Chemical Analyses of Wasp-Associated Streptomyces Bacteria Reveal a Prolific Potential for Natural Products Discovery

Identifying new sources for small molecule discovery is necessary to help mitigate the continuous emergence of antibiotic-resistance in pathogenic microbes. Recent studies indicate that one potentially rich source of novel natural products is Actinobacterial symbionts associated with social and solitary Hymenoptera. Here we test this possibility by examining two species of solitary mud dauber wasps, Sceliphron caementarium and Chalybion californicum. We performed enrichment isolations from 33 wasps and obtained more than 200 isolates of Streptomyces Actinobacteria. Chemical analyses of 15 of these isolates identified 11 distinct and structurally diverse secondary metabolites, including a novel polyunsaturated and polyoxygenated macrocyclic lactam, which we name sceliphrolactam. By pairing the 15 Streptomyces strains against a collection of fungi and bacteria, we document their antifungal and antibacterial activity. The prevalence and anti-microbial properties of Actinobacteria associated with these two solitary wasp species suggest the potential role of these Streptomyces as antibiotic-producing symbionts, potentially helping defend their wasp hosts from pathogenic microbes. Finding phylogenetically diverse and chemically prolific Actinobacteria from solitary wasps suggests that insect-associated Actinobacteria can provide a valuable source of novel natural products of pharmaceutical interest

블루투스 시스템에서의 저연산량 스펙트럼 센싱에 관한 연구

In this paper, we propose a complexity reduced spectrum sensing scheme for Bluetooth to avoid the interference from other communication devices in 2.4 GHz ISM band. By exploiting the spectrum characteristics of interference sources, the proposed scheme detects the availability of channels by comparing the power spectrum density (PSD) with a threshold. To reduce the implementation complexity, the PSD is calculated by means of fast Fourier transform and linear interpolation. The threshold for the detection is determined to maximize the detection probability. To further improve the transmission performance, the proposed scheme dynamically changes the channels by measuring the transmission performance. Finally, the performance of the proposed scheme is verified by computer simulation in the presence of WLANs in the ISM band.Seoul R&BS Progra

Orthogonal Muti-beam Techniques for Multi-user Diversity and Multiplexing Gain in Packet-based Wireless Systems

In this paper, we consider the use of orthogonal multiple beams (OMBs) to simultaneously achieve multi-user diversity and multiplexing gain in a packet-based wireless system. Previous schemes consider the use of a fixed number of OMBs according to the number of transmit antennas. However, unless the number of active users is sufficiently large, the use of multiple beams may not provide desired performance mainly due to the interference from other users signals, being even worse than the use of a single beam. To alleviate this problem, we consider the adjustment of the number of beams in use to maximize the spectral efficiency according to the operating condition. Simulation results show the validity of the proposed scheme

패킷 기반 무선 시스템에서 다중 직교 빔을 이용한 다중 안테나 송수신 기법

In this paper, we consider the use of multiple beams to simultaneously achieve both diversity and multiplexing gain in multi-user domain in multiple access systems. Orthogonal multiple beams are generated to provide the users with multiple channels at the same time, achieving multi-user diversity through each channel. However, when the number of active users is not large, the performance can significantly be affected by the interference from other users. To alleviate this problem, we propose a multi-beam scheme to adjust the number of beams according to the channel condition or the number of users.the Ministry of Information & Communications, Korea, under the Information Technology Research Center (ITRC) Support Progra

수신 상관정보를 이용한 상향링크 셀룰러 시스템에서의 사용자 스케줄링에 관한 연구

In this paper, we consider multi-user scheduling to maximize the ergodic capacity near the cell boundary in the uplink of cellular systems. The base station (BS) determines a user pair that can minimize the interference from other cells by exploiting the receive correlation matrices of users from adjacent BSs. The performance of the proposed scheme is verified by computer simulation. Simulation results show that the proposed multi-cell scheduling significantly increase the ergodic capacity near the cell boundary compared to conventional random user scheduling, particularly in highly correlated channel environments

Multi-user diversity and multiplexing with multiple coherent beams in wireless systems

In this paper, we propose a multi-beam multiplexing scheme that can simultaneously achieve spatial multiplexing gain and multi-user diversity (MUD) gain by generating coherent multiple beams in the multi-user domain. Multiple beams are generated to provide multiple channels in parallel, making it possible to achieve the MUD gain through each channel. Since the transmission power is spilt into multiple channels, the signal-to-noise power ratio (SNR) of each channel is reduced inversely proportional to the number of beams. However, multiple beams are utilized to make the multiplexing gain much larger than the decrease of SNR, increasing the overall system capacity. The proposed scheme is applicable to both multi-input multi-output (MIMO) and multi-input singleoutput (MISO) schemes, enabling the use of flexible antenna structures in the receiver.Korea Research Foundation Grant funded by the Korean Government(MOEHRD

상향링크 셀룰러 시스템에서 채널 상관 기반의 협력 사용자 스케줄링 기법

In this paper, we consider multi-user scheduling to avoid other cell interference (OCI) in the uplink of cellular systems. The base station (BS) determines a user group that can minimize the interference from other cells by exploiting the spatial correlation matrix of users from adjacent BSs. The proposed scheme is applicable to multi-input multi-output (MIMO) as well as single-input multi-output (SIMO) environments by applying an eigen-beamforming technique, enabling the use of flexible antenna structures at the transmitter. Simulation results show that the proposed multi-cell scheduling significantly increase the ergodic capacity by avoiding the OCI compared to conventional scheduling schemes, particularly in high mobility and highly correlated channel environments.Seoul R&BD Progra

Development of a standardized in-hospital cardiopulmonary resuscitation set-up

Objective. This study evaluated whether chest compression in a standardized inhospital cardiopulmonary resuscitation (CPR) set-up can be performed as effectively as when the rescuer is kneeling beside the patient lying on the floor. Specifically, the in-hospital test was standardized according to the rescuers’ average knee height. Methods. Experimental intervention (test 1) was a standardized, in-hospital CPR set-up: first, the bed height was fixed at 70 cm. Second, the height difference between the bed and a step stool was set to the average knee height of the CPR team members (45 cm). Control intervention (test 2) was kneeling on floor. Thirty-eight medical doctors on the CPR team each performed 2 minutes of chest compressions in test 1 and 2 in random order (cross-over trial). A Little Anne was used as a simulated patient who had experienced cardiac arrest. Chest compression parameters, such as average depth and rate, were measured using an accelerometer device. Results. In all tests, the average depths were those recommended in the most recent CPR guidelines (50–60 mm); there were no significant differences between Tests 1 and 2 (53.1 ± 4.3 mm vs. 52.6 ± 4.8 mm, respectively; p = 0.398). The average rate in Test 2 (119.1 ± 12.4 numbers/min) was slightly faster than that in Test 1 (116.4 ± 10.2 numbers/ min; p = 0.028). No differences were observed in any other parameters. Conclusions. Chest compression quality in our standardized in-hospital CPR set-up was similar with that performed in a kneeling position on the floor. Trial Registration: Clinical Research Information Service: KCT000159