1,085 research outputs found
Reviews
Review of The Closed Shop, Industrial Relations in Australia, Toil and Trouble: The Struggle for a Better Life in New Zealan
An integrated circuit for chip-based analysis of enzyme kinetics and metabolite quantification
We have created a novel chip-based diagnostic tools based upon quantification of metabolites using enzymes specific for their chemical conversion. Using this device we show for the first time that a solid-state circuit can be used to measure enzyme kinetics and calculate the Michaelis-Menten constant. Substrate concentration dependency of enzyme reaction rates is central to this aim. Ion-sensitive field effect transistors (ISFET) are excellent transducers for biosensing applications that are reliant upon enzyme assays, especially since they can be fabricated using mainstream microelectronics technology to ensure low unit cost, mass-manufacture, scaling to make many sensors and straightforward miniaturisation for use in point-of-care devices. Here, we describe an integrated ISFET array comprising 216 sensors. The device was fabricated with a complementary metal oxide semiconductor (CMOS) process. Unlike traditional CMOS ISFET sensors that use the Si3N4 passivation of the foundry for ion detection, the device reported here was processed with a layer of Ta2O5 that increased the detection sensitivity to 45 mV/pH unit at the sensor readout. The drift was reduced to 0.8 mV/hour with a linear pH response between pH 2 – 12. A high-speed instrumentation system capable of acquiring nearly 500 fps was developed to stream out the data. The device was then used to measure glucose concentration through the activity of hexokinase in the range of 0.05 mM – 231 mM, encompassing glucose’s physiological range in blood. Localised and temporal enzyme kinetics of hexokinase was studied in detail. These results present a roadmap towards a viable personal metabolome machine
Towards a global analysis of polarized parton distributions
We present a technique for implementing in a fast way, and without any
approximations, higher-order calculations of partonic cross sections into
global analyses of parton distribution functions. The approach, which is set up
in Mellin-moment space, is particularly suited for analyses of future data from
polarized proton-proton collisions, but not limited to this case. The
usefulness and practicability of this method is demonstrated for the
semi-inclusive production of hadrons in deep-inelastic scattering and the
transverse momentum distribution of ``prompt'' photons in pp collisions, and a
case study for a future global analysis of polarized parton densities is
presented.Comment: 20 pages, LaTeX, 6 eps figures, final version to appear in PRD (minor
changes
A colorimetric CMOS-based platform for rapid total serum cholesterol quantification
Elevated cholesterol levels are associated with a greater risk of developing cardiovascular disease and other illnesses, making it a prime candidate for detection on a disposable biosensor for rapid point of care diagnostics. One of the methods to quantify cholesterol levels in human blood serum uses an optically mediated enzyme assay and a bench top spectrophotometer. The bulkiness and power hungry nature of the equipment limits its usage to laboratories. Here, we present a new disposable sensing platform that is based on a complementary metal oxide semiconductor process for total cholesterol quantification in pure blood serum. The platform that we implemented comprises readily mass-manufacturable components that exploit colorimetric changes of cholesterol oxidase and cholesterol esterase reactions. We have shown that our quantification results are comparable to that obtained by a bench top spectrophotometer. Using the implemented device, we have measured cholesterol concentration in human blood serum as low as 29 μM with a limit of detection at 13 μM, which is approximately 400 times lower than average physiological range, implying that our device also has the potential to be used for applications that require greater sensitivity
Magnetic ordering of Mn sublattice, dense Kondo lattice behavior of Ce in (RPd3)8Mn (R = La, Ce)
We have synthesized two new interstitial compounds (RPd3)8Mn (R = La and Ce).
The Mn ions present in "dilute" concentration of just 3 molar percent form a
sublattice with an unusually large Mn-Mn near neighbor distance of ~ 85 nm.
While the existence of (RPd3)8M (where M is a p-block element) is already
documented in the literature, the present work reports for the first time the
formation of this phase with M being a 3d element. In (LaPd3)8Mn, the Mn
sub-lattice orders antiferromagnetically as inferred from the peaks in
low-field magnetization at 48 K and 23 K. The latter peak progressively shifts
towards lower temperatures in increasing magnetic field and disappears below
1.8 K in a field of ~ 8 kOe. On the other hand in (CePd3)8Mn the Mn sublattice
undergoes a ferromagnetic transition around 35 K. The Ce ions form a dense
Kondo-lattice and are in a paramagnetic state at least down to 1.5 K. A
strongly correlated electronic ground state arising from Kondo effect is
inferred from the large extrapolated value of C/T = 275 mJ/Ce-mol K^2 at T = 0
K. In contrast, the interstitial alloys RPd3Mnx (x = 0.03 and 0.06), also
synthesized for the first time, have a spin glass ground state due to the
random distribution of the Mn ions over the available "1b" sites in the parent
RPd3 crystal lattice.Comment: 18 figures and 20 pages of text documen
Simple choreographies of the planar Newtonian -body Problem
In the -body problem, a simple choreography is a periodic solution, where
all masses chase each other on a single loop. In this paper we prove that for
the planar Newtonian -body problem with equal masses, , there are
at least different main simple choreographies. This
confirms a conjecture given by Chenciner and etc. in \cite{CGMS02}.Comment: 31pages, 6 figures. Refinements in notations and proof
Flow-duration curve integration into digital filtering algorithms for simulating climate variability based on river baseflow
A baseflow separation methodology combining the outcomes of the flow–duration curve and the digital filtering algorithms to cope with the restrictions of the traditional procedures has been assessed. Using this methodology as well as the monitored and simulated hydro-climatologic data, the baseflow annual variations due to climate change and human-induced activities were determined. The outcomes show that the long-term baseflow index at the upstream sub-basin is nearly half of that at the downstream from October to April, whereas, they are close to each other for the remaining months. Some of the groundwater reacts to precipitation and an evident rise in the groundwater contribution has been detected for the hydrological years 1998–2001 and 2006–2008. The contrary has been recorded for 1987. The water released from the reservoir in the dry periods lead to distinctions in the detected baseflow index between the pre-damming and post-damming periods of the river
Convex domains of Finsler and Riemannian manifolds
A detailed study of the notions of convexity for a hypersurface in a Finsler
manifold is carried out. In particular, the infinitesimal and local notions of
convexity are shown to be equivalent. Our approach differs from Bishop's one in
his classical result (Bishop, Indiana Univ Math J 24:169-172, 1974) for the
Riemannian case. Ours not only can be extended to the Finsler setting but it
also reduces the typical requirements of differentiability for the metric and
it yields consequences on the multiplicity of connecting geodesics in the
convex domain defined by the hypersurface.Comment: 22 pages, AMSLaTex. Typos corrected, references update
Multiparton Interactions in Photoproduction at HERA
The high energy photoproduction of jets is being observed at the ep collider,
HERA. It may be that the HERA centre-of-mass energy is sufficiently large that
the production of more than one pair of jets per ep collision becomes possible,
owing to the large number density of the probed gluons. We construct a Monte
Carlo model of such multiparton interactions and study their effects on a wide
range of physical observables. The conclusion is that multiple interactions
could have very significant effects upon the photoproduction final state and
that this would for example make extractions of the gluon density in the photon
rather difficult. Total rates for the production of many (i.e. > 2) jets could
provide direct evidence for the presence of multiple interactions, although
parton showering and hadronization significantly affect low transverse energy
jets.Comment: 21 pages, 8 figures include
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