Performance limits for FDMA cellular systems described by hypergraphs

The authors present some preliminary material about hypergraphs, including a discussion of what they call random hypergraph multicolorings, a notion which is central to the analysis of frequency-assignment algorithms. They show that for any frequency-assignment algorithm, the carried traffic function must satisfy T(r)⩽T_0(r), where T_0(r) is a simple function that can be computed by linear programming. They give an asymptotic analysis of a class of 'fixed' frequency-assignment algorithms, and show that in the limit as n→∞, these algorithms achieve carried traffic functions that are at least as large as T_1( r), another simple function that can be computed by linear programming. They show that T_0(r)=T_1(r). This common value, denoted by T_(H,p)(r) is the function referred to above. They also describe some of the most important properties of the function TH,p(r), and identify the 'most favorable' traffic patterns for a given hypergraph H

Hierarchical Coding of High Data Rate Video for Asynchronous Transfer Mode Networks

High data rate video is an integral part of high-quality multimedia for broadband networks. Owing to the high rate, compression of video information is required for an efficient use of network bandwidth. A hierarchical DCT-based video codec is examined that prioritizes and compresses high data rate video for transmission over ATM networks.The video codec utilizes intraframe coding by independently processing each frame of the video sequence. The lossless compression part consists of run length coding to exploit zero values in the high frequency DCT coefficients and variable length coding (VLC) to further reduce the bit rate. Three compression schemes are examined: adaptive Huffman, arithmetic coding, and Lempel-Ziv-Welch coding. For the model-based compression algorithms, we study several models to characterize the input bit stream to the VLC: memoryless, and Markov with either fixed orders or orders determined by an order estimator. For the three VLCs in the codec, the best performance was obtained from a combination of a memoryless Huffman codec and two first-order Huffman codecs. Many of the models incorporating memory, performed poorly due to the small size of the input files.Due to the VLC, the output rate of the system is variable; however, since intraframe coding is utilized, rate variations are small. In order to fully utilize available bandwidth, we examine the rate control problem of converting the codec from a variable rate system to a fixed rate system. The rate control problem is formulated as one of constrained minimization, and analyzed for optimal solutions. Algorithms are presented for optimal rate control

Screening, production, and characterization of biologically active secondary metabolite(s) from marine Streptomyces sp. PA9 for antimicrobial, antioxidant, and mosquito larvicidal activity

1319-1326Bioprospecting of actinobacteria from understudied ecosystems is a promising source for extracting novel bioactive metabolites. A study was undertaken to characterize and analyze the bio-efficacy of actinobacterial extract for antimicrobial, larvicidal, and antioxidant activities. Seven morphologically different actinobacterial cultures isolated from mangrove rhizosphere sediment near Parangipettai, South India, were tested for antimicrobial activity. Bioactive metabolites from one potential strain PA9 were produced by submerged fermentation. The selected Streptomyces sp. PA9 was subjected to the production of crude extract for antimicrobial, larvicidal, and antioxidant activity. The actinobacterial compound was characterized by Fourier transform infrared spectroscopy (FTIR), high-performance liquid chromatography (HPLC), and gas chromatography–mass spectrometry (GC–MS). The PA9 actinobacterial crude extract showed best antimicrobial activity against clinical bacteria, Salmonella typhi (21.6 ± 0.88 mm) and fungi, Candida albicans (26.6 ± 0.88 mm). The PA9 extract showed significant larvicidal activity against Culex quinquefasciatus with LC50=173.21 µg/ml and r2=0.841. The PA9 extract also exhibited antioxidant activity from DPPH (72%) and nitric oxide free radicals (85%). The characterization of the PA9 extract by FTIR analysis showed the presence of possible functional groups. Active compounds were isolated by HPLC and GC–MS with major and minor peaks observed on the basis of retention time. The bio-efficacy of PA9 has warranted further studies to develop a baseline for the drug development

Scattering of polarised light by colloids containing anisotropic particles

It is only recently that the theoretical significance of the elliptic polarisation of light scattered by colloids containing particles of large size has been pointed out and an analysis made of the theoretical conclusions regarding ellipticity from Mie's theory for spherical particles. The earlier qualitative measurements on ellipticity of the scattered light have been explained on the basis of these new ideas and the implications of Mie's theory brought out more clearly. New experiments have been devised and used for measuring the constant phase difference δ that exists between the vertical and horizontal components of the transversely scattered light when the incident light is polarised in any azimuth. Measurements have been made both for systems of spherical particles and anisotropic particles. It is found that even in the case of large anisotropic particles δ is a constant. It follows therefore, that in the most general case of large anisotropic colloidal particles the polarised scattering due to finite size is elliptic in nature and is superposed on the depolarised part due to anisotropy

Bioactive potential of selected actinobacterial strains against Mycobacterium tuberculosis and other clinical pathogens

1307-1311Marine actinobacteria produces diverse array of metabolites with novel chemical structures with potential bioactivities. Exploring the understudied ecosystems may increase the chance of getting novel actinobacteria and new metabolites.The present study explores the bioactive potential of actinobacteria isolated from the marine ecosystem of Andaman and Nicobar Islands, Bay of Bengal, against Mycobacterium tuberculosis and other clinical pathogens. The crude extracts from 15 marine actinobacterial strains were produced through agar surface fermentation using YEME agar and extracted using ethyl acetate. The crude extracts were tested against the standard strain M. tuberculosis H37Rv, clinical drug sensitive M. tuberculosis, and MDR M. tuberculosis strains by luciferase reporter phage (LRP) assay at 500 µg/ml concentration. The anti-microbial activity against other clinical pathogens, namely, Staphylococcus aureus, Escherichia coli, Salmonella paratyphi, Klebsiellapneumoniae, Pseudomonas aeruginosa, Candida albicans, and Cryptococcusneoformans and non-tubercular mycobacteria, M. smegmatis was studied by agar plug method. Among the 15 extracts that were tested for anti-tubercular activity, the crude ethyl acetate extract of the 14 actinobacterial strains showed anti-tubercular activity against at least one of the three M. tuberculosis strains. Exceptionally, the ethyl acetate extract of strain SACC 168 inhibited all three M. tuberculosis strains tested. In anti-microbial screening, the crude extracts of eight strains showed anti-microbial activity including six strains, which were active against the non-tuberculous mycobacteria. Further purification and characterization of the active molecule from the potential extracts will pave way for the potential natural product candidate for tuberculosis and other microbial infections

Developing a serocorrelate of protection against invasive group B streptococcus disease in pregnant women: a feasibility study.

BACKGROUND: Group B streptococcus is the leading cause of infection in infants. Currently, intrapartum antibiotic prophylaxis is the major strategy to prevent invasive group B streptococcus disease. However, intrapartum antibiotic prophylaxis does not prevent maternal sepsis, premature births, stillbirths or late-onset disease. Maternal vaccination may offer an alternative strategy. Multivalent polysaccharide protein conjugate vaccine development is under way and a serocorrelate of protection is needed to expedite vaccine licensure. OBJECTIVES: The ultimate aim of this work is to determine the correlate of protection against the major group B streptococcus disease-causing serotypes in infants in the UK. The aim of this feasibility study is to test key operational aspects of the study design. DESIGN: Prospective cohort study of pregnant women and their infants in a 6-month period (1 July to 31 December 2018). SETTING: Five secondary and tertiary hospitals from London and South England. National iGBS disease surveillance was conducted in all trusts in England and Wales. PARTICIPANTS: Pregnant women aged ≥ 18 years who were delivering at one of the selected hospitals and who provided consent during the study period. There were no exclusion criteria. INTERVENTIONS: No interventions were performed. MAIN OUTCOME MEASURES: (1) To test the feasibility of collecting serum at delivery from a large cohort of pregnant women. (2) To test the key operational aspects for a proposed large serocorrelates study. (3) To test the feasibility of collecting samples from those with invasive group B streptococcus. RESULTS: A total of 1823 women were recruited during the study period. Overall, 85% of serum samples were collected at three sites collecting only cord blood. At the two sites collecting maternal, cord and infant blood samples, the collection rate was 60%. A total of 614 women were screened for group B streptococcus with a colonisation rate of 22% (serotype distribution: 30% III, 25% Ia, 16% II, 14% Ib, 14% V and 1% IV). A blood sample was collected from 34 infants who were born to colonised women. Maternal and infant blood and the bacterial isolates for 15 newborns who developed invasive group B streptococcal disease during the study period were collected (serotype distribution: 29% III, 29% II, 21% Ia, 7% Ib, 7% IV and 7% V). LIMITATIONS: Recruitment and sample collection were dependent on the presence of research midwives rather than the whole clinical team. In addition, individualised consent limited the number of women who could be approached each day, and site set-up for the national surveillance study and the limited time period of this feasibility study limited recruitment of all eligible participants. CONCLUSIONS: We have verified the feasibility of collecting and processing rectovaginal swabs and blood samples in pregnant women, as well as samples from those with invasive group B streptococcal disease. We have made recommendations for the recruitment of cases within the proposed GBS3 study and for controls both within GBS3 and as an extension of this feasibility study. FUTURE WORK: A large case-control study comparing specific immunoglobulin G levels in mothers whose infants develop invasive group B streptococcal disease with those in colonised mothers whose infants do not develop invasive group B streptococcal disease is recommended. TRIAL REGISTRATION: Current Controlled Trials ISRCTN49326091; IRAS project identification number 246149/REC reference number 18/WM/0147. FUNDING: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 67. See the NIHR Journals Library website for further project information

Method for separating single-wall carbon nanotubes and compositions thereof

The invention relates to a process for sorting and separating a mixture of (n, m) type single-wall carbon nanotubes according to (n, m) type. A mixture of (n, m) type single-wall carbon nanotubes is suspended such that the single-wall carbon nanotubes are individually dispersed. The nanotube suspension can be done in a surfactant-water solution and the surfactant surrounding the nanotubes keeps the nanotube isolated and from aggregating with other nanotubes. The nanotube suspension is acidified to protonate a fraction of the nanotubes. An electric field is applied and the protonated nanotubes migrate in the electric fields at different rates dependent on their (n, m) type. Fractions of nanotubes are collected at different fractionation times. The process of protonation, applying an electric field, and fractionation is repeated at increasingly higher pH to separated the (n, m) nanotube mixture into individual (n, m) nanotube fractions. The separation enables new electronic devices requiring selected (n, m) nanotube types

Mitochondrial polymorphisms in rat genetic models of hypertension

Hypertension is a complex trait that has been studied extensively for genetic contributions of the nuclear genome. We examined mitochondrial genomes of the hypertensive strains: the Dahl Salt-Sensitive (S) rat, the Spontaneously Hypertensive Rat (SHR), and the Albino Surgery (AS) rat, and the relatively normotensive strains: the Dahl Salt-Resistant (R) rat, the Milan Normotensive Strain (MNS), and the Lewis rat (LEW). These strains were used previously for linkage analysis for blood pressure (BP) in our laboratory. The results provide evidence to suggest that variations in the mitochondrial genome do not account for observed differences in blood pressure between the S and R rats. However, variants were detected among the mitochondrial genomes of the various hypertensive strains, S, SHR, and AS, and also among the normotensive strains R, MNS, and LEW. A total of 115, 114, 106, 106, and 16 variations in mtDNA were observed between the comparisons S versus LEW, S versus MNS, S versus SHR, S versus AS, and SHR versus AS, respectively. Among the 13 genes coding for proteins of the electron transport chain, 8 genes had nonsynonymous variations between S, LEW, MNS, SHR, and AS. The lack of any sequence variants between the mitochondrial genomes of S and R rats provides conclusive evidence that divergence in blood pressure between these two inbred strains is exclusively programmed through their nuclear genomes. The variations detected among the various hypertensive strains provides the basis to construct conplastic strains and further evaluate the effects of these variants on hypertension and associated phenotypes