Filter Bank Multi-Sub-Band Transmission for Optical Systems with Mode Multiplexing

Mode-multiplexed optical transmission is subject to mode coupling and potentially large differential mode delays. In most recent implementations, these effects are compensated for at the receiver by complex adaptive multiple-input multiple-output (MIMO) equalizers. Although frequency-domain MIMO equalization requires a moderate complexity compared to time-domain equalization, the long required fast Fourier transforms may face implementation issues. In this paper, we evaluate an alternative transceiver architecture based on sub-band partitioning, implemented by filter banks, which enables concurrent time-domain equalization. Single-carrier (SC) and multi-sub-band (MSB) mode division multiplexing transmission are simulated using frequency-domain equalization and time-domain equalization, respectively. Their performance is compared in terms of static transmission performance, channel tracking capability, phase noise tolerance, and computational complexity. The results indicate that compared with an equivalent SC solution, the MSB architecture provides a high degree of parallelism at the cost of a penalty of 0.7-1.3 dB for a laser linewidth of 25-100 kHz and a moderate increase in complexity

An epigenetic memory of pregnancy in the mouse mammary gland.

Pregnancy is the major modulator of mammary gland activity. It induces a tremendous expansion of the mammary epithelium and the generation of alveolar structures for milk production. Anecdotal evidence from multiparous humans indicates that the mammary gland may react less strongly to the first pregnancy than it does to subsequent pregnancies. Here, we verify that the mouse mammary gland responds more robustly to a second pregnancy, indicating that the gland retains a long-term memory of pregnancy. A comparison of genome-wide profiles of DNA methylation in isolated mammary cell types reveals substantial and long-lasting alterations. Since these alterations are maintained in the absence of the signal that induced them, we term them epigenetic. The majority of alterations in DNA methylation affect sites occupied by the Stat5a transcription factor and mark specific genes that are upregulated during pregnancy. We postulate that the epigenetic memory of a first pregnancy primes the activation of gene expression networks that promote mammary gland function in subsequent reproductive cycles. More broadly, our data indicate that physiological experience can broadly alter epigenetic states, functionally modifying the capacity of the affected cells to respond to later stimulatory events.We thank Antoine Molaro for helpful discussions. This work was performed with assistance from the CSHL Flow Cytometry Shared Resource and from the CSHL Histology Shared Resource, which are supported by Cancer Center Support Grant 5P30CA045508. This work was supported by the NIH Grand Opportunity award #1 RC2 CA148507 (G.J.H.), P01 award # 2P01CA013106 (G.J.H.), and NIH grant R01 H6005238 (A.D.S.). G.J.H. is an investigator of the Howard Hughes Medical Institute.This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.celrep.2015.04.01

Discovery of active proteins directly from combinatorial randomized protein libraries without display, purification or sequencing:identification of novel zinc finger proteins.

We have successfully linked protein library screening directly with the identification of active proteins, without the need for individual purification, display technologies or physical linkage between the protein and its encoding sequence. By using 'MAX' randomization we have rapidly constructed 60 overlapping gene libraries that encode zinc finger proteins, randomized variously at the three principal DNA-contacting residues. Expression and screening of the libraries against five possible target DNA sequences generated data points covering a potential 40,000 individual interactions. Comparative analysis of the resulting data enabled direct identification of active proteins. Accuracy of this library analysis methodology was confirmed by both in vitro and in vivo analyses of identified proteins to yield novel zinc finger proteins that bind to their target sequences with high affinity, as indicated by low nanomolar apparent dissociation constants

Nanoporous Anodic Alumina Photonic Crystals for Optical Chemo- and Biosensing: Fundamentals, Advances, and Perspectives

Optical sensors are a class of devices that enable the identification and/or quantification of analyte molecules across multiple fields and disciplines such as environmental protection, medical diagnosis, security, food technology, biotechnology, and animal welfare. Nanoporous photonic crystal (PC) structures provide excellent platforms to develop such systems for a plethora of applications since these engineered materials enable precise and versatile control of light–matter interactions at the nanoscale. Nanoporous PCs provide both high sensitivity to monitor in real-time molecular binding events and a nanoporous matrix for selective immobilization of molecules of interest over increased surface areas. Nanoporous anodic alumina (NAA), a nanomaterial long envisaged as a PC, is an outstanding platform material to develop optical sensing systems in combination with multiple photonic technologies. Nanoporous anodic alumina photonic crystals (NAA-PCs) provide a versatile nanoporous structure that can be engineered in a multidimensional fashion to create unique PC sensing platforms such as Fabry–Pérot interferometers, distributed Bragg reflectors, gradient-index filters, optical microcavities, and others. The effective medium of NAA-PCs undergoes changes upon interactions with analyte molecules. These changes modify the NAA-PCs’ spectral fingerprints, which can be readily quantified to develop different sensing systems. This review introduces the fundamental development of NAA-PCs, compiling the most significant advances in the use of these optical materials for chemo- and biosensing applications, with a final prospective outlook about this exciting and dynamic field

Eddington-Limited Accretion in z~2 WISE-selected Hot, Dust-Obscured Galaxies

Hot, Dust-Obscured Galaxies, or "Hot DOGs", are a rare, dusty, hyperluminous galaxy population discovered by the WISE mission. Predominantly at redshifts 2-3, they include the most luminous known galaxies in the universe. Their high luminosities likely come from accretion onto highly obscured super massive black holes (SMBHs). We have conducted a pilot survey to measure the SMBH masses of five z~2 Hot DOGs via broad H_alpha emission lines, using Keck/MOSFIRE and Gemini/FLAMINGOS-2. We detect broad H_alpha emission in all five Hot DOGs. We find substantial corresponding SMBH masses for these Hot DOGs (~ 10^{9} M_sun), and their derived Eddington ratios are close to unity. These z~2 Hot DOGs are the most luminous AGNs at given BH masses, suggesting they are accreting at the maximum rates for their BHs. A similar property is found for known z~6 quasars. Our results are consistent with scenarios in which Hot DOGs represent a transitional, high-accretion phase between obscured and unobscured quasars. Hot DOGs may mark a special evolutionary stage before the red quasar and optical quasar phases, and they may be present at other cosmic epochs.Comment: 15 pages, 9 figures. Accepted by Ap

Integrating surface plasmon resonance and slow photon effects in nanoporous anodic alumina photonic crystals for photocatalysis

This study explores the potential of gold-coated titania-functionalized nanoporous anodic alumina distributed Bragg reflectors (Au-TiO2-NAA-DBRs) as platforms to enhance photocatalytic reactions by integrating “slow photons” and surface plasmon resonance (SPR). The photocatalytic degradation rate of methylene blue – a model organic compound with a well-defined absorption band in the visible spectral region – by these composite photonic crystals (PCs) upon visible-NIR light irradiation is used as an indicator to identify coupling effects between the “slow photon” effect and SPR. Our study demonstrates that the photocatalytic enhancement in Au-TiO2-NAA-DBRs is strongly associated with “slow photon” effect, while the contribution of SPR to the overall photocatalytic enhancement is weak due to the localized generation of surface plasmons on the top surface of the composite PC structure. Photocatalytic enhancement is optimal when the characteristic photonic stopband of these PCs partially overlaps with the absorption band of methylene blue, which results in edges being positioned away from the absorption maximum of the organic dye. The overall photocatalytic degradation for methylene blue is also correlated to the type of noble metal coating and the geometric features of the PC structures. These results establish a rationale for further development of noble metal-coated NAA-based hybrid plasmonic–photonic crystal photocatalyst platforms to optimally integrate “slow photons” and SPR for enhancing the efficiency of photocatalytic reactions and other light harvesting applications.Related: [http://cer.ihtm.bg.ac.rs/handle/123456789/3007]This is peer-reviewed version of the article: Law, L. Liu, M. Markovic, A. D. Abell and A. Santos, Catalysis Science & Technology, 2019, 9, 12, 3158-3176 [https://dx.doi.org/10.1039/C9CY00627C

Predicting incident radiographic knee osteoarthritis in middle-aged women within 4 years:the importance of knee-level prognostic factors.

ObjectiveDevelop and internally validate risk models and a clinical risk score tool to predict incident radiographic knee osteoarthritis (RKOA) in middle‐aged women.MethodsWe analysed 649 women in the Chingford 1000 Women study. The outcome was incident RKOA, defined as Kellgren/Lawrence grade 0‐1 at baseline and ≥2 at year 5. We estimated predictors' effects on the outcome using logistic regression models. Two models were generated. The clinical model considered patient characteristics, medication, biomarkers, and knee symptoms. The radiographic model considered the same factors, plus radiographic factors (e.g., angle between the acetabular roof and ilium's vertical cortex (hip α‐angle)). The models were internally validated. Model performance was assessed using calibration and discrimination (area under the receiver characteristic curve, AUC).ResultsThe clinical model contained age, quadriceps circumference, and a cartilage degradation marker (CTX‐II) as predictors (AUC = 0.692). The radiographic model contained older age, greater quadriceps circumference, knee pain, knee baseline Kellgren/Lawrence grade 1 (versus 0), greater hip α‐angle, greater spinal bone mineral density, and contralateral RKOA at baseline as predictors (AUC = 0.797). Calibration tests showed good agreement between the observed and predicted incident RKOA. A clinical risk score tool was developed from the clinical model.ConclusionTwo models predicting incident RKOA within 4 years were developed; including radiographic variables improved model performance. First‐time predictor hip α‐angle and contralateral RKOA suggest osteoarthritis origins beyond the knee. The clinical tool has the potential to help physicians identify patients at risk of RKOA in routine practice, but should be externally validated