O-Band Differential Phase-Shift Quantum Key Distribution in 52-Channel C/L-Band Loaded Passive Optical Network

A cost-effective QKD transmitter is evaluated in a 16km reach, 2:16-split PON and yields 5.10-7secure bits/pulse. Co-existence with 20 down-and 1 upstream channel is possible at low QBER degradation of 0.93% and 1.1%

Identification of a lipoteichoic acid glycosyltransferase enzyme reveals that GW-domain containing proteins can be retained in the cell wall of Listeria monocytogenes in the absence of lipoteichoic acid or its modifications

Listeria monocytogenes is a foodborne Gram-positive bacterial pathogen, and many of its virulence factors are either secreted proteins or proteins covalently or noncovalently attached to the cell wall. Previous work has indicated that noncovalently attached proteins with GW (glycine-tryptophan) domains are retained in the cell wall by binding to the cell wall polymer lipoteichoic acid (LTA). LTA is a glycerol phosphate polymer, which is modified in L. monocytogenes with galactose and d-alanine residues. We identified Lmo0933 as the cytoplasmic glycosyltransferase required for the LTA glycosylation process and renamed the protein GtlA, for glycosyltransferase LTA A Using L. monocytogenes mutants lacking galactose or d-alanine modifications or the complete LTA polymer, we show that GW domain proteins are retained within the cell wall, indicating that other cell wall polymers are involved in the retention of GW domain proteins. Further experiments revealed peptidoglycan as the binding receptor as a purified GW domain fusion protein can bind to L. monocytogenes cells lacking wall teichoic acid (WTA) as well as purified peptidoglycan derived from a wild-type or WTA-negative strain. With this, we not only identify the first enzyme involved in the LTA glycosylation process, but we also provide new insight into the binding mechanism of noncovalently attached cell wall proteins.Over the past 20 years, a large number of bacterial genome sequences have become available. Computational approaches are used for the genome annotation and identification of genes and encoded proteins. However, the function of many proteins is still unknown and often cannot be predicted bioinformatically. Here, we show that the previously uncharacterized Listeria monocytogenes gene lmo0933 likely codes for a glycosyltransferase required for the decoration of the cell wall polymer lipoteichoic acid (LTA) with galactose residues. Using L. monocytogenes mutants lacking LTA modifications or the complete polymer, we show that specific cell wall proteins, often associated with virulence, are retained within the cell wall, indicating that additional cell wall polymers are involved in their retention

Partial response signaling for improved chromatic dispersion tolerance in intensity modulation optical transmissions

[EN] We investigate partial response signaling (PRS) as a way of increasing the transmission length achievable by direct detection optical systems. The performance of the duobinary and PRS modulations is evaluated against that of conventional on-off-keying (OOK). We prove by simulation and experimentally that duobinary increases the link distance by up to 1.5 times and PRS by up to 3 times, when no signal processing is employed. The gain is preserved even when equalization is used. PRS is employed also with 4-level pulseamplitude modulation (PAM-4) and is shown to improve the transmission distance by almost 3 times.Prodaniuc, C.; Stojanovic, N.; Karinou, F.; Llorente, R. (2018). Partial response signaling for improved chromatic dispersion tolerance in intensity modulation optical transmissions. Optics Express. 26(3):3013-3019. https://doi.org/10.1364/OE.26.003013S30133019263Essiambre, R.-J., & Tkach, R. W. (2012). Capacity Trends and Limits of Optical Communication Networks. Proceedings of the IEEE, 100(5), 1035-1055. doi:10.1109/jproc.2012.2182970Winzer, P. J., & Essiambre, R.-J. (2006). Advanced Optical Modulation Formats. Proceedings of the IEEE, 94(5), 952-985. doi:10.1109/jproc.2006.873438Tao, L., Ji, Y., Liu, J., Tao Lau, A. P., Chi, N., & Lu, C. (2013). Advanced modulation formats for short reach optical communication systems. IEEE Network, 27(6), 6-13. doi:10.1109/mnet.2013.6678921Wei, J., Eiselt, N., Griesser, H., Grobe, K., Eiselt, M. H., Vegas Olmos, J. J., … Elbers, J.-P. (2016). Demonstration of the First Real-Time End-to-End 40-Gb/s PAM-4 for Next-Generation Access Applications Using 10-Gb/s Transmitter. Journal of Lightwave Technology, 34(7), 1628-1635. doi:10.1109/jlt.2016.2518748Pang, X., Ozolins, O., Gaiarin, S., Kakkar, A., Rodrigo Navarro, J., Iglesias Olmedo, M., … Jacobsen, G. (2017). Experimental Study of 1.55- $\mu$ m EML-Based Optical IM/DD PAM-4/8 Short Reach Systems. IEEE Photonics Technology Letters, 29(6), 523-526. doi:10.1109/lpt.2017.2662948Prodaniuc, C., Stojanovic, N., Karinou, F., Qiang, Z., & Llorente, R. (2016). Performance Comparison Between 4D Trellis Coded Modulation and PAM-4 for Low-Cost 400 Gbps WDM Optical Networks. Journal of Lightwave Technology, 34(22), 5308-5316. doi:10.1109/jlt.2016.2609199Walklin, S., & Conradi, J. (1997). On the relationship between chromatic dispersion and transmitter filter response in duobinary optical communication systems. IEEE Photonics Technology Letters, 9(7), 1005-1007. doi:10.1109/68.593381Wang, J., & Petermann, K. (1992). Small signal analysis for dispersive optical fiber communication systems. Journal of Lightwave Technology, 10(1), 96-100. doi:10.1109/50.108743Forestieri, E., & Prati, G. (2001). Novel optical line codes tolerant to fiber chromatic dispersion. Journal of Lightwave Technology, 19(11), 1675-1684. doi:10.1109/50.964067Slepian, D., & Pollak, H. O. (1961). Prolate Spheroidal Wave Functions, Fourier Analysis and Uncertainty - I. Bell System Technical Journal, 40(1), 43-63. doi:10.1002/j.1538-7305.1961.tb03976.xLandau, H. J., & Pollak, H. O. (1961). Prolate Spheroidal Wave Functions, Fourier Analysis and Uncertainty - II. Bell System Technical Journal, 40(1), 65-84. doi:10.1002/j.1538-7305.1961.tb03977.

Διατροφικές συνήθειες υπέρβαρων και παχύσαρκων παιδιών

ΕΙΣΑΓΩΓΗ: Η υπερβαρότητα και η παχυσαρκία αποτελούν πολύ σοβαρά προβλήματα δημόσιας υγείας τον 21ο αιώνα, καθώς αυξάνουν τον κίνδυνο νόσησης από διαβήτη τύπου 2, καρδιαγγειακές παθήσεις, και κάποια είδη καρκίνου. ΣΚΟΠΟΣ: Σκοπός της παρούσας ανασκόπησης ήταν να προσδιορίσει τη σχέση μεταξύ των διατροφικών συνηθειών/ διατροφικών προτύπων και του κινδύνου παχυσαρκίας μεταξύ των παιδιών. ΜΕΘΟΔΟΛΟΓΙΑ: Πραγματοποιήθηκε ανασκόπηση της διεθνούς βιβλιογραφίας στην ηλεκτρονική βάση δεδομένων PubMed με τις ακόλουθες λέξεις κλειδιά: “obesity,” “eating habits” “dietary pattern,” “childhood,” “children,” “adolescents. Τα κριτήρια επιλογής και αποκλεισμού των άρθρων για συμπερίληψη στην παρούσα ανασκόπηση ήταν τα εξής: (1) οι μελέτες να αφορούν σε υπέρβαρα και σε παχύσαρκα παιδιά (ηλικία < 18 ετών), (2) οι μελέτες να αφορούν στην αξιολόγηση των διατροφικών συνηθειών/ προτύπων μέσω ερωτηματολογίου, (3) η έκβαση των μελετών να είναι η συχνότητα κατανάλωσης των διάφορων τροφίμων, (4) οι μελέτες να είναι πρωτογενείς δημοσιευμένες από 01/01/2015 έως 31/12/2020 και γραμμένες στην αγγλική γλώσσα. ΑΠΟΤΕΛΕΣΜΑΤΑ: Από την ηλεκτρονική αναζήτηση της διεθνούς βιβλιογραφίας προέκυψαν 1202 μελέτες, εκ των οποίων οι 16 συμπεριελήφθησαν στην ανασκόπηση. Η πλειοψηφία των μελετών (n=14) ήταν συγχρονικές μελέτεςς. Οι μελέτες ανέφεραν από δύο έως τέσσερα διατροφικά πρότυπα. Το διατροφικό πρότυπο που βρέθηκε να σχετίζεται με αυξημένο κίνδυνο υπερβαρότητας και παχυσαρκίας περιλάμβανε την κατανάλωση λιπαρών τυριών, ζαχαρούχων ποτών, επεξεργασμένων τροφίμων, γρήγορου φαγητού, σνακ, ζωικών προϊόντων, πλήρους γάλατος και εκλεπτυσμένων σπόρων. Από την άλλη, το διατροφικό πρότυπο που περιλάμβανε την κατανάλωση λαχανικών, φρούτων, δημητριακών ολικής αλέσεως, ψαριών, ξηρών καρπών, οσπρίων και γιαουρτιού δε σχετίστηκε με τον κίνδυνο παχυσαρκίας. ΣΥΜΠΕΡΑΣΜΑΤΑ: Τα παιδιά και οι έφηβοι που τηρούν τα διατροφικά πρότυπα που αποτελούνται από τρόφιμα ενοχοποιημένα για ανάπτυξη παχυσαρκίας, είναι πιθανότερο να αναπτύξουν παχυσαρκία. Για την πρόληψη της παιδικής παχυσαρκίας, και της μείωσης του κινδύνου ανάπτυξης παχύσαρκων ενηλίκων, είναι απαραίτητο να αναπτυχθούν αποτελεσματικές προσεγγίσεις που θα στοχεύουν στην υιοθέτηση υγιεινών διατροφικών προτύπων.BACKGROUND: Overweight and obesity are serious public health problems of the 21st century, as they increase the risk of type 2 diabetes, cardiovascular disease, as well as some types of cancer. AIM: The purpose of this review was to determine the relation between eating habits / eating patterns and the risk of obesity among children and adolescents. METHODOLOGY: PubMed was searched using the following keywords: “obesity,” “eating habits”, “dietary pattern,” “childhood,” “children,” adolescents. The criteria for selecting and/or excluding articles were: (1) studies related to overweight and obese children (age <18 years), (2) studies that identified the eating habits / eating patterns through a questionnaire, (3) the outcome of the studies was the frequency of consumption of various foods, and (4) the studies were original, published from 01/01/2015 to 31/12/2020 and written in English. RESULTS: From the search of the international literature, 1202 studies emerged, of which 16 were included in the review. Most of the studies (n = 14) were cross-sectional studies. Studies reported two to four dietary patterns. The dietary pattern, which included the consumption of fatty cheeses, sugary drinks, processed foods, fast food, snacks, animal products, whole milk, and refined seeds, was associated with an increased risk of developing obesity. On the other hand, the dietary pattern that included the consumption of vegetables, fruits, whole grains, fish, nuts, legumes, and yogurt was not associated with the risk of developing obesity. CONCLUSIONS: Children and adolescents who follow a diet consisting of obesogenic foods are more likely to develop obesity. To prevent childhood obesity and reduce the prevalence of obesity in adulthood, it is necessary to develop effective approaches aimed at adopting healthy eating patterns

Inactivation of the monofunctional peptidoglycan glycosyltransferase SgtB allows Staphylococcus aureus to survive in the absence of lipoteichoic acid

The cell wall of Staphylococcus aureus is composed of peptidoglycan and the anionic polymers lipoteichoic acid (LTA) and wall teichoic acid. LTA is required for growth and normal cell morphology in S. aureus. Strains lacking LTA are usually viable only when grown under osmotically stabilizing conditions or after the acquisition of compensatory mutations. LTA-negative suppressor strains with inactivating mutations in gdpP, which resulted in increased intracellular c-di-AMP levels, were described previously. Here, we sought to identify factors other than c-di-AMP that allow S. aureus to survive without LTA. LTA-negative strains able to grow in unsupplemented medium were obtained and found to contain mutations in sgtB, mazE, clpX, or vraT. The growth improvement through mutations in mazE and sgtB was confirmed by complementation analysis. We also showed that an S. aureus sgtB transposon mutant, with the monofunctional peptidoglycan glycosyltransferase SgtB inactivated, displayed a 4-fold increase in the MIC of oxacillin, suggesting that alterations in the peptidoglycan structure could help bacteria compensate for the lack of LTA. Muropeptide analysis of peptidoglycans isolated from a wild-type strain and sgtB mutant strain did not reveal any sizable alterations in the peptidoglycan structure. In contrast, the peptidoglycan isolated from an LTA-negative ltaS mutant strain showed a significant reduction in the fraction of highly cross-linked peptidoglycan, which was partially rescued in the sgtB ltaS double mutant suppressor strain. Taken together, these data point toward an important function of LTA in cell wall integrity through its necessity for proper peptidoglycan assembly

56 Gb/s, PAM-4 Transmission Over 25 km, Using IQ Modulator and Unequally Spaced Levels

[EN] We propose a PAM-4 modulation scheme with unequally spaced levels in order to mitigate chirp effects caused by IQ modulators. Experimental results of 56 Gb/s transmission over 25 km link demonstrate the robustness of this modulation concept.Prodaniuc, C.; Stojanovic, N.; Karinou, F.; Goeger, G.; Qiang, Z.; Llorente, R. (2015). 56 Gb/s, PAM-4 Transmission Over 25 km, Using IQ Modulator and Unequally Spaced Levels. Optical Society (OSA). 1-2. https://doi.org/10.1364/CLEO_SI.2015.STu4F.6S1

A Sub-Picojoule per Bit Integrated Magneto-Optic Modulator on Silicon: Modeling and Experimental Demonstration

Integrated magneto-optic (MO) modulators are an attractive but not fully explored alternative to electro-optic (EO) modulators. They are current driven, structurally simple, and could potentially achieve high efficiency in cryogenic and room temperature environments where fJ bit−1 optical interfaces are needed. In this paper, the performance and energy efficiency of a novel MO modulator at room temperature are for the first time assessed. First, a model of the micro-ring-based modulator is implemented to investigate the design parameters and their influence on the performance. Then, a fabricated device is experimentally characterized to assess its performance in terms of bit rate and energy efficiency. The model shows efficient operation at 1.2 Gbps using a 16 mA drive current, consuming only 155 fJ bit−1. The experimental results show that the MO effect is suitable for modulation, achieving error-free operation above 16 mA with a power consumption of 258 fJ bit−1 at a transient limited data rate of 1.2 Gbps