Cause Of Asymmetry Research Articles

Symmetric tarsal show is crucial in creating upper eyelid symmetry

PurposeTo illustrate different causes of upper eyelid asymmetry and to stress that detection of any asymmetry is important in avoiding an unhappy patient.MethodsPatients want an ‘upper eyelid correction’ and do not know the real cause of the asymmetry, or even did not notice any asymmetry. Different kind of asymmetric appearances of the upper eyelids will be shown and analyzed.ResultsThe upper eyelid has several landmarks. Besides the palpebral aperture, the margin pupil distance and lid crease height, also the margin fold distance/tarsal show, the lid fullness and braw distance needs to be described. An asymmetric tarsal show is often perceived as ptosis. Also bony orbit, eye position, orbital fat and braw position are all important factors influencing the final upper eyelid shape. In some conditions a perfect upper eyelid symmetry is very difficult to achieve or sometimes impossible.ConclusionsGood preoperative assessment is crucial in eyelid surgery, both in primary surgery and in correcting postoperative asymmetry. Good patient counseling is important to create realistic expectations.

Pubertal Development

Pubertal Development

Temporary Sales Prices and Asymmetric Price Transmission

ABSTRACTWe hypothesize that temporary sales might bias the results of vertical price transmission analysis towards findings of asymmetric price transmission. We test this hypothesis using a scanner dataset of retail butter prices in Germany. To this end we first use filters to identify underlying reference retail prices and thus remove temporary sales prices. We then compare estimates of vertical price transmission from the wholesale to the retail level that are generated with raw and with filtered retail prices. Our results confirm that temporary sales prices increase the speed and asymmetry of vertical price transmission. These results add a potential cause of asymmetry to those, such as market power, that have already been identified in the literature. [EconLit citations: C22; L10; Q11].

Stock markets and industrial production in north and south of Euro-zone: Asymmetric effects via threshold cointegration approach

In this paper, we investigate the relationship between stock prices and industrial production both for South and North of Euro-zone during the period 2004–2013. In contrast to previous studies we identify additional price interaction and dynamics investigating asymmetric adjustment behavior combined with long-run relationship using the Threshold cointegration approach. This method is proper as well because takes into consideration the type of shocks which appears in period 2004–2013. The results demonstrate symmetric adjustment process for the North and asymmetric for the South when stock prices and industrial production adjust to achieve the long-run equilibrium. The main cause of asymmetry is the difference in structural competitiveness which is weakest in South with respect to North. This finding is particularly important because provides the direction of economic policy that should adopt the governments of South of Euro-zone.

Symmetry of electromechanical delay, peak torque and rate of force development in knee flexors and extensors in female and male subjects.

The aim of the study was to evaluate electromechanical delay (EMD), peak torque (PT) and rate of force development (RFD) in selected muscles of right and left lower extremities in groups of female and male subjects. The study evaluated 9 volunteer female subjects (mean ± SD: age: 21.67 ± 0.87 years; height: 168 ± 7 cm; body mass: 59.44 ± 4.8 kg) and 10 male university students (mean ± SD: age 22 ± 1.25 years; height: 179 ± 6 cm; body mass: 74.3 ± 5.1 kg) from the Faculty of Physical Education. Muscle torques and electromyographic activity were measured for knee flexors and extensors in static conditions, separately for the right and the left lower extremities. During the measurements, the subjects generated the maximum torque as fast as possible. Surface electrodes were placed on the right and left lower extremities on the following muscles: rectus femoris, vastus lateralis (m.VL), vastus medialis and biceps femoris. Symmetry of EMD, RFD and "flexors-extensors" ratio was found in the muscles of the right and left lower extremities (with an exception of m.VL) in the group of male and female subjects. Statistical analysis demonstrated the presence of asymmetry in PT (297.66 vs. 272.05 N⋅m) and relative force in knee extensors in the group of men (3.90 vs. 3.54 N⋅m⋅kg-1). Symmetry of EMD and asymmetry of PT might suggest that the cause of asymmetry of the muscular force is mainly morphologi- cal characteristics of the muscle rather than the process of controlling its activity.

Seasonal Sea Surface Temperature Asymmetry in the Northwestern Pacific Marginal Seas

Sea surface temperature (SST) is an important component of climate and weather systems at various time scales. Asymmetric seasonal SST variations in the Northwestern Pacific Marginal Seas (NWPMS) are investigated in this study using observation data and numerical model results. The asymmetry in SST seasonal variation is estimated quantitatively and compared with heat advection and surface net heat flux using SST data and atmospheric variables from the European Centre for Medium-Range Weather Forecast (ECMWF). The SST increases faster than it decreases, whereas air temperature increases slowly. Heat advection and surface heat flux were estimated using numerically modeled SST and ocean currents, which contribute to the asymmetry of seasonal SST variations. Heat advection shows good correlation with the SST seasonal variation asymmetry. Model results without currents along the boundary show more symmetrical SST variations. This suggests that heat advection is a prominent cause of asymmetry in the seasonal variation.

Late-twentieth-century emergence of the El Niño propagation asymmetry and future projections

The El Niño/Southern Oscillation (ENSO) is the Earth's most prominent source of interannual climate variability, exerting profound worldwide effects. Despite decades of research, its behaviour continues to challenge scientists. In the eastern equatorial Pacific Ocean, the anomalously cool sea surface temperatures (SSTs) found during La Niña events and the warm waters of modest El Niño events both propagate westwards, as in the seasonal cycle. In contrast, SST anomalies propagate eastwards during extreme El Niño events, prominently in the post-1976 period, spurring unusual weather events worldwide with costly consequences. The cause of this propagation asymmetry is currently unknown. Here we trace the cause of the asymmetry to the variations in upper ocean currents in the equatorial Pacific, whereby the westward-flowing currents are enhanced during La Niña events but reversed during extreme El Niño events. Our results highlight that propagation asymmetry is favoured when the westward mean equatorial currents weaken, as is projected to be the case under global warming. By analysing past and future climate simulations of an ensemble of models with more realistic propagation, we find a doubling in the occurrences of El Niño events that feature prominent eastward propagation characteristics in a warmer world. Our analysis thus suggests that more frequent emergence of propagation asymmetry will be an indication of the Earth's warming climate.

Circulation Variation Over the Western North Pacific and Its Association with Tropical Ssta Over the Indian Ocean and the Pacific

AbstractThe circulation variation over the western North Pacific and its relationship between circulation and tropical SSTA were investigated in this paper. The results show that western North Pacific (WNP) anticyclone/cyclone are two significantly anomalous phenomena at mid‐low troposphere over WNP, and their variation is related to PJ wave line and zonal wave line at mid‐high latitudes of Eurasia. Owing to this interrelation, WNP anticyclone/cyclone can influence the climate over East Asia and Eurasia. The results also show that the relationship between WNP anticyclone/cyclone in summer and SSTA is obviously asymmetric. Generally, evident WNP anticyclone occurs in summer of feeble El Niño years, related with warm SSTA in winter of mature El Niño years over the equatorial east Pacific and warm SSTA in spring and summer of weakening El Niño years over the Indian Ocean, which further displays that the WNP anticyclone plays an important bridge role in El Niño event influence on summer climate over East Asia. But the relationship between the obvious WNP cyclone and SSTA in the Indian Ocean is not steady. The formation and maintain of WNP anticyclone are mainly related to anomalous westerlies resulting from thermal contrast between SSTA over the Indian Ocean and SSTA over the Pacific. The possible cause of asymmetry is further investigated. The results show that the thermal contrasts between Indo‐Pacific in El Niño and La Niña summer are accordant, which possibly results in asymmetric relationship between WNP anticyclone/cyclone and SSTA.

Free groin flap in hemifacial volume reconstruction

Use of the free groin flap, one of the first microvascular free flaps described, has been neglected recently because it has a short pedicle and varies anatomically. However, we have found its anatomical features and type of tissue ideal for volumetric enhancement in severe hemifacial asymmetry. We present a retrospective review of a consecutive series of 14 patients who had hemifacial augmentation with a free groin flap (mean age at operation 17 years, range 10–42) since 2001, and discuss the surgical technique. The most common cause of asymmetry was hemifacial microsomia (n=6). Anatomical variation of the vessels in the groin did not cause problems. Arterial anastomosis was to the facial artery in 13 patients; 12 patients had simultaneous hard tissue procedures. No flaps failed. The free groin flap is a useful adjunct in the management of hemifacial deficits in volume when free fat grafts will not provide enough bulk. Although the operation can take longer than non-vascularised grafts, little tissue is lost so long-term results may be more predictable. We have found the anatomy fairly consistent and the short pedicle caused no problems.

Testing for Ecological Limitation of Diversification: A Case Study Using Parasitic Plants

Imbalances in phylogenetic diversity could be the result of variable diversification rates, differing limits on diversity, or a combination of the two. We propose an approach to distinguish between rates and limits as the primary cause of phylogenetic imbalance, using parasitic plants as a model. With sister-taxon comparisons, we show that parasitic plant lineages are typically much less diverse than their autotrophic sisters. We then use age estimates for taxa used in the sister-taxon comparisons to test for correlations between clade age and clade diversity. We find that parasitic plant diversity is not significantly correlated with the age of the lineage, whereas there is a strong positive correlation between the age and diversity of nonparasitic sister lineages. The Ericaceae sister pair Monotropoideae (parasitic) and Arbutoideae (autotrophic) is sufficiently well sampled at the species level to allow more parametric comparisons of diversification patterns. Model fitting for this group supports ecological limitation in Monotropoideae and unconstrained diversification in Arbutoideae. Thus, differences in diversity between parasitic plants and their autotrophic sisters might be caused by a combination of ecological limitation and exponential diversification. A combination of sister-taxon comparisons of diversity and age, coupled with model fitting of well-sampled phylogenies of focal taxa, provides a powerful test of likely causes of asymmetry in the diversity of lineages.

Orthodontic and surgical treatment of a patient with hemifacial microsomia

This article describes the surgical and orthodontic treatment of a 12-year-old boy with a significant deformity and functional involvement caused by hemifacial microsomia. The left mandibular ramus and condyle were hypoplastic and abnormal in form and location. The lower third of the face was increased, with mandibular retrusion and significant facial asymmetry. He had difficulties in speaking and chewing and problems related to his facial appearance, which caused severe psychosocial disturbances. The patient received orthodontic treatment and temporomandibular joint reconstruction with a costochondral graft on the left side while he was still growing. Three-year follow-up records are presented.

Explaining the cause of asymmetry in the electron foreshock

As the solar wind nears the edge of Earth's magnetosphere, it creates a bow shock, a region in which the solar wind speed drops abruptly. Some solar wind electrons bounce off the bow shock; these reflected electrons interact with oncoming solar wind in a region known as the electron foreshock. In the electron foreshock the reflected electrons generate plasma wave activity that results in radio wave emission. A new study shows that the sunward and antisunward wings of this electron foreshock differ. Analyzing wave and electron measurements from the Wind spacecraft, Pulupa et al. show that the asymmetry is due to the strahl, a beam of high‐velocity electrons that is a component of the solar wind. Strahl electrons bounce off the bow shock only into the sunward wing of the foreshock, and this asymmetry leads to enhanced plasma wave activity in the sunward wing. (Geophysical Research Letters, doi:10.1029/ 2011GL048029, 2011)

Analysis of $\hbox {IM}_{\rm 3}$ Asymmetry in MOSFET Small-Signal Amplifiers

This paper describes and analyzes asymmetry issues for weakly nonlinear MOSFET Common-Gate (CG) and Common-Source (CS) architectures. Using a Volterra series analysis, the cause of asymmetry in CG and CS amplifiers is explained. The asymmetry between high-side and low-side products in the CG amplifier exhibits a larger amplitude difference at low-frequency offset than at high frequency offset, while the CS amplifier shows more asymmetry at a high frequency offset. The magnitude of the product asymmetry in the CS amplifier can be significantly higher than the CG amplifier. Methods of mitigating asymmetry are suggested for both CG and CS amplifiers. A 65 nm Si CMOS technology is used for the simulation verification of the results derived in this paper.

Running Impulse, Functional Strength and Dynamic Balance Asymmetry in Healthy Recreational Runners

Researchers have assumed that normal healthy running is a symmetrical process and gait asymmetry is associated with a pathological condition or injury. However, bilateral asymmetry has been found in healthy individuals during walking and running. The causes of asymmetries remain unclear, but could be the result of lateral dominance. A functional asymmetry hypothesis has been proposed in which the dominant limb (D) provides more propulsion and the non-dominant limb (ND) provides more support during walking. If asymmetry is natural and the lower extremities are responsible for different tasks, then there may be functional strength and dynamic balance asymmetries that could reflect the task demands of each leg. PURPOSE: To test the functional asymmetry hypothesis and asymmetry in functional strength and dynamic balance in healthy, recreational runners. METHODS: Participants (male 14, female 14) were healthy runners (mean ± sd, age 27.39 ± 6.39 years; mass 67.48 ± 9.15 kg; weekly training 37.35 ± 24.51 km; running history 8.88 ± 6.99 years). Vertical impulse (VI) and propulsive impulse (PI) were used to represent the supportive and propulsive function of the lower extremities. Participants ran across a force plate at 3.5 ± 5% m/s, in which VI and PI were measured in the D and ND limb. The Star Excursion Balance Test (SEBT) and Triple hop distance test (THD) were used to test dynamic balance and functional strength, respectively. A two-tailed, paired samples t-test with Bonferonni adjustment was calculated to compare the mean scores between the D and ND limbs in each of the measures. An Absolute Asymmetry Index (ASI) was calculated to determine differences in the test measures, regardless of direction. RESULTS: No significant differences were found between the mean scores of the D and ND limbs in any of the tests. ASI revealed that the participants in this study exhibited some level of asymmetry in all of the measures tested (mean ± sd, SEBT 3.80 ± 3.30%, THD 4.76 ± 4.46%, VI 4.61 ± 4.77%, PI 16.73 ± 15.13%). CONCLUSIONS: Pooling data can hide asymmetries that exist in healthy individuals. Levels of asymmetry can vary greatly between and within individuals in different tests. Lateral dominance may not be a predictor of asymmetries in healthy individuals. However, asymmetries could be the result of individual compensations or individual differences in lateral dominace in varying tasks. Perfect symmetry should not be expected in healthy individuals, and asymmetry does not necessarily implicate a pathological condition. The high ASI of the propulsive impulse in the participants indicates that a functional asymmetry might exist, but is unique for each individual. PRACTICAL APPLICATIONS: Coaches and trainers can address the specific demands of the individual limbs and/or decrease asymmetries, if desired, by having their athletes perform unilateral training, such as single leg squats, single leg dead lifts, multidirectional lunges and low level single leg plyometric exercises. Consequently, the individual kinetics and kinematics of the limbs will more closely replicate that which is performed while running. Researchers should analyze individual participant data and utilize an asymmetry index when making left/right or dominant/non-dominant comparisons.

Asymmetry in certain morphological characters of the carangid species Decapterus russelli, collected from the Lemah coastal area, on the northern part of Oman Sea

Asymmetry in certain morphological characters of the carangid species Decapterus russelli, collected from the Lemah coastal area, on the northern part of Oman Sea Asymmetry analysis has been carried out for some bilateral characters of Decapterus russelli (Family: Carangidae) collected from Oman Sea. The results showed that postorbital length demonstrated the highest incidence of asymmetry among the characters studied. The lowest asymmetry value was for the number of pectoral fin rays. An increasing trend in the asymmetry value with fish length is also obtained for preorbital length, number of pectoral fins and number of lateral line scutes. A similar trend is also evident in the postorbital length and eye lens diameter of individuals with body sizes <160 mm. The possible causes of asymmetry in this species are herein discussed in relation to different pollutants and their presence in the area.

Natural Convection as an Asymmetrical Factor of the Transport Through Porous Membrane

For nonionic substances, which density of solution depends on its concentration, concentration polarization of the membrane in horizontal plane depends not only on diffusion but on the hydrodynamic instabilities at the membrane surfaces also. Such instabilities are the cause of asymmetry of membrane transport in gravitational field. On the basis of results of glucose transport through the Nephrophan membrane in horizontal plane we can state that this asymmetry was observed for the cases with concentration Rayleigh number greater than critical value (R C )crit = 1709.3. The mathematical model based on Kedem–Katchalsky equations and Rayleigh number was presented. On the basis of this model and the dependence of volume flux through the Nephrophan membrane as a function of glucose concentration in the upper (configuration B) and lower (configuration A) chamber of the membrane system, the dependencies of thickness of concentration boundary layer, Rayleigh number, and introduced coefficient of asymmetry as a function of glucose concentration were presented for both configurations. These dependencies show that asymmetry of the membrane transport is observed for glucose concentration higher than 0.015 mol l−1.

Barchan dune asymmetry: Observations from Mars and Earth

Barchan dune asymmetry refers to the extension of one barchan limb downwind. It is a common dune form on Earth and also occurs on Mars and Titan. A new classification of barchan limbs is presented where three types of limb morphology are identified: linear, kinked and beaded. These, along with other dune-scale morphological signatures, are used to identify three of the causes of barchan asymmetry on Mars: bi-directional winds, dune collision and the influence of inclined topography. The potential for specific dune asymmetric morphologies to indicate aspects of the formative wind regime on planetary surfaces is shown. For example, the placement of dune limbs can indicate the general direction and relative strength of formative oblique winds; an extreme barchan limb length may indicate a long duration oblique wind; a kinked limb may be evidence of the passage of a storm; beaded limbs may represent surface-wave instabilities caused by an increase in wind energy parallel to the dune. A preliminary application of these signatures finds evidence for bi-modal winds on Mars. However, these and other morphological signatures of wind direction and relative strength should be applied to planetary landforms with caution as more than one process (e.g., bi-modal winds and collision) may be operating together or sequentially on the dunefield. In addition, analysis should be undertaken at the dunefield scale and not on individual dunes. Finally, morphological data should be acquired from similar-scale dunes within a dunefield. In addition to bi-modal wind regimes on Mars, the frequent parallel alignment of the extended barchan limb to the dune suggests that dune collision is also an important cause of asymmetry on Mars. Some of the more complex dunefield patterns result from a combination of dune collision, limb extension and merging with downwind dunes. Dune asymmetric form does not inhibit dune migration in the Namib Desert or on Mars. Data from the Namib suggest that dune migration rates are similar for symmetric and asymmetric dunes. Further modeling and field studies are needed to refine our understanding of the potential range of limb and dune morphologies that can result from specific asymmetry causes.

Clinician's Commentary

Clinician's Commentary

Les asymétries constitutionnelles en chirurgie d’augmentation mammaire esthétique : incidence, satisfaction et applications chirurgicales

The clinically observable, constitutional breast asymmetries are frequent and physiological in the general population. Although there has been a preponderance of literature concerning breast augmentation, a conspicuous lack of data exists regarding the preoperative breast and chest wall asymmetries seen in the patient seeking consultation for aesthetic breast augmentation. These asymmetries can lead to postoperative dissatisfaction in patients.An independent plastic surgeon analysed the data of 200 patients who had a primary aesthetic breast augmentation. The mean follow-up was 36 months. All patients had pre- and postoperative standardized pictures of the anterior chest wall. The clinical examination was achieved using an original evaluation form. Patients were also asked to fill an exhaustive satisfaction form. Breasts and chest wall asymmetries were diagnosed by clinical examination and photographic analysis. Mastopexy-augmentations, breast reconstructions, breast malformations (tuberous breasts and Poland syndrome) and patients with incomplete data were excluded from the study. Stastical analysis was done using SPSS software version 15.There were 77% of chest wall and breast asymmetries and 69,5% of breasts asymmetries (26,5% of breast mound volume asymmetry and 62,5% of shape asymmetry). An isolated chest wall asymmetry was found in 17% of patients. Scoliosis was the main cause of asymmetry (52,9% of chest wall asymmetries) as it is often associated with chest wall rotation, chest wall depression, submammary depression or rib asymmetry. Patients often noticed an asymmetry postoperatively (28%). Among the patients complaining from a postoperative asymmetry, 83,3% had a constitutional breast or chest wall asymmetry. Asymmetry was the third cause of dissatisfaction and the third argument for revision surgery (after volume dissatisfaction and ptosis). Thirty per cent of patients asking for a surgical revision and 35.3% of unsatisfied patients complained about asymmetry, which was preoperative in 83.3% of cases.The asymmetry rate of our study is compared with the others studies found in the literature. In the daily practice, asymmetry can be diagnosed by a complete clinical examination and standardized chest wall pictures. Patients with constitutional asymmetry should be educated, helping to increase postoperative satisfaction. The authors propose and discuss a surgical pattern for the handling of the different types of asymmetries in breast augmentation.

Contour-enhanced meta-analysis funnel plots help distinguish publication bias from other causes of asymmetry

Objectives To present the contour-enhanced funnel plot as an aid to differentiating asymmetry due to publication bias from that due to other factors. Study Design and Setting An enhancement to the usual funnel plot is proposed that allows the statistical significance of study estimates to be considered. Contour lines indicating conventional milestones in levels of statistical significance (e.g., <0.01, <0.05, <0.1) are added to funnel plots. Results This contour overlay aids the interpretation of the funnel plot. For example, if studies appear to be missing in areas of statistical nonsignificance, then this adds credence to the possibility that the asymmetry is due to publication bias. Conversely, if the supposed missing studies are in areas of higher statistical significance, this would suggest the cause of the asymmetry may be more likely to be due to factors other than publication bias, such as variable study quality. Conclusions We believe this enhancement to funnel plots (i) is simple to implement, (ii) is widely applicable, (iii) greatly improves interpretability, and (iv) should be used routinely.