26 research outputs found
Full-time dynamics of modulational instability in spinor Bose-Einstein condensates
We describe the full-time dynamics of modulational instability in F=1 spinor
Bose-Einstein condensates for the case of the integrable three-component model
associated with the matrix nonlinear Schroedinger equation. We obtain an exact
homoclinic solution of this model by employing the dressing method which we
generalize to the case of the higher-rank projectors. This homoclinic solution
describes the development of modulational instability beyond the linear regime,
and we show that the modulational instability demonstrates the reversal
property when the growth of the modulation amplitude is changed by its
exponential decay.Comment: 6 pages, 2 figures, text slightly extended, a reference adde
Observation of a low-lying metastable electronic state in highly charged lead by Penning-trap mass spectrometry
Highly charged ions (HCIs) offer many opportunities for next-generation clock
research due to the vast landscape of available electronic transitions in
different charge states. The development of XUV frequency combs has enabled the
search for clock transitions based on shorter wavelengths in HCIs. However,
without initial knowledge of the energy of the clock states, these narrow
transitions are difficult to be probed by lasers. In this Letter, we provide
experimental observation and theoretical calculation of a long-lived electronic
state in Nb-like Pb which could be used as a clock state. With the mass
spectrometer Pentatrap, the excitation energy of this metastable state is
directly determined as a mass difference at an energy of 31.2(8) eV,
corresponding to one of the most precise relative mass determinations to date
with a fractional uncertainty of . This experimental result
agrees within 1 with two partially different \textit{ab initio}
multi-configuration Dirac-Hartree-Fock calculations of 31.68(13) eV and
31.76(35) eV, respectively. With a calculated lifetime of 26.5(5.3) days, the
transition from this metastable state to the ground state bears a quality
factor of and allows for the construction of a HCI clock
with a fractional frequency instability of
Wave Solutions of Evolution Equations and Hamiltonian Flows on Nonlinear Subvarieties of Generalized Jacobians
The algebraic-geometric approach is extended to study solutions of
N-component systems associated with the energy dependent Schrodinger operators
having potentials with poles in the spectral parameter, in connection with
Hamiltonian flows on nonlinear subvariaties of Jacobi varieties. The systems
under study include the shallow water equation and Dym type equation. The
classes of solutions are described in terms of theta-functions and their
singular limits by using new parameterizations. A qualitative description of
real valued solutions is provided
Detection of metastable electronic states by Penning trap mass spectrometry
State-of-the-art optical clocks achieve fractional precisions of
and below using ensembles of atoms in optical lattices or individual ions in
radio-frequency traps. Promising candidates for novel clocks are highly charged
ions (HCIs) and nuclear transitions, which are largely insensitive to external
perturbations and reach wavelengths beyond the optical range, now becoming
accessible to frequency combs. However, insufficiently accurate atomic
structure calculations still hinder the identification of suitable transitions
in HCIs. Here, we report on the discovery of a long-lived metastable electronic
state in a HCI by measuring the mass difference of the ground and the excited
state in Re, the first non-destructive, direct determination of an electronic
excitation energy. This result agrees with our advanced calculations, and we
confirmed them with an Os ion with the same electronic configuration. We used
the high-precision Penning-trap mass spectrometer PENTATRAP, unique in its
synchronous use of five individual traps for simultaneous mass measurements.
The cyclotron frequency ratio of the ion in the ground state to the
metastable state could be determined to a precision of , unprecedented in the heavy atom regime. With a lifetime of about 130
days, the potential soft x-ray frequency reference at has a linewidth of only , and one of the highest electronic quality factor
() ever seen in an experiment. Our low
uncertainty enables searching for more HCI soft x-ray clock transitions, needed
for promising precision studies of fundamental physics in a thus far unexplored
frontier
Dynamical Supersymmetry Breaking
Supersymmetry is one of the most plausible and theoretically motivated
frameworks for extending the Standard Model. However, any supersymmetry in
Nature must be a broken symmetry. Dynamical supersymmetry breaking (DSB) is an
attractive idea for incorporating supersymmetry into a successful description
of Nature. The study of DSB has recently enjoyed dramatic progress, fueled by
advances in our understanding of the dynamics of supersymmetric field theories.
These advances have allowed for direct analysis of DSB in strongly coupled
theories, and for the discovery of new DSB theories, some of which contradict
early criteria for DSB. We review these criteria, emphasizing recently
discovered exceptions. We also describe, through many examples, various
techniques for directly establishing DSB by studying the infrared theory,
including both older techniques in regions of weak coupling, and new techniques
in regions of strong coupling. Finally, we present a list of representative DSB
models, their main properties, and the relations between them.Comment: 113 pages, Revtex. Minor changes, references added and corrected. To
appear in Reviews of Modern Physic
Penning-trap measurement of the -value of the electron capture in for the determination of the electron neutrino mass
The investigation of the absolute scale of the effective neutrino mass
remains challenging due to the exclusively weak interaction of neutrinos with
all known particles in the standard model of particle physics. Currently, the
most precise and least model-dependent upper limit on the electron antineutrino
mass is set by the KATRIN experiment from the analysis of the tritium
\b{eta}-decay. Another promising approach is the electron capture in
, which is under investigation using microcalorimetry within
the ECHo and HOLMES collab orations. An independently measured Q-value of this
process is vital for the assessment of systematic uncertainties in the neutrino
mass determination. Here, we report a direct, independent determination of this
-value by measuring the free-space cyclotron frequency ratio of highly
charged ions of and in the Penning trap
experiment \textsc{Pentatrap}. Combining this ratio with atomic physics
calculations of the electronic binding energies yields a -value of
- a more than 50-fold improvement over the
state-of-the-art. This will enable the determination of the electron neutrino
mass on a sub-eV level from the analysis of the electron capture in
Efficacy of Endoscopic Submucosal Dissection for Superficial Gastric Neoplasia in a Large Cohort in North America
Background & Aims
Endoscopic submucosal dissection (ESD) is a widely accepted treatment option for superficial gastric neoplasia in Asia, but there are few data on outcomes of gastric ESD from North America. We aimed to evaluate the safety and efficacy of gastric ESD in North America.
Methods
We analyzed data from 347 patients who underwent gastric ESD at 25 centers, from 2010 through 2019. We collected data on patient demographics, lesion characteristics, procedure details and related adverse events, treatment outcomes, local recurrence, and vital status at the last follow up. For the 277 patients with available follow-up data, the median interval between initial ESD and last clinical or endoscopic evaluation was 364 days. The primary endpoint was the rate of en bloc and R0 resection. Secondary outcomes included curative resection, rates of adverse events and recurrence, and gastric cancer-related death.
Results
Ninety patients (26%) had low-grade adenomas or dysplasia, 82 patients (24%) had high-grade dysplasia, 139 patients (40%) had early gastric cancer, and 36 patients (10%) had neuroendocrine tumors. Proportions of en bloc and R0 resection for all lesions were 92%/82%, for early gastric cancers were 94%/75%, for adenomas and low-grade dysplasia were 93%/ 92%, for high-grade dysplasia were 89%/ 87%, and for neuroendocrine tumors were 92%/75%. Intraprocedural perforation occurred in 6.6% of patients; 82% of these were treated successfully with endoscopic therapy. Delayed bleeding occurred in 2.6% of patients. No delayed perforation or procedure-related deaths were observed. There were local recurrences in 3.9% of cases; all occurred after non-curative ESD resection. Metachronous lesions were identified in 14 patients (6.9%). One of 277 patients with clinical follow up died of metachronous gastric cancer that occurred 2.5 years after the initial ESD.
Conclusions
ESD is a highly effective treatment for superficial gastric neoplasia and should be considered as a viable option for patients in North America. The risk of local recurrence is low and occurs exclusively after non-curative resection. Careful endoscopic surveillance is necessary to identify and treat metachronous lesions