14,347 research outputs found
Integrated cost-benefit analysis of tsetse control and herd productivity to inform control programs for animal African trypanosomiasis
Animal African trypanosomiasis (AAT) and its tsetse vector are responsible for annual losses estimated in billions of US dollars ($). Recent years have seen the implementation of a series of multinational interventions. However, actors of AAT control face complex resource allocation decisions due to the geographical range of AAT, diversity of ecological and livestock systems, and range of control methods available. The study presented here integrates an existing tsetse abundance model with a bio-economic herd model that captures local production characteristics as well as heterogeneities in AAT incidence and breed. These models were used to predict the impact of tsetse elimination on the net value of cattle production in the districts of Mambwe, in Zambia, and Faro et Déo in Cameroon. The net value of cattle production under the current situation was used as a baseline, and compared with alternative publicly funded control programmes. In Zambia, the current baseline is AAT control implemented privately by cattle owners (Scenario Z0). In Cameroon, the baseline (Scenario C0) is a small-scale publicly funded tsetse control programme and privately funded control at farm level. The model was run for 10 years, using a discount rate of 5%
A model checking approach to the parameter estimation of biochemical pathways
Model checking has historically been an important tool to
verify models of a wide variety of systems. Typically a model has to exhibit
certain properties to be classed ‘acceptable’. In this work we use
model checking in a new setting; parameter estimation. We characterise
the desired behaviour of a model in a temporal logic property and alter
the model to make it conform to the property (determined through
model checking). We have implemented a computational system called
MC2(GA) which pairs a model checker with a genetic algorithm. To
drive parameter estimation, the fitness of set of parameters in a model is
the inverse of the distance between its actual behaviour and the desired
behaviour. The model checker used is the simulation-based Monte Carlo
Model Checker for Probabilistic Linear-time Temporal Logic with numerical
constraints, MC2(PLTLc). Numerical constraints as well as the
overall probability of the behaviour expressed in temporal logic are used
to minimise the behavioural distance. We define the theory underlying
our parameter estimation approach in both the stochastic and continuous
worlds. We apply our approach to biochemical systems and present
an illustrative example where we estimate the kinetic rate constants in
a continuous model of a signalling pathway
Acetazolamide-based fungal chitinase inhibitors
Chitin is an essential structural component of the fungal cell wall. Chitinases are thought to be important for fungal cell wall remodelling, and inhibition of these enzymes has been proposed as a potential strategy for development of novel anti-fungals. The fungal pathogen Aspergillus fumigatus possesses two distinct multi-gene chitinase families. Here we explore acetazolamide as a chemical scaffold for the inhibition of an A. fumigatus ‘plant-type’ chitinase. A co-crystal structure of AfChiA1 with acetazolamide was used to guide synthesis and screening of acetazolamide analogues that yielded SAR in agreement with these structural data. Although acetazolamide and its analogues are weak inhibitors of the enzyme, they have a high ligand efficiency and as such are interesting leads for future inhibitor development
Dissociation in a polymerization model of homochirality
A fully self-contained model of homochirality is presented that contains the
effects of both polymerization and dissociation. The dissociation fragments are
assumed to replenish the substrate from which new monomers can grow and undergo
new polymerization. The mean length of isotactic polymers is found to grow
slowly with the normalized total number of corresponding building blocks.
Alternatively, if one assumes that the dissociation fragments themselves can
polymerize further, then this corresponds to a strong source of short polymers,
and an unrealistically short average length of only 3. By contrast, without
dissociation, isotactic polymers becomes infinitely long.Comment: 16 pages, 6 figures, submitted to Orig. Life Evol. Biosp
Estimating the nuclear level density with the Monte Carlo shell model
A method for making realistic estimates of the density of levels in even-even
nuclei is presented making use of the Monte Carlo shell model (MCSM). The
procedure follows three basic steps: (1) computation of the thermal energy with
the MCSM, (2) evaluation of the partition function by integrating the thermal
energy, and (3) evaluating the level density by performing the inverse Laplace
transform of the partition function using Maximum Entropy reconstruction
techniques. It is found that results obtained with schematic interactions,
which do not have a sign problem in the MCSM, compare well with realistic
shell-model interactions provided an important isospin dependence is accounted
for.Comment: 14 pages, 3 postscript figures. Latex with RevTex. Submitted as a
rapid communication to Phys. Rev.
On Self-Dual Gravity I
(One typo corrected and one incorrect statement removed. Extra details on
conserved quantities and symmetry algebras added).Comment: 17 pages, Latex, DAMTP-R92/4
Observation of Thermodynamical Properties in the Dy, Er and Yb Nuclei
The density of accessible levels in the (He,) reaction has
been extracted for the Dy, Er and Yb nuclei. The
nuclear temperature is measured as a function of excitation energy in the
region of 0 -- 6 MeV. The temperature curves reveal structures indicating new
degrees of freedom. The heat capacity of the nuclear system is discussed within
the framework of a canonical ensemble.Comment: 12 pages, 4 figures include
Penatalaksanaan Uveitis Pada Kehamilan dan Pasca Persalinan
Purpose: To report the management of uveitis in pregnancy. Methods: A case report. Result: Themanagement of uveitis in pregnancy is still not clear, so far there was no report from Indonesia. Pregnancyitself is a relative immunosupresive condition where hormonal alteration being changed after delivery. Theuveitis can relaps after delivery. Pregnancy restricts the use of medicine, which can be harmful to motherand the baby. We report the second trimester pregnancy with uveitis, treated with low dose systemicsteroid, cycloplegic and topical steroid. The patient condition remain stable after delivery, suggesting thatlow dose systemic steroid and topical cycloplegic and steroid could give good result. Conclusion : Propermanagement of uveitis in pregnancy can give satisfied result, without anyhazard for the mother and theinfant.
Double Extra Sharp Chopper Increase Efficacy of Phacoemulsification for Hard Mature Cataract Surgery
Objective: To assess the efficacy and safety of a modified double extra sharp chopper for removal of hard cataracts.
Design: Prospective non-comparative interventional clinical study.
Participants: Forty eyes from 25 patients with hard mature cataract grades 3-4.
Methods: The pre-modified Koch chopper was sharpened under the slit lamp to become extra sharp at the tip and inside the edge and 2 mm in length. Patients with hard mature cataract grades 3-4 (grade 4 being the hardest) underwent phacoemulsification by single surgery and were analyzed prospectively.
Results: The mean effective phaco time was 23.73 ± 5.75 seconds. Minimal power was facilitated by using horizontal chopping using a self-made double extra sharp chopper. No resistance was encountered while moving the chopper, regardless of cataract persistency. Preoperative BCVA were count fingers (47%), hand movement (35%), and light perception (18%). Postoperative BCVA on day 1and day 7 were 0.57 and 0.95, respectively. There was no difference of effective phaco time among nuclear hardness (P = 0.467), which represent the effectiveness of the extra sharp chopper.
Conclusions: The double extra sharp chopper facilitated a safe and rapid visual rehabilitation and maximal subject comfort when doing phacoemulsification for hard mature cataracts.
KEYWORDS:: mature cataract, sharp chopper, topical anesthesia, horizontal chopping, phacoemulsificatio
Doppler cooling of a Coulomb crystal
We study theoretically Doppler laser-cooling of a cluster of 2-level atoms
confined in a linear ion trap. Using several consecutive steps of averaging we
derive, from the full quantum mechanical master equation, an equation for the
total mechanical energy of the one dimensional crystal, defined on a
coarse-grained energy scale whose grid size is smaller than the linewidth of
the electronic transition. This equation describes the cooling dynamics for an
arbitrary number of ions and in the quantum regime. We discuss the validity of
the ergodic assumption (i.e. that the phase space distribution is only a
function of energy). From our equation we derive the semiclassical limit (i.e.
when the mechanical motion can be treated classically) and the Lamb-Dicke limit
(i.e. when the size of the mechanical wave function is much smaller than the
laser wavelength). We find a Fokker-Planck equation for the total mechanical
energy of the system, whose solution is in agreement with previous analytical
calculations which were based on different assumptions and valid only in their
specific regimes. Finally, in the classical limit we derive an analytic
expression for the average coupling, by light scattering, between motional
states at different energies.Comment: 19 pages, 3 figure
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