Production Threshold Research Articles

Cost-Effectiveness Analysis of Follow-Up Schedule for Hepatocellular Carcinoma after Radiofrequency Ablation.

Methods A Markov model was established to evaluate the cost-effectiveness of every 2 months or 2-3 months (2- to 3-month group) versus every 3 months or 3-4 months (3- to 4-month group) posttreatment surveillance in the first two years for HCC after RFA. Transition probabilities and utility values were derived from the literature review. Costs of follow-up were estimated from our institution. The incremental cost-effectiveness ratio (ICER), which was less than $10888 per quality-adjusted life-year (QALY), was considered cost-effective. Sensitivity analyses were performed to determine the uncertainty of the model. Results The 2- to 3-month group gained 1.196 QALYs at a cost of $2212.66, while the effectiveness and cost of the 3- to 4-month group were 1.029 QALYs and $1268.92, respectively. The ICER of the 2- to 3-month group versus the 3- to 4-month group was $5651.14 per QALY gained, which was less than the willingness-to-pay threshold of 1-time gross domestic product per capita of China ($10888/QALY). One-way sensitivity analysis showed that the model was most sensitive to the utility of progression-free survival. The probabilistic sensitivity analysis demonstrated that the 2- to 3-month group had a higher probability of being more cost-effective than the 3- to 4-month group when willingness to pay was over $1088.8. Conclusions Every 2 months or 2-3 months of follow-up intervals were more cost-effective than 3 months or 3-4 months of follow-up intervals. Thus, the intensive follow-up interval in the first two years was recommended for Child-Pugh class A or B HCC patients within the Milan criteria following RFA.

Cost Effectiveness of Bevacizumab Plus Chemotherapy for the Treatment of Advanced and Metastatic Cervical Cancer in India-A Model-Based Economic Analysis.

PURPOSEPatients with advanced and metastatic cervical cancer have a poor prognosis with a 1-year survival rate of 10%-15%. Recently, an antiangiogenic humanized monoclonal antibody bevacizumab has shown to improve the survival of these patients. This study was designed to assess the cost effectiveness of incorporating bevacizumab with standard chemotherapy for the treatment of patients with advanced and metastatic cervical cancer in India.METHODSUsing a disaggregated societal perspective and lifetime horizon, a Markov model was developed for estimating the costs and health outcomes in a hypothetical cohort of 1,000 patients with advanced and metastatic cervical cancer treated with either standard chemotherapy alone or in combination with bevacizumab. Effectiveness data for each of the treatment regimen were assessed using estimates from Gynecologic Oncology Group 240 trial. Data on disease-specific mortality in metastatic cervical cancer, health system cost, and out-of-pocket expenditure were derived from Indian literature. Multivariable probabilistic sensitivity analysis was undertaken to account for parameter uncertainty.RESULTSOver the lifetime of one patient with advanced and metastatic cervical cancer, bevacizumab along with standard chemotherapy results in a gain of 0.275 (0.052-0.469) life-years (LY) and 0.129 (0.032-0.218) quality-adjusted life-years (QALY), at an additional cost of $3,816 US dollars (USD; 2,513-5,571) compared with standard chemotherapy alone. This resulted in an incremental cost of $19,080 USD (7,230-52,434) per LY gained and $34,744 USD (15,782-94,914) per QALY gained with the use of bevacizumab plus standard chemotherapy.CONCLUSIONAddition of bevacizumab to the standard chemotherapy is not cost effective for the treatment of advanced and metastatic cervical cancer in India at a threshold of 1-time per-capita gross domestic product.

Sentiment Classification Method Based on Blending of Emoticons and Short Texts.

With the development of Internet technology, short texts have gradually become the main medium for people to obtain information and communicate. Short text reduces the threshold of information production and reading by virtue of its short length, which is in line with the trend of fragmented reading in the context of the current fast-paced life. In addition, short texts contain emojis to make the communication immersive. However, short-text content means it contains relatively little information, which is not conducive to the analysis of sentiment characteristics. Therefore, this paper proposes a sentiment classification method based on the blending of emoticons and short-text content. Emoticons and short-text content are transformed into vectors, and the corresponding word vector and emoticon vector are connected into a sentencing matrix in turn. The sentence matrix is input into a convolution neural network classification model for classification. The results indicate that, compared with existing methods, the proposed method improves the accuracy of analysis.

Import, Export and Trade Intermediaries: What Matters the Most?

This paper undertakes a multi-country study to investigate heterogeneity in productivity levels across firms choosing to trade either directly or indirectly through intermediaries, both in the export and import markets. To this end, we implement a stochastic dominance criterion to compare the entire distribution of Total Factor Productivity (TFP) of traders, and we use a generalized ordered logit model to investigate the extent to which a shift in TFP produces a reallocation of firms among different categories of traders. Compared to previous research, our novel findings suggest a productivity sorting of firms which mostly depends on the mode of trade rather than the side. From a policy perspective, our work implies the need to create the conditions for endowing local firms with the necessary knowledge and capabilities to overcome the productivity threshold levels to enter and benefit from direct international trade.

Assessment of ecological restoration projects under water limits: Finding a balance between nature and human needs

Revegetation has significantly contributed to improvements in ecosystem services, such as carbon sequestration and soil retention. Yet, vegetation expansion in water-limited regions may generate conflict of water demand between nature and humans. Present studies are still lacking when it comes to identifying the permissible vegetation capacity, i.e. net primary productivity (NPP) threshold, based on the local water resources limits, and further proposing adjustment and optimization strategies to keep water use balanced in anthropogenic-biological systems. Under such a circumstance, this study assesses the difference between the actual NPP and NPP thresholds at regional and ecosystem scales in China. The results show that 8 out of 31 provinces have their provincial actual NPP above the regional NPP thresholds, mainly concentrated in northern China between 400 and 800 mm iso-precipitation line, i.e. North China Plain (Beijing-Tianjin-Hebei), the middle reaches of the Yellow River Basin (Shaanxi and Henan provinces), and the Northeast China (Heilongjiang, Jilin and Liaoning). Forest ecosystems dominate the difference between the actual total woodland and grassland ecosystems NPP and the permissible NPP thresholds in these regions, ranging from 67% (Beijing) to 99% (Tianjin). If the current vegetation intensity in these regions remains unchanged, the areas of woodland and grassland ecosystems should be optimized 0–48% and 0–100% of their present areas to balance the water demand between the ecosystems and humans, without considering the potential consequence of climate change and soil erosion. Although 23 provinces have their regional actual NPP below their permissible NPP thresholds, 6 out of 23 provinces still have their woodland and grassland ecosystems NPP above the corresponding NPP thresholds, mainly focusing on the Northwestern China north over the 400 mm iso-precipitation line, including Inner Mongolia, Qinghai, Hainan, Shanxi, Gansu and Xinjiang. Forest ecosystems also dominate the negative NPP differences in these regions, ranging from 91% (Inner Mongolia) to 46% (Gansu). These reveal the hidden and potential pressure in the 6 provinces to balance limited water resources in the local anthropogenic-biological system. This study provides a method to assess the water-resources permissible NPP threshold and further proposes the specific adjustment and optimization plans for the areas with actual NPP above the corresponding NPP thresholds, which can provide guidance for ecological restoration program implementations in a more sustainable way.

X17 Discovery Potential in the γN→e^{+}e^{-}N Process at Electron Scattering Facilities.

We propose a direct search for the X17 particle, which was conjectured to explain the ATOMKI ^{8}Be and ^{4}He anomalies, through the dilepton photoproduction process on a nucleon in the photon energy range below or around the pion production threshold. For the scenarios of either pseudoscalar, vector, or axial-vector quantum numbers of the conjectured X17, we use existing constraints to estimate the X17 signal process. For dilepton invariant mass resolutions which have been achieved in previous experiments, a signal-to-background ratio of up to an order of magnitude is found for a neutron target, and, in particular, for the pseudoscalar and vector X17 scenarios.

Relativistic Coulomb screening in pulsational pair instability supernovae

Context.Pulsational pair-instability supernovae (PPISNe) and pair instability supernovae (PISNe) are the result of a thermonuclear runaway in the presence of a background electron-positron pair plasma. As such, their evolution and resultant black hole masses could possibly be affected by screening corrections due to the electron pair plasma.Aims.The sensitivity of PISNe and PPISNe to relativistic weak screening has been explored.Methods.In this paper a weak screening model that includes effects from relativistic pair production has been developed and applied at temperatures approaching and exceeding the threshold for pair production. This screening model replaces “classical” screening commonly used in astrophysics. Modifications to the weak screening electron Debye length were incorporated in a computationally tractable analytic form.Results.In PPISNe the BH masses were found to increase somewhat at high temperatures, though this increase is small. The BH collapse is also found to occur at earlier times, and the pulsational morphology also changes. In addition to the resultant BH mass, the sensitivity to the screening model of the pulsational period, the pulse structure, the PPISN-to-PISN transition, and the shift in the BH mass gap has been analyzed. The dependence of the composition of the ejected mass was also examined.

Safety Production Threshold and Land Quality Classification of Vegetable Pb in High Geological Background Area of Southwest China

In order to ensure the safe production of vegetables in Pb-contaminated farmland under the complex interactions of an extreme geological background area and human activities in Southwest China, 32 types of widely planted vegetable varieties in the southwest region were collected. Correlation analysis, multiple linear regression analysis, and other methods were used to study the accumulation of Pb in soil-vegetables and the key constraints. The threshold of soil Pb ecological security in farmland in southwest China was determined by the method of species sensitivity distribution. The results showed that ω(Pb) of the soils was 47.59-462.38 mg·kg-1, which was 1.88 times higher than that of the background value of soil Pb in Yunnan Province (90 mg·kg-1), and 68.40% of the soil samples exceeded the screening value of the "Soil Environmental Quality Agricultural Land Soil Pollution Risk Management Standard" (GB 15618-2018). The content of Pb in the edible parts of vegetable crops ranged from 0.02 to 0.49 mg·kg-1, and the exceeding rate reached 20.49%. Pb concentration in the vegetables was in the decreasing sequence of leafy vegetables > roots and stems vegetables > eggplant vegetables > edible bean vegetables > pepper vegetables. Based on soil pH, OM, and CEC, the model of Pb accumulation in vegetables was constructed, in which pH was the first critical factor affecting Pb accumulation in vegetables. The sensitivity index of vegetable Pb species showed that leafy vegetables, eggplant vegetables, and a small number of frame bean vegetables were less sensitive to Pb. The soil Pb classification thresholds of the three types (priority protection, safe use, and strict control) of areas for vegetable safety production was ≤ 100, 100-353, and ≥ 353 mg·kg-1, respectively.

Photoinduced release of odorous volatile organic compounds from aqueous pollutants: The role of reactive oxygen species in increasing risk during cross-media transformation

Photoinduced volatile organic compounds (VOCs) release from fatty alcohols at the air-water interface, has attracted considerable attention. This paper comprehensively explores the release of odorous VOCs from aqueous micropollutants under photoirradiation, especially in terms of the important role of the reactive oxygen species (ROS) in increased risk by cross-media transformation. The formation and distribution of photoinduced VOCs produced by aqueous benzyl alcohol (BzOH), a common ingredient in personal care products, were monitored in situ by online gas chromatography equipped with mass spectrometry and flame ionization detector (GC–MS/FID). The photoreaction of BzOH followed first-order kinetics with a rate constant of 0.0158/min under air. After 180 min of ultraviolet irradiation, the accumulated output of the gas-phase products benzene and benzaldehyde (BA) reached 3.8 μmol and 2.6 μmol respectively, being approximately 10 times that under nitrogen. According to electron paramagnetic resonance measurements, singlet oxygen mainly promoted the oxidation of BzOH to BA, which was an important intermediate producing benzene via photocleavage. Odorous alicyclic hydrocarbons were also generated through photorearrangement under nitrogen. On the other hand, the Henry's law constants of the main products were much lower than those of BzOH, indicating that the photoproducts would volatilize from the aqueous phase into the gas phase. The odor threshold of gas-phase products decreased to varying degrees after photoirradiation. Especially for BA, one of the main products, its odor threshold decreased 130 times compared with BzOH. This study shows that the risk of cross-media pollution could significantly increase due to the transformation of aqueous pollutants into odorous VOCs under photoirradiation and provides new insight into its risk prevention.

The chloride binding capacity and stability of gap-graded blended cement with calcined hydrotalcite and metakaolin

Enhancing chloride binding capacity and stability of cement paste is beneficial to blocking chloride ingress and preventing the release of bound chloride, and consequently to improve the chloride resistance of cement-based materials. Incorporating supplementary cementitious materials (SCMs) into blended cement cannot increase the chloride binding remarkably, due to the chloride binding threshold of normal hydration products, even though the SCMs with high activity are introduced. In this study, a gap-graded particle distribution model was used to achieve higher packing density and continuous hydration of clinker and SCMs, then more hydration products were generated to reduce chloride ingress and heighten chloride binding. On this basis, metakaolin and calcined hydrotalcite were introduced to enhancing chloride binding capacity and stability furtherly by generating monocarboaluminate and hydrotalcite. The results show that the chloride binding capacity of modified gap-graded blended cement paste is 22% higher than that of interground blended cement paste. Introducing metakaolin helped the generation of Friedel’s salt, and improving the chloride binding stability of modified gap-graded blended cement, which can be attributed to the more hydrogen bonds around the interlayer chloride in Friedel’s salt compared with that in hydrotalcite. The provided method for design of blended cement with high binding capacity and the mechanism related to binding stability also lay solid foundation for the improvement of durability of cement-based materials.

Experimental Review of ΛΛ¯ Production

Exclusive hyperon-antihyperon production provides a unique insight for understanding of the intrinsic dynamics when strangeness is involved. In this paper, we review the results of ΛΛ¯ production via different reactions from various experiments, e.g., via p¯p annihilation from the LEAR experiment PS185, via electron-positron annihilation using the energy scan method at the CLEO-c and BESIII experiments and the initial-state-radiation approach utilized at the BaBar experiment. The production cross section of ΛΛ¯ near the threshold is sensitive to QCD based prediction. Experimental high precision data for p¯p→Λ¯Λ close to the threshold region is obtained. The cross section of e+e−→ΛΛ¯ is measured from its production threshold to high energy. A non-zero cross section for e+e−→ΛΛ¯ near threshold is observed at BaBar and BESIII, which is in disagreement with the pQCD prediction. However, more precise data is needed to confirm this observation. Future experiments, utilizing p¯p reaction such as PANDA experiment or electron-positron annihilation such as the BESIII and BelleII experiments, are needed to extend the experimental data and to understand the ΛΛ¯ production.

Precipitation and nitrogen deposition alter biocrust–vascular plant coexistence in a desert ecosystem: Threshold and mechanisms

Abstract Dryland ecosystems exist in various vegetation landscapes with contrasting compositions of vascular plants and biocrusts (surface‐soil mats comprised of soil particles, cyanobacteria, lichens, mosses and fungi), and they are very vulnerable to ongoing global change. However, compared to vascular plants, the responses of biocrusts and their coexistence with vascular plants to global change remain elusive. We conducted a 5‐year experiment involving multi‐level precipitation and nitrogen addition in a desert shrubland of northern China to examine these responses. We found that shrubs, perennial herbs and annuals exhibited facilitative, competitive and insignificant effects on biocrusts respectively. Biocrusts coexisted with vascular plants below a threshold of herbaceous productivity of approximately 70 g/m2 and tended to be replaced by herbs beyond this threshold, resulting from the balance between the shade tolerance of biocrusts and herb‐induced light limitation. Increased precipitation and nitrogen enrichment altered biocrust–vascular plant composition by influencing this balance and tended to shift from a biocrust‐dominated to a vascular plant‐dominated state when the threshold was crossed. Synthesis. Our results suggest that biocrusts can coexist with dwarf shrubs and annuals, but cannot withstand perennial herbs when the herbaceous productivity threshold was exceeded. Our findings provide new insights into the threshold and mechanisms of biocrust–vascular plant coexistence, which may greatly contribute to managing dryland ecosystems for global change.

Kaon flow in Au+Au collisions at 1.23AGeV measured with HADES

We present results on the anisotropic transverse flow of kaons (K+, K0S and K−) in Au+Au collisions at √sNN = 2:42 GeV measured with HADES. It was proposed already in the mid-nineties that kaon flow close to its production threshold might be a good probe for the kaon-nucleon potential and, consequently, or the nuclear equation-of-state. The presented analysis was performed on more than 2 billion events of the 40% most central collisions, which opened the possibility of analyzing the kaon flow differentially as a function of transverse momentum, rapidity, and centrality, even in this low-energy regime. The measurements are compared to microscopic transport model predictions and to other data at similar collision energies. Implications on the properties of compressed nuclear matter will be discussed.

Research and Implementation of an OpenMV-Based Target Edge Detection and Tracking System

The improvement of ARM microcontroller unit (MCU) processing capability has greatly broadened the application fields of machine vision, and the huge benefits brought by machine vision can be seen in scenarios such as medicare and health, industrial production, military and national defense. Edge detection is a common processing method in image processing, which can provide basic guarantee for subsequent target tracking and other controls. In this paper, OpenMV is used as a hardware platform to extract the edges of a target in combination with specific algorithms, and then the common PID algorithm in the field of automatic control is written in the OpenMV integrated development environment (IDE) using Python language to achieve low-latency tracking of dynamic target objects. In addition, this thesis uses the color threshold tool in the IDE to capture the color threshold of defective product as an eigenvalue, and then calls the Canny operator in the function library and functions such as kernel filtering to process the image. Through actual testing and comparison, it can be found that the image edge is retained more completely after the kernel filtering process. After the general area of the defective products is calibrated on the object to be detected, the defective products can be screened.

Exploring the neutron skin by hyperon–antihyperon production in antiproton–nucleus interactions

In this work we propose a new method to measure the evolution of the neutron skin thickness between different isotopes. We consider antiproton–nucleus interactions close to the production threshold of ΛΛ̅ and Σ− Λ̅ pairs. At low energies, ΛΛ̅ pairs are produced in p̅ + p collisions, while Σ−Λ̅ pairs can only be produced in p̅ + n interactions. Measuring these cross sections provides information on the neutron skin thickness.

Economic Threshold Analysis of Supplementing Dairy Cow Diets with Betaine and Fat during a Heat Challenge: A Pre- and Post-Experimental Comparison.

Simple SummaryEconomic analysis can be used before animal experiments to estimate the change in production that would be needed for experimental treatments to be as equally profitable as the control treatment. After the experiment, the results can be examined to assess if the production threshold was met. This approach was applied before and after an animal experiment that tested the effect of feeding dietary supplements on the milk production of dairy cows experiencing a heat event in climate-controlled chambers. Heat stress reduces the milk yield of cows, but the inclusion of supplements such as betaine and fat could lessen the impact. The pre-experimental economic threshold analysis showed that cows fed a diet containing betaine, fat, or betaine plus fat would need to produce 1%, 9% and 11% more milk, respectively, to be equally as profitable as the control diet. Results from the subsequent animal experiment combined with previously modelled projections of heat stress conditions showed that supplementing diets with fat or betaine, but not in combination could exceed the milk production threshold required to be as profitable as the control diet.Ex ante economic analysis can be used to establish the production threshold for a proposed experimental diet to be as profitable as the control treatment. This study reports (1) a pre-experimental economic analysis to estimate the milk production thresholds for an experiment where dietary supplements were fed to dairy cows experiencing a heat challenge, and (2) comparison of these thresholds to the milk production results of the subsequent animal experiment. The pre-experimental thresholds equated to a 1% increase in milk production for the betaine supplement, 9% increase for the fat supplement, and 11% increase for fat and betaine in combination, to achieve the same contribution to farm profit as the control diet. For the post-experimental comparison, previously modelled climate predictions were used to extrapolate the milk production results from the animal experiment over the annual hot-weather period for the dairying region in northern Victoria, Australia. Supplementing diets with fat or betaine had the potential to produce enough extra milk to exceed the production thresholds, making either supplement a profitable alternative to feeding the control diet during the hot-weather period. Feeding fat and betaine in combination failed to result in the extra milk required to justify the additional cost when compared to the control diet.

Additive Manufacturing on the Threshold of Mass Production

Additive Manufacturing on the Threshold of Mass Production

Resilience dynamics and productivity-driven shifts in the marine communities of the Western Mediterranean Sea.

Ecological resilience has become a conceptual cornerstone bridging ecological processes to conservation needs. Global change is increasingly associated with local changes in environmental conditions that can cause abrupt ecosystem reorganizations attending to system‐specific resilience fluctuations with time (i.e. resilience dynamics).Here we assess resilience dynamics associated with climate‐driven ecosystems transitions, expressed as changes in the relevant contribution of species with different life‐history strategies, in two benthopelagic systems.We analysed data from 1994 to 2019 coming from a scientific bottom trawl survey in two environmentally contrasting ecosystems in the Western Mediterranean Sea—Northern Spain and Alboran Sea. Benthopelagic species were categorized according to their life‐history strategies (opportunistic, periodic and equilibrium), ecosystem functions and habitats. We implemented an Integrated Resilience Assessment (IRA) to elucidate the response mechanism of the studied ecosystems to several candidate environmental stressors and quantify the ecosystems’ resilience. We demonstrate that both ecosystems responded discontinuously to changes in chlorophyll‐a concentration more than any other stressor. The response in Northern Spain indicated a more overarching regime shift than in the Alboran Sea. Opportunistic fish were unfavoured in both ecosystems in the recent periods, while invertebrate species of short life cycle were generally favoured, particularly benthic species in the Alboran Sea.The study illustrates that the resilience dynamics of the two ecosystems were mostly associated with fluctuating productivity, but subtle and long‐term effects from sea warming and fishing reduction were also discernible. Such dynamics are typical of systems with wide environmental gradient such as the Northern Spain, as well as systems with highly hydrodynamic and of biogeographical complexity such as the Alboran Sea. We stress that management should become more adaptive by utilizing the knowledge on the systems’ productivity thresholds and underlying shifts to help anticipate both short‐term/less predictable events and long‐term/expected effects of climate change.

Tau neutrino identification in atmospheric neutrino oscillations without particle identification or unitarity

The largest tau neutrino dataset to date is IceCube's atmospheric tau neutrino appearance dataset containing $>1,000$ tau neutrino and antineutrino events as determined by a fit to a standard three-flavor oscillation framework. On an event-by-event basis, however, it is impossible to know that any given event is a tau neutrino as they are identical to either an electron neutrino charged-current event or a neutral-current interaction of any active flavor. Nonetheless, we conclusively show that, using only the cascade sample even without knowledge of the oscillation parameters and without assuming that the lepton mixing matrix is unitary, tau neutrino identification is still possible and there is no viable scenario in which all of the tau neutrino candidates are actually electron neutrinos. This is primarily due to the matter effect and the tau lepton production threshold, as well as the fact that tau neutrinos are systematically reconstructed at a lower energy than electron neutrinos due to one or more outgoing neutrinos. This conclusively shows that it is possible for an atmospheric neutrino oscillation experiment to confirm that $U_{\tau1}$, $U_{\tau2}$, and $U_{\tau3}$ are not all zero even with limited particle identification.

Multi-day hail clusters and isolated hail days in Switzerland – large-scale flow conditions and precursors

Abstract. In Switzerland, hail regularly occurs in multi-day hail clusters. The atmospheric conditions prior to and during multi-day hail clusters are described and contrasted to the conditions prior to and during isolated hail days. The analysis focuses on hail days that occurred between April and September 2002–2019 within 140 km of the Swiss radar network. Hail days north and south of the Alps are defined using a minimum area threshold of a radar-based hail product. Multi-day clusters are defined as 5 d windows containing 4 or 5 hail days and isolated hail days as 5 d windows containing a single hail day. The reanalysis ERA-5 is used to study the large-scale flow in combination with objectively identified cold fronts, atmospheric blocking events, and a weather type classification. Both north and south of the Alps, isolated hail days have frequency maxima in May and August–September, whereas clustered hail days occur mostly in July and August. Composites of atmospheric variables indicate a more stationary and meridionally amplified atmospheric flow both north and south of the Alps during multi-day hail clusters. On clustered hail days north of the Alps, blocks are more frequent over the North Sea, and surface fronts are located farther from Switzerland than on isolated hail days. Clustered hail days north of the Alps are also characterized by significantly higher most unstable convective available potential energy (MUCAPE) values, warmer daily maximum surface temperatures, and higher atmospheric moisture content than isolated hail days. Hence, both stationary flow conditions and anomalous amounts of moisture are necessary for multi-day hail clusters on the north side. In contrast, differences in MUCAPE on the south side between clustered hail days and isolated hail days are small. The mean sea level pressure south of the Alps is significantly deeper, the maximum temperature is colder, and local moisture is significantly lower on isolated hail days. Both north and south of the Alps, the upper-level atmospheric flow over the eastern Atlantic is meridionally more amplified 3 d prior to clustered hail days than prior to isolated days. Moreover, blocking occurs prior to more than 10 % of clustered hail days over Scandinavia, but no blocks occur prior to isolated hail days. Half of the clustered hail days south of the Alps are also clustered north of the Alps. On hail days clustering only south of the Alps, fronts are more frequently located on the Alpine ridge, and local low-level winds are stronger. The temporal clustering of hail days is coupled to specific synoptic- and local-scale flow conditions; this information may be exploited for short- to medium-range forecasts of hail in Switzerland.