143 research outputs found
Long spin coherence times in the ground state and an optically excited state of Er:YSiO at zero magnetic field
Spins in solids are an ideal candidate to act as a memory and interface with
superconducting qubits due to their long coherence times. We spectroscopically
investigate erbium-167-doped yttrium orthosilicate as a possible
microwave-addressed memory employing its microwave frequency transitions that
occur without applying an external magnetic field. We obtain coherence times of
380 s in a ground state spin transition and 1.48 ms in an excited state
spin transition. This is 28 times longer compared to previous zero field
measurements, as well as 200 times longer than a previous microwave memory
demonstration in the same material. These long coherence times show that
erbium-167-doped yttrium orthosilicate has potential as a microwave-addressed
quantum memory.Comment: 9 pages, 7 figures. The paper has been expanded compared to the
previous version on arXiv, and the title has change
Extending Phenomenological Crystal-Field Methods to Point-Group Symmetry: Characterization of the Optically-Excited Hyperfine Structure of Er:YSiO
We show that crystal-field calculations for point-group symmetry are
possible, and that such calculations can be performed with sufficient accuracy
to have substantial utility for rare-earth based quantum information
applications. In particular, we perform crystal-field fitting for a
C-symmetry site in Er:YSiO. The calculation
simultaneously includes site-selective spectroscopic data up to 20,000
cm, rotational Zeeman data, and ground- and excited-state hyperfine
structure determined from high-resolution Raman-heterodyne spectroscopy on the
1.5 m telecom transition. We achieve an agreement of better than 50 MHz
for assigned hyperfine transitions. The success of this analysis opens the
possibility of systematically evaluating the coherence properties, as well as
transition energies and intensities, of any rare-earth ion doped into
YSiO .Comment: 6 pages, plus 5 pages in supplementary information, 4 figures tota
Optically unstable phase from ion-ion interactions in an erbium doped crystal
We demonstrate an optical unstable phase for a laser driven erbium ion
ensemble. The transmitted light through an erbium-doped yttrium orthosillicate
crystal becomes dynamically unstable when illuminated by a strong
continuous-wave laser. Transient net gain was recorded if the light passes the
sample twice. The experimental results are understood in the framework of a
many-body system interacting with a classical field, where the ion-ion
interaction becomes significant as a result of the high erbium concentration. A
Bloch-equation model that includes the excitation-induced frequency-shift is
introduced to discuss the conditions of the instabilities.Comment: 5 pages, 4 figure
Mapping a New Spontaneous Preterm Birth Susceptibility Gene, IGF1R, Using Linkage, Haplotype Sharing, and Association Analysis
Peer reviewe
Primate-specific evolution of noncoding element insertion into PLA2G4C and human preterm birth
Background
The onset of birth in humans, like other apes, differs from non-primate mammals in its endocrine physiology. We hypothesize that higher primate-specific gene evolution may lead to these differences and target genes involved in human preterm birth, an area of global health significance.
Methods
We performed a comparative genomics screen of highly conserved noncoding elements and identified PLA2G4C, a phospholipase A isoform involved in prostaglandin biosynthesis as human accelerated. To examine whether this gene demonstrating primate-specific evolution was associated with birth timing, we genotyped and analyzed 8 common single nucleotide polymorphisms (SNPs) in PLA2G4C in US Hispanic (n = 73 preterm, 292 control), US White (n = 147 preterm, 157 control) and US Black (n = 79 preterm, 166 control) mothers.
Results
Detailed structural and phylogenic analysis of PLA2G4C suggested a short genomic element within the gene duplicated from a paralogous highly conserved element on chromosome 1 specifically in primates. SNPs rs8110925 and rs2307276 in US Hispanics and rs11564620 in US Whites were significant after correcting for multiple tests (p < 0.006). Additionally, rs11564620 (Thr360Pro) was associated with increased metabolite levels of the prostaglandin thromboxane in healthy individuals (p = 0.02), suggesting this variant may affect PLA2G4C activity.
Conclusions
Our findings suggest that variation in PLA2G4C may influence preterm birth risk by increasing levels of prostaglandins, which are known to regulate labor.Children’s Discovery InstituteMarch of Dimes Birth Defects FoundationNational Institute of General Medical Sciences (U.S.) (grant T32 GM081739)Washington University (Saint Louis, Mo.) (Mr. and Mrs. Spencer T. Olin Fellowship for Women in Graduate Study)Sigrid Jusélius FoundationSigne and Anne Gyllenberg FoundationAcademy of FinlandVanderbilt University (Turner-Hazinski grant award
An Evolutionary Genomic Approach to Identify Genes Involved in Human Birth Timing
Peer reviewe
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