1,127 research outputs found
Automation of the longwall mining system
Cost effective, safe, and technologically sound applications of automation technology to underground coal mining were identified. The longwall analysis commenced with a general search for government and industry experience of mining automation technology. A brief industry survey was conducted to identify longwall operational, safety, and design problems. The prime automation candidates resulting from the industry experience and survey were: (1) the shearer operation, (2) shield and conveyor pan line advance, (3) a management information system to allow improved mine logistics support, and (4) component fault isolation and diagnostics to reduce untimely maintenance delays. A system network analysis indicated that a 40% improvement in productivity was feasible if system delays associated with all of the above four areas were removed. A technology assessment and conceptual system design of each of the four automation candidate areas showed that state of the art digital computer, servomechanism, and actuator technologies could be applied to automate the longwall system
Accessibility levels to potable Water Supply in Rural Areas of Akwa Ibom State, Nigeria
The UN in the year 2000 enlisted improved access to potable water supply as one of the development goals to be achieved by 2015 in developing countries including Nigeria. This study therefore, examined the levels of access to potable water supply in rural areas of Akwa Ibom State against the background of meeting the Millennium Development Goals (MDGs) in 2015. to carry out the investigation, the map of the study area was divided into 500 grid squares (quadrates) and a total of 50 rural communities were sampled using table of random numbers. Community heads or their spokesmen/women in the sampled areas were target respondents and data on major sources of water supply, distance to the nearest major source of water supply and the number of water boreholes in the communities were collected and analyzed. The population of the communities provided a basis for evolving an index that measured the levels of access to potable water supply in the study area. The use of GIS was subsequently employed to map out the study area on the basis of levels of access to potable water supply. The overall result depicts a very poor status scenario as majority of the communities studied have deteriorating conditions. The study recommends among others that a state of emergency be declared in the water sector, if the MDGs are to be achieved in the water sector by 2015.Key words: Rural, Water Supply, Akwa Ibom, NigeriaKey words: Rural, Water Supply, Akwa Ibom, Nigeri
Expression and downstream purification of insulin molecules in Pichia pastoris
In the next decade and beyond global demand for insulin is expected to rise significantly requiring additional manufacturing capacity. The next generation of insulin manufacturing plants will likely be based on new and robust expression and bioprocess platforms that are flexible, safe, simple to implement in a manufacturing setting and capable of step improvements in productivity and cost compared to current manufacturing techniques. Towards this end, Pichia pastoris expression systems has been evaluated for insulin due to its capacity to secrete a variety of heterologous proteins and its ability to grow to high cell densities. Under the well-characterized, tightly regulated AOX1 promoter, yields of 1.5 to nearly 3 g/L of purified insulin have been reported.1,2,3 However, methanol is a very volatile substance requiring specialized facilities, which can hamper large-scale production. Downstream processing of insulin precursors also requires use of organic solvents which can also burden manufacturing. We report development of an insulin process using a constitutive promoter expression system in place of the inducible AOX1 promoter, and a simplified downstream purification process using precipitation. Fermentations were carried out in 2 L scale bioreactors and culture supernatant collected after 65 hours. A design of experiment (DoE) was performed to identify optimal conditions for polyelectrolyte precipitation of the recombinant protein using polyvinyl sulfonic acid (PVS).4 The resulting pellets were then analyzed via SDS-PAGE and HPLC.
1. Gurramkonda, C. et al. Application of simple fed-batch technique to high-level secretory production of insulin precursor using Pichia pastoris with subsequent purification and conversion to human insulin. Microb. Cell Fact. 9, 31 (2010).
2. Polez, S. et al. A Simplified and Efficient Process for Insulin Production in Pichia pastoris. PLoS One 11, e0167207 (2016).
3. Xie, T., Liu, Q., Xie, F., Liu, H. & Zhang, Y. Secretory expression of insulin precursor in pichia pastoris and simple procedure for producing recombinant human insulin. Prep. Biochem. Biotechnol. 38, 308–17 (2008).
4. Buddha, M. et al. Precipitation as an Alternative to Chromatography in the Insulin Manufacturing Process. BioPharm Int. 30–36 (2016)
A TV-Gaussian prior for infinite-dimensional Bayesian inverse problems and its numerical implementations
Many scientific and engineering problems require to perform Bayesian
inferences in function spaces, in which the unknowns are of infinite dimension.
In such problems, choosing an appropriate prior distribution is an important
task. In particular we consider problems where the function to infer is subject
to sharp jumps which render the commonly used Gaussian measures unsuitable. On
the other hand, the so-called total variation (TV) prior can only be defined in
a finite dimensional setting, and does not lead to a well-defined posterior
measure in function spaces. In this work we present a TV-Gaussian (TG) prior to
address such problems, where the TV term is used to detect sharp jumps of the
function, and the Gaussian distribution is used as a reference measure so that
it results in a well-defined posterior measure in the function space. We also
present an efficient Markov Chain Monte Carlo (MCMC) algorithm to draw samples
from the posterior distribution of the TG prior. With numerical examples we
demonstrate the performance of the TG prior and the efficiency of the proposed
MCMC algorithm
Notch Signaling in Cancer
Notch signaling plays a key role in the normal development of many tissues and cell types, through diverse effects on differentiation, survival, and/or proliferation that are highly dependent on signal strength and cellular context. Because perturbations in the regulation of differentiation, survival, and/or proliferation underlie malignant transformation, pathophysiologic Notch signals potentially contribute to cancer development in several different ways.
Notch signaling was first linked to tumorigenesis through identification of a recurrent t(7;9)(q34;q34.3) chromosomal translocation involving the human Notch 1 gene that is found in a small subset of human pre-T-cell acute lymphoblastic leukemias (T-ALL).1 Since this discovery, aberrant Notch signaling has been suggested to be involved in a wide variety of human neoplasms. In this review, we will focus on recent studies linking aberrant Notch signaling with cancer. First, we discuss various mechanisms through which Notch signaling may influence cellular transformation. Then, we critically review literature pertaining to the role of Notch signaling in several cancers, and discuss possible therapeutic targets in the Notch pathway
Fitting the Light Curve of 1I/`Oumuamua with a Nonprincipal Axis Rotational Model and Outgassing Torques
In this paper, we investigate the nonprincipal axis (NPA) rotational state of
1I/`Oumuamua -- the first interstellar object discovered traversing the inner
Solar System -- from its photometric light curve. Building upon Mashchenko
(2019), we develop a model which incorporates NPA rotation and {Sun-induced,
time-varying} outgassing torques to generate synthetic light curves of the
object. The model neglects tidal forces, which are negligible compared to
outgassing torques over the distances that `Oumuamua was observed. We implement
an optimization scheme that incorporates the NPA rotation model to calculate
the initial rotation state of the object. We find that an NPA rotation state
with an average period of hr best reproduces the
photometric data. The discrepancy between this period and previous estimates is
due to continuous period modulation induced by outgassing torques in the
rotational model, {as well as different periods being used}. The best fit to
the October 2017 data does not reproduce the November 2017 data (although the
later measurements are too sparse to fit). The light curve is consistent with
no secular evolution of the angular momentum, somewhat in tension with the
empirical correlations between nuclear spin-up and cometary outgassing. The
complex rotation of `Oumuamua may be {the result of primordial rotation about
the smallest principal axis} if (i) the object experienced hypervolatile
outgassing and (ii) our idealized outgassing model is accurate.Comment: 22 pages, 8 figures, 1 animation. Accepted to the Planetary Science
Journal. The animation can be found on YouTube (https://youtu.be/f5YEAMTvIeo)
and in the online publication by PSJ (when available
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