V-shaped Pattern Research Articles

Getting the ducks in a row

Vessels – in the widest sense – travelling on a water surface continuously do work the water surrounding it, causing energy to be radiated in the form of surface waves. The concomitant resistance force, the wave resistance, can account for as much as half the total drag on the vessel, so reducing it to a minimum has been a major part of ship design research for many decades. Whether the ‘vessel’ is an ocean-going ship or a swimming duckling, the physics governing the V-shaped pattern of radiated waves behind it is in essence the same, and just as fuel economy is important for commercial vessels, it is reasonable to assume that also swimming waterfowl seek to minimise their energy expenditure. Using theory and methods from classic marine hydrodynamics, Yuan et al. (J. Fluid Mech., vol. 928, 2021, R2) consider whether, by organising themselves optimally, ducklings in a row behind a mother duck can reduce, eliminate or even reverse their individual wave resistance. They describe two mechanisms which they term ‘wave riding’ and ‘wave passing.’ The former is intuitive: the ducklings closest to the mother can receive a forward push by riding its mother's stern waves. The latter is perhaps a more striking phenomenon: when the interduckling distance is precisely right, every duckling in the row can, in principle, swim without wave resistance due to destructive wave interference. The phenomenon appears to be the same as motivates the recent US military research project Sea Train, a row of unmanned vehicles travelling in row formation.

A novel light interception trait of a hybrid rice ideotype indicative of leaf to panicle ratio

One of the major challenges facing rice breeding is to produce ideotype or ideal plant architecture (IPA) to improve canopy radiation use efficiency and hence grain yield. The hybrid japonica rice Jiayou Zhongke 6 (JYZK-6) is one of the benchmark cultivars with IPA characteristics, but the physio-ecological foundation of its high yield potential is still imperfectly understood. In this study, two-year field experiments were conducted using four japonica rice cultivars including JYZK-6 with contrasting canopy structures. A dynamic canopy light interception simulating device was constructed to capture canopy images representing the diurnal dynamics of solar angles throughout the grain-filling stage. Subsequently, leaf to panicle ratio (LPR), a newly developed physiological trait indicative of source-sink relations, was exploited to quantify the light distribution pattern within the rice canopy. The LPRs with high spatio-temporal resolution clearly showed the diurnal changes of light interception within the rice canopy. Genotypic differences in diurnal pattern of LPR were detected among the tested cultivars in both growing seasons, with the amplitude varying with grain-filling stages. Notably, LPR of the IPA cultivar JYZK-6 and its analogue WYJ-29, had a pattern of a V-shaped graph, peaking at sunrise and sunset while dropping to the lowest at noon during middle and late stages. Morphological measurement showed that the V-shaped pattern was associated with the height difference between flag leaf and panicle, panicle curvature, ratio of leaf area to panicle area, as well as the changing solar angles along with the progression of growth stage. This distinguishing feature of light pattern indicates that within the canopy of IPA cultivars, the leaf receives more light in the morning and afternoon whereas the panicle harvests more light at noon. It is inferred that such novel characteristics may provide the IPA cultivar with advantages of reducing midday suppression over the conventional cultivars, while more work is needed to verify this hypothesis. In summary, findings of this study offer a deeper insight into the physio-ecological processes underpinning radiation use efficiency at canopy level, and hence are valuable for breeding programs for ideotype cultivars.

Success and complication rate of miniscrew assisted non-surgical palatal expansion in adults - a consecutive study using a novel force-controlled polycyclic activation protocol

IntroductionBone-borne miniscrew assisted palatal expansion (MAPE) is a common technique to improve maxillary transverse deficiency in young adolescents. Adult patients usually present a challenge, as they often require additional surgical assisted maxillary expansion (SARPE). There is still no clear statement about non-surgical expansion in adult patients using this technique. The aim of this study was to evaluate the success and complication rate of non-surgical palatal expansion in adults utilizing MAPE with a novel force-controlled polycyclic expansion protocol (FCPC).MethodsThis consecutive study consisted of 33 adult patients with an average age of 29.1 ± 10.2 years (min. 18 years, max. 58 years), including one dropout patient. First, four miniscrews were inserted and after 12-weeks latency, the expander was placed and the FCPC protocol was applied (MAPE group). In case of missing expansion, a SARPE was performed (SARPE group). After maximum expansion, a cone beam CT was made and widening of the midpalatal suture was measured. The outcome variables were successful non-surgical expansion and, with sample size power above 80%, the odds of failed non-surgical expansion and associated complications were evaluated. The primary predictor variable was age. Statistical analysis was performed using R (Version 3.1) to calculate power, to construct various models for measuring the odds of requiring surgical intervention/complications, and others.ResultsSuccessful non-surgical expansion was achieved in 27 patients (84.4%), ranging from 18 to 49 years. Mean age differed significantly between both groups (26.8 ± 8.2 years vs. 41.3 ± 9.9 years; p < 0.001). Mean expansion at the anterior and posterior palate for the MAPE group was 5.4 ± 1.5 mm and 2.5 ± 1.1 mm, respectively. Among these subjects’ complications were observed in 18.5%. Age significantly increased the odds of complications (p = 0.019).Conclusions1. The success rate of MAPE among individuals aged 18 to 49 years was 84.4%.2. A V-shaped expansion pattern in the antero-posterior dimension was mostly observed.3. Complications were significantly associated with age.4. A careful expansion protocol seems to be beneficial to prevent unfavorable results in adult patients.Trial registrationConsecutive cohort study, Review Board No. EK-2-2014/0016.

First report of Anthracnose on Peach Fruit Caused by Colletotrichum siamense in Uruguay.

Peach (Prunus persica L.) is an economically important deciduous fruit crop in Uruguay. Anthracnose caused by species of the genus Colletotrichum is one of the major diseases in peach production, originating significant yield losses in United States (Hu et al. 2015), China (Du et al. 2017), Korea (Lee et al. 2018) and Brazil (Moreira et al. 2020). In February 2017, mature peach fruits cv. Pavia Canario with symptoms resembling anthracnose disease were collected from a commercial orchard located in Rincon del Colorado, Canelones, in the Southern region of Uruguay. Symptoms on peach fruit surface were characterized as circular, sunken, brown to dark-brown lesions ranging from 1 to 5 cm in diameter. Lesions were firm to touch with wrinkled concentric rings. All lesions progressed to the fruit core in a V-shaped pattern. The centers of the lesions were covered by orange conidial masses. Monosporic isolates obtained from the advancing margin of anthracnose lesions were grown on PDA at 25ºC and 12h photoperiod under fluorescent light. The representative isolates DzC1, DzC2 and DzC6 were morphologically and molecularly characterized. Upper surface of colonies varied from white or pale-gray to gray and on the reverse dark-gray with white to pale-gray margins. Conidia were cylindrical, with both ends predominantly rounded or one slightly acute, hyaline and aseptate. The length and width of conidia ranged from 9.5 to 18.9 µm (x ̅=14.1) and from 3.8 to 5.8 µm (x ̅=4.6), respectively. The ACT, βTUB2, GAPDH, APN2, APN2/MAT-IGS, and GAP2-IGS gene regions were amplified and sequenced with primers ACT-512F/ACT-783R (Carbone and Kohn, 1999), BT2Fd/BT4R (Woudenberg et al. 2009), GDF1/GDR1 (Guerber et al. 2003), CgDLR1/ColDLF3, CgDLF6/CgMAT1F2 (Rojas et al. 2010) and GAP1041/GAP-IGS2044 (Vieira et al. 2017) respectively and deposited in the GenBank database (MZ097888 to MZ097905). Multilocus phylogenetic analysis revealed that Uruguayan isolates clustered in a separate and well supported clade with sequences of the ex-type (isolate ICMP 18578) and other C. siamense strains (isolates Coll6, 1092, LF139 and CMM 4248). To confirm pathogenicity, mature and apparently healthy peach fruit cv. Pavia Canario were inoculated with the three representative isolates of C. siamense (six fruit per isolate). Fruit were surface disinfested with 70% ethanol and wounded with a sterile needle at two equidistant points (1 mm diameter x 1 mm deep). Then, fruit were inoculated with 5 µl of a spore suspension (1×106 conidia mL-1) in four inoculation points per fruit (two wounded and two unwounded). Six fruit mock-inoculated with 5 µl sterile water were used as controls. Inoculated fruit were placed in moist chamber and incubated at 25°C during 10 days. Anthracnose lesions appeared at 2 and 4 days after inoculation in wounded and unwounded points, respectively. After 7 days, disease incidence was 100% and 67% for wounded and unwounded fruit, respectively. The control treatment remained symptomless. The pathogens were re-isolated from all lesions and re-identified as C. siamense. C. siamense was previously reported in South Carolina causing anthracnose on peach (Hu et al. 2015). To our knowledge, this is the first report of anthracnose disease on peach caused by C. siamense in Uruguay. Effective management strategies should be implemented to control anthracnose and prevent the spread of this disease to other commercial peach orchards.

Urban residential energy switching in China between 1980 and 2014 prevents 2.2 million premature deaths

Urban residential energy switching in China between 1980 and 2014 prevents 2.2 million premature deaths

Contribution of Biophysical Factors to Regional Variations of Evapotranspiration and Seasonal Cooling Effects in Paddy Rice in South Korea

Previous studies have observed seasonal cooling effects in paddy rice as compared to temperate forest through enhanced evapotranspiration (ET) in Northeast Asia, while rare studies have revealed biophysical factors responsible for spatial variations of ET and its cooling effects. In this study, we adopted a data fusion method that integrated MODIS 8-day surface reflectance products, gridded daily climate data of ground surface, and a remote sensing pixel-based Penman-Monteith ET model (i.e., the RS–PM model) to quantify ET patterns of paddy rice in South Korea from 2011 to 2014. Results indicated that the regional variations of the rice-growing season ET (RGS-ET, the sum of daily ET from the season onset of rapid canopy expansion (SoS) to the end of the rice-growing season (EGS)) were primarily influenced by phenological factors (i.e., the length of growing period-LGP), followed by growing season mean climatic factors (i.e., vapor pressure deficit-VPD, and air temperature). For regional variations of the paddy field ET (PF-ET, the sum of daily ET from the field flooding and transplanting date detected by satellite observations (FFTDsat) to SoS, and to EGS), the extents were substantially reduced, only accounting for 54% of the RGS-ET variations. The FFTDsat and SoS were considered critical for the reduced PF-ET variations. In comparison to the temperate forest, changes in monthly ground surface air temperature (Ts) in paddy fields showed the V-shaped seasonal pattern with significant cooling effects found in late spring and early summer, primarily due to a large decline in daytime Ts that exceeded the nighttime warming. Bringing FFTDsat towards late spring and early summer was identified as vital field management practices, causing significant declines in daytime Ts due to enhanced ET. Results highlighted climate-warming mitigation by paddy fields due to early flooding practices.

Dynamics of interfacial gravity–capillary waves in three-dimensional fluids of great depth

This paper proposes a new isotropic bidirectional model for weakly nonlinear gravity–capillary waves propagating between two incompressible, inviscid, and immiscible fluids of different densities. The newly developed equation is a generalization of the celebrated two-dimensional Benjamin equation. It is derived based on the nonlocal formulation of water wave (i.e., the Ablowitz–Fokas–Musslimani formulation) and computed with the modified exponential time-differencing method. It is found that horizontally two-dimensional, fully localized traveling waves (known as lumps) exist in the model equation, and plane solitary waves are unstable subject to long transverse perturbations, which evolve into groups of lumps in the long-term dynamics. When considering topographical disturbances on the rigid upper boundary, the nonlinear effect becomes important when a uniform flow passes beneath a locally confined topography with a near-critical speed, and the phenomenon of time-periodic shedding of lumps occurs. Unlike the near-critical situation, the subcritical flows usually generate steady elevation waves, while the supercritical ones produce a V-shaped pattern of wake lines. Furthermore, it is shown that a uniformly accelerated motion can also generate lumps provided that the flow stays in the transcritical regime for a considerably long time.

Chasing Diamonds and Crowns: Consumer Limited Attention and Seller Response

Online platforms often assign sellers summary symbols based on whether their ratings pass certain thresholds. Consumers may focus on the symbols and pay limited attention to the ratings. This bias leads to discontinuously increased demand at the thresholds. I use a theoretical model to illustrate that sellers will lower the prices before their ratings reach the thresholds and increase their prices afterward due to the positive demand shock. I collect data from Taobao to test the theoretical predictions. Using regression discontinuity, I find that on the demand side, the hourly sales increase significantly when a seller passes the threshold, even conditional on the same item. On the supply side, the prices indeed exhibit a V-shaped pattern with respect to the ratings. Furthermore, sellers preemptively increase prices shortly before reaching thresholds, supporting the theoretical predictions. This paper was accepted by Juanjuan Zhang, marketing.

The Association Pattern between Ambient Temperature Change and Leukocyte Counts.

Ambient temperature change is one of the risk factors of human health. Moreover, links between white blood cell counts (WBC) and diseases have been revealed in the literature. Still, we do not know of any association between ambient temperature change and WBC counts. The aim of our study is to investigate the relationship between ambient temperature change and WBC counts. We conducted this two-year population-based observational study in Kaohsiung city, recruiting voluntary community participants. Total WBC and differential counts, demographic data and health hazard habits were collected and matched with the meteorological data of air-quality monitoring stations with participants’ study dates and addresses. Generalized additive models (GAM) with penalized smoothing spline functions were performed for the trend of temperature changes and WBC counts. There were 9278 participants (45.3% male, aged 54.3 ± 5.9 years-old) included in analysis. Compared with stable weather conditions, the WBC counts were statistically higher when the one-day lag temperature changed over 2 degrees Celsius, regardless of whether colder or hotter. We found a V-shaped pattern association between WBC counts and temperature changes in GAM. The ambient temperature change was associated with WBC counts, and might imply an impact on systematic inflammation response.

The Focusing Waves Induced by Bragg Resonance with V-Shaped Undulating Bottom

Intensive wave reflection occurs when the wavelengths of the incident waves and bottom undulations are in a 2:1 ratio. Existing studies have included the Bragg resonance phenomenon of waves passing over a continuous undulating bottom parallel to and oblique to the shoreline. More generally, the Bragg resonance mechanism is used as a means of coastal protection, rather than wave power generation. To focus the wave energy in a specific area, here, we propose sinusoidal sandbars of a horizontal V-shaped pattern, which is formed by two continuous undulating bottoms inclined at an angle to each other and the center axis of the angle is perpendicular to the shoreline. Based on the high-order spectral (HOS) numerical model, both the characteristics of Bragg resonance induced by the regular waves and random waves are investigated. In the scenario of regular waves, it shows that the wave-focusing effect is related to the angle of the V-shaped undulating bottom, and the optimal angle of inclination for the V-shaped undulating bottom is 162.24°. On that basis, considering the interactions between the random waves and the V-shaped undulating bottom of 162.24°, the Bragg resonance characteristics of random waves are studied. The BFI factor combining wave steepness and spectrum width can evaluate the focusing intensity of the Bragg resonance of the random waves. For BFI, in the range of 0.15–1.0, the values of Hsmax/Hs0 linearly increase with the increase of BFI.

LILRB1: A Novel Diagnostic B-Cell Marker to Distinguish Neoplastic B Lymphoblasts From Hematogones.

New B-cell markers are needed for monitoring B lymphoblastic leukemia (B-ALL) in the era of immunotherapies directed against CD19 and CD22. The expression of leukocyte immunoglobulin-like receptor subfamily B member 1 (LILRB1) on hematogones in bone marrow (BM) and neoplastic B lymphoblasts has not yet been systematically investigated. We assessed LILRB1 expression pattern on B cells in 19 control BMs and 22 B-ALL cases by flow cytometry. In all cases, mature B cells and hematogones exhibited a consistent pattern of LILRB1 expression with variable intensity over different stages of maturation, including a characteristic V-shaped pattern on hematogones. While neoplastic B lymphoblasts in all cases expressed LILRB1, the pattern of expression was distinctly abnormal relative to hematogones (loss of the dynamic pattern in all cases and abnormal expression levels in 83% of cases). LILRB1 is a novel diagnostic B-cell marker to aid in distinguishing neoplastic B lymphoblasts from hematogones.

Modeling of Diurnal Changing Patterns in Airborne Crop Remote Sensing Images

Airborne remote sensing technologies have been widely applied in field crop phenotyping. However, the quality of current remote sensing data suffers from significant diurnal variances. The severity of the diurnal issue has been reported in various plant phenotyping studies over the last four decades, but there are limited studies on the modeling of the diurnal changing patterns that allow people to precisely predict the level of diurnal impacts. In order to comprehensively investigate the diurnal variability, it is necessary to collect time series field images with very high sampling frequencies, which has been difficult. In 2019, Purdue agricultural (Ag) engineers deployed their first field visible to near infrared (VNIR) hyperspectral gantry platform, which is capable of repetitively imaging the same field plots every 2.5 min. A total of 8631 hyperspectral images of the same field were collected for two genotypes of corn plants from the vegetative stage V4 to the reproductive stage R1 in the 2019 growing season. The analysis of these images showed that although the diurnal variability is very significant for almost all the image-derived phenotyping features, the diurnal changes follow stable patterns. This makes it possible to predict the imaging drifts by modeling the changing patterns. This paper reports detailed diurnal changing patterns for several selected plant phenotyping features such as Normalized Difference Vegetation Index (NDVI), Relative Water Content (RWC), and single spectrum bands. For example, NDVI showed a repeatable V-shaped diurnal pattern, which linearly drops by 0.012 per hour before the highest sun angle and increases thereafter by 0.010 per hour. The different diurnal changing patterns in different nitrogen stress treatments, genotypes and leaf stages were also compared and discussed. With the modeling results of this work, Ag remote sensing users will be able to more precisely estimate the deviation/change of crop feature predictions caused by the specific imaging time of the day. This will help people to more confidently decide on the acceptable imaging time window during a day. It can also be used to calibrate/compensate the remote sensing result against the time effect.

Strategic Trading When Central Bank Intervention Is Predictable

Abstract Market prices are noisy signals of economic fundamentals. In a two-period model, we show that if the central bank uses market prices as guidance for intervention, large strategic investors who benefit from high prices would depress market prices to induce a market-supportive intervention. Stronger anticipated interventions lead to deeper price depressions preintervention and sharper price reversals post-intervention. The central bank intervention harms strategic investors even though it is the investors who tried to mislead the central bank. The model predicts a V-shaped price pattern around central bank interventions, consistent with recent evidence. (JEL G14, G18)

Molecular markers of Neoproterozoic-Lower Paleozoic petroleum systems and their geological significance: A case study of the cratonic basins in western China

In this article, we report the investigation of the Ediacaran and Lower Paleozoic petroleum systems using their molecular markers. The cratonic basins located in western China were selected as a case study, whereas worldwide published samples where compiled for comparison. The study aimed in characterizing specifically and generally the molecular markers, and providing their geological significance as well. Gas chromatography-mass spectrometry experiments (GC-MS) were applied on Ediacaran reservoir solid bitumen extracts (Dengying Formation, member-Z2dn2) and Cambrian oil/rock extracts samples respectively from Sichuan Basin and Tarim Basin. The results show a predominance of n-alkanes over isoprenoids (e.g. Pr/nC17, Ph/nC18), a noticeable absence of 25-norhopane and monoaromatic steroids among all the samples. The values of pristane to phytane ratio (Pr/Ph) fall below 0.8 for all the solid bitumen samples, whereas they are equal to 0.9, on average, for the Lower-Middle Cambrian oils and rock extracts. Relatively high values of gammacerane to C30 17α (H)-hopane ratio (G/C30H), low values of C30 17α (H)-diahopane/C30H (average = 0.09), and a V-shaped distribution pattern for the following C29–C28–C27 regular steranes with C27 > C29 > C28 and C28 < C27 < C29 respectively for Ediacaran and Cambrian samples, have been noticed as well. Moreover, the values of the following ratios: ββ/(ββ+αα) and 20S/(20S + 20R) C29 steranes, tricyclic terpanes/(tricyclic terpanes +17α-hopanes), and Ts/(Ts + Tm) fall below their respective equilibrium endpoints, notwithstanding the calculated equivalent vitrinite reflectance values range within 1.69%–2.20%. The data shows that the source rocks of all the Ediacaran and Lower-Middle Cambrian samples of the western China were deposited in an anoxic and stratified environment, with the initial organic matter showing a prevalence of type II kerogen (marine algal). The organic matter have experienced none or at least a very slight biodegradation rate, in spite that the maturity rate corresponds to post-maturity level.

Naïve Earnings Growth Extrapolation

Exploiting the unique financial reporting format in China, we document that stocks with the strongest past year-to-date earnings growth experience a significant price run-up of 1.2% during the five trading days before their quarterly earnings announcements and a significant return reversal of -1.35% in the five trading days afterward. This inverted V-shaped pattern on cumulative return spreads is more pronounced among smaller firms with lower institutional ownership and fewer analyst coverage, and it is less pronounced among foreign B-share. Consistent with investor excess demand driving the price run-up, we find retail investor sentiment and buy-sell order imbalance rise ahead of earnings announcements for firms with high past earnings growth. Our findings support models of fundamental extrapolation and suggest investors naively extrapolate the salient but not-so-informative year-to-date earnings growth when forming expectations about the upcoming earnings.

Efficient adhesion of bubble on superhydrophobic tapered groove surface

Efficient adhesion of gas bubbles in aqueous environments has great application potentials in various gas-related processes, especially in wastewater treatment. In previous research, much attention has been paid to the design of underwater bubbles transport platforms, however, the bubble adhesion abilities of them are explored insufficiently. Herein, we investigated the bubble adhesion abilities of the superhydrophobic V-shaped pattern (SVP) and a designed superhydrophobic tapered groove (STG). It is revealed that the STG exhibits efficient bubble adhesion abilities compared with the SVP, including bubble retention time (t), adhesion volume and holding efficiency (η). In addition, the STG can retain stable adhesion abilities after several adhesion cycles. We believe that these results provide an alternative approach for subaqueous bubble practical applications.

Effects of different plasma expanders on rats subjected to severe acute normovolemic hemodilution

BackgroundPlasma expanders are widely used for acute normovolemic hemodilution (ANH). However, existing studies have not focused on large-volume infusion with colloidal plasma expanders, and there is a lack of studies that compare the effects of different plasma expanders.MethodsThe viscosity, hydrodynamic radius (Rh) and colloid osmotic pressure (COP) of plasma expanders were determined by a cone-plate viscometer, Zetasizer and cut-off membrane, respectively. Sixty male rats were randomized into five groups with Gelofusine (Gel), Hydroxyethyl Starch 200/0.5 (HES200), Hydroxyethyl Starch 130/0.4 (HES130), Hydroxyethyl Starch 40 (HES40), and Dextran40 (Dex40), with 12 rats used in each group to build the ANH model. ANH was performed by the withdrawal of blood and simultaneous infusion of plasma expanders. Acid-base, lactate, blood gas and physiological parameters were detected.ResultsGel had a lower intrinsic viscosity than HES200 and HES130 (P < 0.01), but at a low shear rate in a mixture of colloids, red cells and plasma, Gel had a higher viscosity (P < 0.05 or P < 0.01, respectively). For hydroxyethyl starch plasma expanders, the COP at a certain concentration decreases from 11.1 mmHg to 6.1 mmHg with the increase of Rh from 10.7 nm to 20.2 nm. A severe ANH model, with the hematocrit of 40% of the baseline level, was established and accompanied by disturbances in acid-base, lactate and blood gas parameters. At the end of ANH and 60 min afterward, the Dex40 group showed a worse outcome in maintaining the acid-base balance and systemic oxygenation compared to the other groups. The systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) decreased significantly in all groups at the end of ANH. The DBP and MAP in the Dex40 group further decreased 60 min after the end of ANH. During the process of ANH, the Dex40 group showed a drop and recovery in SBP, DBP and MAP. The DBP and MAP in the HES200 group were significantly higher than those in the other groups at some time points (P < 0.05 or P < 0.01).ConclusionGel had a low intrinsic viscosity but may increase the whole blood viscosity at low shear rates. Rh and COP showed a strong correlation among hydroxyethyl starch plasma expanders. Dex40 showed a worse outcome in maintaining the acid-base balance and systemic oxygenation compared to the other plasma expanders. During the process of ANH, Dex40 displayed a V-shaped recovery pattern for blood pressure, and HES200 had the advantage in sustaining the DBP and MAP at some time points.

Experimental substantiation of the layout of external fixation apparatus for lengthening the tibia in children

Achondroplasia is a genetically caused disease, which is accompanied mainly by a violation of the growth of the skeleton and limbs in length. Most authors came to the conclusion that it is advisable to carry out the elongation simultaneously on the symmetrical segments, and begin with the legs. At the same time, the authors note a significant number of complications, among which the most severe are the appearance of secondary deformations of the segment during distraction. Objective: to determine the stabilizing capabilities of external fixators (EF) with their various configurations in the experiment on physical models. Methods: an experimental study was carried out on physical models of plastic tibia that was cut in the upper third of the diaphysis. In the experimental group, EF were fixed on the model according to the author’s scheme with a V-shaped arrangement of rods in the proximal tibia (3 models). As a comparison group, we used models with EF, which were fixed according to the «classical» scheme with the location of all the rods in one plane (3 models). All models were tested under axial compressive loads. Bending loads were performed in two planes: parallel and perpendicular to the support beam of the EF. Results: at compression loads of up to 50 N, the displacement of the proximal fragments of the tibia does not have statistically significant differences (p = 0.066). At loads of 100 N or more, the EFs, which were fixed according to the V-shaped scheme, provided smaller displacements of the proximal fragment of the tibia in the diastasis zone compare to EFs with an in-line layout of the rods. At loads of 50 and 150 N, the in-line arrangement of the EF provides a statistically significantly less (at the level of p = 0.001 and 0.019, respectively) displacement of the proximal tibia fragment in the area of EF application of the load than the EF according to the V-shaped pattern. At loads of 100 and 200 N, there is no statistically significant difference between the displacements of the fragments in the both models. (р > 0.2). Under bending loads in the plane perpendicular to the supporting beam of the EF, devices with a V-shaped arrangement provide more stable fixation of the proximal fragment of the tibia than comparative model. Conclusions: the V-shaped arrangement of the EF allows statistically significantly stabilize fixation of fragments of the tibia than the EF with the in-line layout of the rods in almost all the studied loading methods.

Modeling of fiber-optic strain responses to hydraulic fracturing

We modeled cross-well strain/strain rate responses of fiber optic sensing, including distributed strain sensing (DSS) and low-frequency distributed acoustic sensing (DAS), to hydraulic stimulation. DSS and low-frequency DAS have been used to measure strain or the strain rate to characterize hydraulic fractures. However, the current application of DSS/DAS is limited to acquisition, processing, and qualitative interpretations. The lack of geomechanical models hinders the development of the technology toward quantitative interpretation and inversion. We have developed a strategy to use the displacement discontinuity method to model the strain field around kinematically propagating fractures. For a horizontal monitoring well, modeling results were able to explain the heart-shaped extending pattern before a fracture hit, the polarity flip due to fracture interaction during stimulation, and the V-shaped pattern when a fracture does not intersect with the monitoring well. For a vertical monitoring well, modeling shows the different characters of strain rate responses when a fracture is near and far away from a vertical monitoring well. We also investigated the effects of fractures with various geometries such as elliptic and layered fractures. We compared and verified the modeling with field data from the Hydraulic Fracturing Test Site 2, a research experiment performed in the Permian Basin. Our modeling work can be used to identify patterns in field observations. The results also help to improve acquisition design and lay the groundwork for quantitative interpretation and inversion.

Temperature Structures of Embedded Disks: Young Disks in Taurus Are Warm

Abstract The chemical composition of gas and ice in disks around young stars sets the bulk composition of planets. In contrast to protoplanetary disks (Class II), young disks that are still embedded in their natal envelope (Class 0 and I) are predicted to be too warm for CO to freeze out, as has been confirmed observationally for L1527 IRS. To establish whether young disks are generally warmer than their more evolved counterparts, we observed five young (Class 0/I and I) disks in Taurus with the Atacama Large Millimeter/submillimeter Array, targeting C17O 2 − 1, H2CO , HDO , and CH3OH 5 K − 4 K transitions at 0.″48 × 0.″31 resolution. The different freeze-out temperatures of these species allow us to derive a global temperature structure. C17O and H2CO are detected in all disks, with no signs of CO freeze-out in the inner ∼100 au and a CO abundance close to ∼10−4. The H2CO emission originates in the surface layers of the two edge-on disks, as witnessed by the especially beautiful V-shaped emission pattern in IRAS 04302+2247. HDO and CH3OH are not detected, with column density upper limits more than 100 times lower than for hot cores. Young disks are thus found to be warmer than more evolved protoplanetary disks around solar analogs, with no CO freeze-out (or only in the outermost part of ≳100 au disks) or processing. However, they are not as warm as hot cores or disks around outbursting sources and therefore do not have a large gas-phase reservoir of complex molecules.