Theory of radio-frequency spectroscopy of impurities in quantum gases

We present a theory of radio-frequency spectroscopy of impurities interacting with a quantum gas at finite temperature. By working in the canonical ensemble of a single impurity, we show that the impurity spectral response is directly connected to the finite-temperature equation of state (free energy) of the impurity. We consider two different response protocols: "injection", where the impurity is introduced into the medium from an initially non-interacting state; and "ejection", where the impurity is ejected from an initially interacting state with the medium. We show that there is a simple mapping between injection and ejection spectra, which is connected to the detailed balance condition in thermal equilibrium. To illustrate the power of our approach, we specialize to the case of the Fermi polaron, corresponding to an impurity atom that is immersed in a non-interacting Fermi gas. For a mobile impurity with a mass equal to the fermion mass, we employ a finite-temperature variational approach to obtain the impurity spectral response. We find a striking non-monotonic dependence on temperature in the impurity free energy, the contact, and the radio-frequency spectra. For the case of an infinitely heavy Fermi polaron, we derive exact results for the finite-temperature free energy, thus generalizing Fumi's theorem to arbitrary temperature. We also determine the exact dynamics of the contact after a quench of the impurity-fermion interactions. Finally, we show that the injection and ejection spectra obtained from the variational approach compare well with the exact spectra, thus demonstrating the accuracy of our approximate method.Comment: 15 pages, 10 figure

Radio-frequency response and contact of impurities in a quantum gas

We investigate the radio-frequency spectroscopy of impurities interacting with a quantum gas at finite temperature. In the limit of a single impurity, we show using Fermi's golden rule that introducing (or injecting) an impurity into the medium is equivalent to ejecting an impurity that is initially interacting with the medium, since the "injection" and "ejection" spectral responses are simply related to each other by an exponential function of frequency. Thus, the full spectral information for the quantum impurity is contained in the injection spectral response, which can be determined using a range of theoretical methods, including variational approaches. We use this property to compute the finite-temperature equation of state and Tan contact of the Fermi polaron. Our results for the contact of a mobile impurity are in excellent agreement with recent experiments and we find that the finite-temperature behavior is qualitatively different compared to the case of infinite impurity mass.Comment: 4 pages, 2 figure

Data-Driven Multimodal Patrol Planning for Anti-poaching

Wildlife poaching is threatening key species that play important roles in the ecosystem. With historical ranger patrol records, it is possible to provide data-driven predictions of poaching threats and plan patrols to combat poaching. However, the patrollers often patrol in a multimodal way, which combines driving and walking. It is a tedious task for the domain experts to manually plan such a patrol and as a result, the planned patrol routes are often far from optimal. In this paper, we propose a data-driven approach for multimodal patrol planning. We first use machine learning models to predict the poaching threats and then use a novel mixed-integer linear programming-based algorithm to plan the patrol route. In a field test focusing on the machine learning prediction result at Jilin Huangnihe National Nature Reserve (HNHR) in December 2019, the rangers found 42 snares, which is significantly higher than the historical record. Our offline experiments show that the resulting multimodal patrol routes can improve the efficiency of patrol and thus they can serve as the basis for future deployment in the field

To Angulate or Not to Angulate the Ulna during the Progressive Distraction Period Performed with a Monolateral External Fixator in Paediatric Patients with a Chronic Monteggia Fracture?

Background and Objectives: The purpose of this study was to compare the clinical and radiographic evolution of chronic Monteggia fractures (CMFs) treated by ulnar osteotomy and monolateral external fixators (MEFs) with or without angulation of the ulna during the distraction period. Materials and Methods: This retrospective study evaluated 20 children (14 boys and 6 girls) with CMFs. According to the strategy of ulnar lengthening, two groups of patients were identified: patients undergoing gradual lengthening with (Group A, n = 11) or without ulna angulation (Group B, n = 9). The mean age at the time of surgery was 7.7 years old (range, 5.4–12.9). The mean time from initial trauma to surgery was 26.3 months (range, 1–96), and the mean follow-up was 24.6 months (range, 5.5–45.4). Clinical outcomes were evaluated by Kim et al.’s Elbow Performance Score, while radiographic outcomes were assessed on plain radiographs. Results: Age at surgery, sex, laterality, time between trauma and surgery, and time of follow up in the two groups of patients showed no significant differences. The radial head was successfully reduced in 9 of 9 and 10 of 11 patients in Groups B and A, respectively (p = 1.00). The mean time to achieve radial head reduction was shorter in Group B (18.1 ± 5.3 days) than in Group A (39.2 ± 18.7 days; p = 0.004). The mean angulation of the ulna at the end of treatment was significantly lower in Group B (0.6° ± 1.1°) than in Group A (25.9° ± 6.3°; p < 0.0001). The average ulnar lengthening at the end of treatment in Group B (14.1 ± 5.8 mm) was, on average, 7.7 mm less than that in Group A (21.8 ± 9.7 mm; p = 0.05). The Kim et al. Elbow Performance Score at the last follow-up visit was comparable between the two groups of patients (p = 1.00). Conclusions: A shorter time to achieve radial head reduction and less deformity of the ulna can be expected in paediatric patients with CMFs undergoing intraoperative restoration of ulnar alignment and gradual lengthening without angulation postoperatively

Subtyping of Cryptosporidium cuniculus and genotyping of Enterocytozoon bieneusi in rabbits in two farms in Heilongjiang Province, China

Cryptosporidium spp. and Enterocytozoon bieneusi are two prevalent opportunistic pathogens in humans and animals. Currently, few data are available on genetic characterization of both pathogens in rabbits in China. The aim of the present study was to understand prevalence and genetic characterization of Cryptosporidium spp. and E. bieneusi in rabbits. We collected 215 fecal samples from 150 Rex rabbits and 65 New Zealand White rabbits on two different farms in Heilongjiang Province, China. Cryptosporidium spp. and E. bieneusi were tested by polymerase chain reaction (PCR) and sequencing the partial small subunit of ribosomal DNA (SSU rDNA) and the internal transcribed spacer (ITS) region of rDNA, respectively. Cryptosporidium was detected in 3.3% (5/150) of Rex rabbits and 29.2% (19/65) of New Zealand White rabbits. All the 24 Cryptosporidium isolates were identified as C. cuniculus. Enterocytozoon bieneusi was only found in 14.7% (22/150) of Rex rabbits. Five known genotypes: CHN-RD1 (n = 12), D (n = 3), Type IV (n = 2), Peru6 (n = 1), and I (n = 1), and three novel ones CHN-RR1 to CHN-RR3 (one each) were detected. By analyzing the 60-kDa glycoprotein (gp60) gene sequences of C. cuniculus isolates, three subtypes were obtained: VbA28 (n = 2), VbA29 (n = 16), and VbA32 (n = 3). All these three C. cuniculus subtypes were reported previously in humans. Four known E. bieneusi genotypes have been found to be present in humans. The three novel ones fell into zoonotic group 1. The results suggest zoonotic potential of C. cuniculus and E. bieneusi isolates in rabbits

Subtyping of

Cryptosporidium spp. and Enterocytozoon bieneusi are two prevalent opportunistic pathogens in humans and animals. Currently, few data are available on genetic characterization of both pathogens in rabbits in China. The aim of the present study was to understand prevalence and genetic characterization of Cryptosporidium spp. and E. bieneusi in rabbits. We collected 215 fecal samples from 150 Rex rabbits and 65 New Zealand White rabbits on two different farms in Heilongjiang Province, China. Cryptosporidium spp. and E. bieneusi were tested by polymerase chain reaction (PCR) and sequencing the partial small subunit of ribosomal DNA (SSU rDNA) and the internal transcribed spacer (ITS) region of rDNA, respectively. Cryptosporidium was detected in 3.3% (5/150) of Rex rabbits and 29.2% (19/65) of New Zealand White rabbits. All the 24 Cryptosporidium isolates were identified as C. cuniculus. Enterocytozoon bieneusi was only found in 14.7% (22/150) of Rex rabbits. Five known genotypes: CHN-RD1 (n = 12), D (n = 3), Type IV (n = 2), Peru6 (n = 1), and I (n = 1), and three novel ones CHN-RR1 to CHN-RR3 (one each) were detected. By analyzing the 60-kDa glycoprotein (gp60) gene sequences of C. cuniculus isolates, three subtypes were obtained: VbA28 (n = 2), VbA29 (n = 16), and VbA32 (n = 3). All these three C. cuniculus subtypes were reported previously in humans. Four known E. bieneusi genotypes have been found to be present in humans. The three novel ones fell into zoonotic group 1. The results suggest zoonotic potential of C. cuniculus and E. bieneusi isolates in rabbits

Unveiling the Catalytic Role of Zeolite P1 in Carbonylation Reaction

Zeolite P1, a significant conversion product of fly ash, is predominantly utilized for the removal of metal ions, adsorption of carbon dioxide, and capture of aromatic compounds. Despite its diverse applications, its role as a catalyst remains underexplored in the scientific community. Traditionally, mordenite (MOR) zeolites are considered typical dimethyl ether (DME) carbonylation catalysts, whose Brønsted acid sites located on the 8-membered rings (8-MR) are the key active sites for this reaction. This conventional approach underscores the importance of specific zeolite structures in facilitating catalytic processes. H–P1 zeolite was synthesized through a template-free approach in this paper. When applied to DME carbonylation, this zeolite exhibited an impressive selectivity of up to 93% for methyl acetate (MA), suggesting its potential as a highly effective catalyst. This promising outcome hints at a new frontier for the application of the P1 zeolite, potentially revolutionizing its role in catalysis and expanding its utility beyond traditional adsorption processes. The findings suggest that the P1 zeolite could be a versatile material in the realm of catalytic chemistry, offering new pathways and methodologies for various chemical reactions