A BCS wavefunction approach to the BEC-BCS crossover of exciton-polariton condensates

The crossover between low and high density regimes of exciton-polariton condensates is examined using a BCS wavefunction approach. Our approach is an extension of the BEC-BCS crossover theory for excitons, but includes a cavity photon field. The approach can describe both the low density limit, where the system can be described as a Bose-Einstein condensate (BEC) of exciton-polaritons, and the high density limit, where the system enters a photon dominated regime. In contrast to the exciton BEC-BCS crossover where the system approaches an electron-hole plasma, the polariton high density limit has strongly correlated electron-hole pairs. At intermediate densities, there is a regime with BCS-like properties, with a peak at non-zero momentum of the singlet pair function. We calculate the expected photoluminescence and give several experimental signatures of the crossover.Comment: 10 pages, 3 figure

The negative Bogoliubov dispersion in exciton-polariton condensates

Bogoliubov's theory states that self-interaction effects in Bose-Einstein condensates produce a characteristic linear dispersion at low momenta. One of the curious features of Bogoliubov's theory is that the new quasiparticles in the system are linear combinations of creation and destruction operators of the bosons. In exciton-polariton condensates, this gives the possibility of directly observing the negative branch of the Bogoliubov dispersion in the photoluminescence (PL) emission. Here we theoretically examine the PL spectra of exciton-polariton condensates taking into account of reservoir effects. At sufficiently high excitation densities, the negative dispersion becomes visible. We also discuss the possibility for relaxation oscillations to occur under conditions of strong reservoir coupling. This is found to give a secondary mechanism for making the negative branch visible

Threshold of photoelectron emission from CNx films deposited at room temperature and at 500 °C

The threshold of photoelectron emission was measured for amorphous CNx films deposited at room temperature (RT) and at 500 °C. The x values of the films deposited at RT and at 500 °C by magnetron sputtering of a graphite target in a mixed N2/Ar gas were 0.6 and 0.3, respectively. Ratios of the sp2- to sp3-hybridized components of both C and N for the film deposited at 500 °C were larger by 4 times than those for the film deposited at RT. The onsets of the electron emission by photon irradiation were 5.0 and 4.7 eV for the films deposited at RT and at 500 °C, respectively

Polyploidy of Endosymbiotically Derived Genomes in Complex Algae

Chlorarachniophyte and cryptophyte algae have complex plastids that were acquired by the uptake of a green or red algal endosymbiont via secondary endosymbiosis. The plastid is surrounded by four membranes, and a relict nucleus, called the nucleomorph, remains in the periplastidal compartment that is the remnant cytoplasm of the endosymbiont. Thus, these two algae possess four different genomes in a cell: Nuclear, nucleomorph, plastid, and mitochondrial. Recently, sequencing of the nuclear genomes of the chlorarachniophyte Bigelowiella natans and the cryptophyte Guillardia theta has been completed, and all four genomes have been made available. However, the copy number of each genome has never been investigated. It is important to know the actual DNA content of each genome, especially the highly reduced nucleomorph genome, for studies on genome evolution. In this study, we calculated genomic copy numbers in B. natans and G. theta using a real-time quantitative polymerase chain reaction approach. The nuclear genomes were haploid in both species, whereas the nucleomorph genomes were estimated to be diploid and tetraploid, respectively. Mitochondria and plastids contained a large copy number of genomic DNA in each cell. In the secondary endosymbioses of chlorarachniophytes and cryptophytes, the endosymbiont nuclear genomes were highly reduced in size and in the number of coding genes, whereas the chromosomal copy number was increased, as in bacterial endosymbiont genomes. This suggests that polyploidization is a general characteristic of highly reduced genomes in broad prokaryotic and eukaryotic endosymbionts

Structural and photophysical characterisation of coordination and optical isomers of mononuclear ruthenium(II) polypyridyl 1,2,4-triazole complexes

The X-ray crystal structure of the N2 isomers of the Ru(bipy)2 complexes of Hphpztr (1) and Hpztr (2), (bipy = 2,2'-bipyridine, Hphpztr = 2-(5'-phenyl-4'H-[1,2,4]triazol-3'-yl)pyrazine and Hpztr = 2-(4'H-[1,2,4]triazol-3'-yl)pyrazine) are reported. The molecular structure obtained for 2 demonstrates an interesting structural aspect in the sharing of a single proton between two molecular units. The isolation of the Δ and Λ stereoisomers of 1 and [Ru(phen)2(pztr)]+ (phen = 1,10-phenanthroline) (3) by semipreparative HPLC is also reported. The compounds obtained are characterised by electronic spectroscopy and particular attention is paid to the photophysical properties of Δ and Λ isomers of 1 and 3, in chiral enantiopure and racemic solvents

A case of undifferentiated carcinoma of the bladder treated by combination therapy of surgery, local radiation, and immune checkpoint inhibitors

Undifferentiated carcinoma of the bladder is a rare malignancy with a poor prognosis. We present the case of an 81-year-old woman complaining of bladder irritation. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed a bulky bladder tumor, which was diagnosed as cT4aN0M0. A transurethral resection of the bladder tumor revealed pT2 or higher urothelial carcinoma. The patient underwent total cystectomy with an ileal conduit diversion. Histological examination revealed a primary undifferentiated bladder carcinoma with a sarcoma component, pT3aN0M0. Postoperative adjuvant chemotherapy with gemcitabine plus carboplatin was administered. However, this regimen was discontinued after one course due to significant myelosuppression. Four months after total cystectomy, a pelvic tumor with suspected local recurrence was detected on CT. The patient was diagnosed with recurrent undifferentiated carcinoma with a sarcoma component by a transperineal ultrasound-guided biopsy. Local radiation therapy and immunotherapy with immune checkpoint inhibitors were prescribed. After three courses of immunotherapy with pembrolizumab, the primary tumor disappeared. Upon continuing immune checkpoint inhibitor treatment, the patient has maintained a complete response without tumor recurrence in the following six months.departmental bulletin pape

Design of Internal Model Control Based on an Optimal Control for a Servo System

This paper describes a design of internal model control based on an optimal control for a servo system. The control system has the feedback based on the proposed disturbance compensator in the disturbance response. The compensator is designed to become the denominator of the transfer function without a dead time in the disturbance responses. The disturbance response of the proposed method is faster than that of the previous method

Characterization of a novel type of carbonic anhydrase that acts without metal cofactors

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Development of workshop framework empowering local stakeholders for “place strategy” in a district: An implementation at Omotesando, Tokyo

This research aims to structure the workshop framework ‘empowering local stakeholders to create a “place strategy”’, a spatial planning and management strategy for enhancing place function in a district. This strategy primarily focuses on the team-up phase for stakeholders with human and financial resources, whose mission is to bridge a backcasting vision to the next step involving others and users of the streets. Referring to the ‘link and place’ theory, originally developed in England and adapted to fit the alternative plans suggested by municipal officials at the community level, the paper establishes a toolkit and sessions for the conduct of a community-led workshop in Japan. The prototype workshop was implemented for the place strategy of Omotesando, a mixed land-use district with a famous shopping avenue in Tokyo. The validity of the workshop was examined based on opinion changes and the feedback of participants at each session. The results show that the prototype can draw the participant's consciousness on both the link and place functions, including a perspective on effective bus service. The policy option guides affected the participants' choice of flexible tactics by illustrating the relationship of link and place, which is not necessarily a trade-off