122 research outputs found
When Fewer Layers Break More Chains: Layer Pruning Harms Test-Time Scaling in LLMs
No full textLayer pruning has emerged as a widely adopted technique for improving the efficiency of large language models (LLMs). Although existing methods demonstrate strong performance retention on general knowledge tasks, their effect on long-chain reasoning, a more brittle yet crucial capability, remains largely unexplored. In this work, we study the impact of layer pruning on long-chain reasoning through the lens of test-time scaling, a key mechanism in modern LLMs that enables strong reasoning capacity by allocating more computation at inference time. With extensive experiments, we demonstrate that pruning even one or two layers can severely impair test-time scaling, with performance collapsing drastically on long reasoning benchmarks even when performance on knowledge-intensive and shallow reasoning tasks remains stable. Furthermore, we find that standard supervised fine-tuning remedies fail to recover test-time scaling once it has deteriorated. Through in-depth analyses, we identify the mechanisms underlying this fragility of test-time scaling and highlight the fundamental risks of applying layer pruning to reasoning-intensive LLMs. These findings call for a rethinking of layer pruning strategies and provide insights for developing methods that preserve the robustness of reasoning. We open-source the codebase in \href{https://github.com/keyu-wang-2002/Layer-Pruning-Harms-Inference-Scaling}{https://github.com/keyu-wang-2002/Layer-Pruning-Harms-Inference-Scaling}
Laser-Induced Carbon Nanofibers as Permeable Nonenzymatic Sensor for Biomarker Detection in Breath Aerosol
No full text: A novel breathable electrochemical enzyme-free sensor made from laser-induced carbon nanofibers embedding Ni nanocatalysts (Ni-LCNFs) is proposed for the capture and detection of biomarkers in breath aerosol. The permeable Ni-LCNF electrodes were fabricated on filter paper where a hydrophobic wax barrier was created to confine the device's working area. The device was tested with aerosolized glucose, which was collected on the porous Ni-LCNF electrode. After a subsequent drying step, 0.1 M NaOH was dropped onto the device, and the electrocatalytic reaction of the captured glucose enabled by a Ni nanocatalyst was monitored via cyclic voltammetry (CV). Taking the oxidation/reduction peak ratios from CV as analytical signals improves the reliability and reproducibility of the glucose measurement. In the measurement step, closing the sensing area with adhesive tape, named closed device, enhances the detection sensitivity and enables the detection limit of 0.71 μM, which is 11.5 and 50 times, respectively, better when compared to the open device configuration. Measurements with simulated glucose aerosols containing clinically relevant glucose levels and comparison to screen-printed electrodes demonstrated the device's superiority for breath analysis. Although in vivo validation studies must be conducted in future work, the proposed device results in a captivating point-of-care device integratable in breathing masks and breath analysis devices
Author response image 1. Author response
No full textAnkyrin adaptors together with their spectrin partners coordinate diverse ion channels and cell adhesion molecules within plasma membrane domains and thereby promote physiological activities including fast signaling in the heart and nervous system. Ankyrins specifically bind to numerous membrane targets through their 24 ankyrin repeats (ANK repeats), although the mechanism for the facile and independent evolution of these interactions has not been resolved. Here we report the structures of ANK repeats in complex with an inhibitory segment from the C-terminal regulatory domain and with a sodium channel Nav1.2 peptide, respectively, showing that the extended, extremely conserved inner groove spanning the entire ANK repeat solenoid contains multiple target binding sites capable of accommodating target proteins with very diverse sequences via combinatorial usage of these sites. These structures establish a framework for understanding the evolution of ankyrins' membrane targets, with implications for other proteins containing extended ANK repeat domains.</p
Ji yu jin chang sheng xue xuan fu de zi yun xing he zi fu dong er wei zhi dong qi
No full textM.Phil.Acoustic radiation force in the near-field of a vibrating source can be utilized to lift and transport objects, which provides a non-contact driving technology in addition to maglev. This research presents a novel self-running planar motion stage utilizing near-field acoustic transportation phenomenon and coupled resonant vibration of the device.Finite element analysis models have been established to find the needed resonant modes and optimize the design of the structure. The first longitudinal and the second bending modes are designed to have an identical frequency to create elliptical vibration of the structure, which can provide vertical levitation force as well as the propulsion force. A dynamic model based on the Reynolds Equation has been established to study the levitation and driving mechanism of the proposed device. The levitation and driving forces are analyzed; and the relationship between the driving force and the input phase difference is investigated to optimize the following position control. A capacitance surface encoder is proposed to provide the levitation height and two dimensional position feedback for the stage. The encoder design is based on the measurement of capacitance change between the driving stage and the metal sensing plates embedded in the ground. The lateral position (in the XY plane) of the circular stage can be uniquely determined based on the capacitance values.A prototype including the stage, encoder, and controller is implemented and characterized to demonstrate the performance of the proposed design. Two motion characteristics of the stage are first tested: one is the influence of the excitation voltage amplitude on the levitation height, and the other is the influence of the amplitude and phase angles of the excitation signals on the velocity and thrust force. In the calibration of the encoder, the calculated coordinates are firstly compensated for the scaling and the misalignment of the encoder axis and the precision stage. And the systematic errors from the nonlinear features are identified and fitted to a third-order polynomial equation in each axis. In the control scheme, the capacitance encoder works as the feedback module, and a LabVIEW program is used for date acquisition and processing. The stage is tested and demonstrated to follow a circular trajectory with a radius of 3.5mm.This work investigates a novel self-floating and self-running two-dimensional actuator using near-field acoustic levitation and coupled resonant vibration of the device. Compared with the conventional designs based on near-field acoustic levitation, the proposed design eliminates any external component such as guide rail, which contributes to bigger working space. This design also has two-dimensional motion capability with higher load capacity and energy efficiency. A dynamic model based on the Reynolds Equation is established to study the driving mechanism. A capacitance surface encoder is proposed to provide the two dimensional position feedback for the stage. A prototype including the stage, encoder, and controller is implemented and characterized to demonstrate the capability of the proposed design.振動源在近場中產生的輻射力可以用於提升和運輸物體，這現象可用於非接觸驅動技術，並有別於磁懸浮技術。本研究提出了一種新型的自運行平面運動機構，該機構利用了近場聲學傳播現象和裝置的耦合諧振。通過有限元分析可以找到機構的共振模態，並且用於指導結構的優化設計。通過結構設計，使得一階縱向模態和二階橫向模態具有相同的振動頻率，以產生橢圓振動，橢圓振動同時提供懸浮立和前進驅動力。建立了基於雷諾方程的運動模型，來分析機構的懸浮和運動機制。通過分析懸浮力和驅動力，獲得驅動力與輸入信號相位差之間的關係，用於之後定位平臺的位置控制。基於表面電容的編碼器被用於定位平臺的位置反饋，這個反饋包括了平臺的懸浮高度以及它的二維平面位置。編碼器可以測量懸浮平臺和固定在地上的金屬感應板間的電容。基於測得的電容值，通過相應的計算，可以得出平臺在XY平面內的確定位置。建立了包括運動器，編碼器和控制器在內的實驗模型，用於驗證設計的性能。首先是關於驅動器運動性能的測定，第一個是電壓大小對懸浮高度的影響，第二個是電壓大小以及電壓相位角對於運動速度和驅動力的影響。在編碼器的校準過程中，首先補償了由於編碼器和精密平臺錯位以及縮放而引起的誤差， 然後運用三階多項式來擬合每個軸的非線性系統誤差。在控制方案中，電容式編碼器起反饋作用，一個LabVIEW程序用於對電信號的處理。在運動測試中，平臺行走了一個半徑為3.5mm的圓形軌跡。這項研究成功研發了一種新型的自懸浮和自運動的二維運動機構，這個機構運用了近場超聲懸浮和耦合共振效應。與傳統的近場超聲懸浮裝置相比，新的設計不需要導軌之類的任何外部部件，這有助於提供更大的工作空間。該設計具有二維運動能力，並有更高的負載能力和能量效率。建立了基於雷諾方程的運動模型來研究其運動機制。用電容編碼器來當作二維定位平臺的位置反饋。包括運動機構，編碼器和控制器在內的實驗模型被建立，用於驗證設計的性能。Chen, Keyu.Thesis M.Phil. Chinese University of Hong Kong 2017.Includes bibliographical references (leaves 56-60).Abstracts also in Chinese.Title from PDF title page (viewed on 06, February, 2020).Chen, Keyu
Systèmes intégrables, algèbres de Borel affines quantiques, et équations aux différences elliptiques
No full textThe subjects of this thesis are organized into three parts. In the first part, we prove a conjecture formulated by E. Frenkel and D. Hernandez. More specifically, we have established the TQ systems and the QQ~ systems for the twisted quantum affine algebras, Langlands dual to the quantum affine algebras. To prove these systems, we develop the representation theory of the Borel subalgebras of twisted quantum affine algebras. In addition, we formulate a conjecture stating a relationship between the Grothendieck ring of the category O of representations of twisted Borel subalgebras and that of the corresponding untwisted type. We establish our conjecture for certain remarkable families of representations. As a result, we deduce the TQ and QQ~ systems for the twisted Borel subalgebras. In the second part, our focus shifts to the untwisted types, where we examine a Weyl group symmetry associated with the category O of representations of Borel subalgebras Uqb. For each element w in W, we study the q-characters normalized by an l-weight labeled by w. We propose a conjecture on the convergence phenomenon of the w-normalized q-characters of finite-dimensional representations. To explain this phenomenon, we define and explore the categories Ow of Uqb-modules, where we classify their simple objects. Specific representations in Ow are constructed as the inductive limit of finite-dimensional representations. We also formulate a conjecture that establishes a link between the usual category O and the new categories Ow. This conjecture suggests a method for calculating the q-characters of a large number of representations in O. In the last part, we redirect our focus to elliptic quantum groups. In this collaborative work with Giovanni Felder and Tommaso Botta, we solve the quantum KZB equations for elliptic quantum groups based on geometric methods. We examine the shuffle structure of the elliptic stable envelopes of Aganagic-Maulik-Okounkov. This shuffle structure allows us to construct solutions to the quantum KZB equations. This work generalizes the construction initially developed by Felder-Tarasov-Varchenko for the specific case of sl2.Les sujets abordés dans cette thèse sont organisés en trois parties. Dans la première partie, nous démontrons une conjecture formulée par E. Frenkel et D. Hernandez. Plus précisément, nous avons prouvé les systèmes TQ et les systèmes QQ~ pour les algèbres affines quantiques tordues, duales de Langlands des algèbres affine quantiques. Pour démontrer ces systèmes, nous développons la théorie des représentations des sous-algèbres de Borel des algèbres affines quantiques tordues. Nous proposons de plus une conjecture énonçant une relation entre l'anneau de Grothendieck de la catégorie O des représentations des sous-algèbres de Borel tordues et celui du type non tordu correspondant. Nous établissons notre conjecture pour une certaines familles de représentations. Nous en déduisons des systèmes TQ et QQ~ pour les sous-algèbres de Borel tordues. Dans la deuxième partie de la thèse, notre attention se porte sur les types non tordus, où nous examinons une symétrie du groupe de Weyl W associée à la catégorie O des représentations des sous-algèbres de Borel Uqb. Pour chaque élément w dans W, nous étudions les q-caractères normalisés par un l-poids marqué par w. Nous proposons une conjecture sur le phénomène de convergence des q-caractères w-normalisés des représentations de dimension finie. Pour expliquer ce phénomène, nous définissons et explorons les catégories Ow de Uqb-modules, où nous classifions leurs objets simples. Des représentations spécifiques dans Ow sont construites comme la limite inductive de représentations de dimension finie. Nous formulons également une conjecture qui établit un lien entre la catégorie usuelle O et les nouvelles catégories Ow. Cette conjecture suggère une méthode pour calculer les q-caractères d'un grand nombre de représentations dans O. Dans la dernière partie de la thèse, nous orientons notre attention vers les groupes quantiques elliptiques. Dans ce travail collaboratif avec Giovanni Felder et Tommaso Botta, nous résolvons les équations KZB quantiques pour les groupes quantiques elliptiques avec des méthodes géométriques. Nous étudions la structure de mélange des enveloppes stables elliptiques d'Aganagic-Maulik-Okounkov. Cette structure de mélange nous permet de construire des solutions aux équations KZB quantiques. Ce travail généralise la construction initialement élaborée par Felder-Tarasov-Varchenko pour le cas spécifique de sl2
Influence of Microbial Treatment on the Preparation of Porous Biochar with Stepped-Up Performance and Its Application in Organic Pollutants Control
No full textIn this study, Irisensata Thunb grass (ITG) was used as a biomass carbon resource to prepare biochars for the first time. After microbial treatment, the obtained microbial-treated ITG (MITG) was activated by using a mixed base as an activator for preparation of biochar (MITGB). The specific surface area and total pore volume of MITGB were 3036.4 m2/g and 1.5252 cm3/g, which were higher than those of biochar prepared without microbial treatment (ITGB, 2930.0 m2/g and 1.5062 cm3/g). Besides, the physicochemical properties of MITGB and ITGB were also quite different including micro morphology, surface chemistry, functional groups, etc. In the experiment of removing organic pollutants with synthetic dye RhB and antibiotic TH as the models, MITGB showed excellent treatment ability. The maximum adsorption capacities of MITGB for RhB and TH were 1354.2 and 1462.6 mg/g, which were higher than most of the biochars. In addition, after five cycles of recycling, the adsorption capacities of the organic pollutant models can still be maintained at more than 80%, which showed high stability. This work verified the feasibility of microbial treatment to further improve the performance of biochar and provided a new idea and direction for exploring other biochars
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