Time-Frequency Warped Waveforms for Well-Contained Massive Machine Type Communications

This paper proposes a novel time-frequency warped waveform for short symbols, massive machine-type communication (mMTC), and internet of things (IoT) applications. The waveform is composed of asymmetric raised cosine (RC) pulses to increase the signal containment in time and frequency domains. The waveform has low power tails in the time domain, hence better performance in the presence of delay spread and time offsets. The time-axis warping unitary transform is applied to control the waveform occupancy in time-frequency space and to compensate for the usage of high roll-off factor pulses at the symbol edges. The paper explains a step-by-step analysis for determining the roll-off factors profile and the warping functions. Gains are presented over the conventional Zero-tail Discrete Fourier Transform-spread-Orthogonal Frequency Division Multiplexing (ZT-DFT-s-OFDM), and Cyclic prefix (CP) DFT-s-OFDM schemes in the simulations section.Comment: This paper has been accepted by IEEE JSAC special issue on 3GPP Technologies: 5G-Advanced and Beyond. Copyright may be transferred without notice, after which this version may no longer be accessibl

Centralized and Decentralized ML-Enabled Integrated Terrestrial and Non-Terrestrial Networks

Non-terrestrial networks (NTNs) are a critical enabler of the persistent connectivity vision of sixth-generation networks, as they can service areas where terrestrial infrastructure falls short. However, the integration of these networks with the terrestrial network is laden with obstacles. The dynamic nature of NTN communication scenarios and numerous variables render conventional model-based solutions computationally costly and impracticable for resource allocation, parameter optimization, and other problems. Machine learning (ML)-based solutions, thus, can perform a pivotal role due to their inherent ability to uncover the hidden patterns in time-varying, multi-dimensional data with superior performance and less complexity. Centralized ML (CML) and decentralized ML (DML), named so based on the distribution of the data and computational load, are two classes of ML that are being studied as solutions for the various complications of terrestrial and non-terrestrial networks (TNTN) integration. Both have their benefits and drawbacks under different circumstances, and it is integral to choose the appropriate ML approach for each TNTN integration issue. To this end, this paper goes over the TNTN integration architectures as given in the 3rd generation partnership project standard releases, proposing possible scenarios. Then, the capabilities and challenges of CML and DML are explored from the vantage point of these scenarios.Comment: This work was supported in part by the Scientific and Technological Research Council of Turkey (TUBITAK) under Grant No. 5200030 with the cooperation of Vestel and Istanbul Medipol Universit

Reproductive Outcome After Surgical Treatment of Endometriosis – Retrospective Analytical Study

Objective: The aim of the study was to investigate the reproductive outcomes of patients after surgical treatment of endometriosis. Material and Methods: The study included 100 infertile women, aged 21 to 41 years, who underwent surgical treatment of endometriosis. From January 2007 to January 2012, excision of endometriosis was performed by operative laparoscopy or laparotomy. Demographic, clinical, surgical and reproductive outcomes of 52 patients were retrospectively analyzed. Result: Twenty-three pregnancies (44%) were obtained in 52 patients, resulting in 16 term pregnancies, 4 spontaneous abortions under 16 weeks gestation, 2 spontaneous abortions at 20 gestational weeks and 1 ectopic pregnancy. Twenty nine patients did not achieve pregnancy and 68.9% (20/29) of them were treated with IVFICSI. Spontaneous pregnancies were obtained within 7 months after the surgery, whereas IVF-ICSI pregnancies were obtained within the period of 11 months. Seven patients were stage I, 14 patients stage II, 19 patients stage III, and 12 patients stage IV according to the American Fertility Society (AFS) Classification of Endometriosis. The pregnancy rate was 57% in stages I-II, 47% in stage III, 16% in stage IV endometriosis; and the rate of term pregnancies was 83%, 66%, and 0%, respectively. Seven pregnancies (7/14) were obtained in patients with bilateral endometriosis and 5 of them resulted in term pregnancy. Sixteen pregnancies (16/38) were obtained in patients with unilateral endometriosis and 11 of them resulted in term pregnancy. Conclusion: After surgical treatment of endometriosis, the pregnancy and live birth rates seem to be improved. Reproductive outcome is closely associated with the AFS score. Bilaterality of endometriosis does not affect pregnancy outcome

Suprascapular foramen: a rare variation caused by ossified suprascapular ligaments

Background: The aim of this study was to investigate the incidence of the suprascapular foramen in West Anatolian population. Materials and methods: Eighty-one dried human scapulae of West Anatolian people of unknown ages and gender belonging to the Anatomy Department Laboratory of Dokuz Eylul University Medical School were examined macroscopically. The vertical and transverse diameters of the suprascapular foramen and central thickness of the ossified ligaments were measured with calliper in millimetres and digital calliper, respectively. Results: We observed the suprascapular foramen due to ossification of the suprascapular ligament only in 2 of 81 (2.47%) scapulae. The vertical and transverse diameters of the suprascapular foramen and central thickness of the ossified ligaments (No. 1 and No. 2) were measured as 8.0 mm vs. 4.0 mm, 3.6 mm vs. 2.0 mm and 4.0 mm vs. 1.4 mm, respectively. Conclusions: The suprascapular foramen caused by ossified suprascapular ligament is rarely observed variation in West Anatolian population.

Nondata-aided channel estimation for OFDM systems with space-frequency transmit diversity

This paper proposes a computationally efficient nondata-aided maximum a posteriori (MAP) channel-estimation algorithm focusing on the space-frequency (SF) transmit diversity orthogonal frequency division multiplexing (OFDM) transmission through frequency-selective channels. The proposed algorithm properly averages out the data sequence and requires a convenient representation of the discrete multipath fading channel based on the Karhunen-Loeve (KL) orthogonal expansion and estimates the complex channel parameters of each subcarrier iteratively, using the expectation maximization (EM) method. To further reduce the computational complexity of the proposed MAP algorithm, the optimal truncation property of the KL expansion is exploited. The performance of the MAP channel estimator is studied based on the evaluation of the modified Cramer-Rao bound (CRB). Simulation results confirm the proposed theoretical analysis and illustrate that the proposed algorithm is capable of tracking fast fading and improving overall performance. © 2006 IEEE

Benzodithiophene bearing conjugated polymer-based surface anchoring for sensitive electrochemical glucose detection

An amino-functionalized, conjugated polymer (P(BDBT)) modified glassy carbon electrode (GCE) was employed as an immobilization platform for glucose oxidase (GOx) enzyme to assemble a novel glucose biosensor. Amino groups available on the polymer backbone served as bioconjugation sites for GOx via glutaraldehyde (GA). The biosensor response to the reduction in oxygen amount because of the enzyme reaction was monitored at ???0.7 V potential versus Ag/AgCl. The biosensor displayed a broad linear range between 0.1???1.0 mM glucose with a detection limit of 0.17 mM. The values of the apparent Michaelis-Menten constant (KMapp) and sensitivity were determined as 1.74 mM, and 28.17 ??A/(mM??cm2), respectively. GOx immobilized P(BDBT) film displayed high stability, selectivity, and reproducibility. Cyclic voltammetry (CV) and Scanning electron microscopy (SEM) techniques were utilized for the characterization of surface modifications. The fabricated biosensor was adept at determining the amount of glucose in a commercial beverage. The simple electrochemical method for the construction of P(BDBT)/GOx biosensors could pave the way to new perspectives in developing profitable biosensors.10OCT1012-10211

Rational Molecular Design Enables Efficient Blue TADF−OLEDs with Flexible Graphene Substrate

Observation of thermally activated delayed fluorescence (TADF) in conjugated systems redefined the molecular design approach to realize highly efficient organic light emitting diodes (OLEDs) in the early 2010s. Enabling effective reverse intersystem crossing (RISC) by minimizing the difference between singlet and triplet excited state energies (ΔEST) is proven to be a widely applicable and fruitful approach, which results in remarkable external quantum efficiencies (EQE). The efficacy of RISC in these systems is mainly dictated by the first-order mixing coefficient (λ), which is proportional to spin-orbit coupling (HSO) and inversely proportional to ΔEST. While minimizing ΔEST has been the focus of the OLED community over the last decade, the effect of HSO in these systems is largely overlooked. Here, molecular systems with increased HSO are designed and synthesized by substituting selected heteroatoms of high-performance TADF materials with heavy-atom selenium. A new series of multicolor TADF materials with remarkable EQEs are achieved. One of these materials, SeDF-B, results in pure blue emission with EQEs approaching 20%. Additionally, flexible graphene-based electrodes are developed for OLEDs and revealed to have similar performance as standard indium tin oxide (ITO) in most cases. These devices are the first report of TADF based OLEDs that utilize graphene-based anodes

Electrical Conductivity Response of Poly(Phenylene-vinylene)/Zeolite Composites Exposed to Ammonium Nitrate

Poly(p-phenylenevinylene) (PPV) was chemically synthesized via the polymerization of p-xylene-bis(tetrahydrothiophenium chloride) monomer and doped with H2SO4. To improve the electrical conductivity sensitivity of the conductive polymer, Zeolites Y (Si/Al = 5.1, 30, 60, 80) were added into the conductive polymer matrix. All composite samples show definite positive responses towards NH4NO3. The electrical conductivity sensitivities of the composite sensors increase linearly with increasing Si/Al ratio: with values of 0.201, 1.37, 2.80 and 3.18, respectively. The interactions between NH4NO3 molecules and the PPV/zeolite composites with respect to the electrical conductivity sensitivity were investigated through the infrared spectroscopy

Dissymmetrical U-Shaped π-Stacked Supramolecular Assemblies by Using a Dinuclear CuI Clip with Organophosphorus Ligands and Monotopic Fully π-Conjugated Ligands

International audienceReactions between the U-shape binuclear CuI complex A bearing short metal-metal distances and the cyano-capped monotopic π-conjugated ligands 1-5 carrying gradually bulkier polyaromatic terminal fragments lead to the formation of π-stacked supramolecular assemblies 6-10 respectively in 50-80 % yields. These derivatives have been characterized by multinuclear NMR spectroscopy and X-ray diffraction studies. Their solid state structures show the selective formation of U-shaped supramolecular assemblies in which two monotopic π-conjugated systems present large (6,7,9) or medium (8,10) intramolecular π-overlap revealing π-π interactions. These assemblies self-organize into head-to-tail π-stacked dimers that in turn self-assemble affording infinite columnar π-stacks. The nature, the extentand the complexity of the intermolecular contacts within the head-to-tail π-stacked dimer depends on the nature of the terminal polyaromatic fragment carried by the cyano-capped monotopic ligand but it does not alter the result of the self-assembling process. These results demonstrate that the dinuclear molecular clip A bearing short metal-metal distance allows selective supramolecular assembling processes driven by the formation of intra- and intermolecular short π-π interactions in the resulting self-assembled structures demonstrating that their shape is not only dictated by the symmetry of the building blocks. This approach opens perspectives toward the formation of extented π-stacked columns based on dissymmetrical and functionnal π-conjugated systems