Sharp bounds for harmonic numbers

In the paper, we first survey some results on inequalities for bounding harmonic numbers or Euler-Mascheroni constant, and then we establish a new sharp double inequality for bounding harmonic numbers as follows: For $n\in\mathbb{N}$, the double inequality -\frac{1}{12n^2+{2(7-12\gamma)}/{(2\gamma-1)}}\le H(n)-\ln n-\frac1{2n}-\gamma<-\frac{1}{12n^2+6/5} is valid, with equality in the left-hand side only when $n=1$, where the scalars $\frac{2(7-12\gamma)}{2\gamma-1}$ and $\frac65$ are the best possible.Comment: 7 page

High sensitivity micro-fiber Mach-Zehnder interferometric temperature sensors with a high index ring layer

The influence of the high index ring layer (HIRL) in a tapered fiber Mach-Zehnder interferometer (MZI) on the interference observed, and thus on its potential applications in temperature sensing, has been investigated. The MZI was comprised of a tapered Ring Core Fiber (RCF), spliced between two single mode fibers (SMF). Since part of core mode from the SMF was converted into cladding modes in the RCF, due to the mismatch in the cores between the RCF and SMF, the residual power enters and then propagates along the center of the RCF (silica). The difference in phase between the radiation travelling along these different paths is separated by the HIRL to generate an interference effect. Compared with fiber interferometers based on core and cladding mode interference, the thin fiber HIRL is capable of separating the high order cladding modes and the silica core mode, under grazing incident conditions. Therefore, the optical path difference (OPD) and the sensitivity are both substantially improved over what is seen in conventional devices, showing their potential for interferometric temperature sensor applications. The optimum temperature sensitivity obtained was 186.6 pm/°C, which is ∼ 11.7 times higher than has been reported previously

Rate adaptation for 802.11 multiuser mimo networks

In multiuser MIMO (MU-MIMO) networks, the optimal bit rate of a user is highly dynamic and changes from one packet to the next. This breaks traditional bit rate adaptation algorithms, which rely on recent history to predict the best bit rate for the next packet. To address this problem, we introduce TurboRate, a rate adaptation scheme for MU-MIMO LANs. TurboRate shows that clients in a MU-MIMO LAN can adapt their bit rate on a per-packet basis if each client learns two variables: its SNR when it transmits alone to the access point, and the direction along which its signal is received at the AP. TurboRate also shows that each client can compute these two variables passively without exchanging control frames with the access point. A TurboRate client then annotates its packets with these variables to enable other clients to pick the optimal bit rate and transmit concurrently to the AP. A prototype implementation in USRP-N200 shows that traditional rate adaptation does not deliver the gains of MU-MIMO WLANs, and can interact negatively with MU-MIMO, leading to low throughput. In contrast, enabling MU-MIMO with TurboRate provides a mean throughput gain of 1.7x and 2.3x, for 2-antenna and 3-antenna APs respectively.National Science Council (China) (contract No. NSC 100-2221-E-001-005-MY2)National Science Foundation (U.S.) (NSF Grant CNS-1117194

Practical gigahertz quantum key distribution robust against channel disturbance

Quantum key distribution (QKD) provides an attractive solution for secure communication. However, channel disturbance severely limits its application when a QKD system is transfered from the laboratory to the field. Here, a high-speed Faraday-Sagnac-Michelson QKD system is proposed that can automatically compensate for the channel polarization disturbance, which largely avoids the intermittency limitations of environment mutation. Over a 50-km fiber channel with 30-Hz polarization scrambling, the practicality of this phase-coding QKD system was characterized with an interference fringe visibility of 99:35% over 24 hours, and a stable secure key rate of 306k bits/s over 7 days without active polarization alignment

AMNP: ad hoc multichannel negotiation protocol for multihop mobile wireless networks

Abstract — Increasing the capacity of wireless communication is an important and urgent research area, which has attracted more attentions. One of potential solutions is to divide the radio spectrum into several independent radio channels, which can be operated and accessed by all nodes within their radio transmission range simultaneously. Many solutions adopt mul-tiple transceivers to fulfill this goal. However, these solutions are short in implementation and may increase the prime cost of the device since most wireless devices only equip one single transceiver. Moreover, with a few exceptions, most researchers have emphasized centralized resource allocation algorithms for cellular systems where the base station keeps track of the requirements of the various users and is thus responsible for the management of network resources. Nevertheless, on the other hand, a multihop mobile ad hoc network (MANET) is generally configured as peer-to-peer networks with no centralized hubs or controllers to coordinate channel allocations. Therefore, in this paper, we proposed a multichannel medium access control (MAC) protocol, named ad hoc multichannel negotiation protocol (AMNP), for multichannel transmission by using the distributed fashion. We address the issue of distributed resource allocation for multihop MANETs by presenting an AMNP that builds on the multichannel request-to-send/clear-to-send (MRTS/MCTS) bandwidth reservation mechanism under the constraint of a single transceiver. Besides, to conquer the problem of broadcast transmissions in multichannel environment under the constrain of one single transceiver, we further design a broadcast announce-ment scheme for AMNP. Moreover, an enhancement version of AMNP called AMNP with channel scheduling (AMNP/s) is also introduced to improve the channel utilization. We show via simulations that AMNP/s provides a higher throughput compared to its single channel counterpart by promoting simultaneous transmissions in different channels. Simulation results also show that the proposed AMNP/s derives higher performance than other multichannel transmission schemes, which equip multiple transceivers

The role of cytochrome c oxidase subunit Va in non-small cell lung carcinoma cells: association with migration, invasion and prediction of distant metastasis

BACKGROUND: Lung cancer is one of the most lethal malignancies worldwide, but useful biomarkers of lung cancer are still insufficient. The aim of this study is to identify some membrane-bound protein(s) associated with migration and invasion in human non-small cell lung cancer (NSCLC) cells. METHODS: We classified four NSCLC cell lines into high and low migration/invasion groups by Transwell and Matrigel assays. Using two-dimensional gel electrophoresis and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), we identified 10 membrane-associated proteins being significantly overexpressed in the high migration/invasion group. The expression of the target protein in the four NSCLC cell lines was then confirmed by reverse transcription polymerase chain reaction (RT-PCR), western blot and immunostaining. RNA interference technique was applied to observe the influence of the target protein on migration and invasion. Gelatin zymography was also performed to evaluate the activities of matrix metalloproteinase (MMP)-2 and MMP-9. Expression condition of the target protein on surgical specimens was further examined by immunohistochemical staining and the clinicopathologic data were analyzed. RESULTS: We identified a mitochondria-bound protein cytochrome c oxidase subunit Va (COX Va) because of its abundant presence found exclusively in tumorous areas. We also demonstrated that migration and invasion of NSCLC cells decreased substantially after knocking down COX Va by siRNA. Meanwhile, we found a positive correlation between COX Va expression, Bcl-2 expression and activities of MMP-2 and MMP-9 in NSCLC cells. Immunohistochemical staining of surgically resected lung adenocarcinomas in 250 consecutive patients revealed that strong COX Va expression was found in 54.8% (137/250) of patients and correlated positively with the status of lymph node metastasis (P = 0.032). Furthermore, strong COX Va expression was associated with the presence of distant metastasis (P = 0.033). CONCLUSIONS: Our current study showed that COX Va may play a role in migration and invasion of NSCLC cells and can be used as a biomarker to predict aggressiveness of NSCLC

Self-ICL: Zero-Shot In-Context Learning with Self-Generated Demonstrations

Large language models (LMs) have exhibited superior in-context learning (ICL) ability to adopt to target tasks by prompting with a few input-output demonstrations. Towards better ICL, different methods are proposed to select representative demonstrations from existing training corpora. However, such a setting is not aligned with real-world practices, as end-users usually query LMs without accesses to demonstration pools. Inspired by evidence suggesting LMs' zero-shot capabilities are underrated, and the role of demonstrations are primarily for exposing models' intrinsic functionalities, we introduce Self-ICL, a simple framework for zero-shot ICL. Given a test input, Self-ICL first prompts the model to generate pseudo-inputs. Next, the model predicts pseudo-labels for the pseudo-inputs via zero-shot prompting. Finally, we construct pseudo-demonstrations from pseudo-input-label pairs, and perform ICL for the test input. Evaluation on BIG-Bench Hard shows Self-ICL steadily surpasses zero-shot and zero-shot chain-of-thought baselines on head-to-head and all-task average performance. Our findings suggest the possibility to bootstrap LMs' intrinsic capabilities towards better zero-shot performance.Comment: Work in progres