стееланда о путешествии в Россию, вышедший в свет в 1843 г. под названием «Поездка на север». В 1842 г. два бельгийца предприняли путешествие в далекую, мало еще посещавшуюся европейцами Россию. Это были видный деятель фламандской культуры каноник Ян-Баптист Давид и его более молодой спутник голландец Ян Нолет де Браувере ван Стееланд. Оба были противниками бельгийской революции 1830 г., давшей стране конституционную монархию, скоро ставшую образцом всей передовой Европы. В России царя Николая I наши путешественники нашли как раз ту страну, то правление, что им было по душе, – строгую, но справедливую власть, единовластие, веру в доброго царя, который управлял страной без крикливого парламента и оппозиции. Они были в Петербурге и Москве, видели много того, что было им не знакомо, удивлялись на каждом шагу увиденному. Они с уважением и пониманием пишут о России и русских, им очень нравится величественная фигура царствующего царя Николая I. Это тем более удивительно, потому что после подавления польского восстания 1831 г. симпатии Запада по отношению к России (после Петровских реформ и режима Екатерины II, после победы Александра I над Наполеоном) были совершенно исчерпаны. Именно с этого события начинается постоянная критика российских порядков западными путешественниками и журналистами, которая будет продолжаться до 1917 г. Восприятие России глазами бельгийских путешественников интересно еще и потому, что в то же время вышла в свет книга известного французского публициста Астольфа де Кюстина, который критиковал многие стороны российской действительности

The Triumph of Autocracy: Alexei Petrovich versus Peter Alexeevich. The Conflict of Fathers and Sons in the Dutch Drama of the 19th century

The article was submitted on 23.08.2014.The author explores an episode of 18th century Russian history: i.e. the conflict between Peter I and his son Alexei Petrovich, reflected in the plays of Dutch playwrights in the first half of the 19th century. Referring to Peter de Groote, Zar van Rusland of Arent van Halmael, the author describes the peculiarities of the Dutch writer’s understanding of the conflict. The writer focuses on showing the reader the tsar’s inner conflict caused by the necessity to execute his son as a traitor while sensing his paternal attachment to him. It is in Johannes de Wal’s Peter de Groote, Treurspel, that the discrepancy between the love of a father and the tsar’s duty as head of the country takes on an even more pronounced shape. The young playwright portrays the son’s deep attachment to his father, demonstrating a theme that power exacts a heavy price. The Dutch reader’s attention is stimulated through the unique Russian portrayal of events. Translated by Evgeniia Kosych.Автор рассматривает художественное воплощение сюжета из русской истории XVIII в. — конфликт между Петром Первым и его сыном Алексеем Петровичем — в пьесах голландских драматургов первой половины XIX в. Обращение к произведению Арента ван Халмаля (Arent van Halmael) «Петр Великий, царь России» (Peter de Groote, Zar van Rusland) показывает особенности понимания конфликта автором пьесы. Для него оказывается важным открытие зрителю переживаний государя, связанных с трагическим конфликтом между необходимостью казни сына как изменника и отцовской привязанностью. В еще большей степени диссонанс родительской любви и государственного долга запечатлен в произведении Йоханнеса де Валя (Johannes de Wal) «Петр Великий. Трагедия» (Peter de Groote. Treurspel). Молодой драматург передает искреннюю привязанность сына к отцу, поднимая в историческом сюжете общечеловеческую тему неизбежной и жестокой платы за обладание властью. Усиливает интерес голландского читателя российский контекст описываемых событий

Processing and characterization of syndiotactic polystyrene into a free flowing powder

C

Learning experiences of final-year student midwives inlabor wards : a qualitative exploratory study

Introduction: Clinical placements are an integral part of midwifery education and are crucial for achieving professional competencies. Although students’ experiences on placements have been shown to play a meaningful role in their learning, they have received scant attention in the literature. The aim of this paper is to describe the learning experiences of final-year student midwives in labor wards within the Brussels metropolitan region, Belgium. Methods: A qualitative exploratory study was conducted using two focus groups (N=20). Data analysis included: transcription of audio recordings, thematic content analysis with coding into recurrent and common themes, and broader categories. Discussions among researchers were incorporated in all phases of the analysis for integrity and data fit. Results: Data analysis identified the following categories as determining student learning experiences in labor wards: 1) managing opportunities, 2) being supported, and 3) dealing with the environment. Overall, respondents were positive and enthusiastic about their learning experiences, although some felt tense and unprepared. Students expressed concerns about differences in learning opportunities between placements and found it challenging to achieve all competencies. Student learning experiences were enhanced when they had placements for longer periods with the same supportive mentors. Conclusions: Factors related to students’ functioning, the healthcare professional, midwifery education and hospital environment affected their learning in labor wards. The combination of a more persevered preparation of students and mentors, together with a student-centered organization of placements, is crucial to create a positive learning experience for midwifery students in labor wards

Advanced perturbation technique for digital backward propagation in WDM systems

An improved digital backward propagation (DBP) is proposed to compensate inter-nonlinear effects and dispersion jointly in WDM systems based on an advanced perturbation technique (APT). A non-iterative weighted concept is presented to replace the iterative in analytical recursion expression, which can dramatically simplify the complexity and improve accuracy compared to the traditional perturbation technique (TPT). Furthermore, an analytical recursion expression of the output after backward propagation is obtained initially. Numerical simulations are executed for various parameters of the transmission system. The results indicate that the advanced perturbation technique will relax the step size requirements and reduce the oversampling factor when launch power is higher than -2 dBm. We estimate this technique will reduce computational complexity by a factor of around seven with respect to the conventional DBP

The transcriptome of lung tumor-infiltrating dendritic cells reveals a tumor-supporting phenotype and a microRNA signature with negative impact on clinical outcome

Targeting immunomodulatory pathways has ushered a new era in lung cancer therapy. Further progress requires deeper insights into the biology of immune cells in the lung cancer micro-environment. Dendritic cells (DCs) represent a heterogeneous and highly plastic immune cell system with a central role in controlling immune responses. The intratumoral infiltration and activation status of DCs are emerging as clinically relevant parameters in lung cancer. In this study, we used an orthotopic preclinical model of lung cancer to dissect how the lung tumor micro-environment affects tissue-resident DCs and extract novel biologically and clinically relevant information. Lung tumor-infiltrating leukocytes expressing generic DC markers were found to predominantly consist of CD11b(+) cells that, compare with peritumoral lung DC counterparts, strongly overexpress the T-cell inhibitory molecule PD-L1 and acquire classical surface markers of tumor-associated macrophages (TAMs). Transcriptome analysis of these CD11b(+) tumor-infiltrating DCs (TIDCs) indicates impaired antitumoral immunogenicity, confirms the skewing toward TAM-related features, and indicates exposure to a hypoxic environment. In parallel, TIDCs display a specific microRNA (miRNA) signature dominated by the prototypical lung cancer oncomir miR-31. In vitro, hypoxia drives intrinsic miR-31 expression in CD11b(+) DCs. Conditioned medium of miR-31 overexpressing CD11b(+) DCs induces pro-invasive lung cancer cell shape changes and is enriched with pro-metastatic soluble factors. Finally, analysis of TCGA datasets reveals that the TIDC-associated miRNA signature has a negative prognostic impact in non-small cell lung cancer. Together, these data suggest a novel mechanism through which the lung cancer micro-environment exploits the plasticity of the DC system to support tumoral progression

GATA3 induces human T-cell commitment by restraining Notch activity and repressing NK-cell fate

The gradual reprogramming of haematopoietic precursors into the T-cell fate is characterized by at least two sequential developmental stages. Following Notch1-dependent T-cell lineage specification during which the first T-cell lineage genes are expressed and myeloid and dendritic cell potential is lost, T-cell specific transcription factors subsequently induce T-cell commitment by repressing residual natural killer (NK)-cell potential. How these processes are regulated in human is poorly understood, especially since efficient T-cell lineage commitment requires a reduction in Notch signalling activity following T-cell specification. Here, we show that GATA3, in contrast to TCF1, controls human T-cell lineage commitment through direct regulation of three distinct processes: repression of NK-cell fate, upregulation of T-cell lineage genes to promote further differentiation and restraint of Notch activity. Repression of the Notch1 target gene DTX1 hereby is essential to prevent NK-cell differentiation. Thus, GATA3-mediated positive and negative feedback mechanisms control human T-cell lineage commitment

The transcriptome of lung tumor-infiltrating dendritic cells reveals a tumor-supporting phenotype and a microRNA signature with negative impact on clinical outcome

Targeting immunomodulatory pathways has ushered a new era in lung cancer therapy. Further progress requires deeper insights into the biology of immune cells in th

Humoral and cellular immune correlates of protection against COVID-19 in kidney transplant recipients.

peer reviewedAs solid organ transplant recipients are at high risk of severe COVID-19 and respond poorly to primary SARS-CoV-2 mRNA vaccination, they have been prioritized for booster vaccination. However, an immunological correlate of protection has not been identified in this vulnerable population. We conducted a prospective monocentric cohort study of 65 kidney transplant recipients who received 3 doses of BNT162b2 mRNA vaccine. Associations among breakthrough infection (BTI), vaccine responses, and patient characteristics were explored in 54 patients. Symptomatic COVID-19 was diagnosed in 32% of kidney transplant recipients during a period of 6 months after booster vaccination. During this period, SARS-CoV-2 delta and omicron were the dominant variants in the general population. Univariate Analyses identified the avidity of SARS-CoV-2 receptor binding domain binding IgG, neutralizing antibodies, and SARS-CoV-2 S2-specific interferon gamma responses as correlates of protection against BTI. No demographic or clinical parameter correlated with the risk of BTI. In multivariate analysis, the risk of BTI was best predicted by neutralizing antibody and S2-specific interferon gamma responses. In conclusion, T cell responses may help compensate for the suboptimal antibody response to booster vaccination in kidney transplant recipients. Further studies are needed to confirm these findings