Exploring the origin of ultra-diffuse galaxies in clusters from their primordial alignment

We find that the minor axes of the ultra-diffuse galaxies (UDGs) in Abell 2634 tend to be aligned with the major axis of the central dominant galaxy, at a $\gtrsim 95\%$ confidence level. This alignment is produced by the bright UDGs with the absolute magnitudes $M_r<-15.3$ mag, and outer-region UDGs with $R>0.5R_{200}$. The alignment signal implies that these bright, outer-region UDGs are very likely to acquire their angular momenta from the vortices around the large-scale filament before they were accreted into A2634, and form their extended stellar bodies outside of the cluster; in this scenario, the orientations of their primordial angular momenta, which are roughly shown by their minor axes on the images, should tend to be parallel to the elongation of the large-scale filament. When these UDGs fell into the unrelaxed cluster A2634 along the filament, they could still preserve their primordial alignment signal before violent relaxation and encounters. These bright, outer-region UDGs in A2634 are very unlikely to be the descendants of the high-surface-brightness dwarf progenitors under tidal interactions with the central dominant galaxy in the cluster environment. Our results indicate that the primordial alignment could be a useful probe of the origin of UDGs in large-scale structures.Comment: Accepted for publication in MNRAS Lette

Advanced Ulcerated Squamous Cell Carcinoma of the Hand with Locoregional Axillary Lymph Node Metastasis – Case Report and Literature Review

BACKGROUND: Cutaneous squamous cell carcinoma (SCC) of the hand is the most common soft-tissue malignancy in this particular region. A literature survey suggested a higher rate of metastases in advanced SCC of the hand compared to head-and-neck cutaneous SCC. CASE REPORT: An 84-year-old man presented with an ulcerated firm tumour on the dorsum of his right hand. A diagnostic biopsy confirmed the diagnosis SCC. Imaging suggested an involvement of the tendons of digits 3 and 4. A diagnostic ultrasound suggested a loco-regional axillary lymph node metastasis. After discussion in the interdisciplinary tumour board, amputation of the affected digits followed by lymph node excision was recommended. CONCLUSIONS: Advanced SCC of the hand requires interdisciplinary management. Amputation is part of the surgical spectrum in advanced cases

Advanced Ulcerated Squamous Cell Carcinoma of the Hand with Locoregional Axillary Lymph Node Metastasis – Case Report and Literature Review

BACKGROUND: Cutaneous squamous cell carcinoma (SCC) of the hand is the most common soft-tissue malignancy in this particular region. A literature survey suggested a higher rate of metastases in advanced SCC of the hand compared to head-and-neck cutaneous SCC. CASE REPORT: An 84-year-old man presented with an ulcerated firm tumour on the dorsum of his right hand. A diagnostic biopsy confirmed the diagnosis SCC. Imaging suggested an involvement of the tendons of digits 3 and 4. A diagnostic ultrasound suggested a loco-regional axillary lymph node metastasis. After discussion in the interdisciplinary tumour board, amputation of the affected digits followed by lymph node excision was recommended. CONCLUSIONS: Advanced SCC of the hand requires interdisciplinary management. Amputation is part of the surgical spectrum in advanced cases

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Temperature dependence of pulsed polariton lasing in a GaAs microcavity

The second-order correlation function g((2))(tau = 0), input-output curves and pulse duration of the emission from a microcavity exciton-polariton system subsequent to picosecond-pulsed excitation are measured for different temperatures. At low temperatures a two-threshold behaviour emerges, which has been attributed to the onset of polariton lasing and conventional lasing at the first and the second threshold, respectively. We observe that polariton lasing is stable up to temperatures comparable with the exciton binding energy. At higher temperatures a single threshold displays the direct transition from thermal emission to photon lasing.Publisher PDFPeer reviewe

Determination of operating parameters for a GaAs-based polariton laser

We report on a systematic study of the phase transitions to polariton condensation (PC) and further to cavity lasing in a GaAs-based microcavity with respect to exciton-cavity detuning and lattice temperature. Using far field and time-resolved spectroscopy, we determined the parameter space in which PC can be achieved and the corresponding variation of PC threshold power. We found a lower bound of -12 meV for the exciton-cavity detuning and an upper bound of 90 K for the lattice temperature.Publisher PDFPeer reviewe

Extrapolation of the intensity autocorrelation function of a quantum-dot micropillar laser into the thermal emission regime

We present investigations on the coherence of the emission from the fundamental mode of an AlGaInAs/GaAs quantum-dot microcavity laser. We measure the first-order field-correlation function g((1))(tau) with a Michelson interferometer, from which we determine coherence times of up to 20 ns for the highest pump powers. To fully characterize the coherence properties of the cavity emission, we apply a phenomenological model that connects the first-and second-order correlation functions. Hereby it is possible to overcome the limited sensitivity of the streak camera used for photon-correlation measurements, and thus to extend the accessible excitation-power range for g((2))(tau) down to the thermal regime. (C) 2011 Optical Society of America</p

From polariton condensates to highly photonic quantum degenerate states of bosonic matter

Bose-Einstein condensation (BEC) is a thermodynamic phase transition of an interacting Bose gas. Its key signatures are remarkable quantum effects like superfluidity and a phonon-like Bogoliubov excitation spectrum, which have been verified for atomic BECs. In the solid state, BEC of exciton-polaritons has been reported. Polaritons are strongly coupled light-matter quasiparticles in semiconductor microcavities and composite bosons. However, they are subject to dephasing and decay and need external pumping to reach a steady state. Accordingly the polariton BEC is a nonequilibrium process of a degenerate polariton gas in self-equilibrium, but out of equilibrium with the baths it is coupled to and therefore deviates from the thermodynamic phase transition seen in atomic BECs. Here we show that key signatures of BEC can even be observed without fulfilling the self-equilibrium condition in a highly photonic quantum degenerate nonequilibrium system.</p