Impact of Analog and Digital Pre-emphasis on the Signal-to-Noise Ratio of Bandwidth-limited Optical Transceivers

The ever-growing machine-to-machine traffic in data centers has stimulated the increase of transceiver data rate from 25Gb/s/λ to 100Gb/s/λ and beyond. It is believed that advanced modulation formats and digital-to-analog converters (DACs) will be employed in next generation short-reach transceivers. Digital pre-emphasis techniques are widely employed in DAC-based transceivers to compensate for the high frequency roll-off due to the RF and optoelectronics components in optical transceivers. However, digital pre-emphasis essentially reduces the magnitude of the signal low frequency components for a flat frequency response, which unavoidably increases quantization error, reducing the overall signal-to-noise ratio. This trade-off between SNR and bandwidth conflicts with the high SNR requirement of advanced modulation formats such as the Nyquist-shaped pulse amplitude modulation (PAM). To mitigate the quantization error induced SNR degradation, we show that analog pre-emphasis filters can be used in conjunction with digital pre-emphasis for improved system performance. To understand the impact of the analog pre-emphasis filter on system performance, we analyze the relationship between the flatness of the system frequency response and the SNR degradation due to digital pre-emphasis, and demonstrate 1.1-dB increase of receiver sensitivities, for both 64-Gb/s and 128-Gb/s intensity-modulation direct detection (IM-DD) 20 PAM4 signals, respectively employing a directly modulated laser (DML) and an electroabsorption modulator (EAM)

Evaluating Neighborhood Correlates and Geospatial Distribution of Breast, Cervical, and Colorectal Cancer Incidence

Introduction: Though cancer research has traditionally centered on individual-level exposures, there is growing interest in the geography of both cancer and its risk factors. This geographic and epidemiological research has consistently shown that cancer outcomes and their known causal exposures exhibit geographic variation that coincide with area-level socioeconomic status and the composition of neighborhoods. A retrospective study was conducted to evaluate geospatial variation for female breast, cervical, and colorectal cancer incidence in Baltimore City.Materials and Methods: Using a Maryland Cancer Registry dataset of incident breast, cervical, and colorectal cancers (N = 4,966) among Baltimore City female residents diagnosed from 2000 to 2010, spatial and epidemiological analyses were conducted through choropleth maps, spatial cluster identification, and local Moran's I. Ordinary least squares regression models identified characteristics associated with the geospatial clusters.Results: Each cancer type exhibited geographic variation across Baltimore City with the neighborhoods showing high incidence differing by cancer type. Specifically, breast cancer had significant low incidence in downtown Baltimore while cervical cancer had high incidence. The neighborhood covariates associated with the geographic variation also differed by cancer type while local Moran's I identified discordant clusters.Discussion: Cancer incidence varied geographically by cancer type within a single city (county). Small area estimates are needed to detect local patterns of disease when developing health and preventative programs. Given the observed variability of community-level characteristics associated with each cancer type incidence, local information is essential for developing place-, social-, and outcome-specific interventions

49 Gbit/s Direct-Modulation and Direct-Detection Transmission over 80 km SMF-28 without Optical Amplification or Filtering

We demonstrate direct-modulation of a discrete mode laser using Discrete Multi-Tone modulation for transmission distances up to 100 km in the 1550 nm band. A large operational temperature range (0-65ºC) is also demonstrated

Prenatal Maternal Mood Patterns Predict Child Temperament and Adolescent Mental Health

Background This study quantifies the dynamics of maternal mood focusing on unpredictability, and to assess if greater unpredictability of prenatal maternal mood predicts child temperament and internalizing symptoms through early adolescence. Methods The association between prenatal mood predictability and child internalizing symptoms were assessed in two longitudinal cohorts (N’s = 227 and 180). Maternal mood was assessed repeatedly during pregnancy as early as 15 weeks’ gestation. Predictability of maternal mood was calculated by applying Shannon’s entropy to the distribution of responses on mood questionnaires. Maternal reports of child negative affectivity (a predictor of later internalizing) were collected at 6, 12, 24 months and 7 years of age. Child self-reports of anxiety symptoms were collected at 10 years and reports of depression symptoms at 13 years. Results Fetal exposure to more elevated maternal mood entropy predicted higher levels of child negative affectivity at 12 months (r = .36; p \u3c 01), 24 months (r = .31; p \u3c 01) and 7 years (r = .32; p \u3c 01) of age. In addition, children exposed to higher prenatal maternal mood entropy, reported higher levels of anxiety symptoms at 10 years (r = .24; p \u3c 01) and elevated depressive symptoms at 13 years (r = .29; p \u3c .01). These associations persisted after adjusting for maternal pre and postnatal mood valence (e.g. depression levels) and for other relevant demographic characteristics. Conclusions Our findings provide strong support for the notion that patterns of maternal mood influence the developing brain. More specifically, they suggest that prenatal maternal mood predictability may be a critical predictor of developmental mental health trajectories and should be considered when assessing early life influences on lifespan mental health

Inherited Forms of Bladder Cancer: A review of Lynch Syndrome and Other Inherited Conditions

Environmental factors that play a role in the urothelial carcinogenesis have been well characterized. Current research is continuously exploring potential heritable forms of bladder cancer. Lynch syndrome is a well-known inheritable disease that increases the risk for a variety of cancers, including urothelial carcinomas. Screening of patients with known Lynch syndrome is important to evaluate for development of new primary tumors. Further study may provide more information on what level of follow-up each patient needs. Recent data suggest that mismatch repair mutations confer a greater risk for urothelial cancer. Additional large patient series as well as advancement of molecular testing may provide triage for Lynch syndrome patients in regards to the frequency and type of screening best suited for individual patient

How do older people discuss their own sexuality? A systematic review of qualitative research studies

This study captured older people’s attitudes and concerns about sex and sexuality in later life by synthesising qualitative research published on this issue. The systematic review was conducted between November 2015 and June 2016 based on a pre-determined protocol. Key words were used to ensure a precise search strategy. Empirically based, qualitative literature from 18 databases was found. Twenty studies met the inclusion criteria. Thomas and Harden’s thematic synthesis was used to generate ‘analytical themes’ which summarise this body of literature. Three main themes were identified: (a) social legitimacy for sexuality in later life; (b) health, not age, is what truly impacts sexuality, and (c) the hegemony of penetrative sex. The themes illustrate the complex and delicate relation between ageing and sexuality. Older adults facing health issues that affect sexual function adopt broader definitions of sexuality and sexual activit

Optical Injection-Locked Directly-Modulated Lasers for Dispersion Pre-compensated Direct-Detection Transmission

The growing traffic demand in inter-data center and metro communications requires high-speed and low-cost transceivers that can flexibly adapt to different transmission distances of up to a few hundred km. Ultimately low-cost transceivers will use the simplest optical hardware: namely a directly-modulated transmitter and direct detection receiver. Using optical injection-locked directly-modulated lasers (OIL-DML), we propose a transmitter that can control the full field of the optical signal and achieve error-free transmission over up to 300 km of dispersion uncompensated SMF-28. We demonstrate such a transmission system and discuss its potential for short and medium reach communication systems

Modulator-free quadrature amplitude modulation signal synthesis

The ability to generate high-speed on–off-keyed telecommunication signals by directly modulating a semiconductor laser’s drive current was one of the most exciting prospective applications of the nascent field of laser technology throughout the 1960s. Three decades of progress led to the commercialization of 2.5 Gbit s−1-per-channel submarine fibre optic systems that drove the growth of the internet as a global phenomenon. However, the detrimental frequency chirp associated with direct modulation forced industry to use external electro-optic modulators to deliver the next generation of on–off-keyed 10 Gbit s−1 systems and is absolutely prohibitive for today’s (>)100 Gbit s−1 coherent systems, which use complex modulation formats (for example, quadrature amplitude modulation). Here we use optical injection locking of directly modulated semiconductor lasers to generate complex modulation format signals showing distinct advantages over current and other currently researched solutions