927 research outputs found
Isomeric states close to doubly magic Sn studied with JYFLTRAP
The double Penning trap mass spectrometer JYFLTRAP has been employed to
measure masses and excitation energies for isomers in Cd,
Cd, Cd and Te, for isomers in In and
In, and for isomers in Sn and Sb. These first
direct mass measurements of the Cd and In isomers reveal deviations to the
excitation energies based on results from beta-decay experiments and yield new
information on neutron- and proton-hole states close to Sn. A new
excitation energy of 144(4) keV has been determined for Cd. A good
agreement with the precisely known excitation energies of Cd,
Sn, and Sb has been found.Comment: 10 pages, 6 figures, submitted to Phys. Rev.
MDL Convergence Speed for Bernoulli Sequences
The Minimum Description Length principle for online sequence
estimation/prediction in a proper learning setup is studied. If the underlying
model class is discrete, then the total expected square loss is a particularly
interesting performance measure: (a) this quantity is finitely bounded,
implying convergence with probability one, and (b) it additionally specifies
the convergence speed. For MDL, in general one can only have loss bounds which
are finite but exponentially larger than those for Bayes mixtures. We show that
this is even the case if the model class contains only Bernoulli distributions.
We derive a new upper bound on the prediction error for countable Bernoulli
classes. This implies a small bound (comparable to the one for Bayes mixtures)
for certain important model classes. We discuss the application to Machine
Learning tasks such as classification and hypothesis testing, and
generalization to countable classes of i.i.d. models.Comment: 28 page
Precision mass measurements of radioactive nuclei at JYFLTRAP
The Penning trap mass spectrometer JYFLTRAP was used to measure the atomic
masses of radioactive nuclei with an uncertainty better than 10 keV. The atomic
masses of the neutron-deficient nuclei around the N = Z line were measured to
improve the understanding of the rp-process path and the SbSnTe cycle.
Furthermore, the masses of the neutron-rich gallium (Z = 31) to palladium (Z =
46) nuclei have been measured. The physics impacts on the nuclear structure and
the r-process paths are reviewed. A better understanding of the nuclear
deformation is presented by studying the pairing energy around A = 100.Comment: 4 pages and 4 figures, RNB7 conf. pro
Mass measurements in the vicinity of the doubly-magic waiting point 56Ni
Masses of 56,57Fe, 53Co^m, 53,56Co, 55,56,57Ni, 57,58Cu, and 59,60Zn have
been determined with the JYFLTRAP Penning trap mass spectrometer at IGISOL with
a precision of dm/m \le 3 x 10^{-8}. The QEC values for 53Co, 55Ni, 56Ni, 57Cu,
58Cu, and 59Zn have been measured directly with a typical precision of better
than 0.7 keV and Coulomb displacement energies have been determined. The Q
values for proton captures on 55Co, 56Ni, 58Cu, and 59Cu have been measured
directly. The precision of the proton-capture Q value for 56Ni(p,gamma)57Cu,
Q(p,gamma) = 689.69(51) keV, crucial for astrophysical rp-process calculations,
has been improved by a factor of 37. The excitation energy of the proton
emitting spin-gap isomer 53Co^m has been measured precisely, Ex = 3174.3(10)
keV, and a Coulomb energy difference of 133.9(10) keV for the 19/2- state has
been obtained. Except for 53Co, the mass values have been adjusted within a
network of 17 frequency ratio measurements between 13 nuclides which allowed
also a determination of the reference masses 55Co, 58Ni, and 59Cu.Comment: 14 pages, 13 figures, submitted to Phys. Rev.
Q_EC values of the Superallowed beta-Emitters 10-C, 34-Ar, 38-Ca and 46-V
The Q_EC values of the superallowed beta+ emitters 10-C, 34-Ar, 38-Ca and
46-V have been measured with a Penning-trap mass spectrometer to be 3648.12(8),
6061.83(8), 6612.12(7) and 7052.44(10) keV, respectively. All four values are
substantially improved in precision over previous results.Comment: 9 pages, 7 figures, 5 table
Detecting periodicity in experimental data using linear modeling techniques
Fourier spectral estimates and, to a lesser extent, the autocorrelation
function are the primary tools to detect periodicities in experimental data in
the physical and biological sciences. We propose a new method which is more
reliable than traditional techniques, and is able to make clear identification
of periodic behavior when traditional techniques do not. This technique is
based on an information theoretic reduction of linear (autoregressive) models
so that only the essential features of an autoregressive model are retained.
These models we call reduced autoregressive models (RARM). The essential
features of reduced autoregressive models include any periodicity present in
the data. We provide theoretical and numerical evidence from both experimental
and artificial data, to demonstrate that this technique will reliably detect
periodicities if and only if they are present in the data. There are strong
information theoretic arguments to support the statement that RARM detects
periodicities if they are present. Surrogate data techniques are used to ensure
the converse. Furthermore, our calculations demonstrate that RARM is more
robust, more accurate, and more sensitive, than traditional spectral
techniques.Comment: 10 pages (revtex) and 6 figures. To appear in Phys Rev E. Modified
styl
Evaluation of multivalency as an organization principle for the efficient synthesis of doubly and triply threaded amide rotaxanes
Mono-, di- and trivalent pseudorotaxanes with tetralactam macrocycle hosts and
axles containing diamide binding stations as the guests have been synthesised.
Their threading behaviour was analyzed in detail by NMR experiments and
isothermal titration calorimetry. An X-ray crystal structure of the monovalent
pseudorotaxane confirms the binding motif. Double mutant cycle analysis
provides the effective molarities and insight into the chelate cooperativity
of multivalent binding. While the second binding event in a trivalent
pseudorotaxane exhibits a slightly positive cooperativity, the third binding
is nearly non-cooperative. Nevertheless, the enhanced binding affinities
resulting from the multivalent interaction are the basis for a highly
efficient synthesis of di- and trivalent rotaxanes through stoppering the axle
termini by âclickâ chemistry. Evidence for the multiply threaded geometry
comes from NMR spectroscopy as well as tandem mass-spectrometric fragmentation
experiments of mass-selected rotaxane ions in the gas phase. Furthermore, the
trivalent rotaxane can be controlled by external stimuli (chloride addition
and removal) which lead to an elevator-type movement of the wheel along the
axle
Altered expiratory flow dynamics at peak exercise in adult men with well-controlled type 1 diabetes.
Peer reviewe
The risk of psychiatric disorders among Finnish ART and spontaneously conceived children: Finnish population-based register study
Evidence regarding the psychiatric morbidity of children born after Assisted Reproductive Techniques (ART) is inconsistent and limited. While normal mental well-being for ART children is usually reported, concerns are still being raised. Previous studies examine only some psychiatric disorders, but not all of them, ignore the impact of multiplicity, and limit the follow-up time to childhood. We examined all psychiatric diagnoses for singletons until their young adulthood. The aim was to study whether the risk of psychiatric disorders differs between ART and spontaneously conceived (SC) singletons until young adulthood. This retrospective Finnish population-based register study includes all ART and SC live-born children born in Finland during 1990-2013 and their hospital care in 1990-2014 (n = 1,425,975 of which 1,385,956, 97.2% were singletons). After excluding multiples, the final population included 17,610 ART and 1,368,346 SC singletons in 1990-2013 from the Finnish Medical Birth Registry. These data were linked to the Finnish Hospital Discharge Registry with the child's and mother's encrypted IDs. ART singletons had fewer psychiatric diagnoses (ART 10.2%, n = 1796, SC 12.0%, n = 164,408), but they received their diagnoses earlier (mean 8.3 years old, SD 5.0) than SC singletons (mean 10.5 years old, SD 5.7). After adjusting for confounding factors, ART singletons had an increased likelihood of getting a psychiatric diagnosis until young adulthood and the results were similar for boys (adjusted hazard ratios [aHR] = 1.16, 95% confidence interval (CI) 1.10-1.24) and girls (aHR = 1.25, 95% CI 1.16-1.35). We conclude that ART children receive their psychiatric diagnoses earlier than SC children, in particular during childhood and early adolescence. After adjusting for confounding factors ART children a slightly increased likelihood of any psychiatric diagnosis compared to SC controls
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