New bounds on dark matter coupling from a global network of optical atomic clocks.

We report on the first Earth-scale quantum sensor network based on optical atomic clocks aimed at dark matter (DM) detection. Exploiting differences in the susceptibilities to the fine-structure constant of essential parts of an optical atomic clock, i.e., the cold atoms and the optical reference cavity, we can perform sensitive searches for DM signatures without the need for real-time comparisons of the clocks. We report a two orders of magnitude improvement in constraints on transient variations of the fine-structure constant, which considerably improves the detection limit for the standard model (SM)-DM coupling. We use Yb and Sr optical atomic clocks at four laboratories on three continents to search for both topological defect and massive scalar field candidates. No signal consistent with a DM coupling is identified, leading to considerably improved constraints on the DM-SM couplings.

Direct comparison of optical lattice clocks with an intercontinental baseline of 9000 km.

We have demonstrated a direct frequency comparison between two 87Sr lattice clocks operated in intercontinentally separated laboratories in real time. Two-way satellite time and frequency transfer technique, based on the carrier-phase, was employed for a direct comparison, with a baseline of 9000 km between Japan and Germany. A frequency comparison was achieved for 83,640 s, resulting in a fractional difference of (1.1±1.6)×10⁻¹5, where the statistical part is the largest contributor to the uncertainty. This measurement directly confirms the agreement of the two optical frequency standards on an intercontinental scale.

Development of LC-MS method for detection of mutant uromodulin protein.

Mutations in the uromodulin gene cause the autosomal disorders familial juvenile hyperuricemic nephropathy (FJHN) and medullary cystic kidney disease type 2 (MCKD2). However, methods to detect the mutant form of the uromodulin protein have not been developed. In this study, we developed a liquid chromatography-mass spectrometry (LC-MS) method for detection of the mutated uromodulin peptide (C148W). Our method can distinguish the mutant peptide, GWHWE, from wildtype peptide, GWHC*E. Using MS/MS analysis with a selected reaction monitoring (SRM) mode, peptide-specific fragment ions (m/z 714 --> 381, 471, 567, and 679 for GWHWE and m/z 688 --> 381, 445, 541, and 653 for GWHC*E) were detected.

Trapping of neutral mercury atoms and prospects for optical lattice clocks.

We report vapor-cell magneto-optical trapping of Hg isotopes on the (1)S(0)-(3)P(1) intercombination transition. Six abundant isotopes, including four bosons and two fermions, were trapped. Hg is the heaviest nonradioactive atom trapped so far, which enables sensitive atomic searches for "new physics" beyond the standard model. We propose an accurate optical lattice clock based on Hg and evaluate its systematic accuracy to be better than 10;{-18}. Highly accurate and stable Hg-based clocks will provide a new avenue for the research of optical lattice clocks and the time variation of the fine-structure constant.

Electrodynamic trapping of spinless neutral atoms with an atom chip.

Three-dimensional electrodynamic trapping of neutral atoms has been demonstrated. By applying time-varying inhomogeneous electric fields with micron-sized electrodes, nearly 10(2) strontium atoms in the 1S0 state have been trapped with a lifetime of 80 ms. In order to design the electrodes, we numerically analyzed the electric field and simulated atomic trajectories in the trap, which showed reasonable agreement with the experiment.

Required thermal environments for the quadriplegic persons: Analyses of questionnaires and experiments on their daily life.

A physically disabled person often has additional disabilities on adaptation to the thermal environment. Since 1976, our group has carried out a series of studies to find required thermal conditions for disabled persons on several typical disabilities. This paper reports on the results of our latest questionnaire and experiments on daily thermal environment for quadriplegic persons. Among 292 quadriplegic persons with valid questionnaire, 184 (63%) were fully paralyzed. Nearly 90% of these and 60% of partially paralyzed patients were dissatisfied with the thermal environment and sweating. Several suggestive differences were found according to the broken positions of vertebrae. The results of 48 hours of field measurements on three quadriplegic subjects are compared with those obtained from questionnaire.

Secondary aneurysm due to arterial injury during surgical procedures.

Most secondary aneurysms following trauma to the cerebral artery were reported as a complication of head injury. Three cases of aneurysm due to arterial injury during operations are reported. A search of the world literature revealed ten other cases. The responsible surgical procedure and the location of these aneurysms varied. Rupture of these aneurysms was observed in four cases at 10 to 23 days following the primary operation. Only two patients died.