Negative / Null Result ReportOpen accessMathematics
Birgul Koc, Muhammad Mohebujjaman, Changhong Mou et al. · 2018 · arXiv
For reduced order models (ROMs) of fluid flows, we investigate theoretically and computationally whether differentiation and ROM spatial filtering commute, i.e., whether the commutation error (CE) is nonzero. We study the CE for the Laplacian and two ROM filters: the ROM projection and the ROM differential filter. Furthermore, when the CE is nonzero, we investigate whether it has any significant effect on ROMs that are constructed by using spatial filtering. As numerical tests, we use the Burgers equation with viscosities $ν=10^{-1}$ and $ν=10^{-3}$ and a 2D flow past a circular cylinder at Re
Negative / Null Result ReportOpen accessComputer Science
Xinyi Liu, Weiguang Wang, Hangfeng He · 2025 · arXiv
With the growing adoption of Large Language Models (LLMs) for open-ended tasks, accurately assessing epistemic uncertainty, which reflects a model's lack of knowledge, has become crucial to ensuring reliable outcomes. However, quantifying epistemic uncertainty in such tasks is challenging due to the presence of aleatoric uncertainty, which arises from multiple valid answers. While bias can introduce noise into epistemic uncertainty estimation, it may also reduce noise from aleatoric uncertainty. To investigate this trade-off, we conduct experiments on Visual Question Answering (VQA) tasks and
Negative / Null Result ReportOpen accessComputer Science
Lennart Meincke, Ethan Mollick, Lilach Mollick et al. · 2025 · arXiv
This is the third in a series of short reports that seek to help business, education, and policy leaders understand the technical details of working with AI through rigorous testing. In this report, we investigate two commonly held prompting beliefs: a) offering to tip the AI model and b) threatening the AI model. Tipping was a commonly shared tactic for improving AI performance and threats have been endorsed by Google Founder Sergey Brin (All-In, May 2025, 8:20) who observed that 'models tend to do better if you threaten them,' a claim we subject to empirical testing here. We evaluate model p
Negative / Null Result ReportOpen accessComputer Science
Danai Korre · 2023 · arXiv
Embodied conversational agents (ECAs) are paradigms of conversational user interfaces in the form of embodied characters. While ECAs offer various manipulable features, this paper focuses on a study conducted to explore two distinct levels of presentation realism. The two agent versions are photorealistic and animated. The study aims to provide insights and design suggestions for speech-enabled ECAs within serious game environments. A within-subjects, two-by-two factorial design was employed for this research with a cohort of 36 participants balanced for gender. The results showed that both th
Negative / Null Result ReportOpen accessPhysics
Ludovic Huguet, Victor Lherm, Renaud Deguen et al. · 2025 · arXiv
Turbulent thermals emerge in a wide variety of geophysical and industrial flows, such as atmospheric cumulus convection and pollutant dispersal in oceans and lakes. When a buoyant fluid mass rises, or sinks, heat and mass transfers occur by the engulfment of the fresh surrounding fluid inside the thermal - a process that spans over multiple scales from macroscopic entrainment of ambient fluid to microscopic diffusive processes. Turbulent thermals are typically investigated through their integral properties (radius, depth, entrainment rate). However, mixing processes depend on the internal dist
Negative / Null Result ReportOpen accessPhysics
N. Nardetto, A. Fokin, P. Fouqué et al. · 2011 · arXiv
Context. Recent observations of LMC Cepheids bring new constraints on the slope of the period-projection factor relation (hereafter Pp relation) that is currently used in the Baade-Wesselink (hereafter BW) method of distance determination. The discrepancy between observations and theoretical analysis is particularly significant for short period Cepheids Aims. We investigate three physical effects that might possibly explain this discrepancy: (1) the spectroscopic S/N that is systematically lower for LMC Cepheids (around 10) compared to Galactic ones (up to 300), (2) the impact of the metallici
Negative / Null Result ReportOpen accessComputer Science
Márton Tápai, Zoltán Keresztes, László Árpád Gergely · 2016 · arXiv
We derive the conservative secular evolution of precessing compact binaries to second post-Newtonian order accuracy, with leading-order spin-orbit, spin-spin and mass quadrupole-monopole contributions included. The emerging closed system of first-order differential equations evolves the pairs of polar and azimuthal angles of the spin and orbital angular momentum vectors together with the periastron angle. In contrast with the instantaneous dynamics, the secular dynamics is autonomous. This secular dynamics reliably characterizes the system over timescales starting from a few times the radial p
Negative / Null Result ReportOpen accessPhysics
N. D. Padilla, D. G. Lambas · 2003 · arXiv
We analyse the correlation function of mock galaxy clusters in redshift space. We constructed several mock catalogues designed to mimic the selection biases inherent in a variety of observational surveys. We explore different effects that contribute to the distortion of the clustering pattern; the pairwise velocity distribution of galaxy systems, coherent bulk motions, redshift errors and systematics in cluster identification. Our tests show that the redshift-space clustering pattern of galaxy systems is highly influenced by effects associated with the identification procedure from two dimensi
Negative / Null Result ReportOpen accessPhysics
Angus Hawkey, Aditya Dash, Xabier Rodríguez-Martínez et al. · 2025 · arXiv
Semiconducting single-walled carbon nanotubes (SWCNTs) are a promising thermoelectric material with high power factors after chemical p- or n-doping. Understanding the impact of dopant counterions on charge transport and thermoelectric properties of nanotube networks is essential to further optimize doping methods and to develop better dopants. Here, we utilize ion-exchange doping to systematically vary the size of counterions in thin films of small and large diameter, polymer-sorted semiconducting SWCNTs with AuCl3 as the initial p-dopant and investigate the impact of ion size on conductivity
Negative / Null Result ReportOpen accessComputer Science
Amit Bendkhale · 2025 · arXiv
Verifiable geometric reasoning is a critical component for trustworthy and controllable agentic AI. Despite impressive capabilities, Vision-Language Models (VLMs) often fail under realistic scene changes. We present Tri-Bench, a compact benchmark of planar triangle problems that isolates relative geometric reasoning while stressing two deployment-critical factors: camera pose (planar vs. tilted) and scene context via object interference (10 everyday objects). To test verifiability and control, we evaluate four recent VLMs using a single, fixed prompt whose guardrail explicitly describes a surr
Negative / Null Result ReportOpen accessComputer Science
Amador Durán, Pablo Fernández, Beatriz Bernárdez et al. · 2023 · arXiv
Context. Software Engineering (SE) has low female representation due to gender bias that men are better at programming. Pair programming (PP) is common in industry and can increase student interest in SE, especially women; but if gender bias affects PP, it may discourage women from joining the field. Objective. We explore gender bias in PP. In a remote setting where students cannot see their peers' gender, we study how perceived productivity, technical competency and collaboration/interaction behaviors of SE students vary by perceived gender of their remote partner. Method. We developed an onl
Negative / Null Result ReportMedicine
Okada, Tominaga, Iwakura et al. · 2026 · Resuscitation
Out-of-hospital cardiac arrest (OHCA) is a public health concern. Whether conventional cardiopulmonary resuscitation (CPR) with rescue breathing may improve outcomes compared with compression-only or no CPR in suffocation-related OHCA is…
View details →DOI: 10.1016/j.resuscitation.2026.111189 Negative / Null Result ReportOpen accessPhysics
Ozgur Akarsu, Suresh Kumar, Shivani Sharma et al. · 2019 · arXiv
We consider the simplest anisotropic generalization, as a correction, to the standard $Λ$CDM model, by replacing the spatially flat Robertson-Walker metric by the Bianchi type-I metric, which brings in a new term $Ω_{σ0}a^{-6}$ (mimicking the stiff fluid) in the average expansion rate $H(a)$ of the Universe. From Hubble and Pantheon data, relevant to the late Universe ($z\lesssim 2.4$), we obtain the constraint $Ω_{\sigma0}\lesssim10^{-3}$, in line with the model-independent constraints. When the baryonic acoustic oscillations and cosmic microwave background (CMB) data are included, the constr
Negative / Null Result ReportOpen accessComputer Science
Arif Ahmed, Gondy Leroy, Agrim Sachdeva et al. · 2026 · arXiv
Background: Generative artificial intelligence (GenAI) is increasingly used for health information, yet its influence on users' trust calibration remains unclear. Objective: This study examines whether learned dependency on GenAI influences trust in AI-generated health information and whether text highlighting reduces overreliance on incorrect outputs. Methods: Two randomized controlled experiments were conducted with 338 college students and 563 Amazon Mechanical Turk participants. Both experiments used a 2 by 2 between-subjects design manipulating information accuracy (correct versus incorre
Negative / Null Result ReportOpen accessPhysics
Sina Feldmann, Juliane Adrian, Maik Boltes · 2025 · arXiv
Impulse propagation in crowds is a phenomenon that is crucial for understanding collective dynamics, but has been scarcely addressed so far. Therefore, we have carried out experiments in which persons standing in a crowd are pushed forward in a controlled manner. Variations of experimental parameters include (i) the intensity of the push, (ii) the initial inter-person distance, (iii) the preparedness of participants and (iv) the crowd formation. Our analysis links the intensity of an impulse recorded by a pressure sensor with individual movements of participants based on head trajectories reco
Negative / Null Result ReportOpen accessEngineering
Yanyu Cheng, Chongjun Ouyang, Yuanwei Liu et al. · 2025 · arXiv
This paper conducts a comprehensive performance analysis for pinching-antenna systems (PASS) under both orthogonal multiple access (OMA) and non-orthogonal multiple access (NOMA) transmission. Given the cost of waveguides, we consider a scenario where the waveguide is not deployed in all rooms, i.e., some users are beyond the line-of-sight (LoS) link service area of the PASS. Specifically, we consider a PASS where a pinching antenna in one room serves two users located in separate rooms. The wireless transmissions between the pinching antenna and the users are performed via LoS and non-line-of
Negative / Null Result ReportOpen accessPhysics
P. Hazarika, U. D. Goswami, V. R. Chitnis et al. · 2014 · arXiv
We have investigated some features of the density and arrival time distributions of Cherenkov photons in extensive air showers using the CORSIKA simulation package. The main thrust of this study is to see the effect of hadronic interaction models on the production pattern of Cherenkov photons with respect to distance from the shower core. Such studies are very important in ground based $γ$-ray astronomy for an effective rejection of huge cosmic ray background, where the atmospheric Cherenkov technique is being used extensively within the energy range of some hundred GeV to few TeV. We have fou
Negative / Null Result ReportOpen accessPhysics
Nicolas Abi Chebel, Olivier Masbernat, Frédéric Risso et al. · 2008 · arXiv
The present work investigates free damped oscillations of an oil drop in water after its release from a capillary tube. Both pure heptane drops and diluted crude oil drops are considered (in the second case the interface is covered by amphiphilic species, natural components of crude oil). Shadowgraph images of the drops are taken by means of a high speed camera and the drop contour is detected by image processing. The axisymmetric drop shape is then decomposed into spherical harmonics, which constitute the eigenmodes of oscillations predicted by the Rayleigh-Lamb theory. Time evolution of each
Negative / Null Result ReportMedicine
AlDhafeeri, AlMugeiren · 2026 · Quintessence international (Berlin, Germany : 1985)
The use of lasers in dental implant procedures raises questions regarding the preservation of keratinized tissues and implant outcomes. This study aimed to compare the clinical effects (pain and impression time) and soft tissue healing…
View details →DOI: 10.3290/j.qi.b7041768 Negative / Null Result ReportOpen accessAgricultural and Biological Sciences
Carlota Muniz, Christopher McQuaid, Nicolas Weidberg · 2024 · arXiv
While the importance of extreme conditions is recognised, patterns in species abundances are often interpreted through average environmental conditions within their distributional range. For marine species with pelagic larvae, temperature and phytoplankton concentration are key variables. Along the south coast of South Africa, conspicuous spatial patterns in recruitment rates and the abundances of different mussel species exist, with focal areas characterized by large populations. We studied 15 years of sea surface temperature (SST) and chlorophyll-a (chl-a) satellite data, using spectral anal
Negative / Null Result ReportOpen accessPhysics
Miki Kurihara, Masahiro Tsujimoto, Megan E. Eckart et al. · 2023 · arXiv
Electromagnetic interference (EMI) for low-temperature detectors is a serious concern in many missions. We investigate the EMI caused by the spacecraft components to the x-ray microcalorimeter of the Resolve instrument onboard the X-Ray Imaging and Spectroscopy Mission (XRISM), which is currently under development by an international collaboration and is planned to be launched in 2023. We focus on the EMI from (a) the low-frequency magnetic field generated by the magnetic torquers (MTQ) used for the spacecraft attitude control and (b) the radio-frequency (RF) electromagnetic field generated by
Negative / Null Result ReportOpen accessAgricultural and Biological Sciences
Sina Sajjadi, Mohammad Reza Ejtehadi, Fakhteh Ghanbarnejad · 2020 · arXiv
We first propose a quantitative approach to detect high risk outbreaks of independent and coinfective SIR dynamics on three empirical networks: a school, a conference and a hospital contact network. This measurement is based on the k-means clustering method and identifies proper samples for calculating the mean outbreak size and the outbreak probability. Then we systematically study the impact of different temporal correlations on high risk outbreaks over the original and differently shuffled counterparts of each network. We observe that, on the one hand, in the coinfection process, randomizat
Negative / Null Result ReportOpen accessPhysics
Ce Zhang, Fang Zhang, Jeroen A. van Kan et al. · 2008 · arXiv
Single T4-DNA molecules were confined in rectangular-shaped channels with a depth of 300 nm and a width in the range 150-300 nm casted in a poly(dimethylsiloxane) nanofluidic chip. The extensions of the DNA molecules were measured with fluorescence microscopy as a function of the ionic strength and composition of the buffer as well as the DNA intercalation level by the YOYO-1 dye. The data were interpreted with scaling theory for a wormlike polymer in good solvent, including the effects of confinement, charge, and self-avoidance. It was found that the elongation of the DNA molecules with decre
Negative / Null Result ReportOpen accessComputer Science
Alexandros Liapis, Christos Katsanos, Michalis Xenos · 2018 · arXiv
Think aloud protocols are widely applied in user experience studies. In this paper, the effect of two different applications of the Retrospective Think Aloud (RTA) protocol on the number of user-reported usability issues is examined. To this end, 30 users were asked to use the National Cadastre and Mapping Agency web application and complete a set of tasks, such as measuring the land area of a square in their hometown. The order of tasks was randomized per participant. Next, participants were involved in RTA sessions. Each participant was involved in two different RTA modes: (a) the strict gui
Negative / Null Result ReportOpen accessComputer Science
Mahdis Tajdari, Jason Forsyth, Sol Lim · 2025 · arXiv
Navigating peripersonal space requires reaching targets in both horizontal (e.g., desks) and vertical (e.g., shelves) layouts with high precision. We developed a haptic glove to aid peri-personal target navigation and investigated the effectiveness of different feedback delivery methods. Twenty-two participants completed target navigation tasks under various conditions, including scene layout (horizontal or vertical), guidance approach (two-tactor or worst-axis first), guidance metaphor (push or pull), and intensity mode (linear or zone) for conveying distance cues. Task completion time, hand
Negative / Null Result ReportOpen accessPhysics
David L. Miller, Mark W. Keller, Justin M. Shaw et al. · 2012 · arXiv
Films of (111)-textured Cu, Ni, and Cu$_x$Ni$_y$ were evaluated as substrates for chemical vapor deposition of graphene. A metal thickness of 400 nm to 700 nm was sputtered onto a substrate of $α-$Al$_2$O$_3$(0001) at temperatures of 250 C to 650 C. The films were then annealed at 1000 C in a tube furnace. X-ray and electron backscatter diffraction measurements showed all films have (111) texture but have grains with in-plane orientations differing by $60^{\circ}$. The in-plane epitaxial relationship for all films was $[110]_{metal}$||$[10\bar{1}0]_{{Al}_{2}{O}_{3}}$. Reactive sputtering of Al
Negative / Null Result ReportOpen accessComputer Science
Christopher Plumberg, Dekrayat Almaalol, Travis Dore et al. · 2024 · arXiv
Conservation laws play a crucial role in the modeling of heavy-ion collisions, including the those for charges such as baryon number (B), strangeness (S), and electric charge (Q). In this study, we present a new 2+1 relativistic viscous hydrodynamic code called CCAKE which uses the Smoothed Particle Hydrodynamics (SPH) formalism to locally conserve BSQ charges, together with an extended description of the multi-dimensional equation of state (EoS) obtained from lattice Quantum Chromodynamics. Initial conditions for CCAKE are supplied by the ICCING model, which samples gluon splittings into quar
Negative / Null Result ReportOpen accessComputer Science
Mohamed Elsayed, Kenneth Fulton, Jeong Yang · 2026 · arXiv
Developers and organizations are using Large Language Models (LLMs) to generate security-critical code more frequently than ever, including cryptographic solutions for their products. This study presents an empirical evaluation of cryptographic security in 240 Rust code samples for two crypto algorithms (AES-256-GCM and ChaCha20-Poly1305) generated by three LLMs (Gemini 2.5 Pro, GPT-4o, and DeepSeek Coder) using four different prompt strategies. For each successfully compiled code sample, CodeQL static analysis and our rule-based crypto-specific analyzer were used to detect vulnerabilities, wh
Negative / Null Result ReportOpen accessComputer Science
Taiheng Pan · 2026 · arXiv
We describe ConvMemory, a small 3.6M-parameter learned reranker for conversational long-term memory retrieval, trained with cross-encoder teacher supervision over fused dense and lexical features. On the LongMemEval memory family, ConvMemory operates above the BGE-large cross-encoder in Recall@10 at 12-47x lower latency, remains within 0.025 Recall@10 of mxbai-rerank-large-v1 on Clean500 while running 28x cheaper; under Stress1000 distractors the Recall@10 gap widens to 0.081 but ConvMemory still operates at 117x lower latency; these LongMemEval numbers are single-run or single-seed and are re
Negative / Null Result ReportOpen accessPhysics
S. H. Naqib, R. S. Islam · 2011 · arXiv
The effect of Zn substitution in the CuO2 plane on the superconducting transition temperature, Tc, was studied for the La2-xSrxCu1-yZnyO4 and YBa2(Cu1-yZny)3O7-d compounds over a wide range of hole concentration, p, and Zn content (y). Zn induced rate of suppression of Tc, dTc(p)/dy, was found to be strongly p-dependent and showed a monotonic variation with p, except in the vicinity of p ~ 0.125, i.e., near the so-called 1/8th anomaly where the charge/spin stripe correlations are at their strongest in hole doped cuprates. The magnitude of dTc(p)/dy decreased significantly around this hole conc
