210,320 research outputs found
Violation of a Leggett-Garg inequality with ideal non-invasive measurements
No full textThe quantum superposition principle states that an entity can exist in two different states simultaneously, counter to our 'classical' intuition. Is it possible to understand a given system's behaviour without such a concept? A test designed by Leggett and Garg can rule out this possibility. The test, originally intended for macroscopic objects, has been implemented in various systems. However to date no experiment has employed the 'ideal negative result' measurements that are required for the most robust test. Here we introduce a general protocol for these special measurements using an ancillary system, which acts as a local measuring device but which need not be perfectly prepared. We report an experimental realization using spin-bearing phosphorus impurities in silicon. The results demonstrate the necessity of a non-classical picture for this class of microscopic system. Our procedure can be applied to systems of any size, whether individually controlled or in a spatial ensemble.</p
Characterization of the APEX2-GARG-1060 proximity biotinylation system.
No full textA. Domain organization of GBF1 and the C-terminally truncated GBF1 constructs fused to EGFP (positive control) and APEX2. Both GBF1 truncated constructs contain the BFA-resistant Sec7 domain from ARNO. B. Polio replicon replication was assessed in the presence or absence of 2μg/ml of BFA in HeLa cells transfected with plasmids expressing the C-terminally truncated GBF1 fusions with APEX2 or EGFP, or an empty vector C. Polio replicon replication assay was performed in control HeLa cells, or HeLa cells stably expressing APEX2-GARG-1060 with or without 2μg/ml of BFA. D. HeLa cells stably expressing APEX2-GARG-1060 were infected (or mock-infected) with 10 PFU/cell of poliovirus, and the biotinylation reaction was performed at 4 h p.i. The cells were processed for visualization of biotinylated proteins with a fluorescent streptavidin conjugate and immunostaining for a poliovirus antigen 3A. E. HeLa cells stably expressing APEX2-GARG-1060 were infected (or mock-infected) with poliovirus and the biotinylation reaction was performed as in D. The cells were stained with a fluorescent streptavidin conjugate and antibodies against a poliovirus antigen 2B and processed for structural illumination superresolution (SIM) microscopy. The arrow shows biotinylation-positive structures identified as stress granules. The scale bar is 10μm. F. HeLa cells stably expressing APEX2-GARG-1060 were infected (PV), or mock-infected (M) with 10 PFU/cell of poliovirus, and protein biotinylation was assessed after performing the biotinylation reaction at 4 h p.i. with biotin-phenol (BP) and hydrogen peroxide (complete reaction), or without one, or both compounds.</p
Biotinylation of viral proteins by APEX2-GARG-1060.
No full textA. Poliovirus genome and polyprotein processing scheme. The cleavage sites for the viral proteases 2A, 3C, and 3CD are indicated by green, red, and blue-filled triangles, respectively. The dashed empty green triangle indicates a 2A cleavage site in 3D believed to be dispensable for replication. The purple star indicates the autocatalytic cleavage site in VP0. B. HeLa cells stably expressing APEX2-GARG-1060 were infected (PV), or mock-infected (M) with 10 PFU/cell of poliovirus, and biotinylation reactions were performed at the indicated times post-infection. Unfractionated cellular lysates (input) and isolated biotinylated proteins were analyzed in a Western blot with indicated antibodies. The antibodies recognize the final and intermediate polyprotein cleavage products containing the corresponding antigen. Red stars on anti-3A and anti-3D panels indicate polyprotein fragments that do not match the known polyprotein cleavage products.</p
Comment on 'A scattering quantum circuit for measuring Bell's time inequality:a nuclear magnetic resonance demonstration using maximally mixed states'
No full textA recent paper by Souza, Oliveira and Sarthour (SOS) reports the experimental violation of a Leggett-Garg (LG) inequality (sometimes referred to as a temporal Bell inequality). The inequality tests for quantum mechanical superposition: if the inequality is violated, the dynamics cannot be explained by a large class of classical theories under the heading of macrorealism. Experimental tests of the LG inequality are beset by the difficulty of carrying out the necessary so-called 'non-invasive' measurements (which for the macrorealist will extract information from a system of interest without disturbing it). SOS argue that they nevertheless achieve this difficult goal by putting the system in a maximally mixed state. The system then allegedly undergoes no perturbation during their experiment. Unfortunately, the method is ultimately unconvincing to a skeptical macrorealist and so the conclusions drawn by SOS are unjustified.</p
Garg PhD Thesis Metabolic Modeling Calculations
No full textThis fits the metabolic model developed by Mehdi Alemi and Alan Asbeck to the raw data from Garg 1976 PhD Thesis, p. 198 and beyond (raw data tables).Citation for Garg 1976:GARG, Arun, 1947- A METABOLIC RATE PREDICTION MODEL FOR MANUAL MATERIALS HANDLING JOBS. The University of Michigan, Ph.D., 1976 Engineering, industrial.</div
Leggett-Garg inequalities and the geometry of the cut polytope
No full textThe Bell and Leggett-Garg tests offer operational ways to demonstrate that nonclassical behavior manifests itself in quantum systems, and experimentalists have implemented these protocols to show that classical worldviews such as local realism and macrorealism are false, respectively. Previous theoretical research has exposed important connections between more general Bell inequalities and polyhedral combinatorics. We show here that general Leggett-Garg inequalities are closely related to the cut polytope of the complete graph, a geometric object well-studied in combinatorics. Building on that connection, we offer a family of Leggett-Garg inequalities that are not trivial combinations of the most basic Leggett-Garg inequalities. We then show that violations of macrorealism can occur in surprising ways, by giving an example of a quantum system that violates the pentagon Leggett-Garg inequality but does not violate any of the basic triangle Leggett-Garg inequalities. © 2010 The American Physical Society
Memory-Sample Lower Bounds for Learning Parity with Noise
No full textIn this work, we show, for the well-studied problem of learning parity under noise, where a learner tries to learn x = (x₁,…,x_n) ∈ {0,1}ⁿ from a stream of random linear equations over ₂ that are correct with probability 1/2+ε and flipped with probability 1/2-ε (0 < ε < 1/2), that any learning algorithm requires either a memory of size Ω(n²/ε) or an exponential number of samples.
In fact, we study memory-sample lower bounds for a large class of learning problems, as characterized by [Garg et al., 2018], when the samples are noisy. A matrix M: A × X → {-1,1} corresponds to the following learning problem with error parameter ε: an unknown element x ∈ X is chosen uniformly at random. A learner tries to learn x from a stream of samples, (a₁, b₁), (a₂, b₂) …, where for every i, a_i ∈ A is chosen uniformly at random and b_i = M(a_i,x) with probability 1/2+ε and b_i = -M(a_i,x) with probability 1/2-ε (0 < ε < 1/2). Assume that k,, r are such that any submatrix of M of at least 2^{-k} ⋅ |A| rows and at least 2^{-} ⋅ |X| columns, has a bias of at most 2^{-r}. We show that any learning algorithm for the learning problem corresponding to M, with error parameter ε, requires either a memory of size at least Ω((k⋅)/ε), or at least 2^{Ω(r)} samples. The result holds even if the learner has an exponentially small success probability (of 2^{-Ω(r)}). In particular, this shows that for a large class of learning problems, same as those in [Garg et al., 2018], any learning algorithm requires either a memory of size at least Ω(((log|X|)⋅(log|A|))/ε) or an exponential number of noisy samples.
Our proof is based on adapting the arguments in [Ran Raz, 2017; Garg et al., 2018] to the noisy case
Quantum Nondemolition Measurement Enables Macroscopic Leggett-Garg Tests
No full textWe show how a test of macroscopic realism based on Leggett-Garg inequalities (LGIs) can be performed in a macroscopic system. Using a continuous-variable approach, we consider quantum nondemolition (QND) measurements applied to atomic ensembles undergoing magnetically driven coherent oscillation. We identify measurement schemes requiring only Gaussian states as inputs and giving a significant LGI violation with realistic experimental parameters and imperfections. The predicted violation is shown to be due to true quantum effects rather than to a classical invasivity of the measurement. Using QND measurements to tighten the “clumsiness loophole” forces the stubborn macrorealist to recreate quantum backaction in his or her account of measurement
Understanding variability in performance of type il cements: insights from Raman imaging
No full textPortland-limestone cement (PLC), designated as Type IL under ASTM C595, has emerged as a lower-carbon alternative to ordinary Portland cement (OPC). By replacing up to 15% of clinker with finely ground limestone, PLC reduces calcination-related emissions and offers an average greenhouse gas reduction of more than 8%. Although this environmental benefit has accelerated the adoption of PLC across North America, significant performance variability has been reported in the field, including reductions in 28-day strength, increased water demand, and inconsistent set behavior. The origins of this performance variability remain insufficiently understood because commercial PLCs differ in both clinker phase composition and fineness.
This thesis investigates twelve commercial Type IL cements to quantify their performance variability and understand how their physical and chemical properties influence it. Multimodal characterization was applied, combining compressive strength testing and open porosity measurements (at 1, 3, 7, and 28 days of hydration), isothermal calorimetry, and rheology of fresh paste, with laser diffractometry, X-ray diffraction (XRD), and Raman imaging. A key contribution of the work is also the development of an automated Raman imaging algorithm that improves reproducibility by relying on objective criteria for Raman band and peak-top band selection.
Performance testing revealed substantial differences across the 12 PLCs. Early-age compressive strength varied between 2000 to 3800 psi at 1 day (mean: 3000 ± 465 psi), while calorimetry showed a range from 180 – 230 J/g in cumulative heat at 1 day (mean: 200 ± 18 J/g) and a 2.5 hour difference in set times. Rheological measurements also differed significantly, with dynamic yield stress varying between 16 to 59 Pa (mean: 34 ± 9.8 Pa) and the plastic viscosity of the stiffest cement being 0.61 Pa.s while that of the most compliant one was 0.12 Pa.s. Open porosity at 28 days ranged between 24% to 32% (mean: 28 ± 2.3%), and strong relationships were observed between porosity reduction and compressive strength (R2 = 0.75, RMSE = 12.7%). Bulk particle size analysis indicated wide variability in fineness, with D50 ranging from 9.8 – 12.3 m (mean: 11.2 ± 0.8 m) and a range of 2 – 4 m in D10 across cements (mean: 3 ± 0.7 m). The D10 showed the strongest correlation with early hydration heat at 1 day (R2 = 0.65, RMSE= 5.0%) and 3 days (R2 = 0.67, RMSE= 3.2%), confirming that ultrafine particles dominate early dissolution, nucleation, and reactivity. Chemical analysis using XRD showed large differences in clinker phase composition as well.
Raman imaging played a key role in linking chemistry and fineness at the phase level. The automated algorithm developed in this thesis produced Raman-based phase quantification that agreed closely with XRD, with a RMSE of 3.22% and most phase measurements within 5%. More importantly, Raman imaging enabled extraction of phase-specific PSDs revealed substantial differences in the fineness of individual phases that were masked in bulk PSD measurements. A composition coefficient (C_"c" ) that uses Raman phase composition and a phase-specific PSD factor (F_"psd" ) that represents the geometric mean of phase-D50 values were both correlated with hydration heat. When combined as the product (C_"combined" ), the predictive capability improved further, achieving the strongest correlation with 3 day cumulative heat (R2 = 0.71, RMSE= 3.0%).
These results show that performance variability in commercial Type IL cements arises from the combined effects of clinker phase composition and the fineness of reactive phases. By integrating laser diffractometry, XRD, and Raman imaging, this thesis provides a more complete framework for understanding PLC variability and offers quantitative tools for predicting hydration and strength. The automated Raman imaging approach developed here also advances the technique toward more routine use in industrial characterization and performance control.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-12-01The student, Yaman Garg, accepted the attached license on 2025-12-10 at 22:54.The student, Yaman Garg, submitted this Thesis for approval on 2025-12-10 at 23:05.This Thesis was approved for publication on 2025-12-11 at 08:18.DSpace SAF Submission Ingestion Package generated from Vireo submission #23115 on 2026-02-19 at 20:10:0
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