Degree Of Concavity Research Articles

Study on the mechanical properties of cylindrical mechanical metamaterials with biomimetic honeycomb units of the diabolical ironclad beetle

In the long process of evolution in nature, the elytra of the diabolical ironclad beetle are connected in a jigsaw way, so that the overall structure of the beetle has strong pressure resistance. The study of the geometric features and interlocking effect of elytra junctions provides new ideas for the development of new bionic applications. The honeycomb structure is a new type of material structure with excellent mechanical properties, and has broad application prospects in building structure, aerospace and other aspects. Through the reasonable design and modification of the honeycomb structure, the honeycomb structure has different characteristics. Based on the concave hexagonal honeycomb structure, combined with the geometric characteristics of the diabolical ironclad beetle jigsaw connection, the concave hexagonal honeycomb structure is redesigned, and a new type of bionic honeycomb structure is proposed. Through the combination of experiments and simulations, the mechanical response of the bionic honeycomb structure of diabolical ironclad beetles was studied. Research has shown that as the connection angle increases, the curvature on both sides of the unit also increases, making the units more compact. The overall structure exhibits two types of mechanical responses under compression: "U" and "Γ". The structure with connection angle of 25° can rely on the support and buckling on both sides of the unit, thus having the best energy absorption characteristics. As the axial ratio of the ellipse (a:b) increases, the degree of concavity in the structural unit continues to deepen, resulting in three forms of deformation of the structural unit. The structural unit changes from being supported on both sides to being bent on both sides, resulting in a stacking phenomenon in structures with ratios of 2.2:1 and 2.4:1, and the overall structure has better deformation resistance.

Controllable synthesis of star-shaped FeCoMnOx nanocrystals and their self-assembly into superlattices with low-packing densities.

We present a novel method for synthesizing monodisperse, star-shaped FeCoMnOx nanocrystals with tunable concavity. Through liquid-air interfacial assembly, these colloidal nanostars can form two-dimensional superlattices, which are characterized by low packing densities. Notably, the ability to adjust the degree of concavity of nanostars allows for the tuning of the packing symmetry of the assembled superlattices.

Influence of the magnetic field curvature on the radial–azimuthal dynamics of a Hall thruster plasma discharge with different propellants

The topology of the applied magnetic field is an important design aspect of Hall thrusters. For modern Hall thrusters, the magnetic field topology most often features curved lines with a concave (negative) curvature upstream of the field's peak and a convex (positive) curvature downstream. Additionally, the advent of the magnetic shielding technique has resulted in Hall thruster designs with non-conventional field topologies that exhibit high degrees of concavity upstream of the field's peak. In this article, a detailed study is carried out on the effects that the magnetic field curvature has on the plasma discharge in a 2D configuration representative of a Hall thruster's radial–azimuthal cross section. The analyses are performed for discharges of three propellants of high applied interest: xenon, krypton, and argon. For each propellant, high-fidelity electrostatic reduced-order particle-in-cell (PIC) simulations are performed with various degrees of positive and negative curvatures of the magnetic field. Corresponding 1D radial PIC simulations are also performed for xenon to compare the observations against the 2D results. Most notably, it is observed that the instability spectra in the positive-curvature cases are mostly dominated by electron cyclotron drift instability, whereas the modified two stream instability is dominant in the negative-curvature cases. The distributions of electron and ion temperatures, in particular, as well as the contribution of various mechanisms to electrons’ cross-field transport show notable variations between the positive and negative curvature values. Finally, the field curvature is observed to majorly influence the ion beam divergence along the radial and azimuthal coordinates.

Evaluating feedback dynamics between poaching and population with an application to Indian tigers

AbstractA cornerstone of conservation policy for endangered species subject to illegal harvest involves estimating their population and offtake numbers. Census enumerations are expensive to conduct on nationwide scales, especially in resource‐constrained countries housing such species. Resource and data limitations necessitate the estimation of population counts. The effect of poaching on species recruitment is often ignored in scientific population projections. Estimation of population counts should account for the interactive feedback between harvest and recruitment. Data on tiger population sizes and poaching from 51 reserves in India between 1994 and 2022 were obtained to calibrate a coupled ecological‐economic model of tiger population dynamics and poaching. Cobb–Douglas harvest functions with differing degrees of concavity and scale economies are used to characterize the economics of poaching. Population dynamics are evaluated using exponential and critical depensation growth functions. The predictive abilities of linked models and their parameter parsimony are evaluated using information criteria. Poaching is shown to substantially affect recruitment dynamics and is best characterized by a Schaefer function coupled with critical depensation growth. This paper provides a novel perspective of the interaction between tiger poaching and population dynamics in India. A systematic understanding of coupled ecological‐economic processes would improve the management of high‐value endangered species.

Development of a continuous operation hop-kiln with power supply

Introduction.Hop production in the Russian Federation averages 116 thousand tons from 54 thousand hectares. The HS-400 hop-kiln used in the hop drying process line is energy-intensive. The concept of hop growing development in the Chuvash Republic for 2020–2025, approved by the decree of the Cabinet of Ministers of the Chuvash Republic (dated 20.08.2020 No. 738-r), provides for the development of up to 45–50 hectares of new areas for hop, at the rate of 15–17 hectares per one hop-kiln HS-400. To expand the production of hop, it is necessary to effectively master innovative technologies and installations for drying freshly harvested hop that are not inferior in technical and economic parameters of foreign analogues. The development of a hop-kiln that provides dehydration and disinfection of freshly harvested hop, pre-servs consumer properties with reduced operating costs, is currently relevant.Methodology.The electrophysical parameters of hop cones (according to the Rogov method) were analyzed depending on the frequency of the electromagnetic field, humidity and temperature, heat and mass transfer processes during the supply of convective heat to the volumetric resonator of the microwave installation were theoretically investigated, and the effective technological parameters of the hop-kiln were determined. Studies of the electromagnetic field strength, current density, and intrinsic Q-factor of resonators were carried out in the CST Studio Suite 2017 three-dimensional computer modeling program and its CST Microwave Studio subprogram.Results.A multi-resonator hop-kiln with an energy supply in an electromagnetic field has been developed. The proposed hop-kiln contains resonators sequentially arranged in a horizontal plane with curved surfaces, docked through ceramic biconvex perforated plates. The design and technological scheme of the hop-kiln has been developed. The intrinsic Q-factor of elliptical toroidal resonator is 14600, of triangular prismatic resonator — in the range of 9000–1200, depending on the degree of concavity of the upper face. The calculation of the installation productivity amounts to 180–200 kg/h with a power of 15.66 kW, which made it possible to determine energy costs — to 0.1 kWh/kg.

Camouflage of Class III Malocclusion by the Maxillary Protrusion and Retrusion Of The Mandible Using a Removable Functional Appliance Model: Case Report

The objective of this case report was to present the camouflage of class III malocclusion with functional forces using a type 4 morpho-functional inducer. Methods: The patient was a 10-year-old Latin girl. Patient in front and profile was carried out. The position of the left and right superciliary arches, the position of the orbital cavities, and the position of both labial corners were evaluated. Similarly, the type of profile of the patient, the degree of concavity, the position of the lower lip concerning the upper lip, and the position of the chin concerning the nose and forehead were evaluated. In the lateral cephalometric analysis, the sagittal position of the maxilla and mandibular was evaluated through the SNA and SNB angles as well as the level of discrepancy obtained by the ANB angle. SNA before treatment was 79 degrees and SNB 87 and ANB -3 Results: after treatment, the SNA angle varied to 86 degrees, the SNB to 84, and ANB to 3 degrees. The linear measurement between the projection of points A and B to the Frankfort plane before treatment was - 2mm and after + 2 mm. The incisive angles changed to camouflage. The upper incisor angle before treatment was 122 degrees and after 118. The lower incisor angle before treatment was 96 degrees and suffered a decrease of 1 degree. Conclusion: The treatment of class III in skeletal using morpho-functional inducers in well-diagnosed cases and young patients is an alternative that allows obtaining favorable results that allow avoiding surgery.

Optic-fiber vector magnetic field sensor utilizing magneto-shape effect of magnetic fluid

In this work, an optic-fiber sensor utilizing magneto-shape effect of magnetic fluid (MF) has been put forward to measure magnetic field direction. MF magneto-shape effect has been presented, simulated and verified through experiments as a magneto-optical effect. The sensor consists of a capillary glass tube, two single-mode fibers (SMFs) and MF. The interface between MF and air is concave because the glass tube is attractive to MF. As magnetic field rises, the concavity degree becomes more obvious, in other words, edge length of MF cavity is extended and central length of cavity is shortened. The interference wavelength of sensor will change with magnetic field, so as to achieve the purpose of monitoring magnetic field. The phenomenon is defined as the magneto-shape effect of MF. Due to the magnetic field direction dependence of pressure difference between the MF and air, the magneto-shape effect of MF has different perception of axial magnetic field and radial magnetic field, realizing vector magnetic field measurement. Results of experiment are shown as follows: the sensor can easily react to field strength and orientation. The wavelength shows the shape of number “8″ with magnetic field direction changing. The field sensitivity reaches up to 296.1 pm/Gs from 22.6 Gs to 121.8 Gs in the axial field. Moreover, direction sensitivity reaches 311.6 pm/° at 104.4 Gs. The wavelength shift in the axial direction is 25.5 times higher than that of the radial direction. The presented sensing structure could monitor vector magnetic field without constructing a non-circular symmetrical structure. The proposed sensing structure is provided with characteristics of simple to make, highly-sensitive and little fabrication consumption. It possesses potential applications in electronic power industry and aerospace.

P9. Sex differences in response to recombinant human bone morphogenetic protein-2 (rhBMP-2) in a rat posterolateral fusion spine model

<h3>BACKGROUND CONTEXT</h3> Estrogen modulates bone activity largely through inhibition of osteoclast bone resorption and bone morphogenetic protein-2 (BMP-2) signaling pathways in osteoblasts. Minimal data exist concerning potential sex-dependent differences in BMP-2-mediated bone regeneration. Here, we aimed to quantify sex-dependent differences in the bone healing response to recombinant human BMP-2 (rhBMP-2) treatment in a rat posterolateral spinal fusion model. <h3>METHODS</h3> A total of 48 female and male Sprague-Dawley rats (N=24/group), underwent L4-L5 posterolateral fusion with bilateral placement of absorbable collagen sponges, loaded with 5 µg of rhBMP-2 (10 µg/animal). At 8 weeks postoperatively, 10 specimens of each sex were tested in flexion-extension with quantification of range of motion (ROM) and stiffness. The remaining specimens were evaluated for new bone growth and fusion via radiography, blinded manual palpation and microcomputed tomography (microCT). Laboratory microCT quantified bone microarchitecture and synchrotron microCT examined bone microstructure. On histology, the number of adipocytes within a standardized field of view was counted for both male and female fusion masses. <h3>RESULTS</h3> Manual palpation scores differed significantly between sexes, with mean fusion scores of 2.4±0.4 in females vs 3.1±0.6 in males, p < 0.001. Biomechanical stiffness did not differ between sexes, but ROM was significantly greater and more variable for females vs males (3.7°±5.6° vs 0.27°±0.15°,p < 0.005, respectively. Laboratory microCT showed significantly smaller volumes of fusion masses in females vs males (262±87 mm³ vs 732±238 mm³, respectively, p < 0.001) but significantly higher bone volume fraction (0.27±0.08 vs 0.12±0.05, respectively, p < 0.001). Mean trabecular thickness was not different, but trabecular number was significantly greater in females (3.1±0.5 mm-1vs 1.5±0.4 mm-1, respectively, p<0.001). Synchrotron microCT showed fine bone structures developing in both sexes at the 8-week time point. Adipocyte density was found to be significantly higher in male fusion masses than in female fusion masses. <h3>CONCLUSIONS</h3> This study demonstrates that sex-based factors may influence both the quantity and quality of bone formation in patients receiving rhBMP-2 for a variety of orthopedic applications. We found that male rats had significantly higher fusion scores, greater fusion-mass volume, and lower ratio of new bone volume to total volume compared to female rats. Male and female mean trabecular thicknesses were equal, but the female fusion masses were more densely filled with trabeculae (higher trabecular number) than those of males. MicroCT results suggested that the male trabeculae were more rod-like and the female more plate-like, although the methods that were used are generally considered less accurate for trabecular bone, which has a high degree of concavity. The incomplete fusions on three female rats, evidenced by high ROM and small gaps on microCT, suggest that females may have a more variable response to rhBMP-2. Investigation into whether these sex-based differences are specific to rhBMP-2-induced bone formation or are more general to bone regeneration/healing is prudent. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Multidimensional risk aversion: the cardinal sin

Attitudes towards multidimensional risk depend both on the shape of the indifference map under certainty and on the degree of concavity of the utility function representing preferences under risk. A decomposition of the risk premium is built on the new notion of “compensated risk aversion”. The balance between the two components is shown to depend on the association of the risks. Several applications are also presented, including the intertemporal model.

Deterministic and stochastic survival models of injured ozonated Giardia cysts.

Giardia cysts exposed to short sublethal ozonation in lake waters continue to die-off well after the ozone complete dissipation. This delayed inactivation can be the manifestation of injured cysts' mortality, which the traditional Chick-Watson-Hom type models of disinfection do not account for. But it can be described by a slightly modified version of a general microbial survival model adapted for injured cysts or other targeted microorganisms surviving disinfection. The downward concavity of the cysts' semi-logarithmic survival ratio vs. time relationships suggests that the cysts' deaths had unimodal temporal distribution. Indeed, the cumulative (CDF) forms of the Weibull and lognormal distribution functions both had excellent fit to the experimental survival data. Such a survival pattern can also be described by a fully probabilistic model devised from the injured cysts' Markov chain, where the mortality's probability rate rises linearly with time. The stochastic model explains the ubiquitous observation that microbial survival curves become increasingly irregular and irreproducible as the number of survivors dwindles, regardless of their concavity degree and direction. Although based on ozonated Giardia cyst data, the concept should be applicable to the delayed mortality of other microorganisms surviving sublethal treatments of other kinds but unable to recover and/or multiply. KEY POINTS: • Deterministic and stochastic survival models can describe delayed inactivation. • The Weibull and lognormal distributions can describe cysts' times to mortality. • Stochastic model explains the progressively growing scatter in survival curves.

A self-templating dilution strategy for preparation of hollow concave polystyrene nanoparticles in a styrene/ethanol-water ternary system

Hollow concave polymer particles have attracted wide attention due to their particular properties and applications, however, the controllable synthesis of hollow concave polystyrene nanoparticles (HC-PSNPs) based on soap-free emulsion polymerization via a one-pot method has not been achieved. Herein, based on a styrene/ethanol-water (St/EtOH-H2O) ternary system, a simple green self-templating dilution strategy was established to produce monodisperse HC-PSNPs. In the synthesis, the degree of concavity and opening size of HC-PSNPs can be controlled by adjusting polymerization parameters such as the pre-polymerization time (polymerization time before dilution) and dilution conditions (including dilution ratio and ethanol content of the diluents). Furthermore, one opening or multiple openings in the surface of HC-PSNPs can be controlled by varying the post-polymerization temperature (polymerization temperature after dilution). Based on our results and observations, we propose a plausible mechanism for the formation of HC-PSNPs.

Engineering the degree of concavity of one-dimensional Au-Cu alloy nanorods with partial intermetallic compounds by facile wet chemical synthesis.

Finely modulating the morphology of bimetallic nanomaterials plays a vital role in enhancing their catalytic activities. Among the various morphologies, concave structures have received considerable attention due to the three advantageous features of high-index facets, high surface areas, and high curvatures, which contribute greatly to enhancing the catalytic performance. However, concave morphologies are not the products generated from thermodynamically controlled growth with minimized surface energy. Additionally, most nanocrystals with concave shapes are currently in the state of mono-metals or alloys with disordered arrangements of atoms. The synthesis of alloy structures with ordered atom arrangements, intermetallic compounds, which tend to display superior catalytic performance on account of their optimal geometric and electronic effects, has rarely been reported as high-temperature annealing is usually needed, which constrains the modulation of morphology and surface structure. In this work, concave one-dimensional Au-Cu nanorods with a partially ordered intermetallic structure were synthesized via a facile wet chemical method. By simply adjusting the reaction kinetics via the concentrations of the corresponding metal precursors, the degree of concavity of the one-dimensional Au-Cu nanorods could be regulated. In both the p-nitrophenol reduction and CO2 electro-reduction reactions, the concave-shaped Au-Cu nanorods demonstrated superior catalytic activity compared to corresponding non-concave samples with the same structure due to the morphological advantages provided by the concave structure.

Patterns of interfacial flow around a lubricated rolling point contact region

It is of great importance to develop an in-depth understanding of interfacial flow around a lubricated rolling point contact region (RPCR). Consideration of the flow patterns around an RPCR will be important for the lubrication, cooling, and cleaning of machine parts, such as rolling bearings and gearboxes. In this study, an experiment using laser-induced fluorescence and a simulation using computational fluid dynamics of interfacial flow around an oil-lubricated ball-on-disk RPCR are presented. The results show good agreement with each other, and the flow patterns are clearly classified. The forming mechanisms are analyzed in terms of force competition caused by inertia, viscosity, pressure gradient, and air–oil surface tension. Quantitative criteria are proposed to evaluate the behaviors at the air–oil interface and the transition of flow patterns. Analyses have shown that the competition between these forces drives the motion of the air–oil interface, and the formation of flow patterns can be considered a self-adjusting process for the air–oil interface toward the equilibrium positions of the forces. High surface tension is beneficial for maintaining interface stability and can prevent the meniscus from rupturing at an outlet and concaving at an inlet. High capillary numbers may increase the risk for outlet meniscus rupture and the degree of concavity of the inlet meniscus.

The Family of Alpha,[a,b] Stochastic Orders: Risk vs. Expected Value

In this paper we provide a novel family of stochastic orders that generalizes second order stochastic dominance, which we call the α,[a,b]-concave stochastic orders. These stochastic orders are generated by a novel set of “very” concave functions where α parameterizes the degree of concavity. The α,[a,b]-concave stochastic orders allow us to derive novel comparative statics results for important applications in economics that cannot be derived using previous stochastic orders. In particular, our comparative statics results are useful when an increase in a lottery’s riskiness changes the agent’s optimal action in the opposite direction to an increase in the lottery’s expected value. For this kind of situation, we provide a tool to determine which of these two forces dominates — riskiness or expected value. We apply our results in consumption–savings problems, self-protection problems, and in a Bayesian game.

Evaluation of anatomic variations of mandibular lingual concavities from cone beam computed tomography scans in a Malaysian population

Statement of problemLingual plate perforation can be life-threatening when vital structures are damaged during implant placement. Knowledge of the anatomy of lingual concavities is imperative for safe implant surgery. PurposeThe purpose of this clinical study was to determine the prevalence of type of posterior mandibular ridge morphology in a Malaysian population and to evaluate the buccolingual width of the alveolar ridge (Wb and Wc); alveolar ridge height (Vcb); and concavity angle, length, and depth for both left and right first and second molars in different age groups and sexes by using cone beam computed tomography (CBCT). Material and methodsBilateral posterior mandibular lingual concavities at the first and second molars were retrospectively studied in cross-sectional views of 150 CBCT scans (n=600 sites evaluated). The sample size was calculated at a power of 80%, confidence interval of 95%, and margin of error of .05. The buccolingual width from the base and crest of the ridge and the ridge height were measured to determine the type of ridge. For the U-shaped ridge, the concavity angle, length, and depth were assessed. The independent t test was used to compare mean values of CBCT measurements between sexes and tooth type, while the ANOVA and Pearson chi-squared test were used to determine the correlations with age groups and types of ridge morphology, respectively. To compare the left and right readings for first and second molars in the same patient, the paired t test was performed (α=.05 for all tests). ResultsThe Pearson correlation showed a strong agreement between the 2 examiners with an interobserver reliability of 87.3%. Significant difference was noted in all dimensional measurements when comparing right and left first and second molars (P<.001). The degree of concavity was significantly different (P<.05), except for the depth of the concavity at the left molars (P=.075). The type C ridge (51.7%) was the most prevalent ridge among a Malaysian population. Only dimensional measurements were significantly different when compared among age groups (P<.05). Ridge width and height were significantly greater in men (P<.05). Men exhibited greater concavity depth than women in the left second molar region (P=.03). ConclusionsLingual concavity was found in the mandible in 32.8% of a Malaysian population. Significant differences were found in dimensional measurements and degree of concavity between left and right first and second molars, with deeper concavity depth found in second molars. Significant age and sex-related variations were found in the dimensional measurements of the mandible between left and right sides with no significant difference in degree of concavity.

Fair innings? The utilitarian and prioritarian value of risk reduction over a whole lifetime

The social value of risk reduction (SVRR) is the marginal social value of reducing an individual’s fatality risk, as measured by some social welfare function (SWF). This Article investigates SVRR, using a lifetime utility model in which individuals are differentiated by age, lifetime income profile, and lifetime risk profile. We consider both the utilitarian SWF and a “prioritarian” SWF, which applies a strictly increasing and strictly concave transformation to individual utility.We show that the prioritarian SVRR provides a rigorous basis in economic theory for the “fair innings” concept, proposed in the public health literature: as between an older individual and a similarly situated younger individual (one with the same income and risk profile), a risk reduction for the younger individual is accorded greater social weight even if the gains to expected lifetime utility are equal. The comparative statics of prioritarian and utilitarian SVRRs with respect to age, and to (past, present, and future) income and baseline survival probability, are significantly different from the conventional value per statistical life (VSL). Our empirical simulation based upon the U.S. population survival curve and income distribution shows that prioritarian SVRRs with a moderate degree of concavity in the transformation function conform to widely held views regarding lifesaving policies: the young should take priority but income should make no difference.

A virtual element method for isotropic hyperelasticity

This work considers the application of a displacement-based virtual element method to plane hyperelasticity problems with a novel approach to the selection of stabilization parameters. The method is applied to a range of numerical examples and well known strain energy functions, including neo-Hookean, Mooney-Rivlin and Ogden material models. For each of the strain energy functions the performance of the method under varying degrees of compressibility, including near-incompressibility, is investigated. Through these examples the convergence behaviour of the virtual element method is demonstrated. Furthermore, the method is found to be robust and locking free for a variety of element geometries, including elements with a high degree of concavity.

Responses of macroinvertebrate functional traits to riverbed structure of typical debris flow gullies in the upper reaches of the Yangtze River, China

Debris flow is a typical natural disaster in mountainous areas. Its occurrence has serious impacts on the ecological environment and the life, property safety of local people. The structure of mountain riverbed plays an important role in maintaining the ecological stability of debris flow gullies (DFGs) and improving the ecological condition. However, the effects of hydro-geomorphological processes induced by riverbed structure on local macroinvertebrates have not been well examined. A functional approach was applied to macroinvertebrate data collected in a field survey at sites with different riverbed structure to investigate the response of macroinvertebrate functional traits and environment factors to riverbed structure-induced processes. Riverbed structure was quantitatively calculated by concavity-convexity degree. The results showed that (a) Macroinvertebrates were mainly composed of individuals with the ability of avoiding risks and recovering quickly in DFGs. (b) The environmental factors affecting macroinvertebrates (i.e., average particle size, velocity, flow rate, water depth, and gradient) had a great relationship with riverbed structure. (c) Only 3 (trophic habit, attachment and drift) of the 10 benthic functional traits in the study area had a good correlation with riverbed structure. This study thus found that riverbed structure, as a complex of various environmental factors directly or indirectly affected the community structure and functional traits of macroinvertebrates in DFGs. Besides, it was more suitable for macroinvertebrates of different species to live, and more conducive to the maintenance of ecological stability when the concavity-convexity degree value was about 0.075. Because 5 environmental factors affecting macroinvertebrates were moderate when the degree of concavity was about 0.075. These results can provide scientific basis for ecological conservation and management in DFGs where eco-environment is very fragile.

Age, Human Capital and the Quality of Work: New Evidence from Old Masters

The links between individual ability, human capital investment, and labor productivity are generally hard to address because productivity is unobservable. We overcome this problem by examining artist productivity as reflected in art auction prices. First, we observe an inverted-U shaped age-quality of work profile similar to the conventional age-wage profile. Second, we find that the degree of concavity increases for those with higher native ability. Third, we find that working for a patron rather than selling directly to the market is associated with a flatter age profile. Fourth, we find evidence that formal education increases the concavity of the age-quality of work profile. These results are consistent with the theory and demonstrate that artists respond to incentives to invest in human capital.

The Family of Alpha,[a,b] Stochastic Orders: Risk vs. Expected Value

In this paper we provide a novel family of stochastic orders that generalizes second order stochastic dominance, which we call the $\alpha,[a,b]$-concave stochastic orders. These stochastic orders are generated by a novel set of ``very concave functions where $\alpha$ parameterizes the degree of concavity. The $\alpha,[a,b]$-concave stochastic orders allow us to derive novel comparative statics results for important applications in economics that cannot be derived using previous stochastic orders. In particular, our comparative statics results are useful when an increase in a lottery's riskiness changes the agent's optimal action in the opposite direction to an increase in the lottery's expected value. For this kind of situation, we provide a tool to determine which of these two forces dominates -- riskiness or expected value. We apply our results in consumption-savings problems, self-protection problems, and in a Bayesian game.