Comprehensive Analysis of a Dense Sample of FRB 121102 Bursts

We present an analysis of a densely repeating sample of bursts from the first repeating fast radio burst, FRB 121102. We reanalyzed the data used by Gourdji et al. and detected 93 additional bursts using our single-pulse search pipeline. In total, we detected 133 bursts in three hours of data at a center frequency of 1.4 GHz using the Arecibo telescope, and develop robust modeling strategies to constrain the spectro-temporal properties of all of the bursts in the sample. Most of the burst profiles show a scattering tail, and burst spectra are well modeled by a Gaussian with a median width of 230 MHz. We find a lack of emission below 1300 MHz, consistent with previous studies of FRB 121102. We also find that the peak of the log-normal distribution of wait times decreases from 207 to 75 s using our larger sample of bursts, as compared to that of Gourdji et al. Our observations do not favor either Poissonian or Weibull distributions for the burst rate distribution. We searched for periodicity in the bursts using multiple techniques, but did not detect any significant period. The cumulative burst energy distribution exhibits a broken power-law shape, with the lower- and higher-energy slopes of −0.4 ± 0.1 and −1.8 ± 0.2, with the break at (2.3 ± 0.2) × 1037 erg. We provide our burst fitting routines as a Python package burstfit 4 4 https://github.com/thepetabyteproject/burstfit that can be used to model the spectrogram of any complex fast radio burst or pulsar pulse using robust fitting techniques. All of the other analysis scripts and results are publicly available. 5 5 https://github.com/thepetabyteproject/FRB121102

Driving Safety Assurance Method in Work Zone Crossovers of Highway Reconstruction and Expansion Project

Work zone crossover is an important area in highway reconstruction and expansion projects because it profoundly impacts the traffic safety and efficiency of the construction sites. This research sets the different median opening widths in the driving simulation experiment, collects the vehicle control signal parameters during entrance by-pass and exit by-pass, and analyzes the driving characteristics in these sections. Comparison of the driving features between the simulation experiment and the actual driving under the same median width has been also made. We should set the median width separately because the results show that driving behaviors significantly differ between entrance by-pass and exit by-pass. When the median opening width is 70 m, the driving simulation experiment and actual driving characteristics are quite different. However, both show that driving factors of the entrance and exit by-pass are not the same. When there are two lanes in the traffic control zone and the speed limit is 60 km/h, we should set the median width at 90 m to ensure transportation safety.

Design of median ends at at-grade intersection layout plans

Median represents a portion of an urban road separating opposing directions of the traveled way. Due to their function to provide enough space for separate traffic lane and storage of left-turning vehicles, the medians are highly desirable on city arteries carrying two or more lanes per travel direction. Type and dimensions of turning vehicles significantly affect the design of a median openings and median ends. The design solution and the geometry of median ends should be based on the composition of all left-turning movements occurring simultaneously at at-grade intersection. After selection of design vehicles for swept path analysis of the characteristic turning maneuvers in intersection, larger vehicles should be further checked for their ability to turn without undue encroachment on adjacent traffic lanes. The critical design parameter is the median width, especially at the ends of the median openings. Dragging paths of left-turning vehicles shape the median ends geometry. In traditional design practice established in Europe, three-centered compound curves with radii rations R1 : R2 : R3 = 2 : 1 : 3 and R1 : R2 : R3 = 2.5 : 1 : 5.5 are used to approximate dragging pahs of turning vehicles. In this paper, considering the median width, the deficiencies of the traditional design approach are revealed and new findings regarding the design of the median ends at at-grade intersections are presented.

Primary Reattachment of Near-Complete Ear Amputation: A Successful Outcome

Objectives: Traumatic amputation of the ear constitutes a great aesthetic deformity that can have a tremendous negative impact. Reports describing the survival of near-complete ear amputation using non-microsurgical replantation are scarce. We aimed to study the surgical outcome of patients with near-complete ear amputations supplied by small pedicle bridges that were treated with primary reattachment. Methods: We retrospectively studied patients with near-complete ear amputation who were admitted at Al Ain Hospital from January 2016 to December 2019. Results: Five patients were studied. The most common mechanism of injury was motor vehicle injury, followed by cutting injury. The skin pedicle was inferior in 3 (60%) patients of patients. The median width of the skin pedicles was 8.5 mm. The median interval between the injury and the surgical management was 4 hours. All patients underwent primary reattachment of the ear without microsurgery. One patient developed a small area of necrosis of the ear lobe. All patients recovered with a completely healed pinna and satisfactory overall appearance. Conclusions: Primary reattachment without microsurgery of the near-complete ear amputation can be safely performed in the presence of an intact skin pedicle. It can achieve an aesthetically satisfactory outcome without severe complications.

Probing the initial conditions of high-mass star formation

Context. The initial stage of star formation is a complex area of study because of the high densities (nH2 > 106 cm−3) and low temperatures (Tdust < 18 K) involved. Under such conditions, many molecules become depleted from the gas phase by freezing out onto dust grains. However, the deuterated species could remain gaseous under these extreme conditions, which would indicate that they may serve as ideal tracers. Aims. We investigate the gas dynamics and NH2D chemistry in eight massive precluster and protocluster clumps (G18.17, G18.21, G23.97N, G23.98, G23.44, G23.97S, G25.38, and G25.71). Methods. We present NH2D 111–101 (at 85.926 GHz), NH3 (1, 1), and (2, 2) observations in the eight clumps using the PdBI and the VLA, respectively. We used 3D GAUSSCLUMPS to extract NH2D cores and provide a statistical view of their deuterium chemistry. We used NH3 (1, 1) and (2, 2) data to investigate the temperature and dynamics of dense and cold objects. Results. We find that the distribution between deuterium fractionation and kinetic temperature shows a number density peak at around Tkin = 16.1 K and the NH2D cores are mainly located at a temperature range of 13.0 to 22.0 K. The 3.5 mm continuum cores have a kinetic temperature with a median width of 22.1 ± 4.3 K, which is obviously higher than the temperature in NH2D cores. We detected seven instances of extremely high deuterium fractionation of 1.0 ≤ Dfrac ≤ 1.41. We find that the NH2D emission does not appear to coincide exactly with either dust continuum or NH3 peak positions, but it often surrounds the star-formation active regions. This suggests that the NH2D has been destroyed by the central young stellar object (YSO) due to heating. The detected NH2D lines are very narrow with a median width of 0.98 ± 0.02 km s−1, which is dominated by non-thermal broadening. The extracted NH2D cores are gravitationally bound (αvir < 1), they are likely to be prestellar or starless, and can potentially form intermediate-mass or high-mass stars in future. Using NH3 (1, 1) as a dynamical tracer, we find evidence of very complicated dynamical movement in all the eight clumps, which can be explained by a combined process with outflow, rotation, convergent flow, collision, large velocity gradient, and rotating toroids. Conclusions. High deuterium fractionation strongly depends on the temperature condition. Tracing NH2D is a poor evolutionary indicator of high-mass star formation in evolved stages, but it is a useful tracer in starless and prestellar cores.

Investigating the Effects of Pavement Roughness on Freeway Safety using Data from Five States

Traffic crashes occur usually because of a combination of human, roadway/environment, and vehicle factors. Pavement condition is closely related to these three factors as it is one of the most important roadway/environment factors and it affects driving behavior and vehicle performance at the same time. Previous studies have shown that pavement condition plays an important role in safety. This study develops four different safety performance functions to evaluate the effect of pavement roughness, measured by the International Roughness Index (IRI), on the number of crashes using the interstate highway data from five U.S. states representing different geographical and weather regions: Arizona, Colorado, Florida, Maryland, and Michigan. The modeling results identify many significant variables including traffic volume and proportion of trucks, through lane count, shoulder type, median width, high-occupancy vehicle (HOV) lane operation and HOV lane count, speed limit, area type along with IRI-related factors. The results indicate that increased IRI (deterioration of pavement quality) contributes to large numbers of total crashes. On interstate highways with speed limits of 70 mph and higher, the effects of IRI are relatively smaller. On the other hand, the effects of IRI increase with a larger traffic volume. Based on the modeling results, seven crash modification functions of IRI values by crash type and speed limit were estimated. The findings from this study are expected to be useful for both pavement and safety engineers to understand the relationship between IRI and safety on freeways.

Traffic Control Devices for Deterring Wrong-Way Movements at Unsignalized Intersections on Divided Highways

Motorists driving the wrong way on divided roadways has been an area of concern for over 50 years. However, little is known about the nature of wrong-way crashes on divided highways. Thus, the research team conducted exploratory and statistical analyses to assess the effects of median width and select traffic control devices upon wrong-way crashes on high-speed divided highways. The exploratory analysis revealed that most of the wrong-way crashes on high-speed divided highways resulted in serious injury and happened at night. More than two-thirds of the wrong-way crashes resulted from a wrong-way maneuver at an intersecting roadway where a median opening was present. The statistical analysis found numerous sites where the traffic control in the median opening did not fully comply with the Manual on Uniform Traffic Control Devices (MUTCD) with respect to treating the location as one or two intersections. There was also evidence from the statistical analysis that the 30-ft median width threshold may not be appropriate for distinguishing between one or two intersections. In addition, researchers were able to identify several traffic control devices that may be effective in reducing wrong-way movements on high-speed divided highways. The final effort of the project was to develop recommended MUTCD language for implementing the research findings. The recommended language includes a new method for distinguishing between divided highway crossings that function as a single intersection or two separate intersections, thereby eliminating the 30-ft median width threshold used in the current MUTCD.

DESAIN TEBAL PERKERASAN TERHADAP VOLUME LALU LINTAS PADA KONDISI TANAH RAWA JALAN LABUHA–TOMORI BACAN KABUPATEN HALMAHERA SELATAN

This research was carried out on Jalan Oesman Shah on Labuha-Tomori Road. In determiningflexible pavement thickness, based on the results of analysis and calculation of PavementThickness Design Against Traffic Volume on Swamp Conditions on the Labuha-Tomori RoadSection using the Road Pavement Design Manual Number 02 / M / BM / 2013. Based on theexisting plan, this Labuha-Tomori road section in South Halmahera Regency, North MalukuProvince is an arterial road with 2-lane 2-way road type using the median (2/2 UD), plan width of10 meters, width of existing traffic lane 4, 5 meters, median width of 1 meter, and plannedshoulder width 2.40 m. Based on the results of the analysis of growth rates obtained traffic growthrates of 33.066% over the life of the plan, determining the distribution factor of the lane and thecapacity of the lane of lane 1 and the vehicle in the design lane taken 100%. The equivalent loadfactor can be determined using the value of VDF (Vehicle Damage Factor) according to thesurvey results in the field. The traffic volume plan to determine the CESA4 value = 18,835,021.85= 18.84 million is used for the selection of pavement types while the CESA5 value =33,903,039.33 = 33.90 million is used to determine the type of flexible pavement based on thedesign chart provided in The Road Pavement Design Manual Number 02 / M / BM / 2013, ishighly emphasized in terms of the improvement of subgrade, by looking at the condition of theCBR of the subgrade and CESA5 which will be received by pavement. So if the pavement CBR is5.20% and CESA5 is 33.90 Million, the flexible pavement design is of 2 kinds in the design ofpavement thickness: AC - WC = 4 cm, AC - BC = 15.5 cm, CTB = 15 cm, LPA Class A = 15 cm,Choice of 10 cm and AC - WC = 4 cm, AC - BC = 6 cm, AC BASE = 18 cm, LPA = 30 cm, Choiceof Stock = 10 cm, and Subgrade = 5.20%

Investigating and Modeling the Illegal U-Turn Violations at Medians of Limited Access Facilities

Illegal U-turns on freeways and toll roads are risky maneuvers that sometimes result in the turning vehicles causing various types of collisions or disturbances to approaching traffic. These illegal U-turn maneuvers can occur at traversable grass medians and emergency crossovers. Limited literature was found regarding the impact of illegal U-turns on these facilities. Therefore, to understand the roadway and median characteristics that could influence drivers’ propensity to commit illegal U-turns, a sequential modeling methodology was adopted. This methodology combined a Poisson regression model with a Least Absolute Shrinkage and Selection Operator (LASSO) regression procedure to predict the cited violations at traversable median segments. Additionally, a logistic regression model was developed to predict the probability of a cited violation at official use only emergency crossovers. These models included illegal U-turn citations and crashes for the Orlando and Miami metropolitan areas in Florida from 2011 to 2016. The findings indicated that the average distance between access points, median width, speed limit, segment length, and distance to nearest segment were significant in predicting cited violations at traversable medians. Furthermore, the distance to the nearest interchange, distance to the nearest adjacent crossover, and median width were significant in predicting the probability of a cited violation occurring at an emergency crossover. This study helps agencies to predict the locations of illegal U-turn violations and to prioritize roadways for possible treatment to minimize the potential risk of head-on or other collisions due to illegal U-turn events.