Large Field Sizes Research Articles

Validation of the Elekta Synergy Platform Linac at 6 MV Photon Beam using PRIMO Monte Carlo Software

Aims: The objective was to validate the initial beam parameters of the Davao Doctors Hospital’s 6 MV Elekta Synergy Platform linac, which performs to the specification of the commissioning data per our records using the gamma-index analysis toolkit integrated inside PRIMO software. Materials and Methods: In PRIMO, a sequence of optimization processes is performed, in which the measured and simulated percent depth dose (PDD) and lateral beam profiles at various depths are compared, using the stringent gamma-index passing rate at 1%/1 mm criteria (GPR11). Using four fields of sizes 3 cm × 3 cm, 4 cm × 4 cm, 5 cm × 5 cm, and 10 cm × 10 cm, the dose is calculated on a water phantom measuring 16.2 cm × 16.2 cm × 30.0 cm. In addition, one field of size 20 cm × 20 cm is used on a 50.0 cm × 50.0 cm × 30.0 cm water phantom with a bin size of 0.2 cm × 0.2 cm × 0.2 cm at a source-surface distance of 100.0 cm. Results: For PDD and beam profiles comparison at the largest field size, the 6.5 MeV initial electron beam energy, 0.25 MeV full-width-half-maximum energy, 0.20 cm focal spot size, and 3° beam divergence tuned configuration yield GPR11 values of 94.0% and 97.7% (PRIMO PDD and lateral beam profile at 200 mm scan depth, respectively) with a statistical uncertainty of 2.9%. For lower field sizes, the GPR11 values are consistent at more than 90% for the PDD, whereas GPR11 values of 80.3% and 70.6% for the lateral beam profiles (at 15 mm and 200 mm scan depths) at 10 cm × 10 cm and 5 cm × 5 cm, respectively. The percentage difference between the measured and simulated PDD 20,10 ratios of not more than 2.45% is observed in all field settings. Conclusions: These tuned beam parameters are remarkably in agreement with the suggested beam parameters listed on the PRIMO website for the 6 MV Elekta linac which was optimized with a different set of measurements.

63: Assessment of various dosimetric correction factors for small and large field sizes of photon beams

63: Assessment of various dosimetric correction factors for small and large field sizes of photon beams

MR compatible detectors assessment for a 0.35 T MR-linac commissioning

PurposeTo assess a large panel of MR compatible detectors on the full range of measurements required for a 0.35 T MR-linac commissioning by using a specific statistical method represented as a continuum of comparison with the Monte Carlo (MC) TPS calculations. This study also describes the commissioning tests and the secondary MC dose calculation validation.Material and methodsPlans were created on the Viewray TPS to generate MC reference data. Absolute dose points, PDD, profiles and output factors were extracted and compared to measurements performed with ten different detectors: PTW 31010, 31021, 31022, Markus 34045 and Exradin A28 MR ionization chambers, SN Edge shielded diode, PTW 60019 microdiamond, PTW 60023 unshielded diode, EBT3 radiochromic films and LiF µcubes. Three commissioning steps consisted in comparison between calculated and measured dose: the beam model validation, the output calibration verification in four different phantoms and the commissioning tests recommended by the IAEA-TECDOC-1583.Main resultsThe symmetry for the high resolution detectors was higher than the TPS data of about 1%. The angular responses of the PTW 60023 and the SN Edge were − 6.6 and − 11.9% compared to the PTW 31010 at 60°. The X/Y-left and the Y-right penumbras measured by the high resolution detectors were in good agreement with the TPS values except for the PTW 60023 for large field sizes. For the 0.84 × 0.83 cm2 field size, the mean deviation to the TPS of the uncorrected OF was − 1.7 ± 1.6% against − 4.0 ± 0.6% for the corrected OF whereas we found − 4.8 ± 0.8% for passive dosimeters. The mean absolute dose deviations to the TPS in different phantoms were 0 ± 0.4%, − 1.2 ± 0.6% and 0.5 ± 1.1% for the PTW 31010, PTW 31021 and Exradin A28 MR respectively.ConclusionsThe magnetic field effects on the measurements are considerably reduced at low magnetic field. The PTW 31010 ionization chamber can be used with confidence in different phantoms for commissioning and QA tests requiring absolute dose verifications. For relative measurements, the PTW 60019 presented the best agreement for the full range of field size. For the profile assessment, shielded diodes had a behaviour similar to the PTW 60019 and 60023 while the ionization chambers were the most suitable detectors for the symmetry. The output correction factors published by the IAEA TRS 483 seem to be applicable at low magnetic field pending the publication of new MR specific values.

Woody semi‐natural habitats modulate the effects of field size and functional crop diversity on farmland birds

Abstract Agricultural intensification has simplified landscape composition and configuration, which has led to biodiversity declines. Increasing landscape‐wide crop heterogeneity can promote farmland biodiversity. However, knowledge is still lacking on how the effects of configurational and compositional crop heterogeneity (i.e. field size and crop diversity) are modulated by the amount of semi‐natural habitats in the landscape, especially across large scales. We tested how mean field size and functional crop diversity affect farmland bird diversity and abundance over three consecutive years, and how these effects are modulated by the amount of small woody features (SWF) in the landscape. We related data from a national bird monitoring scheme to field‐level information from a novel, high‐resolution remote sensing‐based crop type map. Smaller field sizes and higher functional crop diversity were not generally associated with a higher diversity or abundance of farmland birds. Associations varied with species' breeding habitat preferences and were modulated by the amount of SWF. In landscapes with a low SWF amount, species diversity and the abundance of species breeding in field edges or shrubs were negatively associated with increasing field size. However, where the amount of SWF was high, larger field size was associated with higher species diversity and abundance of field and shrub breeders. Diversity increased with higher functional crop diversity, as did the abundance of non‐field breeders in landscapes with a medium to high SWF amount. Field size tended to have a stronger effect on bird diversity and abundance than functional crop diversity. Policy implications: National and EU agricultural policies should adopt a landscape perspective by considering the amount of semi‐natural habitats when designing biodiversity‐enhancing measures that target field size and functional crop diversity. In landscapes with low SWF amount, decreasing field sizes may be particularly effective to promote farmland bird diversity and the abundance of non‐field breeders. In landscapes with a medium to high SWF amount, increasing functional crop diversity is likely more effective than reducing field sizes. Field and shrub breeders may be promoted by maintaining landscapes with large fields, only if these offer a high SWF amount, low agronomic yield potential and low productivity.

Error-Correcting Codes with Large Field Size under Non-Binary Segmented Burst Deletion/Insertion Channels and Unknown Codeword Boundaries

Error-Correcting Codes with Large Field Size under Non-Binary Segmented Burst Deletion/Insertion Channels and Unknown Codeword Boundaries

Factors shaping insectivorous farmland bird abundance in intensively cultivated arable fields: Insights through the former Iron Curtain

The decline of farmland bird populations is a well-documented phenomenon that has primarily been attributed to agricultural intensification. However, the specific mechanisms that make intensively used farmland unsuitable for breeding birds have not yet been satisfactorily elucidated, particularly for insectivorous ground-nesting species. To bridge this knowledge gap, we studied the breeding abundance, invertebrate food supply and habitat characteristics of the Yellow Wagtail (Motacilla flava) in arable fields in the lowlands of south-western Slovakia. This region is characterized by the largest field sizes in the European Union, with conditions that are typical for high-intensity farmland areas in parts of Central and Eastern Europe where farmland underwent collectivization. Since Central and Eastern European farmland is considered one of the strongholds of the Yellow Wagtail in Europe, we tested the capacity of winter wheat, rapeseed and maize to support its local population. The Yellow Wagtail abundance was best predicted by habitat characteristics: birds chose fields without woody plants in their surroundings and with suitable crop height and coverage, while the effect of invertebrate food supply was insignificant. Focussing on individual crops, we found that the birds did not prefer the maize and rapeseed fields despite these having a richer food supply, likely because these crops had an unsuitable vegetation structure. The low overall abundance of the studied species indicates that farmland consisting of large fields creates unsuitable conditions for breeding. Therefore, agricultural policy instruments leading to a reduction of field size or the creation of herbaceous field edges should be supported.

Convolutional neural networks rarely learn shape for semantic segmentation

Shape learning, or the ability to leverage shape information, could be a desirable property of convolutional neural networks (CNNs) when target objects have specific shapes. While some research on the topic is emerging, there is no systematic study to conclusively determine whether and under what circumstances CNNs learn shape. Here, we present such a study in the context of segmentation networks where shapes are particularly important. We define shape and propose a new behavioral metric to measure the extent to which a CNN utilizes shape information. We then execute a set of experiments with synthetic and real-world data to progressively uncover under which circumstances CNNs learn shape and what can be done to encourage such behavior. We conclude that (i) CNNs do not learn shape in typical settings but rather rely on other features available to identify the objects of interest, (ii) CNNs can learn shape, but only if the shape is the only feature available to identify the object, (iii) sufficiently large receptive field size relative to the size of target objects is necessary for shape learning; (iv) a limited set of augmentations can encourage shape learning; (v) learning shape is indeed useful in the presence of out-of-distribution data.

P17.18.B RADIOTHERAPY IN GLIOBLASTOMA MULTIFORME COULD BE PLANNED WITH MARGINS LESS THAN 2 CM WITH LESS THAN 1 CM FROM THE SURGICAL BED

Abstract BACKGROUND The administration of radiotherapy (Rt) plus adjuvant temozolamide (TMZ) with IMR and VMAT techniques has become an increasingly valuable tool in the local control of glioblastoma multiforme with a survival current Rt techniques allow specific conformation with the use of better radiological images that allow us greater precision. For many years large Rt field sizes have been associated with significant adverse effects.Although we continue to give very wide margins that lead us to irradiate non-compromised organs at risk, which translates into a higher rate of radionecrosis and acute and chronic neurological toxicity.Therefore, we consider it valid to ask ourselves if we could reduce the standard margins applied in the planning of Rt. MATERIAL AND METHODS Analysis of 98 GBM patients treatedat the barros luco hospital between 2021 and 2023 with surgery followed by adjuvant therapy, radiotherapy plus concomitant chemotherapy at the Institute. Nacional de Cáncer de Santiago de Chile we reviewed the time of recurrence and the location in relation to the surgical margins vs. radiotherapy margins or other nearby areas. RESULTS After the analysis, we can see that 65% of the recurrences presented a dominant failure pattern, within the field and less than 1cm from the margin between the surgical bed and the radiotherapy margin, evaluated with perfusion brain resonance imaging and spectroscopy CONCLUSION n the local control of GBM, the application of adjuvant therapy is essential in a period of not less than 2 months after surgery, in this institutional analysis we can observe a considerable number of patients under 40 years of age with this pathology, for which reason to consider reducing the diameter of Rt margins can be considered an option, in order to limit deleterious effects in healthy organs in the times that there are advanced Rt techniques, the increasingly frequent application of brain radiosurgery (SRS) thatIt can be used as a rescue method in case of recurrences at the edge of the margin, using radiological images (MRI with perfusion and spectroscopy/C-methionine PET/CT. Figure we can see the CTV and PTV to be treated with modulated intensity technique, evidencing the large field size that receives radiation between 54 to 60 Gy.Radiation oncology must continue to develop and improve the delivery, targeting, and dose of radiation therapy in the GBM to improve its survival and treatment-associated toxicity.

Poster Session: Towards Understanding Retinal Processing of Single-Cone Scale Stimulation.

The magnocellular (M) visual pathway can be distinguished from its finer-grained parvocellular (P) counterpart by its stronger response gain to contrasts near human detection threshold. This distinction is found when stimulus size is matched to the relatively large receptive field size of M cells, but it is less clear if preserved at smaller spatial scales. We examined foveal detection thresholds in tandem with a masking paradigm known to desensitize the M pathway. We used a custom DLP display in Maxwellian view to present either 3 or 23 arcmin spots for 100 ms against a uniform gray disk (1° VA) surrounded by a 0.5 cpd, 100% contrast, square wave grating flickered at 7 frequencies ranging from 0 to 30 Hz. Detection data were fit with psychometric functions to estimate threshold and thresholds were normalized to the static (0 Hz) condition. Relative sensitivity was fit with a modified impulse response function and compared to a constant model with ANOVA. With masking we found a significant reduction in sensitivity for large (23arcmin) increments (mean=0.39 log units; n=4; p<0.01) and decrements (0.31 log units; n=4; p=0.02)at 8.3Hz. By contrast, no significant masking effect was observed for small spot increments or decrements (p>0.05). These data suggest that the M pathway is not the primary determinant of small spot thresholds under the conditions studied. Further investigation with adaptive optics may be necessary to fully elaborate single-cone processing in the fovea.

Increased flexibility and efficiency of a double-scattering FLASH proton beamline configuration for in vivo SOBP radiotherapy treatments

Objective. To commission a proton, double-scattering FLASH beamline by maximizing efficiency and field size, enabling higher-linear energy transfer FLASH radiotherapy to cells and small animals using a spread-out Bragg peak (SOBP) treatment configuration. We further aim to provide a configuration guide for the design of future FLASH proton double-scattering (DS) beamlines. Approach. Beam spot size and spread were measured with film and implemented into TOol for PArticle Simulation (TOPAS). Monte Carlo simulations were optimized to verify the ideal positioning, dimensions, and material of scattering foils, secondary scatterers, ridge filters, range compensators, and apertures. A ridge filter with three discrete heights was used to create a spread-out Bragg peak (SOBP) and was experimentally verified using our in-house experimental FLASH beamline. The increase in dose rate was compared to nominal shoot-through techniques. Results. The configuration and scatterer distance producing the largest field size of acceptable flatness, without drastically compromising dose rate was determined to be an elliptical field of 2 cm × 1.5 cm (25% larger than a previous configuration). SOBP testing yielded three distinct but connected spikes in dose with flatness under 5%. Reducing the thickness of the (first) scattering foil by a factor of two was found to increase efficiency by 50%. The new settings increased the field size, provided a Bragg peak treatment option, and increased the maximum available dose rate by 85%, as compared to the previous, shoot through method. Significance. Beam line updates established FLASH dose rates of over 135 Gy s−1 (potentially higher) at our double-scattering beamline, increased the efficiency and field size, and enabled SOBP treatments by incorporating an optimized ridge filter. Based on our simulations we provide parametric suggestions when commissioning a new proton DS beamline. This enhanced FLASH beamline for SOBP irradiations with higher dose rates and larger field sizes will enable a wider variety of experimentation in future studies.

Commissioning of Elekta Infinity™ 6 MV flattening filter-free using Monte Carlo simulation

Commissioning a simulation model of the linear accelerator (Linac) in radiotherapy needs to be done to validate the dose distribution accuracy. For this purpose, the Monte Carlo simulation method is commonly employed, and it involves using the EGSnrc software. This software consists of BEAMnrc for modeling Linac and DOSXYZnrc for calculating dose distribution in a water phantom. This study used Monte Carlo simulation to commission the Linac Flattening Filter-Free (FFF) Elekta Infinity™ 6 MV photon mode. The commissioning results show that the simulated dose distribution satisfied the acceptance criteria of simulation results using initial electron energy of 6.9 MeV at 5 × 5, 10 × 10, and 20 × 20 cm2 field sizes with average local difference of percent depth dose (PDD) of about 2.99%. The dose and dmax increasedwith higher initial electron energy increased, while percentage depth dose (PDD) decreased at smaller field sizes. At larger field sizes, the dose profile widened and the PDD Linac FFF decreased more significantly than PDD Linac Flattening Filter (FF). Additionally, both exhibited differences in the uniformity of dose values in the umbra area. The surface dose for a 10 × 10 cm2 field size was 25.2% and 34.4% for both 6 MV-FF and 6 MV-FFF, respectively.

Vegetation Structure and Invertebrate Food Availability for Birds in Intensively Used Arable Fields: Evaluation of Three Widespread Crops

Arable land covers a large part of the European landscape, and its biodiversity is declining rapidly due to agricultural intensification. Among the most threatened groups of organisms are insectivorous ground-foraging farmland birds. To reverse their decline, it is necessary to understand the impact of agriculture on the factors potentially shaping their populations. This study therefore evaluates the invertebrate food availability and vegetation structure of three widespread crops—wheat, maize and rapeseed—during their breeding. This research took place in Slovakia, the country with the largest average field size in the EU. Wheat overlapped bird habitat preferences for the longest part of their breeding season by vegetation structure, but it also had the most limited food supply due to frequent treatment with insecticides. Maize and rapeseed provided higher invertebrate abundance and biomass, but their stands created unsuitable vegetation structures for farmland bird nesting and foraging over a major part of the breeding season. The food supply improved closer to the field edges, but the birds’ ability to use these benefits could be considerably limited by the large field sizes. Therefore, conservation measures should include reduction of field size and insecticide application to improve the food supply and switch to spring sowing to improve the vegetation structure.

Imaging doses for different CBCT protocols on the Halcyon 3.0 linear accelerator – TLD measurements in an anthropomorphic phantom

IntroductionImage guided radiotherapy allows for particularly conformal tumour irradiation through precise patient positioning. Becoming the standard for radiotherapy, this increases imaging doses to the patient. The Halcyon 3.0 linear accelerator (Varian Medical Systems, Palo Alto, CA) requires daily imaging due to its geometry. For this reason, the accelerator is equipped with on-line kV and MV imaging. However, daily CBCT images required for irradiation apply additional radiation, which increases the dose to normal tissue and therefore can affect the patient's secondary cancer risk. In this study, actual organ doses were measured for the kV system, and a comparison of normal tissue doses for all available kV CBCT protocols was presented to demonstrate differences in imaging doses across entities and protocols. In addition, effective dose and secondary cancer risk from imaging are evaluated. Material and methodsMeasurements were performed with thermoluminescent dosimeters in an anthropomorphic phantom positioned according to each entity (brain, head and neck, breast, lung, pelvis). CBCT images were obtained, using all available pre-set protocols without further adjustment of the parameters. Measured doses for each position and each protocol were then compared and secondary cancer risk of relevant and specifically radiosensitive organs was calculated. ResultsIt was found that imaging doses for protocols such as Pelvis and Head could be reduced by up to half using the corresponding Fast and Low Dose modes, respectively. On the other hand, larger field sizes or the Large mode yielded higher doses than their initial protocols. Image Gently was found to spare normal tissue best, however it is not suitable for certain entities due to low image quality or insufficient projection data. DiscussionBy using appropriate kV-CBCT protocols, it is possible to reduce imaging doses to a significant extent and therefore spare healthy tissue. Combined with studies of image quality, the results of this study could lead to adjustments in workflow regarding the choice of protocols used in daily routine. This could prevent unnecessary radiation exposure and reduce secondary cancer risk.

Characterization of 250 MeV Protons from the Varian ProBeam PBS System for FLASH Radiation Therapy.

Shoot-through proton FLASH radiation therapy has been proposed where the highest energy is extracted from a cyclotron to maximize the dose rate (DR). Although our proton pencil beam scanning system can deliver 250 MeV (the highest energy), this energy is not used clinically, and as such, 250 MeV has yet to be characterized during clinical commissioning. We aim to characterize the 250-MeV proton beam from the Varian ProBeam system for FLASH and assess the usability of the clinical monitoring ionization chamber (MIC) for FLASH use. We measured the following data for beam commissioning: integral depth dose curve, spot sigma, and absolute dose. To evaluate the MIC, we measured output as a function of beam current. To characterize a 250 MeV FLASH beam, we measured (1) the central axis DR as a function of current and spot spacing and arrangement, (2) for a fixed spot spacing, the maximum field size that achieves FLASH DR (ie, > 40 Gy/s), and (3) DR reproducibility. All FLASH DR measurements were performed using an ion chamber for the absolute dose, and irradiation times were obtained from log files. We verified dose measurements using EBT-XD films and irradiation times using a fast, pixelated spectral detector. R90 and R80 from integral depth dose were 37.58 and 37.69 cm, and spot sigma at the isocenter were σx = 3.336 and σy = 3.332 mm, respectively. The absolute dose output was measured as 0.343 Gy*mm2/MU for the commissioning conditions. Output was stable for beam currents up to 15 nA and gradually increased to 12-fold for 115 nA. Dose and DR depended on beam current, spot spacing, and arrangement and could be reproduced with 6.4% and 4.2% variations, respectively. Although FLASH was achieved and the largest field size that delivers FLASH DR was determined as 35 × 35 mm2, the current MIC has DR dependence, and users should measure dose and DR independently each time for their FLASH applications.

Assessment of digital light processing (DLP) projector stimulators for visual electrophysiology

IntroductionVisual electrophysiology tests require the use of precise and calibrated visual display units (VDUs). Existing VDUs for presenting structured stimuli are now mostly obsolete, with modern solutions limited or unsuitable for clinical testing. Digital light processing (DLP) laser projectors have recently become commercially available and this study aimed to assess their suitability as VDUs for visual electrophysiology testing.MethodsThis study consisted of two sections. The first was a photometric study of two DLP laser projectors (Viewsonic LS831WU and HiSense 100L5FTUK) to assess luminance, contrast, spectral and temporal characteristics of the stimulus. The second was a physiological study comparing pattern electroretinograms (PERG) and visual evoked potentials (PVEPs) amplitudes and peak-times recorded using a DLP laser projector, photometrically and spatially matched to existing plasma VDUs at our institution (Pioneer Electronics Corporation, PDP422MXE).ResultsThe Viewsonic DLP laser projector was capable of high luminance levels (0–587.5 cd/m2) whilst maintaining contrast above 93%. The temporal properties showed fast rise and fall times of 0.5–1 ms and 0.5–1 ms, respectively, without any transient luminance change with reversals. The device required a warm-up time of at least 2 min until reaching near maximal luminance. The second (Hisense) device was observed to have a detrimental input lag jitter so was not used for any further analysis. PERGs and PVEPs showed high agreement and correlation (r = 0.766–0.905) between the Viewsonic DLP device and existing plasma VDUs. No significant differences were observed for P50 and P100 peak-time (p = > 0.05), however P50, N95 and P100 amplitudes were all significantly larger for the DLP device (p = < 0.05).DiscussionThe DLP laser projector tested in this study is a viable and practical replacement VDU for clinical electrophysiology tests of vision. The device is easily capable of meeting ISCEV standards, and showed PERG and PVEP amplitudes larger than existing systems despite photometric and spatial matching. The DLP laser projectors are capable of very large field sizes so are beneficial for paediatric testing or those wishing to examine large field responses. Importantly, it was observed that some devices may suffer input lag jitter, therefore, individual calibration and assessment of DLP projection systems is an important consideration before clinical implementation.

Large Field-Size Throughput/Area Accelerator for Elliptic-Curve Point Multiplication on FPGA

This article presents a throughput/area accelerator for elliptic-curve point multiplication over GF(2571). To optimize the throughput, we proposed an efficient hardware accelerator architecture for a fully recursive Karatsuba multiplier to perform polynomial multiplications in one clock cycle. To minimize the hardware resources, we have utilized the proposed Karatsuba multiplier for modular square implementations. Moreover, the Itoh-Tsujii algorithm for modular inverse computation is operated using multiplier resources. These strategies permit us to reduce the hardware resources of our implemented accelerator over a large field size of 571 bits. A controller is implemented to provide control functionalities. Our throughput/area accelerator is implemented in Verilog HDL using the Vivado IDE tool. The results after the place-and-route are given on Xilinx Virtex-6 and Virtex-7 devices. The utilized slices on Virtex-6 and Virtex-7 devices are 6107 and 5683, respectively. For the same FPGA devices, our accelerator can operate at a maximum of 319 MHz and 361 MHz. The latency values for Virtex-6 and Virtex-7 devices are 28.73 μs and 25.38 μs. The comparison to the state-of-the-art shows that the proposed architecture outperforms in throughput/area values. Thus, our accelerator architecture is suitable for cryptographic applications that demand a throughput and area simultaneously.

Land transfer in Vietnam and makes specifically proposals for improvement of the Land law

The current land law stipulates that there are two mechanisms for land transfer: voluntary land transfer and compulsory land transfer. Voluntary land transfer applies to cases where individuals and organizations reach their own agreement to perform transactions on land use rights. Compulsory land transfer is carried out through the state mechanisms of land acquisition, compensation, and resettlement support. The article analyzes the legal provisions and practices of land transfer in Vietnam. Regarding the voluntary land transfer mechanism, there are still some shortcomings related to the transfer of agricultural land, the problem of land accumulation for agricultural production according to the policy, and large sample field size, as well as the implementation of commercial projects under the voluntary agreement mechanism. For the mechanism of compulsory land transfer through land acquisition, there are also shortcomings, such as the concept of land acquisition for socio-economic development for the benefit of countries or the public interest being unclear, criteria to determine what a project is for the national interest or the public interest has not been established, compensation prices when land recovery is too low compared to market price. Meanwhile, the issue of compensation, support, and resettlement when the State recovers land is still a problem and has not yet ensured the legitimate interests of people whose land is recovered. Finally, the article proposes some recommendations to improve the land law on land transfer.

Spatiotemporal variations in the eco-health condition of China's long-term stable cultivated land using Google Earth Engine from 2001 to 2019

Long-term stable cultivated land (LSCL) is associated with food security. However, relevant studies about monitoring the eco-health condition (EHC) change of LSCL are insufficient at the national level. In our study, the Google Earth Engine platform and the remote sensing pixel-based ecological index model (RSEI-2) were employed to detect the EHC change tendency of LSCL from 2001 to 2019 at the national level. The results showed that approximately half of the LSCL EHC is increasing (56.57%) in China. The EHC increase was present in northeastern and southwestern of China. The EHC decrease occurred in northwestern China and the Inner Mongolia area, which have low rainfall. The results of drought division have proven that the limitation of rainfall could increase the risk of EHC degradation on the LSCL. The analysis of field size showed that large field size LSCL plots (16–25 ha) could increase the EHC (approximately 8-fold), while the very large field size LSCL plots (25–100 ha) showed little positive effects (approximately 1-fold). Population urbanization has played a negative role in the sustainability of LSCL. Low urbanization showed a significant positive effect on the EHC of LSCL. To protect LSCL, we propose optimizing farmers' cropping structure and management methods through the incentives and supervision of policy instruments.

Random Linear Streaming Codes in the Finite Memory Length and Decoding Deadline Regime—Part I: Exact Analysis

<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Streaming codes</i> take a string of source symbols as input and output a string of coded symbols in real time, which eliminate the queueing delay of traditional <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">block codes</i> and are thus especially appealing for delay sensitive applications. Existing works on streaming code performance either focused on the asymptotic error-exponent analyses, or on the optimal code construction under <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">deterministic adversarial channel models</i> . In contrast, this work analyzes the exact error probability of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">random linear streaming codes</i> (RLSCs) in the large field size regime over the stochastic i.i.d. symbol erasure channel model. A closed-form expression of the error probability of large-field-size RLSCs is derived under, simultaneously, the finite memory length and decoding deadline constraints. The result is then used to examine the intricate tradeoff between memory length (complexity), decoding deadline (delay), code rate (throughput), and error probability (reliability). Numerical evaluation shows that under the same code rate and error probability requirements, the end-to-end delay of RLSCs is 40–48% of that of the optimal block codes (i.e., MDS codes). This implies that switching from block codes to streaming codes not only eliminates the queueing delay completely (which accounts for the initial 50% of the delay reduction) but also improves the reliability (which accounts for the additional 2–10% delay reduction).

Legacy of landscape crop diversity enhances carabid beetle species richness and promotes granivores

It is well understood that agricultural expansion and associated loss of semi-natural habitat in the landscape are major drivers for the marked decline in biodiversity. While conserving remaining semi-natural habitat patches is essential to reverse ongoing biodiversity declines, increasing focus has also been put on diversifying cropland itself by increasing landscape crop diversity as a measure of compositional heterogeneity, and reducing field sizes as a measure of configurational heterogeneity. Both these cropland diversification approaches have shown promise to enhance biodiversity in the year of sampling, but it is unknown whether legacies of crop diversity in the landscape promote biodiversity by building up arthropod communities over time. We selected 14 faba bean fields in landscapes dominated by cropland. The fields were chosen along three gradients: landscape crop diversity of the year of sampling (2017), landscape crop diversity of the previous year (2016) and mean field size in landscapes. Using pitfall traps, we show that the carabid beetle species richness is higher in landscapes with higher crop diversity in the previous year. Especially, granivorous carabid beetles benefitted from legacies of crop diversity. Rove beetles were more abundant and genus rich in landscapes with larger field sizes, while spiders were not responding to any of the landscape variables. A diversity of crops in the landscape and their associated weed communities could provide more diverse food resources and shelter habitats, which build populations of carabid beetle species over time. There is a need to explore the effects of agri-environmental schemes across multiple years to better understand legacy effects, and to structure sustainable agricultural landscapes.