234 research outputs found
Application of Flow-Injection Spectrophotometry to Pharmaceutical and Biomedical Analyses
The discovery of new drugs, especially when many samples have to be analyzed in the minimum of time, demand the improvement or development of new analytical methods. Various techniques may be employed for this purpose. In this context, this chapter gathers the collection of paper and represents the review of past work on spectrophotometric technique coupled to a continuous flow system to determine low concentrations of several chemical species in different kinds of pharmaceutical and biological samples. A short historical background of the flow-injection analysis technique and a brief discussion of the basic principles and potential are presented. Part of this chapter is devoted to describing the sample preparation techniques, principles, and figures of merit of analytical methods. Representative applications of flow-injection spectrophotometry to pharmaceutical and biomedical analysis are also described
Open strings in relativistic ion traps
Electromagnetic plane waves provide examples of time-dependent open string
backgrounds free of corrections. The solvable case of open strings in
a quadrupolar wave front, analogous to pp-waves for closed strings, is
discussed. In light-cone gauge, it leads to non-conformal boundary conditions
similar to those induced by tachyon condensates. A maximum electric gradient is
found, at which macroscopic strings with vanishing tension are pair-produced --
a non-relativistic analogue of the Born-Infeld critical electric field. Kinetic
instabilities of quadrupolar electric fields are cured by standard atomic
physics techniques, and do not interfere with the former dynamic instability. A
new example of non-conformal open-closed duality is found. Propagation of open
strings in time-dependent wave fronts is discussed.Comment: 43 pages, 11 figures, Latex2e, JHEP3.cls style; v2: one-loop
amplitude corrected, open-closed duality proved, refs added, miscellaneous
improvements, see historical note in fil
State sampling dependence of the Hopfield network inference
The fully connected Hopfield network is inferred based on observed
magnetizations and pairwise correlations. We present the system in the glassy
phase with low temperature and high memory load. We find that the inference
error is very sensitive to the form of state sampling. When a single state is
sampled to compute magnetizations and correlations, the inference error is
almost indistinguishable irrespective of the sampled state. However, the error
can be greatly reduced if the data is collected with state transitions. Our
result holds for different disorder samples and accounts for the previously
observed large fluctuations of inference error at low temperatures.Comment: 4 pages, 1 figure, further discussions added and relevant references
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The spectral gap for some spin chains with discrete symmetry breaking
We prove that for any finite set of generalized valence bond solid (GVBS)
states of a quantum spin chain there exists a translation invariant
finite-range Hamiltonian for which this set is the set of ground states. This
result implies that there are GVBS models with arbitrary broken discrete
symmetries that are described as combinations of lattice translations, lattice
reflections, and local unitary or anti-unitary transformations. We also show
that all GVBS models that satisfy some natural conditions have a spectral gap.
The existence of a spectral gap is obtained by applying a simple and quite
general strategy for proving lower bounds on the spectral gap of the generator
of a classical or quantum spin dynamics. This general scheme is interesting in
its own right and therefore, although the basic idea is not new, we present it
in a system-independent setting. The results are illustrated with an number of
examples.Comment: 48 pages, Plain TeX, BN26/Oct/9
Quantification of milk adulterants (starch, H2O2, and NaClO) using colorimetric assays coupled to smartphone image analysis
In this paper, a colorimetric method for the detection of milk adulterants using smartphone image analysis is reported. This is based on the reactions to detect hydrogen peroxide, sodium hypochlorite, and starch in milk, where a color variation is observed for each substance. The image analysis was performed by using lab-made apps (PhotoMetrixÂź, and RedGIMÂź) based on partial least squares regression with the histograms of the red-green-blue images. The image histograms are automatically calculated using the smartphone camera and processed within the app. The results have shown the capability of this method to predict the concentration of the three adulterants, demonstrating the potential of the use of digital images and smartphone applications associated with chemometric tools. This method presents a fast, low-cost, and portable way to quantify adulterants in Cow milk
Heavy quarkonium: progress, puzzles, and opportunities
A golden age for heavy quarkonium physics dawned a decade ago, initiated by
the confluence of exciting advances in quantum chromodynamics (QCD) and an
explosion of related experimental activity. The early years of this period were
chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in
2004, which presented a comprehensive review of the status of the field at that
time and provided specific recommendations for further progress. However, the
broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles
could only be partially anticipated. Since the release of the YR, the BESII
program concluded only to give birth to BESIII; the -factories and CLEO-c
flourished; quarkonium production and polarization measurements at HERA and the
Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the
deconfinement regime. All these experiments leave legacies of quality,
precision, and unsolved mysteries for quarkonium physics, and therefore beg for
continuing investigations. The plethora of newly-found quarkonium-like states
unleashed a flood of theoretical investigations into new forms of matter such
as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the
spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b},
and b\bar{c} bound states have been shown to validate some theoretical
approaches to QCD and highlight lack of quantitative success for others. The
intriguing details of quarkonium suppression in heavy-ion collisions that have
emerged from RHIC have elevated the importance of separating hot- and
cold-nuclear-matter effects in quark-gluon plasma studies. This review
systematically addresses all these matters and concludes by prioritizing
directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K.
Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D.
Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A.
Petrov, P. Robbe, A. Vair
Correction : Long term natural history data in ambulant boys with Duchenne muscular dystrophy : 36-month changes
The 6 minute walk test has been recently chosen as the primary outcome measure in international multicenter clinical trials in Duchenne muscular dystrophy ambulant patients. The aim of the study was to assess the spectrum of changes at 3 years in the individual measures, their correlation with steroid treatment, age and 6 minute walk test values at baseline. Ninety-six patients from 11 centers were assessed at baseline and 12, 24 and 36 months after baseline using the 6 minute walk test and the North Star Ambulatory Assessment. Three boys (3%) lost the ability to perform the 6 minute walk test within 12 months, another 13 between 12 and 24 months (14%) and 11 between 24 and 36 months (12%). The 6 minute walk test showed an average overall decline of 1215.8 (SD 77.3) m at 12 months, of 1258.9 (SD 125.7) m at 24 months and 12104.22 (SD 146.2) m at 36 months. The changes were significantly different in the two baseline age groups and according to the baseline 6 minute walk test values (below and above 350 m) (p<0.001). The changes were also significantly different according to steroid treatment (p\u200a=\u200a0.01). Similar findings were found for the North Star Ambulatory Assessment. These are the first 36 month longitudinal data using the 6 minute walk test and North Star Ambulatory Assessment in Duchenne muscular dystrophy. Our findings will help not only to have a better idea of the progression of the disorder but also provide reference data that can be used to compare with the results of the long term extension studies that are becoming available
Collective perspective on advances in Dyson-Schwinger Equation QCD
We survey contemporary studies of hadrons and strongly interacting quarks
using QCD's Dyson-Schwinger equations, addressing: aspects of confinement and
dynamical chiral symmetry breaking; the hadron spectrum; hadron elastic and
transition form factors, from small- to large-Q^2; parton distribution
functions; the physics of hadrons containing one or more heavy quarks; and
properties of the quark gluon plasma.Comment: 56 pages. Summary of lectures delivered by the authors at the
"Workshop on AdS/CFT and Novel Approaches to Hadron and Heavy Ion Physics,"
2010-10-11 to 2010-12-03, hosted by the Kavli Institute for Theoretical
Physics, China, at the Chinese Academy of Science
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