An analytical and experimental study of injection-locked two-port oscillators

A Ku-band IMPATT oscillator with two distinct output power ports was injection-locked alternately at both ports. The transmission locking bandwidth was nearly the same for either port. The lower free running power port had a reflection locking bandwidth that was narrower than its transmission locking one. Just the opposite was found at the other port. A detailed analytical model for two-port injection-locked oscillators is presented, and its results agree quite well with the experiments. A critique of the literature on this topic is included to clear up misconceptions and errors. It is concluded that two-port injection-locked oscillators may prove useful in certain communication systems

Proposal for a Digital Pseudorandom Number Generator

A digital hardware implementation of a linear congruential sequence generator using shift and add techniques of multiplication is described. The sequence is of long period, low serial correlation and is rectangularly distributed. The method has certain advantages over conventional feedback shift register techniques

Disrupting An(Other): Sexuality as Political Resistance

If sexual knowledge can threaten social and political institutions and their control, how do the contents and subjects of literature and publications in the interwar period make that legible? Moreover, if female sexuality–represented or real–was seen as something disruptive to the normal functioning of society, did sexuality offer a useful entry point for social, political, or ideological critiques of the interwar period? My project responds to these questions by analyzing the lives and writings of two female authors of the interwar period: Djuna Barnes (1892-1982) and Katharine Burdekin (1896-1963). In my analysis, I focus on two major points of connection. First, both of the authors lived a life which deviated from societal norms of gender and sexuality, which I argue influenced their own politics regarding sexuality and society. Second, each of the authors draw direct links between the sexual and the political in their writing and, I argue, use sexuality as a platform for social criticism and political intervention. More broadly, this project proposes an understanding of non-normative sexuality as something imbued with the political potential to disrupt or subvert heteronormative structures

Parameterized Algorithms for Graph Partitioning Problems

We study a broad class of graph partitioning problems, where each problem is specified by a graph $G=(V,E)$, and parameters $k$ and $p$. We seek a subset $U\subseteq V$ of size $k$, such that $\alpha_1m_1 + \alpha_2m_2$ is at most (or at least) $p$, where $\alpha_1,\alpha_2\in\mathbb{R}$ are constants defining the problem, and $m_1, m_2$ are the cardinalities of the edge sets having both endpoints, and exactly one endpoint, in $U$, respectively. This class of fixed cardinality graph partitioning problems (FGPP) encompasses Max $(k,n-k)$-Cut, Min $k$-Vertex Cover, $k$-Densest Subgraph, and $k$-Sparsest Subgraph. Our main result is an $O^*(4^{k+o(k)}\Delta^k)$ algorithm for any problem in this class, where $\Delta \geq 1$ is the maximum degree in the input graph. This resolves an open question posed by Bonnet et al. [IPEC 2013]. We obtain faster algorithms for certain subclasses of FGPPs, parameterized by $p$, or by $(k+p)$. In particular, we give an $O^*(4^{p+o(p)})$ time algorithm for Max $(k,n-k)$-Cut, thus improving significantly the best known $O^*(p^p)$ time algorithm

Carbon isotope fractionation during aerobic biodegradation of trichloroethene by Burkholderia cepacia G4: a tool to map degradation mechanisms

The strain Burkholderia cepacia G4 aerobically mineralized trichloroethene (TCE) to CO2 over a time period of similar to20 h. Three biodegradation experiments were conducted with different bacterial optical densities at 540 nm (OD(540)s) in order to test whether isotope fractionation was consistent. The resulting TCE degradation was 93, 83.8, and 57.2% (i.e., 7.0, 16.2, and 42.8% TCE remaining) at OD(540)s of 2.0, 1.1, and 0.6, respectively. ODs also correlated linearly with zero-order degradation rates (1.99, 1.11, and 0.64 mumol h(-1)). While initial nonequilibrium mass losses of TCE produced only minor carbon isotope shifts (expressed in per mille delta C- 13(VPDB)), they were 57.2, 39.6, and 17.0parts per thousand between the initial and final TCE levels for the three experiments, in decreasing order of their OD(540)s. Despite these strong isotope shifts, we found a largely uniform isotope fractionation. The latter is expressed with a Rayleigh enrichment factor, E, and was -18.2 when all experiments were grouped to a common point of 42.8% TCE remaining. Although, decreases of epsilon to -20.7 were observed near complete degradation, our enrichment factors were significantly more negative than those reported for anaerobic dehalogenation of TCE. This indicates typical isotope fractionation for specific enzymatic mechanisms that can help to differentiate between degradation pathways

Dual inoculation of Pisum sativum with Rhizobium leguminosarum and Penicillium bilaji

Non-Peer ReviewedTo investigate the effect of single versus dual inoculation of Trapper-pea with Rhizobium leguminosarum and Penicillium bilaji, a P-solubilizing fungi, an experiment under controlled conditions was carried out using a sandy soil containing low levels of available N and P. The following treatments were installed: control, P application at a rate of 100 kg P/ha, pea inoculated with P. bilaji (PB50) applied at recommended rate as PB50™ supplied by Philom Bios, pea inoculated with R. leguminosarum (R) and all possible combinations of the four treatments. To determine N2 fixation by 15N-natural abundance, flax was included as the reference crop. Treatments were replicated four times and placed in a randomized complete block design. Throughout the experiment, soil was kept at 75 % of field capacity and additional light was provided. After 8 weeks of growth, two plants/pot were harvested and total shoot weight, total N, total P, percent N derived from N2 and the amount of N2 fixed was determined. P fertilization increased yield significantly from 3.0 to 4.2 g/pot. PB50 alone increased shoot yield to 3.6 g/pot. Whereas pea inoculated with R showed only a small yield increase, the additional application of P increased yield to 4.1 g/pot. Application of P and both the inoculants reduced yield to 3.7 g/pot. Total N accumulation was highly dependent on the presence of R. Whereas the control, which was sparsely nodulated, showed a total N yield of 62.3 mg N/pot, inoculation with R and P fertilization increased total N to 100 mg N/pot. Double inoculation with Rand PB50 along with P fertilization reduced the total N yield to 95 mg N/pot. Pea inoculated with PB50 and R showed a total N yield of 78.5 mg N/pot. The highest N2-fixing activity (39 % Ndfa or 39.6 mg of N) was observed in pea inoculated with R and which had received inorganic P. Total P uptake was solely dependent on P fertilization. Results indicate that PB50 had no beneficial influence on P uptake and N2-fixing activity

Detector Channel Combining Results from a High Photon Efficiency Optical Communications Link Test Bed

The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is developing a low cost, scalable, photon-counting receiver prototype for space-to-ground optical communications links. The receiver is being tested in a test bed that emulates photon-starved space-to-ground optical communication links. The receiver uses an array of single-pixel fiber-coupled superconducting nanowire single-photon detectors. The receiver is designed to receive the high photon efficiency serially concatenated pulse position modulation (SCPPM) waveform specified in the Consultative Committee for Space Data Systems (CCSDS) Optical Communications Coding and Synchronization Blue Book Standard. The optical receiver consists of an array of single-pixel superconducting nanowire detectors, analog phase shifters for channel alignment, digitizers for each detector channel, and digital processing of the received signal. An overview of the test bed and arrayed receiver system is given. Simulation and system characterization results are presented. The data rate increase of using a four-channel arrayed detector system over using one single pixel nanowire detector is characterized. Results indicate that a single-pixel detector is capable of receiving data at a rate of 40 Mbps and a four-channel arrayed detector system is capable of receiving data at a rate of 130 Mbps

A note on the differences of computably enumerable reals

We show that given any non-computable left-c.e. real α there exists a left-c.e. real β such that α≠β+γ for all left-c.e. reals and all right-c.e. reals γ. The proof is non-uniform, the dichotomy being whether the given real α is Martin-Loef random or not. It follows that given any universal machine U, there is another universal machine V such that the halting probability of U is not a translation of the halting probability of V by a left-c.e. real. We do not know if there is a uniform proof of this fact

Covering Pairs in Directed Acyclic Graphs

The Minimum Path Cover problem on directed acyclic graphs (DAGs) is a classical problem that provides a clear and simple mathematical formulation for several applications in different areas and that has an efficient algorithmic solution. In this paper, we study the computational complexity of two constrained variants of Minimum Path Cover motivated by the recent introduction of next-generation sequencing technologies in bioinformatics. The first problem (MinPCRP), given a DAG and a set of pairs of vertices, asks for a minimum cardinality set of paths "covering" all the vertices such that both vertices of each pair belong to the same path. For this problem, we show that, while it is NP-hard to compute if there exists a solution consisting of at most three paths, it is possible to decide in polynomial time whether a solution consisting of at most two paths exists. The second problem (MaxRPSP), given a DAG and a set of pairs of vertices, asks for a path containing the maximum number of the given pairs of vertices. We show its NP-hardness and also its W[1]-hardness when parametrized by the number of covered pairs. On the positive side, we give a fixed-parameter algorithm when the parameter is the maximum overlapping degree, a natural parameter in the bioinformatics applications of the problem