Low-temperature Limit Research Articles

Probing Krylov complexity in scalar field theory with general temperatures

Krylov complexity characterizes the operator growth in the quantum many-body systems or quantum field theories. The existing literatures have studied the Krylov complexity in the low temperature limit in the quantum field theories. In this paper, we extend and systematically study the Krylov complexity and Krylov entropy in a scalar field theory with general temperatures. To this end, we propose a new method to calculate the Wightman power spectrum which allows us to compute the Lanczos coefficients and subsequently to study the Krylov complexity (entropy) in general temperatures. We find that the Lanczos coefficients and Krylov complexity (entropy) in the high temperature limit will behave somewhat differently from those studies in the low temperature limit. We give an explanation of why the Krylov complexity does not oscillate in the high-temperature region. Moreover, we uncover the transition temperature that separates the oscillating and monotonic increasing behavior of Krylov complexity.

Scaling properties of (2+1) directed polymers in the low-temperature limit

Abstract In terms of the replica method, we consider the low-temperature limit of (2+1) directed polymers in a random potential. The proposed approach allows us to compute the scaling exponent θ of the free energy fluctuations as well as the left tail of its probability distribution function. It is argued that θ = 1 / 4 , which is slightly different to the zero-temperature numerical value that is close to 0.241.

Fast low-temperature irradiation creep driven by athermal defect dynamics

The occurrence of high stress concentrations in reactor components is a still intractable phenomenon encountered in fusion reactor design. Here, we observe and quantitatively model a non-linear high-dose radiation mediated microstructure evolution effect that facilitates fast stress relaxation in the most challenging low-temperature limit. In situ observations of a tensioned tungsten wire exposed to a high-energy ion beam show that internal stress of up to 2 GPa relaxes within minutes, with the extent and time-scale of relaxation accurately predicted by a parameter-free multiscale model informed by atomistic simulations. As opposed to conventional notions of radiation creep, the effect arises from the self-organisation of nanoscale crystal defects, athermally coalescing into extended polarized dislocation networks that compensate and alleviate the external stress.

Impact of Temperature on Podding in Faba Bean (Vicia faba)

Faba bean is grown globally for human consumption and animal feed and is a significant rotation crop in cereal-dominant areas in many countries, including Australia. It is sensitive to several abiotic stresses, such as drought, frost, and high temperatures, especially at the reproductive stage. However, little is known of the upper and lower temperature limits for successful podding. Experiments were conducted over 2 years at Breeza and Narrabri in northwestern New South Wales to assess the impact of temperature on flowering and podset of three genotypes—Doza, Cairo, and IX1148f—under field conditions. Flowering nodes were tagged from designated plants in the field and scored for podding; field temperatures were recorded. Optimum maximum temperature for podset ranged from 23.7–26.1 °C, and the equivalent minimum temperature was 3.2–3.8 °C. Optimum average daily temperature for podset ranged from 12.7–13.9 °C. The strongest correlations between temperature and podding were observed at minimum temperatures, indicating that low temperatures are more important than high temperatures in determining yield in faba bean.

Finite temperature fermionic condensate and energy–momentum tensor in cosmic string spacetime

Here we analyze the expectation value of the fermionic condensate and the energy–momentum tensor associated with a massive charged fermionic quantum field with a nonzero chemical potential propagating in a magnetic-flux-carrying cosmic string in thermal equilibrium at finite temperature T. The expectation values of the fermionic condensate and the energy–momentum tensor are expressed as the sum of vacuum expectation values and the finite temperature contributions coming from the particles and antiparticles excitation. The thermal expectations values of the fermionic condensate and the energy–momentum tensor are even periodic functions of the magnetic flux with period being the quantum flux, and also even functions of the chemical potential. Because the analyses of vacuum expectation of the fermionic condensate and energy–momentum tensor have been developed in literature, here we are mainly interested in the investigation of the thermal corrections. In this way we explicitly study how these observable behaves in the limits of low and high temperatures, and also for points near the string. Besides the analytical discussions, we included some graphs that exhibit the behavior of these observable for different values of the physical parameters of the model.

Transcriptome Analysis Identified PyNAC42 as a Positive Regulator of Anthocyanin Biosynthesis Induced by Nitrogen Deficiency in Pear (Pyrus spp.)

Anthocyanins are important secondary metabolites in plants, which contribute to fruit color and nutritional value. Anthocyanins can be regulated by environmental factors such as light, low temperature, water conditions, and nutrition limitations. Nitrogen (N) is an essential macroelement for plant development, its deficiency as a kind of nutrition limitation often induces anthocyanin accumulation in many plants. However, there is a lack of reports regarding the effect of nitrogen deficiency on anthocyanin biosynthesis in pears. In this study, we found that N deficiency resulted in anthocyanin accumulation in pear callus and upregulated the expression of anthocyanin biosynthesis pathway structural genes (PyPAL, PyCHS, PyCHI, PyF3H, PyDFR, PyANS, and PyUFGT) and key regulatory factors (PyMYB10, PyMYB114, and PybHLH3). Through analysis of transcriptome data of treated pear callus and RT-qPCR assay, a differentially expressed gene PyNAC42 was identified as significantly induced by the N deficiency condition. Overexpression of PyNAC42 promoted anthocyanin accumulation in “Zaosu” pear peels. Additionally, dual luciferase assay and yeast one-hybrid assay demonstrated that PyNAC42 could not directly activate the expression of PyDFR, PyANS, and PyUFGT. Furthermore, yeast two-hybrid and pull-down assays confirmed that PyNAC42 interacted with PyMYB10 both in vivo and in vitro. Co-expression of PyNAC42 and PyMYB10 significantly enhanced anthocyanin accumulation in “Zaosu” pear peels. Dual luciferase assay showed that PyNAC42 significantly enhanced the activation of PyDFR, PyANS, and PyUFGT promoters by interacting with PyMYB10, which suggests that PyNAC42 can form the PyNAC42-PyMYB10 complex to regulate anthocyanin biosynthesis in pear. Thus, the molecular mechanism underlying anthocyanin biosynthesis induced by N deficiency is preliminarily elucidated. Our finding has expanded the regulatory network of anthocyanin biosynthesis and enhanced our understanding of the mechanisms underlying nutrient deficiency modulates anthocyanin biosynthesis in pear.

Performance analysis of quantum harmonic Otto engine and refrigerator under a trade-off figure of merit

Abstract We investigate the optimal performance of the quantum Otto engine and refrigeration cycles of a time-dependent harmonic oscillator under a trade-off figure of merit for both adiabatic and nonadiabatic (sudden-switch) frequency modulations. For heat engines (refrigerators), the chosen trade-off figure of merit is an objective function defined by the product of efficiency (coefficient of performance) and work output (cooling load), thus representing a compromise between them. We obtain analytical expressions for the efficiency and coefficient of performance of the harmonic Otto cycle for the optimal performance of the thermal machine in various operational regimes. Particularly, in the sudden-switch regime, we discuss the implications of the nonadiabatic driving on the performance of the thermal machine under consideration and obtain analytic expressions for the maximum achievable efficiency and coefficient of performance of the harmonic Otto thermal machine. Particularly, we show that the quantum harmonic Otto cycle driven by sudden-switch protocol cannot work as a heat engine or refrigerator in the low-temperature limit. Finally, we show that in the high-temperature limit, the frictional effects give rise to a richer structure of the phase diagram of the harmonic Otto cycle. We identify the parametric regime for the operation of the Otto cycle as a heat engine, refrigerator, accelerator, and heater.

Steam Reforming of Tar Impurities from Biomass Gasification with Ni-Co/Mg(Al)O Catalysts—Operating Parameter Effects

The elimination of tar impurities from biomass gasification by catalytic steam reforming can provide clean syngas for downstream biofuel synthesis (Fischer–Tropsch). The effects of key operating parameters in CH4/tar steam reforming were investigated. Ni-Co/Mg(Al)O catalyst performance was tested at model conditions (10/35/25/25/5 wt% CH4/H2/CO/CO2/N2), changing the temperature (650–800 °C), steam-to-carbon ratio (2–5), tar loading (10–30 g/Nm3), and tar composition (toluene, 1-methylenaphthalene, and phenol). Complete tar elimination was achieved under all conditions, at the expense of catalyst deactivation by coke formation. Post-operation coke characterization was obtained with TPO-MS, Raman spectroscopy, and STEM analysis, providing vital insight into coke morphology and location. Critical low-temperature and high-tar loading limits were identified, where rapid deactivation was accompanied by increasing amounts of hard coke species. A coke classification scheme is proposed, including strongly adsorbed surface carbon species (soft coke A), initial scattered carbon filaments (hard coke B1.1), filament clusters and fused filaments (B2), and strongly deactivating bulk encapsulating coke (B3), formed through progressive filament cluster graphitization. High-molecular-weight tar was found to enhance the formation of strongly deactivating metal-particle-encapsulating coke (B1.2). The results contribute to the understanding of coke formation in the presence of biomass gasification tar impurities.

Sparsity-Independent Lyapunov Exponent in the Sachdev-Ye-Kitaev Model.

The saturation of a recently proposed universal bound on the Lyapunov exponent has been conjectured to signal the existence of a gravity dual. This saturation occurs in the low-temperature limit of the dense Sachdev-Ye-Kitaev (SYK) model, N Majorana fermions with q body (q>2) infinite-range interactions. We calculate certain out-of-time-order correlators (OTOCs) for N≤64 fermions for a highly sparse SYK model and find no significant dependence of the Lyapunov exponent on sparsity up to near the percolation limit where the Hamiltonian breaks up into blocks. This provides strong support to the saturation of the Lyapunov exponent in the low-temperature limit of the sparse SYK. A key ingredient to reaching N=64 is the development of a novel quantum spin model simulation library that implements highly optimized matrix-free Krylov subspace methods on graphical processing units. This leads to a significantly lower simulation time as well as vastly reduced memory usage over previous approaches, while using modest computational resources. Strong sparsity-driven statistical fluctuations require both the use of a much larger number of disorder realizations with respect to the dense limit and a careful finite size scaling analysis. The saturation of the bound in the sparse SYK points to the existence of a gravity analog that would enlarge substantially the number of field theories with this feature.

Origin of the coeval cordierite granite, metapelite and diorite in the Qinghai Nanshan (NW China): Evidences from petrology, geochemistry, geochronology and P-T conditions

The origin of coeval magmatic and metamorphic rock associations is of great significance in tectonic interpretations. In this study, spatially associated cordierite granite (S-type), metapelite and diorite from the Qinghai Nanshan (NW China) area were dated to be coeval at ∼247–244 Ma. The cordierite granite and metapelite have almost uniform peak pressure-temperature (P–T) conditions of c. 3.8–5.0 kbar / c. 740–790 °C, indicating a geothermal gradient of higher than ∼40 °C / km. The zircon crystallization temperature of the diorite pluton is estimated to be c. 760 °C by Ti-in-zircon thermometer, putting a lower limit of temperature for dioritic magma. Both cotectic (phenocrysts) and restitic cordierite crystals were identified in the cordierite granite. Similar whole rock compositions of the coarse-grained cordierite granite and the metapelite in the Qinghai Nanshan area as well as the average / median pelite worldwide, imply formation of the granite was from almost complete melting of autochthonous metapelite, followed by in-situ recrystallization with negligible / without melt extraction. These data indicate that the cordierite granite and metapelite are both products of the contact aureole surrounding the diorite pluton. This study presents an example for better understanding the transition from high-grade metapelite to S-type granite.

Relativistic hydrodynamics with phase transition

Assessing the applicability of hydrodynamic expansions close to phase transition points is crucial from either theoretical or phenomenological points of view. We explore this within the gauge/gravity duality, using the Einstein–Klein–Gordon model, a bottom-up string theory construction. This model incorporates a parameter, B4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_4$$\\end{document}, that simulates different types of phase transitions in the strongly coupled field theory existing at the boundary. We thoroughly examine the thermodynamics and dynamics of time-dependent, linearized perturbations in the spin-2, spin-1, and spin-0 sectors. Our findings suggest that ‘hydrodynamic series breakdown near transition points” is valid exclusively for second-order phase transitions, not for crossovers or first-order phase transitions. Additionally, we observe that the high-temperature and low-temperature limits of the radius of convergence for the hydrodynamic series (qc2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$q^2_c$$\\end{document}) are equal. We also discover that the relationship (Max|qc2|)spin-2<(Max|qc2|)spin-0<(Max|qc2|)spin-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\ ext {Max}|q^2_c|)_{\ ext {spin-2}}< (\ ext {Max}|q^2_c|)_{\ ext {spin-0}} < (\ ext {Max}|q^2_c|)_{\ ext {spin-1}}$$\\end{document} is consistent for different spin sectors, regardless of the phase transition type. At the chaos point, we observe the emergence of pole-skipping behavior for both gravity and scalar perturbations at ωn=-2πTni\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\omega _n = -2\\pi T n i$$\\end{document}. Lastly, comparing the chaos momentum with qc2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$q^2_c$$\\end{document}, we find that qps2<qc2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$q^2_{ps} < q^2_c$$\\end{document}, except for extremely high temperatures.

Bulk reconstruction from generalized free fields

We propose a generalized protocol for constructing a dual free bulk theory from any boundary model of generalized free fields (GFFs). To construct the bulk operators, we employ a linear ansatz similar to the Hamilton-Kabat-Liftschytz-Lowe (HKLL) construction. However, unlike the HKLL construction, our protocol relies only on boundary data with no presupposed form for the bulk equations of motion, so our reconstructed bulk is fully emergent. For a (1+1)d bulk, imposing the bulk operator algebra as well as a causal structure is sufficient to determine the bulk operators and dynamics uniquely up to an unimportant local basis choice. We study the bulk construction for several two-sided SYK models with and without coupling between the two sides, and find good agreement with known results in the low-temperature conformal limit. In particular, we find bulk features consistent with the presence of a black hole horizon for the TFD state, and characterize the infalling fermion modes. We are also able to extract bulk quantities such as the curvature and bulk state correlators in terms of boundary quantities. In the presence of coupling between the two SYK models, we are able to observe evidence of the shockwave geometry and the traversable wormhole geometry using the two-sided mutual information between the reconstructed bulk operators. Our results show evidence that features of the geometric bulk can survive away from the low temperature conformal limit. Furthermore, the generality of the protocol allows it to be applied to other boundary theories with no canonical holographic bulk.

Thermal Casimir effect for a Dirac field on flat space with a nontrivial circular boundary condition

This work investigates the thermal Casimir effect associated with a massive spinor field defined on a four-dimensional flat space with a circularly compactified spatial dimension whose periodicity is oriented along a vector in the xy plane. We employ the generalized zeta function method to establish a finite definition for the vacuum free energy density. This definition conveniently separates into the zero-temperature Casimir energy density and additional terms accounting for temperature corrections. The structure of existing divergences is analyzed from the asymptotic behavior of the spinor heat kernel function and removed in the renormalization by subtracting scheme. The only non-null heat coefficient is the one associated with the Euclidean divergence. We also address the need for a finite renormalization to treat the ambiguity in the zeta function regularization prescription associated with this Euclidean heat kernel coefficient and ensure that the renormalization procedure is unique. The high- and low-temperature asymptotic limits are also explored. In particular, we explicitly show that free energy density lacks a classical limit at high temperatures, and the entropy density agrees with the Nernst heat theorem at low temperatures. Published by the American Physical Society 2024

Сравнительное изучение сохранности антоцианов в гранатовых соках-заготовках горячего розлива

Abstract. Taking into account the biological and antioxidant activity of anthocyanins and their responsiveness to various technological factors, the purpose of this work was to identify a balance between the total losses of anthocyanins and anthocyanins of sediment in experimental samples of pomegranate juice-semi-finished product. The juice of pomegranates of the Guleisha pink variety from Geokchai (Azerbaijan), obtained from their grains using a laboratory press, was used as the starting material. The freshly squeezed juices were filtered through a multilayer gauze filter, additives were introduced into some of them to stabilize the color, after which they were stabilized by hot filling (heated to 85 оC in 15 minutes), using preservatives (sorbic acid, sodium benzoate) or by instant heating and cooling in tubular heat exchangers. The juices were stored in a regular warehouse at a lower temperature limit of 5 оC and an upper temperature limit of 18 оC. Cold storage of one of the hot filling juices and juice from instant heating to 85 оC and cooling to 15-20 оC (both in 10 seconds) at a temperature of 0...+ 1 оC was also tested. Changes in anthocyanins were judged by the optical density of the tested solutions at a wavelength of 520 nm before and after treatment with hydrogen peroxide, which discolors anthocyanins and does not act on newly formed dark-colored pigments. It was found that at the end of the specified shelf life, the total color intensity of semi-finished juices increased by 6.2...10.2 % was determined by dark-colored products of the melanoidin formation process and other processes that took place without the participation of anthocyanins; the percentage of preservation of anthocyanins proper in semi-finished juices with and without various additives, such as vitamin B1, vitamin E, etc., varied from 40.31 to 60.84, and the total loss of anthocyanins was almost 100 % associated with loss they are precipitated. Keywords: pomegranate juice purchases of long-term storage, glass cylinders, hot filling, anthocyanins of settled juice, anthocyanins of sediment, dark-colored pigments

An in situ exsolution strategy to prepare metallic Sn modified SnO2 with oxygen vacancies for ppb-level NO2 detection

The practical applications of SnO2 materials for NO2 detection in the field of indoor air quality monitoring are strongly plagued by low sensitivity toward ppb-level NO2. Herein, an in situ exsolution strategy was developed to prepare Sn-containing materials with abundant oxygen vacancy defects and Sn/SnO2 heterojunctions (designated as Sn/SnO2-x), which were obtained by annealing mixture of commercial SnO2 and NaBH4 in Ar atmosphere. Compared to commercial SnO2, the optimal Sn/SnO2-x-3 displays the obvious advantages of low operating temperature (110 °C), high sensitivity (response value of 4.65 toward 80 ppb NO2), and low limit of detection (10 ppb NO2 with response value of 1.17). The improvement of NO2 sensing performances is attributed to the synergistic effect of introducing oxygen vacancy defects and constructing Sn/SnO2 heterojunctions. Theoretically, the former leads to increasing the active sites for adsorption of NO2 and the latter reduces the band gap for improvement of carrier concentration. Additionally, this NO2 sensor shows excellent sensing performances for monitoring NO2 concentration in simulated indoor environment. This work not only provides an effective and large-scale approach to prepare novel sensing materials from commercial metal oxides by exsolution method, but also opens the way to fabricate high-performance gas sensors for detection of NO2 with low concentrations.

Influence of the regeneration method of irradiated mixture “30% TBP in Isopar-M” on the lower temperature limit of flame propagation

Influence of the regeneration method of irradiated mixture “30% TBP in Isopar-M” on the lower temperature limit of flame propagation

A method for setting room temperature of district heating in northern China based on local thermal comfort

Currently, the district heating system in northern China primarily employs two types of terminals, namely radiators and radiant floors. The heating design temperature is set for the center of the room without considering local thermal comfort for individuals. As the real thermal environment within buildings is non-uniform, variations in thermal sensation across different parts of the body will affect whole-body thermal comfort. Therefore, it is crucial to prioritize local thermal comfort when setting room temperatures for heating purposes. In this study, we analyzed the data from the chamber experiments and Chinese Thermal Comfort Database, focusing on the district heating environments of residences, office buildings, and university classrooms in severe cold and cold zones. We developed a thermal sensation evaluation model for analyzing the most uncomfortable body part, investigated the lower limit of acceptable air temperature for this specific body part and inferred appropriate setpoint based on both this limit and head-ankle temperature difference. The results indicate that ankles are the most uncomfortable part with an estimated lower limit of acceptable air temperature at approximately 18 °C. Consequently, we recommend setting room temperatures of 20 °C for radiator heating (RH) and 19 °C for floor heating (FH) to ensure ankle thermal comfort. The findings of this study can provide theoretical basis for reasonable settings of heating room temperature for the aforementioned three types of buildings in northern China, thereby further achieving energy conservation.

Large‐scale deviations between realized and fundamental thermal niches in global seaweed distributions

AbstractAimClimate change has profound effects on species' distributions, and it is crucial to understand how well physiological limits correspond to distribution patterns to provide realistic estimations of future range shifts and/or extinctions. Seaweeds are foundation species of global coastal ecosystems, and sea surface temperature is a main predictor to explain their distributions and redistributions under global warming. We here test the hypothesis that, in contrast to other marine ectotherms, physiological knowledge of temperature niches is a weak predictor for seaweed distributions.LocationGlobal.Time PeriodPresent (1984–2019).TaxaSeaweeds.MethodsWe analysed the predictive power of physiological temperature limits to predict real‐world distributions in 126 globally distributed seaweed species with linear and generalized linear mixed models.ResultsIn 72% of the species, there was a difference of ≥|2|°C between the physiological and the realized thermal limits. Both, thermal underfilling (distributional thermal limits narrower than the physiological limits) and overfilling (distributional thermal limits wider than the physiological limits) were present. Thus, in only 28% of the species the physiological limits corresponded to the distributional limits. While heat‐tolerance is a significant predictor for upper distributional temperature limits, we found no relationship between cold‐tolerance and lower distributional temperature limits and the latter two seem to be independent.Main ConclusionsPhysiological thermal limits have limited predictive power for seaweed distributions and deviations may be large. Especially cold‐tolerances are a weak predictor, and forecasting of migrations under changing global conditions (e.g. towards the poles) will need special attention. This indicates that responses towards climate change might be highly variable between seaweed species and difficult to predict. Further, nearly 60% of the investigated species had populations which are close to or beyond their reported upper survival limits and are thus probably under threat of eradication by elevation of sea surface temperature.

Preservation of Bacillus subtilis' cellular liquid state at deep sub-zero temperatures in perchlorate brines.

Although a low temperature limit for life has not been established, it is thought that there exists a physical limit imposed by the onset of intracellular vitrification, typically occurring at ~-20 °C for unicellular organisms. Here, we show, through differential scanning calorimetry, that molar concentrations of magnesium perchlorate can depress the intracellular vitrification point of Bacillus subtilis cells to temperatures much lower than those previously reported. At 2.5 M Mg(ClO4)2, the peak vitrification temperature was lowered to -83 °C. Our results show that inorganic eutectic salts can in principle maintain liquid water in cells at much lower temperatures than those previously claimed as a lower limit to life, raising the prospects of active biochemical processes in low temperature natural settings. Our results may have implications for the habitability of Mars, where perchlorate salts are pervasive and potentially other terrestrial and extraterrestrial, cryosphere environments.

A time-to-event analysis for temperature dependence of seed germination in four conifers: Ecological niche and environmental gradients

Seed germination is a vital process in the plant life cycle. It directly influences seedling establishment and subsequently determines population persistence and species distribution. Germination is highly sensitive to climatic conditions, and germination traits may vary among species and populations within the same species. This study aims to improve our understanding of intraspecific and interspecific variation in temperature dependence of seed germination and how this variation relates to the environment where seeds were collected. We focused on four conifer species (Pinus contorta, Picea engelmannii, Pinus ponderosa, and Pseudotsuga menziesii) and seeds collected at 20 sites spanning the elevation range of each species in the Western United States. We conducted seed germination tests at temperatures from 5 to 40°C in 5°C intervals and tracked germination for 30 days. We used the log-logistic time-to-event model and Gaussian function to fit germination data and analyze their temperature dependence. The climate variables at the seed-collecting sites were summarized by long-term normals (1971–2000) covering most seed-collection years. Climate variables were correlated and thus were combined via Principal Component Analysis (PCA) into several uncorrelated principal components (PC scores) that describe climate at the seed collection sites. The estimated optimal temperature (To), shape coefficient (b), and maximum value at optimal temperature (GPmax) of germination percentages and median germination rates (GR50) were then fit to linear models to determine whether they varied with species identity and the climate-derived PC scores. Results showed that seed germination traits from different species exhibit climate gradients that are correlated with their ecological niche. However, seeds from different elevations within the same species had variable germination traits irrespective of environmental gradients. We also found that variation in germination was more significant near upper and lower temperature limits. Including inter- and intra-specific temperature dependence of seed germination would improve predictions of population dynamics and range shifts under climate warming and could inform forest management, seed transfer, and assisted migration practices.