Critical Point Research Articles

This study presents the first systematic quantum chemical investigation establishing benchmark criteria for distinguishing coordination bonds from intramolecular chalcogen bonds in heavy chalcogen compounds. Through experimental and computational analysis of the tellurium(II) and selenium(II) dithiocarbamate complexes [Te(S2CNEt2)2] (1), [Se(S2CNEt2)2] (2), and [Se(S2CN(CH2)4)2] (3), we demonstrate that anisobidentate coordination arises from a bonding continuum combining covalent coordination and noncovalent chalcogen interactions. Using combined QTAIM, ELF, and RDG analysis, we established quantitative criteria for bond discrimination and discovered a diagnostic RDG method where coordination bonds appear without characteristic contours, while chalcogen bonds display blue regions at bond critical points. This work reinterprets secondary interactions as authentic intramolecular chalcogen bonds with LP(S)→σ*(Ch-S) charge transfer energies up to 39.7 kcal/mol. Results show shorter Ch-S bonds exhibit coordination (Te) and covalent (Se) characteristics, while longer contacts represent intramolecular chalcogen bonds with σ-hole signatures. Comparative analysis with the nickel(II) complex [Ni(S2CNEt2)2], where the ligands are isobidentate, validates covalent nature of the Ni-S bonds through different electron densities (ρ < 0.045 au for chalcogen bonds vs 0.0875 au for the coordination bonds). The methodology provides a framework for characterizing bonding regimes in heavy chalcogen compounds.

This study aims to analyze work time efficiency and determine standard time in the furniture production process at CV. JM Putra using the Time and Motion Study method. The background of this study stems from the problem of low production time efficiency due to suboptimal work methods, ineffective work area layout, and a lack of systematic work time measurement. The research was conducted quantitatively and descriptively through direct observation, interviews, and time measurements using a stopwatch for the table production process, which consisted of five main activities. The results showed that the average total cycle time for one table unit was 347.25 minutes, with the activity of assembling the table frame being the longest activity at 120.13 minutes or about 34.6% of the total working time. After performance assessment and the addition of a 15.5% allowance factor, the standard time was obtained at 129.03 minutes. These results indicate that the activity of assembling the table frame is the most critical point that affects production efficiency. The implications of this study show the importance of improving work methods, area layout, and operator training to increase labor productivity. The application of standard time measurement results can be used as a basis for setting work standards, production capacity planning, and a more objective labor incentive system.

A diverse community of microorganisms inhabits the gastrointestinal tract in a physiological state. While a symbiotic relationship exists between commensal bacteria and the healthy host, an imbalanced microbial population (dysbiosis) is associated with the development of colitis-associated colorectal cancers. The decline of beneficial microbes (eubionts) and the expansion of commensal-derived opportunistic pathogens (pathobionts) are widely recognized as key factors in the microbial etiology of various diseases. In particular, certain bacteria with emerging virulence elements are present in the gut microbiome and have been implicated as contributors to the development of colon cancer, such as Escherichia coli, Bacteroides fragilis, and Fusobacterium nucleatum. Bacterial virulent factors, including lipopolysaccharide, fimbriae and adhesins, and toxins, promote oncogenesis through direct or indirect mechanisms. These microbial products modify host cellular functions, resulting in DNA damage, increased epithelial proliferation, and intensified inflammation, all of which ultimately contribute to tumor formation. Although the existence of pathobionts is generally accepted nowadays, an open question remains regarding why bacteria shift from harmless commensals to disease-causing pathobionts. Accumulating evidence suggests that host epithelial functions influence the composition of the intestinal microbiota by regulating oxygen availability in the lumen, providing antimicrobial defense, activating innate immune responses, synthesizing mucin glycoproteins, and establishing a physical barrier through the organization of microvilli. This review examines the various aspects of mucosal drivers that shape microbiota and provides evidence that intraepithelial stress plays a significant role in configuring colitogenic and tumorigenic microflora. Understanding the mechanisms by which microbes transition from eubionts to pathobionts that promote cancer progression is crucial for developing bacterial precision medicine. Identifying the roles of intestinal pathobionts and the critical time point for host-microbe interactions in tumorigenesis could lead to the development of new strategies for prevention and therapy.

On the basis of thermal unrestricted Hartree-Fock theory of electron-ion lattice gas in the density-matrix formalism, Compton profiles of simple fluid metals are calculated at reduced densities and elevated temperatures. We thereby examine how spatial inhomogeneity of conduction electrons affects the Compton profiles, reciprocal form factors and electron kinetic energies. Comparison of numerical results with experimental data for rubidium suggests a crossover from nearly homogeneous to strongly inhomogeneous expansion as the density is lowered from the ambient condition toward the gas-liquid critical point.

Abstract We study a continuous time branching process where an individual splits into two daughters with rate b and dies with rate a, starting from a single individual at t=0. We show that the model can be mapped exactly to a random walk problem where the population size N(t) performs a random walk on a positive semi-infinite lattice. The hopping rate of this random walker out of a site labelled n is proportional to n, i.e., the walker gets more and more `agitated' as it moves further and further away from the origin--we call this an `agitated random walk' (ARW). We demonstrate that this random walk problem is particularly suitable to obtain exact explicit results on the extreme value statistics, namely, on the distribution of the maximal population size M(t)= \max_{0τ\le t}[N(τ)] up to time t. This extreme value distribution displays markedly different behaviors in the three phases: (i) subcritical (b&lt;a) (ii) critical (b=a) and (iii) supercritical (b&gt;a). In the subcritical and critical phases , Q(L,t) becomes independent of time t for large t and the stationary distribution Q(L, \infty) decays to zero with increasing L, respectively exponentially (subcritical) and algebraically (critical). For finite but large t, the distribution at the critical point exhibits a scaling form Q(L,t)\sim f_c(L/{at})/L^2 where the scaling function f_c(z) has a nontrivial shape that we compute analytically. In the supercritical phase, the distribution Q(L,t) has a `fluid' part that becomes independent of t for large t and a `condensate' part (a delta peak centered at e^{(b-a)t}) which gets disconnected from the `fluid' part and moves rapidly to \infty as time increases. We also verify our analytical predictions via numerical simulations finding excellent agreement.

Tissue homeostasis requires a precise balance between stem cell self-renewal and differentiation. While fate decisions are known to be closely linked with cell cycle progression, the functional significance of this relationship is unclear. We propose a mechanistic framework to analyse cellular dynamics when cell fate is coupled to cell cycle duration. Our model highlights a unique aspect of cell cycle regulation where mitogens serve as control parameters for a bifurcation governing the G1-S transition. Under competitive feedback from cell-cell interactions, the cell cycle regulatory network fine-tunes near the critical point of this bifurcation. Critical positioning lengthens G1 while amplifying cell-to-cell variability in mitogenic signalling and biochemical states. Such regulation confers significant advantages for controlling cell population dynamics, with alternative topologies enabling rapid tissue growth and repair or efficient mutant rejection. Counter-intuitively, we propose that stem cells may couple prolonged G1 with increased self-renewal propensity to efficiently suppress mis-sensing mutants. Our theory provides a distinct explanation to dynamical and statistical patterns of G1 lengthening and predicts regulatory strategies across development, homeostasis, and ageing.

Predictive Indicator of Critical Point in Equilibrium and Nonequilibrium Magnetic Systems

Finite-Disorder Critical Point in the Brittle-to-Ductile Transition of Amorphous Solids in the Presence of Particle Pinning

Abstract The study of strong electron correlations has significantly advanced the frontiers of condensed matter physics, especially in relation to correlation-driven quantum phase transitions (QPTs). In the vicinity of QPTs, quantum critical fluctuations of multiple degrees of freedom enable the emergence of exotic many-body states and quantum critical behaviours beyond the Landau paradigm. Recently, magnetic frustration, traditionally associated with insulating magnets, has been recognized as pivotal to investigating new phases of matter in correlation-driven Kondo breakdown QPTs that are not clearly associated with broken symmetry. The nature of these new phases, however, remains underexplored. Here, we report quantum criticalities emerging from a cluster spin-glass in the heavy-fermion metal TiFexCu2x-1Sb, where frustration originates from intrinsic disorder. Specific heat and magnetic Grüneisen parameter measurements under varying magnetic fields exhibit quantum critical scaling, indicating a quantum critical point (QCP) near 0.13 Tesla. As the magnetic field increases, the cluster spin-glass phase is progressively suppressed. Upon crossing the QCP, resistivity and Hall effect measurements reveal enhanced screening of local moments and an expanding Fermi surface, consistent with the Kondo breakdown scenario. Our findings uncover a new family of iron-based heavy-fermion metals with intricate interplay of multiple degrees of freedom, enabling the exploration of unconventional excitations and exotic quantum critical states and behaviours.

At continuous phase transitions, quantum many-body systems exhibit complex, emergent behavior. Most notably, at a quantum critical point, correlations decay as a power law, with exponents determined by a set of universal scaling dimensions. Experimentally probing such power law correlations is extremely challenging, owing to the interplay between decoherence, the vanishing energy gap, and boundary effects. In this work, we used a Rydberg quantum simulator to adiabatically prepare critical ground states of both a one-dimensional ring and a two-dimensional square lattice. By accounting for and tuning the openness of our quantum system, which is well-captured by a single phenomenological length scale, we directly observed power law correlations and extracted the corresponding scaling dimensions. Our work complements recent studies of quantum criticality that use the Kibble-Zurek mechanism and digital quantum circuits.

Among the various mysteries in cuprate high temperature superconductors, the pseudogap (PG) phase stands out for the difficulty in pinning down its origin and its close connection to unconventional superconductivity. It appears above the superconducting transition temperature ​, where part of the low energy spectral weight becomes depleted and several competing or intertwined orders such as charge and pair density waves, nematicity, and spin fluctuations begin to develop. A persistent challenge lies in the systematic discrepancies revealed by different experimental probes, as transport measurements locate the critical doping near , spectroscopic studies around , and symmetry sensitive techniques close to . These variations reflect the distinct sensitivities of each probe to correlation length scales and electronic coherence rather than experimental inconsistency. This review brings together evidence from angle resolved photoemission spectroscopy (ARPES), scanning tunneling microscopy or spectroscopy (STM or STS), nuclear magnetic resonance (NMR), resonant X ray scattering (RXS), and optical conductivity, showing that the pseudogap is a spatially heterogeneous, symmetry breaking electronic state whose onset temperature decreases roughly linearly with doping and terminates sharply at . Three complementary theoretical frameworks, namely quantum criticality, Mott physics, and intertwined orders, collectively describe these observations. Experiments showing the abrupt disappearance of nematic order and a logarithmic rise in the electronic specific heat coefficient suggest that the pseudogap terminates at a quantum critical point. This transition appears to separate a correlation dominated pseudogapped metal from a coherent Fermi liquid phase rather than occurring through a gradual crossover. The doping level identified from transport data aligns with optimal superconductivity, implying that the recovery of long range phase coherence rather than the complete removal of pseudogap features is what ultimately enhances . Unresolved questions include reconciling probe dependent boundaries through systematic cross technique studies on identical crystals and developing correlation length resolved probes to distinguish spatial scales of electronic reconstruction. A major theoretical challenge remains to unify competing frameworks and to elucidate how the pseudogap terminates and coherence emerges at , which represents a key step toward a microscopic theory of high temperature superconductivity in cuprates.

Abstract Climate critical points amplify the association between climatic effects and climate subsystems. The Tibetan Plateau (TP) is experiencing significant accelerated warming with the Amazon's warming‐drying impact exhibiting interdecadal differences around 2004. During 1981–2004 (P1), Amazonian warming in March, by exciting the North Atlantic Tripole pattern, enhanced the African jet stream and triggered the eastward propagation of Rossby waves leading to an abnormal strengthening of the northern wind over the TP in April. This suppressed snowmelt and expanded snow cover, significantly increasing albedo and thereby inhibiting warming in the central and western TP. From 2005 to 2023 (P2), TP surface skin temperature (SKT) and soil moisture replaced snow albedo as the dominant factor for warming. The Amazon's warm‐dry signal extended northward, triggering warming in the Greenland Sea and exciting anomalous wave trains propagating southeastward. These waves intensified TP warming by regulating atmospheric circulation and surface radiation processes. The study demonstrates that as the Amazon Rainforest approaches a climate critical point, the cross‐continental teleconnection mechanism with the TP undergoes fundamental changes, highlighting the nonlinear impact of climate subsystems' critical states on amplification effects. This finding provides a dynamical basis for understanding the synergistic effects of global climate critical points.

IntroductionPatient safety is a fundamental objective in healthcare practice, aiming to prevent errors and avoid their impact on patients. A significant proportion of these errors occur at the household level, where monitoring is particularly challenging.MethodsAccording to the principles of safety culture, Reason's model of error suggests that human errors can be mitigated through the design of more robust systems that reduce the likelihood of their occurrence. Cytotoxic drugs, such as lomustine, are classified as high-risk medications due to their potential to cause severe harm to patients.ResultsFollowing an incident in which a patient ingested a higher-than-prescribed dose of lomustine, a root cause analysis (RCA) was conducted. This analysis identified critical points in the process that contributed to the error, enabling the design of a comprehensive medication circuit. This circuit was developed collaboratively by the Oncology and Pharmacy departments and addressed key stages such as prescription, validation, custody, and dispensing.ConclusionThe implementation of a structured lomustine circuit successfully eliminated medication errors associated with its use. Since its introduction, no further incidents have been reported, indicating improved safety and reliability in the medication-use process.

Sustainable aquaculture is increasingly vital to meet global protein demands while ensuring fish product safety and environmental stewardship from a One Health perspective. This review addresses fish hygiene as a comprehensive, multi-stage challenge encompassing water quality management, pathogen control, antimicrobial stewardship, feeding practices, humane slaughter, post-harvest handling, and monitoring systems. We examined current practices and technologies that promote hygienic standards and reduce contamination risks across production cycles. The integration of biosecurity measures and alternative health-promoting agents contributes to disease prevention and reduces reliance on antimicrobials. Responsible drug administration aligned with regulatory frameworks minimizes residues and antimicrobial resistance. Feeding strategies incorporating sustainable and safe ingredients further support fish health and product quality. Critical control points during slaughter and post-harvest processing ensure microbial safety and prolong shelf life. Advanced monitoring and traceability systems enable real-time oversight and enhance food safety assurance. Finally, certification programs and robust regulatory policies are essential to standardize practices and facilitate access to international markets. Collectively, these strategies foster sustainable aquaculture that safeguards public health, maintains ecological integrity, and supports economic viability. This holistic approach positions fish hygiene not as a final quality check, but as an integral, continuously managed component of responsible aquaculture production.

Fascicular ventricular tachycardia (VT) is an uncommon idiopathic VT affecting primarily young patients without structural heart disease. It typically involves a reentry mechanism within the Purkinje system, particularly the posterior fascicle, and appears on ECG with a right bundle branch block and left anterior fascicular block pattern. Although generally benign, symptoms such as palpitations or syncope can affect the quality of life. Catheter ablation is the treatment of choice for patients who are refractory to or prefer not to use medical therapy. To our knowledge, a novel 48-electrode paddle-shaped catheter (Optrell) has never been used for mapping fascicular VT. A 34-year-old competitive athlete with recurrent posterior fascicular VT underwent a second ablation after failed initial procedure and partial response to beta-blockers and verapamil. High-density electroanatomic mapping using the 48-electrode paddle-shaped catheter during tachycardia allowed identification of the abnormal Purkinje potentials (P1 and P2) and the critical fusion point of the reentry circuit at the mid-septum. Radiofrequency energy was delivered at this site, resulting in prompt termination of the arrhythmia. No recurrences were observed during the post-procedural observation period or at follow-up (6months). This case demonstrates the safety and efficacy of high-resolution mapping using a novel 48-electrode catheter to facilitate ablation of fascicular VT.

Safe feed is vital for animal health, and is a precondition for food safety and human health. Dietary exposure of poultry chickens to aflatoxin-contaminated feeds may result in negative health implications, and may be carried-over into their by-products such as eggs. The aim of this study was to determine the contamination levels of aflatoxins in feed and egg samples from layer chickens, as well as egg samples from free-range chickens from Bafoussam in Cameroon. Levels of crude proteins and total aflatoxin were determined in layer chickens’ feeds (n=9) from nine poultry farms. Additionally, aflatoxin B1 was quantified in eggs (16 pooled egg samples) from the layer chickens that were fed the studied feeds as well as eggs (10 pooled egg samples) from free-range hens in Bafoussam. All studied feed samples revealed levels of crude proteins (mean: 20.4, range: 17.2-25.6 g/100 g of feed) higher than standard (16 g/100 g feed), and levels of total aflatoxin (mean: 107.6, range: 27-178 μg kg-1) higher than the maximum tolerable limit (20 μg/kg) in feed. Levels of aflatoxin B1 in eggs from layer chickens (mean: 0.0005, range: nd-0.0013 μg/kg; 62.5%) and in eggs from free-range hens (mean: 0.0016, range: 0.0009-0.0024 μg/kg; 100%) did not exceed the maximum tolerable limit (2 μg/kg) of aflatoxin B1 in foods destined for human consumption. The direct proposional relationship between crude proteins and total aflatoxins levels speculate that proteins source for feed production may be a critical control point for aflatoxins contamination in feeds. Although levels of aflatoxins B1 in eggs were generally low, the higher occurrence frequencies may be a concern when considering eggs as a part of diet for all age categories in Cameroon.

We have investigated the evolution of CDW states and structural phases in a Cu-deficient Cu1-δTe (δ = 0.016) by employing high-pressure experiments and first-principles calculations. Raman scattering results reveal that the vulcanite structure at ambient pressure starts to change into the Cu-deficient rickardite (r-CuTe) structure from 6.7 GPa, which then becomes fully stabilized above 8.3 GPa. Resistivity data show that TCDW1 (≈333 K) is systematically suppressed under high pressure, reaching zero at 5.9 GPa. In the pressure range of 5.2–8.2 GPa, a sharp resistivity drop due to superconductivity occurs at the onset temperature TC = ~2.0–3.2 K. The maximum TC = 3.2 K achieved at 5.6 GPa is clearly higher than that of CuTe (2.3 K), suggesting the importance of charge fluctuation in the vicinity of CDW suppression. At 7.5 GPa, another resistivity anomaly appears due to the emergence of a second CDW (CDW2) ordering at TCDW2 = ~176 K, which exhibits a gradual increase to ~203 K with pressure increase up to 11.3 GPa. First-principles calculations on the Cu-deficient Cu11Te12 with the r-CuTe structure show that including on-site Coulomb repulsion is essential for incurring an unstable phonon mode relevant for stabilizing the CDW2 order. These results point out the important role of charge fluctuation in optimizing the pressure-induced superconductivity and that of Coulomb interaction in creating the competing CDW order in the Cu-deficient CuTe system.

Abstract An equicritical stratum is the locus of univariate monic squarefree complex polynomials where the critical points have prescribed multiplicities. Tracking the positions of both roots and critical points, there is a natural “monodromy map” taking the fundamental group into a braid group. We show here that when there are exactly two critical points, this monodromy map is noninjective.

Campylobacter is a constant concern in ensuring food safety, as it is one of the most common pathogens in food. The main source of Campylobacter species in food is poultry meat, and the primary production of this meat is a critical point where measures need to be taken to reduce its presence in the food chain. Therefore, poultry slaughterhouses are recognized as places where it is necessary to implement measures to control and reduce the number of Campylobacter spp. Food business operators are obliged to ensure greater hygiene on the slaughter line, through the inspection of equipment for each step of slaughter and the application of regular cleaning protocols. Continuous monitoring of the presence and abundance of Campylobacter spp. on the slaughter line provides data on the validity of hygiene control measures in the slaughterhouse, as well as the data needed to assess the microbiological risk in poultry meat. Monitoring the presence of Campylobacter spp. in poultry slaughterhouses is a basic activity that is necessary for taking measures to reduce contamination, improve microbiological safety in poultry processing and thus improve the food safety system as a whole. This review aims to highlight the importance of investigating the prevalence of Campylobacter spp. in poultry slaughterhouses, but also the importance of applying measures to prevent and control this pathogen both on farms and in slaughterhouses. These measures are necessary to minimize the presence and transmission of Campylobacter in poultry, thereby reducing the risk of foodborne diseases.

This article highlights strengths-based regenerative intervention practices used in a recent change effort to improve the circularity of compostables and compost within the US composting ecosystem. This whole systems, cross-sector initiative convened over 110 organizations to co-create a unified strategy for the industry at a critical inflection point. The intervention deepened the capacity for collaborative working relationships across organizations and helped participants align together to become a stronger network.