Double resonance of Raman transitions in a degenerate Fermi gas

We measure momentum-resolved Raman spectra of a spin-polarized degenerate Fermi gas of $^{173}$Yb atoms for a wide range of magnetic fields, where the atoms are irradiated by a pair of counterpropagating Raman laser beams as in the conventional spin-orbit coupling scheme. Double resonance of first- and second-order Raman transitions occurs at a certain magnetic field and the spectrum exhibits a doublet splitting for high laser intensities. The measured spectral splitting is quantitatively accounted for by the Autler-Townes effect. We show that our measurement results are consistent with the spinful band structure of a Fermi gas in the spatially oscillating effective magnetic field generated by the Raman laser fields.Comment: 7 pages, 6 figure

Characteristics of R134a/R410A Cascade Heat Pump and Optimization

Single stage air source heat pump has been widely used around the world. However, it has some drawback, for example, deteriorated heating capacity and COP in cold ambient temperature. To overcome these disadvantages, cascade cycle has been suggested and shows better performance at low ambient temperature. Cascade cycle has smaller compression ratio at each cycle and shows higher compression efficiency compared to that of single stage cycle. Intermediate pressure is most critical parameter which decides the system performance. There have been many research studies about cascade heat pump system using NH3/CO2 and C3H8/CO2 as refrigerants at high and low stage, respectively. Most studies conducted on system optimization, finding the optimal intermediate pressure. However, little information has given about the experimental optimization results. In this study, AWHP (air to water heat pump), which is composed by two single stage cycle, was studied experimentally. AWHP high and low cycle adopts R134a and R410A as refrigerants, respectively, because critical temperature of R134a is higher than R410A. Since there are two single stage cycles, each cycle has a different compression ratio. In this research, by introducing numerical analysis, system optimization was studied. Characteristics of cascade cycle with respect to each compressor have been also studied. Experiment was conducted with various operating conditions; ambient temperature, water inlet temperature

Comparative analysis of port efficiency in Yangtze River Delta and Pearl River Delta: a meta Dynamic D.D.F. approach

The Yangtze River Delta and Pearl River Delta are two regions with the highest level of economic development in China, and their port development is at the forefront of the country. This study measures the efficiency of 23 major ports in the two deltas from 2010 to 2018 using the meta Dynamic Directional Distance Function (D.D.F.) model and discusses the technology gap and the reasons for inefficiency of the ports. The research results show that 80% of the ports in these two deltas are inefficient. The Yangtze River Delta’s port efficiency is higher than that of the Pearl River Delta, but the internal efficiency difference of the Yangtze River Delta port cluster is more significant. The efficiency ranking of most ports is inconsistent under the meta-frontier (M.F.) and group frontier (G.F.), and the average technology gap ratio (T.G.R.) of ports in the Pearl River Delta gradually exceeds that in the Yangtze River Delta. The inefficiency of ports in the Pearl River Delta is caused by input factors, and the inefficiency of ports in the Yangtze River Delta is also related to the containerisation level

The smallest quaternary ammonium salts with ether groups for high-performance electrochemical double layer capacitors

Electrochemical double layer capacitors (EDLCs) are energy storage devices that have been used for a wide range of electronic applications. In particular, the electrolyte is one of the important components, directly related to the capacitance and stability. Herein, we first report a series of the smallest quaternary ammonium salts (QASs), with ether groups on tails and tetrafluoroborate (BF4) as an anion, for use in EDLCs. To find the optimal structure, various QASs with different sized head groups and ether-containing tail groups were systematically compared. Comparing two nearly identical structures with and without ether groups, QASs with oxygen atoms showed improved capacitance, proving that ions with oxygen atoms move more easily than their counterparts at lower electric fields. Moreover, the ether containing QASs showed low activation energy values of conductivities, leading to smaller IR drops during the charge and discharge processes, resulting in an overall higher capacitance

Heterogeneous amplification of ERBB2 in primary lesions is responsible for the discordant ERBB2 status of primary and metastatic lesions in gastric carcinoma

Aims: To determine the extent of HER2 homogeneity/heterogeneity in primary versus metastatic gastric carcinoma ( GC). Materials and results: The human epidermal growth factor receptor 2 ( HER2) status in primary and metastatic lesions was evaluated by immunohistochemistry ( IHC) and fluorescence in-situ hybridization ( FISH). Four separate cohorts consisting of primary GC alone or primary GC paired with metastatic lesions were examined. In the FISH analysis of 325 primary GCs, eight cases ( 2.5%) showed amplification with a heterogeneous pattern, whereas 27 cases ( 8.3%) showed amplification with a homogeneous pattern, and in this cohort the discordant: concordant FISH ratio based on examination of three different areas in each primary lesion was 0.30: 1. FISH testing using 250 paired primary and metastatic lesions revealed seven cases (2.8%) with discordant amplification. In metastatic disease positive conversion occurred in six cases (2.4%), whereas negative conversion happened in one case (0.4%). The discordant: concordant ratio of primary versus secondary lesions was 0.23: 1. When the seven discordant cases were re-evaluated using whole sections of primary GCs, six showed a heterogeneous pattern of amplification. Conclusions: These findings suggest that the discordant HER2 amplification observed in metastatic lesions is explained substantially by heterogeneity within primary tumours

Far-Ultraviolet Cooling Features of the Antlia Supernova Remnant

We present far-ultraviolet observations of the Antlia supernova remnant obtained with Far-ultraviolet IMaging Spectrograph (FIMS, also called SPEAR). The strongest lines observed are C IV 1548,1551 and C III 977. The C IV emission of this mixed-morphology supernova remnant shows a clumpy distribution, and the line intensity is nearly constant with radius. The C III 977 line, though too weak to be mapped over the whole remnant, is shown to vary radially. The line intensity peaks at about half the radius, and drops at the edge of the remnant. Both the clumpy distribution of C IV and the rise in the C IV to C III ratio towards the edge suggest that central emission is from evaporating cloudlets rather than thermal conduction in a more uniform, dense medium.Comment: 9 pages, 4 figures, will be published in ApJ December 1, 2007, v670n2 issue. see http://astro.snu.ac.kr/~jhshinn/ms.pd