1,780 research outputs found
Semi-Continuous and Continuous Anaerobic Treatment of Palm Oil Mill Effluent for the Production of Organic Acids and Polyhydroxyalkanoates
The aim of this study was to improve organic acids production in semi and continuous anaerobic treatment of Palm Oil Mill Effluent (POME) using a locally fabricated 50 L Continuously Stirred Tank Reactor (CSTR). The organic acids obtained were then used for polyhydroxyalkanoate (PHA) production by Ralstonia eutropha ATCC 17699 in a 2 L bioreactor. The conditions used in the anaerobic treatment were controlled pH 6.5, sludge to POME ratio at 1:1 and Hydraulic Retention Time (HRT) of 4 days. The organic acids obtained were about 15 g L-1 at steady state for both treatments and the organic acids yield (based on BOD) was 58.3%. The selected organic acids obtained were acetic (51.5%), propionic (27%) and butyric (21.5%) acid. The recovery of the clarified and concentrated organic acids from the treated POME was made using a two-steps evaporation process. The clarified organic acids (distillate) obtained were comprising of 44.6, 20.1 and 22.5 g L-1 acetic, propionic and butyric acids, respectively with a recovery of 76%. The organic acids collected were then used for polyhydroxyalkanoates accumulation by Ralstonia eutropha ATCC 17699 using pH stat fed-batch fermentation under nitrogen limitation of C/N 40 in a 2 L fermenter. The highest PHA concentration of 11.4 g L-1 (>90% w/w) was achieved in this process
Fisher profiles and perceptions of sea turtle-fishery interactions: case study of East Coast Peninsular Malaysia
The paper focuses on coastal fisheries, particularly examining sea turtle-fishery interactions and determining the socioeconomic profile and perception of local fishers about sea turtle issues along the East Coast of Peninsular Malaysia.Turtle fisheries, Nature conservation, Coastal fisheries, Man-induced effects, ISEW, Malaysia, Malaya, Pahang, Malaysia, Malaya, Kelantan, Malaysia, Malaya, Terengganu,
10-Gb/s transmission over 20-km single fiber link using 1-GHz RSOA by discrete multitone with multiple access
We demonstrate a novel 10.5-Gbit/s transmission scheme over 20-km single fiber link by using a remotely fed 1-GHz reflective semiconductor optical amplifier (RSOA). Discrete multitone (DMT) modulation with adaptive bit-/power-loading is applied to overcome the bandwidth limitation of the RSOA. Transmission performance of the proposed scheme is analyzed in terms of various system parameters, such as the nonlinearity of the RSOA, optical signal-to-noise ratio of the optical seed carrier, the overhead size impact on dispersion, the number of DMT subcarriers, and the reflection noise from the single fiber link. We also report flexible-bandwidth-allocated multiple access operation based on the proposed scheme. The throughput for all cases is approximately 10 Gbit/s with BER <10-3
The Design of Microstrip Six-Pole Quasi-Elliptic Filter with Linear Phase Response Using Extracted-Pole Technique
The development of microstrip filters has been in great demand due to the rapid growth of wireless communication systems in this decade. Quasi-elliptic response filters are very popular in communication systems because of their high selectivity, which is introduced by a pair of transmission zeros. A number of ways of implementing the quasi-elliptic response filter on microstrip have been studied over the last two decades, i.e., the cascaded quadruplet filter, canonical filter, and extracted-pole filter. However, there is very little information in the literature giving the design details for microstrip extracted-pole filters. In this paper, design equations of the extracted-pole filter for microstrip are reviewed. A new class of microstrip filter is also presented here. This class of filter will have a quasi-elliptic function response and at the same time linear phase in the passband. The linear phase of the filter is introduced by an in-phase cross coupling, while the transmission zero is realized using an extracted-pole technique. Experimental results, together with a theoretical comparison between the group delay of this design, and the conventional quasi-elliptic six-pole filter are also presente
Dynamics of Baryons from String Theory and Vector Dominance
We consider a holographic model of QCD from string theory, a la Sakai and
Sugimoto, and study baryons. In this model, mesons are collectively realized as
a five-dimensional \ Yang-Mills field and baryons
are classically identified as solitons with a unit Pontryagin number
and electric charges. The soliton is shown to be very small in the large
't Hooft coupling limit, allowing us to introduce an effective field . Its coupling to the mesons are dictated by the soliton structure, and
consists of a direct magnetic coupling to the field strength as well
as a minimal coupling to the gauge field. Upon the dimensional
reduction, this effective action reproduces all interaction terms between
nucleons and an infinite tower of mesons in a manner consistent with the large
expansion. We further find that all electromagnetic interactions, as
inferred from the same effective action via a holographic prescription, are
mediated by an infinite tower of vector mesons, rendering the baryon
electromagnetic form factors completely vector-dominated as well. We estimate
nucleon-meson couplings and also the anomalous magnetic moments, which compare
well with nature.Comment: 65pages, 3 figures, vector mesons and axial-vector mesons are now
canonically normalized (comparisons with data and conclusions unaffected
Bogomol'nyi equations for solitons in Maxwell-Chern-Simons gauge theories with the magnetic moment interaction term
Without assuming rotational invariance, we derive Bogomol'nyi equations for
the solitons in the abelian Chern-Simons gauge theories with the anomalous
magnetic moment interaction. We also evaluate the number of zero modes around a
static soliton configuration.Comment: 9 pages, Revtex, SNUTP-94/6
Gravitating Chern-Simons vortices
The construction of self-dual vortex solutions to the Chern-Simons-Higgs
model (with a suitable eighth-order potential) coupled to Einstein gravity in
(2 + 1) dimensions is reconsidered. We show that the self-duality condition may
be derived from the sole assumption . Next, we derive a family of
exact, doubly self-dual vortex solutions, which interpolate between the
symmetrical and asymmetrical vacua. The corresponding spacetimes have two
regions at spatial infinity. The eighth-order Higgs potential is positive
definite, and closed timelike curves are absent, if the gravitational constant
is chosen to be negative.Comment: 11 pages, LaTe
SELF-DUAL ANYONS IN UNIFORM BACKGROUND FIELDS
We study relativistic self-dual Chern-Simons-Higgs systems in the presence of
uniform background fields that explicitly break CTP. A rich, but discrete
vacuum structure is found when the gauge symmetry is spontaneously broken,
while the symmetric phase can have an infinite vacuum degeneracy at tree level.
The latter is due to the proliferation of neutral solitonic states that cost
zero energy. Various novel self-dual solitons, such as these, are found in both
the symmetric and the asymmetric phases. Also by considering a similar system
on a two-sphere and the subsequent large sphere limit, we isolate sensible and
finite expressions for the conserved angular and linear momenta, which satisfy
anomalous commutation relations. We conclude with a few remarks on unresolved
issues.Comment: LaTeX, 20 pages, 4 uuencoded figures included
Autonomous stochastic resonance in fully frustrated Josephson-junction ladders
We investigate autonomous stochastic resonance in fully frustrated
Josephson-junction ladders, which are driven by uniform constant currents. At
zero temperature large currents induce oscillations between the two ground
states, while for small currents the lattice potential forces the system to
remain in one of the two states. At finite temperatures, on the other hand,
oscillations between the two states develop even below the critical current;
the signal-to-noise ratio is found to display array-enhanced stochastic
resonance. It is suggested that such behavior may be observed experimentally
through the measurement of the staggered voltage.Comment: 6 pages, 11 figures, to be published in Phys. Rev.
Analysis of the Y(4140) and related molecular states with QCD sum rules
In this article, we assume that there exist scalar , , and
molecular states, and study their masses using
the QCD sum rules. The numerical results indicate that the masses are about
above the corresponding ,
, and thresholds, the Y(4140) is unlikely a scalar molecular state. The scalar ,
, and molecular states maybe not exist, while the scalar , , and
molecular states maybe exist.Comment: 19 pages, 36 figures, slight revisio
- …