Symmetry Of Pattern Research Articles

Symmetry patterns of images on megalithic t-shaped pillars from the prehistoric site Göbekli Tepe in Turkey

Symmetry patterns of images on megalithic t-shaped pillars from the prehistoric site Göbekli Tepe in Turkey

No effect of multi-axis dot pattern symmetry on subjective duration.

Previous work has shown that symmetrical stimuli are judged as lasting longer than asymmetrical ones, even when actual duration is matched. This effect has been replicated with different methods and stimuli types. We aimed to a) replicate the effect of symmetry on subjective duration, and b) assess whether it was further modulated by the number of symmetrical axes. There was no evidence for either effect. This null result cannot be explained by reduced statistical power or enhanced floor or ceiling effects. There is no obvious stimulus-based explanation either. However, we are mindful of the reproducibility crisis and file drawer problems in psychology. Other symmetry and time perception researchers should be aware of this null result. One possibility is that the effect of symmetry on subjective duration is limited to very specific experimental paradigms.

Explicit Identities for 3-Variable Degenerate Hermite Kampé de Fériet Polynomials and Differential Equation Derived from Generating Function

We get the 3-variable degenerate Hermite Kampé de Fériet polynomials and get symmetric identities for 3-variable degenerate Hermite Kampé de Fériet polynomials. We make differential equations coming from the generating functions of degenerate Hermite Kampé de Fériet polynomials to get some identities for 3-variable degenerate Hermite Kampé de Fériet polynomials,. Finally, we study the structure and symmetry of pattern about the zeros of the 3-variable degenerate Hermite Kampé de Fériet equations.

Effect of the Hybrid Assistive Limb on the Gait Pattern for Cerebral Palsy.

Background and objectives: Cerebral palsy (CP) is the most frequent childhood motor disability. Achieving ambulation or standing in children with CP has been a major goal of physical therapy. Recently, robot-assisted gait training using the Hybrid Assistive Limb® (HAL) has been effective in improving walking ability in patients with CP. However, previous studies have not examined in detail the changes in gait pattern after HAL training for patients with spastic CP, including gait symmetry. This study aimed to evaluate the immediate effect of HAL training on the walking ability and the changes in gait pattern and gait symmetry in patients with spastic CP. Materials and Methods: We recruited 19 patients with spastic CP (13 male and six female; mean age, 15.7 years). Functional ambulation was assessed using the 10-Meter Walk Test and gait analysis in the sagittal plane before and after a single 20-min HAL intervention session. Results: The walking speed and stride length significantly increased after HAL intervention compared to the pre-intervention values. Two-dimensional gait analysis showed improvement in equinus gait, increase in the flexion angle of the swing phase in the knee and hip joints, and improvement in gait symmetry. Immediate improvements in the walking ability and gait pattern were noted after HAL training in patients with spastic CP. Conclusions: The symmetry of the joint angle of the lower limb, including the trunk, accounts for the improvement in walking ability after HAL therapy.

CuII Complexes and Coordination Polymers with Pyridine or Pyrazine Amides and Amino Benzamides—Structures and EPR Patterns

Isonicotine amide, picoline amide, pyrazine 2-amide, 2- and 4-amino benzamides and various CuII salts were used to target CuII complexes of these ligands alongside with 1D and 2D coordination polymers. Under the criterion of obtaining crystalline and single phased materials a number of new compounds were reliably reproduced. Remarkably, for some of these compounds the ideal Cu:ligand ratio of the starting materials turned out to be very different from Cu:ligand ratio in the products. Crystal and molecular structures from single-crystal XRD were obtained for all new compounds; phase purity was checked using powder XRD. We observed exclusively the Oamide and not the NH2amide function binding to CuII. In most of the cases; this occurred in chelates with the second pyridine, pyrazine or aminophenyl N function. µ-O,N ditopic bridging was frequently observed for the N = pyridine, pyrazine or aminophenyl functions, but not exclusively. The geometry around CuII in these compounds was very often axially elongated octahedral or square pyramidal. X-band EPR spectra of powder samples revealed various spectral symmetry patterns ranging from axial over rhombic to inverse axial. Although the EPR spectra cannot be unequivocally correlated to the observed geometry of CuII in the solid state structures, the EPR patterns can help to support assumed structures as shown for the compound [Cu(Ina)2Br2] (Ina = isonicotine amide). As UV-vis absorption spectroscopy and magnetic measurement in the solid can also be roughly correlated to the surrounding of CuII, we suggest the combination of EPR, UV-vis spectroscopy and magnetic measurements to elucidate possible structures of CuII compounds with such ligands.

Pattern-induced local symmetry breaking in active-matter systems

The emergence of macroscopic order and patterns is a central paradigm in systems of (self-)propelled agents and a key component in the structuring of many biological systems. The relationships between the ordering process and the underlying microscopic interactions have been extensively explored both experimentally and theoretically. While emerging patterns often show one specific symmetry (e.g., nematic lane patterns or polarized traveling flocks), depending on the symmetry of the alignment interactions patterns with different symmetries can apparently coexist. Indeed, recent experiments with an actomysin motility assay suggest that polar and nematic patterns of actin filaments can interact and dynamically transform into each other. However, theoretical understanding of the mechanism responsible remains elusive. Here, we present a kinetic approach complemented by a hydrodynamic theory for agents with mixed alignment symmetries, which captures the experimentally observed phenomenology and provides a theoretical explanation for the coexistence and interaction of patterns with different symmetries. We show that local, pattern-induced symmetry breaking can account for dynamically coexisting patterns with different symmetries. Specifically, in a regime with moderate densities and a weak polar bias in the alignment interaction, nematic bands show a local symmetry-breaking instability within their high-density core region, which induces the formation of polar waves along the bands. These instabilities eventually result in a self-organized system of nematic bands and polar waves that dynamically transform into each other. Our study reveals a mutual feedback mechanism between pattern formation and local symmetry breaking in active matter that has interesting consequences for structure formation in biological systems.

Improved Path Resistance Adjustment As a Valuable Tool to Homogenize the Current Distribution within Interconnected Lithium-Ion-Battery Modules

Range anxiety is one of the leading reasons why people buy conventional cars instead of battery electric vehicles (BEVs). At the same system voltage, an increase in range can be achieved by both higher cell capacities and parallel connection of cells. As cells with sufficient capacity still lack market maturity, parallel connection is currently the remaining alternative for car manufacturers. In parallel-connected lithium-ion battery packs, varying internal cell impedance, different contact resistances or an uneven state of health (SOH) of the cells cause inhomogeneous current distributions within interconnected lithium-ion-batteries (LIBs). However, varying system terminals, different connecting strategies, as well as the number of serial and parallel connections have a major impact on the inhomogeneity of the current distribution. The resulting path resistance of the parallel-connected cells combines all of these influences and is the key to reduce such inhomogeneous current distributions. The extent to which each of the contributors and the interaction between them affects the path resistance within the battery module is crucial to improve both the manufacturing process and the system’s efficiency.In this study, the influence of the stated reasons on the path resistance of parallel-connected LIBs within a battery pack is analyzed, using physicochemical, electrical, and thermal coupled models. Experimental data of the commercially available cylindrical lithium-ion cell LG INR18650MJ1 was used for parameterization and validation of the physicochemical and thermal model. The cell incorporates NMC-811 as cathode active material as well as silicon doped graphite (SiC) on the anode side, which is a promising high energy material combination for future BEVs. To ensure a high practical applicability, the investigated system topologies were restricted from 1s2p to 4s4p. Due to limited installation space, the system terminals often cannot be freely chosen, which is why the positon of the system terminals were varied between side, middle and cross connections. Additionally, the influence of different linking strategies between the serial- and parallel-connected strings was examined.An example of a resulting current distribution for a battery pack with 4s4p topology, using cross- connectors between serial- and parallel-connected LIBs as well as cross-connection of the system terminals is shown in Fig. 1. Part a) illustrates the schematic diagram, while the current distribution is shown in part b). For side connection the system terminal next to cell c4,4 would switch to cell c4,1.As a result, axis and point (see Fig. 1) symmetry patterns within the battery modules could be recognized, depending on the number of serial- and parallel-connected cells and the choice of the system terminals. Furthermore, the presence of cross-connectors leads to equivalent current distributions within the analyzed systems, regardless of whether the system terminals were contacted on the side or crosswise. For car manufacturers, this implicates another level of freedom, since the presence of cross-connectors allows choosing the positon of the system terminals without negative impacts on the current distribution. Additionally, the analyses of different contact resistances showed that particular attention has to be paid to string connectors during the assembling process of battery modules. On the other hand, the impacts of welding spot resistances and cross-connector resistances on the path resistance cannot be neglected by the car manufacturers, but are of minor importance compared to the influence of string connector resistances and the presence of cross-connectors.Current studies therefore focus on verifying these results using measurement data. In particular, the voltage response of parallel-connected cells is considered as an indicator for uneven path resistance, since measurement data of inhomogeneous current distributions are usually missing within battery modules. Furthermore, the influence of varying path resistances on the aging behavior of interconnected LIBs could be of great interest to car manufacturers and has therefore to be investigated in further studies.The results presented were achieved in association with an INI.TUM project, funded by AUDI AG. Figure 1

Role of Stroboscope in Injury of External Branch of Superior Laryngeal Nerve During Thyroid Surgery.

Role of stroboscope in injury of External branch of superior laryngeal nerve during thyroid surgery. Study conducted in a tertiary care hospital. 40 patients were selected and divided into two groups as Group A and B. Benign thyroid swellings were included, excluding preoperative vocal cord pathology by performing videolaryngoscope and videostroboscope. After thyroidectomy procedure stroboscopic fundamental frequency, symmetry, periodicity, glottic closure and mucosal wave pattern were assessed in both the groups and compared. The mean difference in fundamental frequency between pre operative and postoperative in Group A was 37.85 (SD = 33.69) and in Group B was 58.40 (SD = 77.55) with p-value of 0.287. Symmetry of cords in Group A was 90% and asymmetry was 10%, while in Group B symmetry of cords was 75% and asymmetry of 25% with p-value of 0.407. Other parameters like regular periodicity, complete glottic closure, normal mucosal pattern was 95% in Group A and 75% in Group B. Irregular periodicity, incomplete glottis closure, decreased mucosal wave pattern was 5% in Group A and 25% in Group B. Stroboscope is an essential and useful tool in diagnosing EBSLN injury. It is useful in assessing pre operative voice assessment before and after thyroid surgery than a video laryngoscope.

Local R-Symmetry Co-Occurrence: Characterising Leaf Image Patterns for Identifying Cultivars.

Leaf image recognition techniques have been actively researched for plant species identification. However it remains unclear whether analysing leaf patterns can provide sufficient information for further differentiating cultivars. This paper reports our attempt on cultivar recognition from leaves as a general very fine-grained pattern recognition problem, which is not only a challenging research problem but also important for cultivar evaluation, selection and production in agriculture. We propose a novel local R-symmetry co-occurrence method for characterising discriminative local symmetry patterns to distinguish subtle differences among cultivars. Through scalable and moving R-relation radius pairs, we generate a set of radius symmetry co-occurrence matrices (RsCoM)and their measures for describing the local symmetry properties of interior regions. By varying the size of the radius pair, the RsCoM measures local R-symmetry co-occurrence from global/coarse to fine scales. A new two-phase strategy of analysing the distribution of local RsCoM measures is designed to match the multiple scale appearance symmetry pattern distributions of similar cultivar leaf images. We constructed three leaf image databases, SoyCultivar, CottCultivar, and PeanCultivar, for an extensive experimental evaluation on recognition across soybean, cotton and peanut cultivars. Encouraging experimental results of the proposed method in comparison with the state-of-the-art leaf species recognition methods demonstrate the effectiveness of the proposed method for cultivar identification, which may advance the research in leaf recognition from species to cultivar.

Miniaturization re-establishes symmetry in the wing folding patterns of featherwing beetles

Most microinsects have feather-like bristled wings, a state known as ptiloptery, but featherwing beetles (family Ptiliidae) are unique among winged microinsects in their ability to fold such wings. An asymmetrical wing folding pattern, found also in the phylogenetically related rove beetles (Staphylinidae), was ancestral for Ptiliidae. Using scanning electron, confocal laser scanning, and optical microscopy, high-speed video recording, and 3D reconstruction, we analyze in detail the symmetrical wing folding pattern and the mechanism of the folding and unfolding of the wings in Acrotrichis sericans (Coleoptera: Ptiliidae) and show how some of the smaller featherwing beetles have reverted to strict symmetry in their wing folding. The wings are folded in three phases by bending along four lines (with the help of wing folding patches on the abdominal tergites) and locked under the closed elytra; they unfold passively in two phases, apparently with the help of the elasticity provided by resilin unevenly distributed in the wing and of convexities forming in the cross-sections of the unfolding wing, making it stiffer. The minimum duration of folding is 3.5 s; unfolding is much more rapid (minimum duration lowest recorded in beetles, 0.038 s). The folding ratio of A. sericans is 3.31 (without setae), which is greater than in any beetle in which it has been measured. The symmetrical wing folding pattern found in A. sericans and in all of the smallest ptiliids, in which ptiloptery is especially pronounced, is the only known example of symmetry re-established during miniaturization. This direction of evolution is remarkable because miniaturization is known to result in various asymmetries, while in this case miniaturization was accompanied by reversal to symmetry, probably associated with the evolution of ptiloptery. Our results on the pattern and mechanisms of wing folding and unfolding can be used in robotics for developing miniature biomimetic robots: the mechanisms of wing folding and unfolding in Ptiliidae present a challenge to engineers who currently work at designing ever smaller flying robots and may eventually produce miniature robots with foldable wings.

Improved HMSIW Cavity-Cascaded Array With High Front-to-Back Ratio Based on Complementary Element

A new complementary element based on half-mode substrate integrated waveguide (HMSIW) cavity and loaded monopole technology is presented. By slightly breaking the shorting wall of the HMSIW cavity and loading a printed monopole, the resonance characteristics of the HMSIW cavity can be made intact while the additional monopole can be excited. The open edge of the HMSIW cavity is equivalent to a magnetic current. This equivalent magnetic current is orthogonal to the electric current introduced by the monopole, thus they form a pair of complementary sources. Because the backward radiation of the complementary sources can be canceled out, a remarkable unidirectional radiation performance is achieved. To improve the symmetry of the radiation pattern and enhance the antenna gain, a cascaded cavity array is then studied. By alternately connecting the complementary elements, all equivalent magnetic currents of the HMSIW cavities and all electric currents of the monopoles can work in-phase, thus a broadside radiation can be achieved. In this communication, a $1\times 5$ array based on the proposed complementary element and a corresponding array based on the classical HMSIW cavity cell are comparatively analyzed. It is found that the impedance characteristics and radiation gain of the HMSIW cavity can be kept intact by the proposed structure. Meanwhile, a 20 dB enhancement in front-to-back ratio can be attained.

Fractionalized time reversal, parity, and charge conjugation symmetry in a topological superconductor: A possible origin of three generations of neutrinos and mass mixing

The existence of three generations of neutrinos(charged leptons/quarks) and their mass mixing are deep mysteries of our universe. Recently, Majorana's spirit returns in modern condensed matter physics -- in the context of topological Majorana zero modes in certain classes of topological superconductors(TSCs). In this paper, we attempt to investigate the topological nature of the neutrino by assuming that a relativistic Majorana fermion can be divided into four topological Majorana zero modes at cutoff energy scale, e.g. planck scale. We begin with an exactly solvable $1$D lattice model which realizes a $T^2=-1$ time reversal symmetry protected TSC, and show that a pair of topological Majorana zero modes can realize a $T^4=-1$ time reversal symmetry.Moreover, we find that a pair of topological Majorana zero modes can also realize a $P^4=-1$ parity symmetry and even a nontrivial $\overline C^4=-1$ charge conjugation symmetry. Next, we argue that the origin of three generations of neutrinos(charged leptons and quarks) can be naturally explained as three distinguishable ways of forming a pair of complex fermions(with opposite spin polarizations) out of four topological Majorana zero modes, characterized by the $T^4=-1$, $(TP)^4=-1$ and $(T \overline C)^4=-1$ fractionalized symmetries that each complex fermion carries at cutoff energy scale. Finally, we use a semiclassical approach to compute the neutrino mass mixing matrix at leading order(LO), e.g., in the absence of $CP$ violation correction. We obtain $\theta_{12}=31.7^\circ, \theta_{23}=45^\circ$ and $\theta_{13}=0^\circ$(the golden ratio pattern), which is consistent with an $A_5$ flavor symmetry pattern. We further predict an exact mass ratio of the three mass eigenstates of neutrinos with $m_1/m_3=m_2/m_3=3/\sqrt{5}$ and an effective mass of neutrinoless double beta decay $m_{0\nu\beta\beta}=m_1/\sqrt{5}$.

Acoustic Waves for Active Reduction of Contact Time in Droplet Impact

Minimizing droplet impact contact time is critical for applications such as self-cleaning, antierosion or anti-icing. Recent studies have used the texturing of surfaces to split droplets during impact or inducing asymmetric spreading, but these require specifically designed substrates that cannot be easily reconfigured. A key challenge is to realize an effective reduction in contact time during droplet impingement on a smooth surface without texturing but with active and programmable control. Our experimental results show that surface acoustic waves (SAWs), generated at a location distant from a point of droplet impact, can be used to minimize contact time by as much as 35% without requiring a textured surface. Additionally, the ability to switch on and off the SAWs means that a reduction in droplet impact contact time on a surface can be controlled in a programmable manner. Moreover, our results show that, by applying acoustic waves, the impact regime of the droplet on the solid surface can be changed from deposition or partial rebound to complete rebound. To study the dynamics of droplet impact, we develop a numerical model for multiphase flow and simulate different droplet impingement scenarios. Numerical results reveal that the acoustic waves can be used to modify and control the internal velocity fields inside the droplet. By breaking the symmetry of the internal recirculation patterns inside the droplet, the kinetic energy recovered from interfacial energy during the retraction process is increased, and the droplet can be fully separated from the surface with a much shorter contact time. Our work opens up opportunities to use SAW devices to minimize the contact time, change the droplet impact regime, and program or control the droplet's rebounding on smooth or planar and curved surfaces, as well as rough or textured surfaces.

Bogoliubov Fermi surfaces in spin- 12 systems: Model Hamiltonians and experimental consequences

Bogoliubov Fermi surfaces (BFSs) are topologically protected regions of zero energy excitations in a superconductor whose dimension equals that of the underlying normal state Fermi surface. Examples of Hamiltonians exhibiting this "ultranodal" phase are known to preserve charge-conjugation ($C$) and parity ($P$) but break time-reversal ($T$). In this work, we provide examples of model Hamiltonians that do not necessarily preserve this symmetry pattern but have well-defined sign-changing Pfaffians yielding BFSs. While their topological character has not been recognized previously, some of the models we present have been extensively studied in prior literature. We further examine thermodynamic and electronic properties arising from the ultranodal state. In particular, we study the effect of a weak Zeeman field close to the topological transition and propose distinguishing features of BFSs using residual specific heat and tunneling conductance. Our calculation of the superfluid density in a toy multi-band model indicates a window of interband pairing strength where BFSs are stable with a positive superfluid density. We also present additional signatures of BFSs in spin-polarized spectral weight and total magnetization measurements.

Root Canal Morphology of the Permanent Mandibular Incisors by Cone Beam Computed Tomography: A Systematic Review

Knowledge of dental anatomy through the assessment of the anatomic variations of each tooth’s root canal system is essential to undertake endodontic therapy. The aim of this systematic review was to analyze the different studies on the internal morphology of permanent mandibular incisors where Cone-Beam Computed Tomography (CBCT) X-ray imaging is used. Pubmed, CENTRAL, Wiley Library and Web of Science electronic databases were searched for scientific studies included until March 2020. The terms used in the search were: “permanent mandibular incisors”, “root canal morphology” and “cone-beam computed tomography”. The search was limited to studies whose aim was the analysis of the morphology of the root canal system evaluating the parameters of methodology, population, sample, number and configuration. A total of 19 studies met the inclusion criteria. There was a noticeable lack of unanimity in the setting adjustments of each of the CBCT devices used. The presence of two root canals varied from 0.4% to 45%. The most frequent configurations were Vertucci’s Types I, III, II, V, IV, VII and VI. Type VIII configuration was non-existent. CBCT revealed the existence of anatomical symmetry patterns, and there was no unanimity of criteria regarding the presence of a second root canal. Results concerning the presence of a second root canal in the mandibular incisors differ widely, with a possible influence of the geographic area where the study was conducted. The prevalence of a second canal is higher in mandibular lateral incisors than in mandibular central incisors. There was no direct relationship between voxel size (0.125–0.3 mm) and increased prevalence of a second canal.

Broken Symmetries, Random Morphogenesis, and Biometric Distance

This paper discusses the role of symmetry-breaking in biometric recognition. Using publicly available databases, we investigate three kinds of broken symmetries in iris patterns: binocular, monocular, and monozygotic. We report a small but statistically significant difference in similarities between the ipsilateral and the contralateral eyes of twins, and also between genetically identical and nonidentical eyes. Another new finding is a doubling in the variance of Hamming distance scores under a simple monocular mirror transformation, which is consistent with an assessment of entropy.

Plane and Frieze Symmetry Group Determination for Educational Purposes.

Three-dimensional symmetry plays a crucial role in crystallography education. The educational process can be facilitated by introducing the analysis of friezes and plane patterns such as parquets before presenting more sophisticated crystal structures. Analysis of the symmetry of parquets can serve as an opportunity to follow the full routine of finding symmetry group symbols through incorporation of a two-step procedure involving the determination of Bravais lattice type. The aim of this paper is to provide a simple description of the analysis of Bravais lattices and pattern symmetry that can be used by students as well as crystallography educators. The procedure is also summarized in the form of comprehensive tree charts. This form is easy to use and popular with students. It may also aid in the retention of certain facts concerning crystallographic methodology. Examples of patterns in frieze and parquet forms were taken from the interiors of Kórnik Castle (Poland), which exhibit Moorish-style ornamentation including dichroic patterns and constitute an important locus of cultural heritage capable of strengthening students’ motivation.

A Flexible Inference Machine for Global Alignment of Wall Openings

Openings such as windows and doors are essential components of architectural wall surfaces. It is still a challenge to reconstruct them robustly from unstructured 3D point clouds because of occlusions, noises and non-uniformly distributed points. Current research primarily focuses on meliorating the robustness of detection and pays little attention to the geometric correctness. To improve the reconstruction quality, assumptions on the opening layout are usually applied as rules to support the reconstruction algorithm. The commonly used assumptions, such as the strict grid and symmetry pattern, however, are not suitable in many cases. In this paper, we propose a novel approach, named an inference machine, to identify and use flexible rules in wall opening modelling. Our method first detects and models openings through a data-driven method and then refines the opening boundaries by global and flexible rules. The key is to identify the global flexible rules from the detected openings, composed by various combinations of alignments. As our method is oblivious of the type of architectural layout, it can be applied to both interior wall surfaces and exterior building facades. We demonstrate the flexibility of our approach in both outdoor and indoor scenes with a variety of opening layouts. The qualitative and quantitative evaluation results indicate the potential of the approach to be a general method in opening detection and modelling. However, this data-driven method suffers from the existence of occlusions and non-planar wall surfaces.

Atomic resolution energy-loss magnetic chiral dichroism measurements enabled by patterned apertures

We give an experimental demonstration of two types of recently proposed ventilator apertures which can be used to acquire electron magnetic circular dichroic (EMCD) signals in zone axis orientation with high spatial resolution. To simplify the experimental procedures, we propose a third type of aperture and experimentally demonstrate the use of this modified ventilator aperture for the case of multiple symmetries in the diffraction patterns. To show the feasibility of the atomic resolution EMCD, EMCD signals are acquired for a range of beam convergence angles. High quality EMCD signals with convergence angles corresponding to atomic resolution electron probes are obtained.

Coevolutionary patterns caused by prey selection

Many theoretical models have been formulated to better understand the coevolutionary patterns that emerge from antagonistic interactions. These models usually assume that the attacks by the exploiters are random, so the effect of victim selection by exploiters on coevolutionary patterns remains unexplored. Here we analytically studied the payoff for predators and prey under coevolution assuming that every individual predator can attack only a small number of prey any given time, considering two scenarios: (i) predation occurs at random; (ii) predators select prey according to phenotype matching. We also develop an individual based model to verify the robustness of our analytical prediction. We show that both scenarios result in well known similar coevolutionary patterns if population sizes are sufficiently high: symmetrical coevolutionary branching and symmetrical coevolutionary cycling (Red Queen dynamics). However, for small population sizes, prey selection can cause unexpected coevolutionary patterns. One is the breaking of symmetry of the coevolutionary pattern, where the phenotypes evolve towards one of two evolutionarily stable patterns. As population size increases, the phenotypes oscillate between these two values in a novel form of Red Queen dynamics, the episodic reversal between the two stable patterns. Thus, prey selection causes prey phenotypes to evolve towards more extreme values, which reduces the fitness of both predators and prey, increasing the likelihood of extinction.