By carefully observing shear bands generated by tensile deformation in a transmission electron microscope, we report evidence of shear delocalization in a Cu-based glass containing nanoparticle ...dispersions. Nanocrystals grow in shear bands, delocalize the shear and deviate and blunt cracks. The results are consistent with matter in operating shear bands behaving like a semi-solid slurry.
Direct drilling systems usually have lower traffic intensities than those using conventional tillage, but despite this, after several years of continuous direct drilling yields tend to decrease. This ...could be the result of increased weed control problems and root diseases as well as a gradual increase in soil compaction due to agricultural traffic. The draft required, soil cone index, root growth, soybean (
Glycine max L.) yield and traffic (planters and tractors) compaction over the subsequent three growing seasons were measured. This initially high level of soil compaction in some direct sowing systems might suggest that the impact of subsequent traffic would be minimal, but data have not been consistent. Soil compaction is caused by the high traffic intensity and weight of tractor and seeding machines and combines in harvest operations, especially when these operations are carried out on wet soil or with high ground pressure. The techniques commonly used for control and management of topsoil and subsoil compaction are: subsoiling and chiseling and axle load reduction. Outlined hypothesis was: Traffic with high axle load equipment increases soil compaction and decreases soybean yield. This article quantifies: (a) the effects of subsoiling and chisel plowing were carried out at 350 and 280
mm depth, respectively, on soil compacted under 12 years of direct drill systems and (b) traffic effect on this soil conditions of two equipment for direct sowing (planters and tractors) on soybean yields (
G. max L.) with two different loads: light equip (LE) and heavy equip (HE). The study showed that: In topsoil for three growing season, traffic with HE (185
kN) caused mean values of CI of 2178, 1506 and 1406
kPa for direct sowing, chiseled and subsoiled soil, respectively, while for the LE (127
kN) the values were of 1855, 1210 and 1206
kPa, respectively. Also in the subsoil traffic with HE caused higher CI values than the LE in all treatments. The CI mean values of the HE traffic were: 2465, 1920 and 1854
kPa for direct sowing, chiseled and subsoiled soil, respectively, while the LE traffic produced 2298, 1639 and 1637
kPa, respectively. For three growing seasons the HE traffic in soil under direct sowing reduces soybean grain yields close to 460
kg
ha
−1, while for the LE was 250
kg
ha
−1. When the traffic was made with LE on subsoiled soil there is an effective increase in soybean grain yields of about 330
kg
ha
−1.
Selecting the appropriate tyre configuration and settings for heavy farm vehicles is important to ensure that soil compaction and power loss in rolling resistance are minimised and traction is ...optimised. This study investigated the effect of front-wheel assist (FWA, ≈75 kN) and four-wheel drive (4 WD, ≈100 kN) tractors fitted with different tyre configurations (single, dual), tyre sizes and inflation pressures on soil strength (a proxy for soil compaction), and rolling resistance. Single-pass tests were performed on a Typic Argiudoll (≈23% clay, bulk density: 1305 kg m−3) managed under permanent no-tillage. Results showed that average power losses in rolling resistance were 7.5 kN and 5 kN for the 4 WD and FWA tractors, respectively. The average rut depth increased by approximately 1.4 times after a pass of the 4 WD compared with the FWA tractor. The soil cone index (0–600 mm depth) increased from 2023 kPa (before traffic) to 2188 and 2435 kPa after single passes of the FWA and 4WD tractors, respectively (p < 0.05). At the centreline of the tyre rut, dual tyres reduced the soil cone index a little compared with single tyres, but they significantly increased the volume of soil over which soil strength, and therefore soil compaction, was increased. For both tractors (regardless of tyre configuration or settings), soil strength increased to the full measured depth (600 mm), but relative changes before vs. after traffic became progressively smaller with increased soil depth. The power loss in rolling resistance was consistently greater with the heavier tractor, and rut depth was directly related to tyre inflation pressure.
Patients with a single small Hepatocellular Carcinoma (HCC) may be definitively treated by Radiofrequency ablation (RFA) with a very low rate of peri-operative morbidity. However, results are still ...controversial comparing RFA to Liver Resection (LR).
All consecutive patients treated by RFA or LR for a single untreated small HCC on liver cirrhosis between January 2006-December 2016 were enrolled. Patients were matched 1:1 basing on: age, MELD-score, platelet count, nodule's diameter, HCV status, α-fetoprotein level, and Albumin-Bilirubin score. First analysis compered LR to RFA. Second analysis compared Laparoscopic LR (LLR) to RFA.
Of 484 patients with single small HCC, 91 patients were selected for each group after a 1:1 propensity score matching (PS-M). The 5-years OS was 70% and 60% respectively for LR and RFA group (P = 0.666). The 5-year RFS was 36% and 21% respectively for LR and RFA group (P < 0.001). Patients treated by LR had a significantly longer hospital stay and higher complications rate. Comparing 50 cases of LLR and 50 of RFA, the 5-years OS was 79% and 56% respectively for LLR and RFA group (P = 0.22). The 5-year RFS was 54% and 19% respectively for LR and RFA group (P < 0.001). Post-operative complications were not significantly different.
LLR confers similar peri-operative complications rate compared to RFA. LLR should be considered as a first-line approach for the treatment of a single small HCC as it combines the effectiveness of open LR and the safety profile of RFA.
Patient-specific absorbed dose calculation for nuclear medicine therapy is a topic of increasing interest. 3D dosimetry at the voxel level is one of the major improvements for the development of more ...accurate calculation techniques, as compared to the standard dosimetry at the organ level. This study aims to use the FLUKA Monte Carlo code to perform patient-specific 3D dosimetry through direct Monte Carlo simulation on PET-CT and SPECT-CT images. To this aim, dedicated routines were developed in the FLUKA environment. Two sets of simulations were performed on model and phantom images. Firstly, the correct handling of PET and SPECT images was tested under the assumption of homogeneous water medium by comparing FLUKA results with those obtained with the voxel kernel convolution method and with other Monte Carlo-based tools developed to the same purpose (the EGS-based 3D-RD software and the MCNP5-based MCID). Afterwards, the correct integration of the PET/SPECT and CT information was tested, performing direct simulations on PET/CT images for both homogeneous (water) and non-homogeneous (water with air, lung and bone inserts) phantoms. Comparison was performed with the other Monte Carlo tools performing direct simulation as well. The absorbed dose maps were compared at the voxel level. In the case of homogeneous water, by simulating 10(8) primary particles a 2% average difference with respect to the kernel convolution method was achieved; such difference was lower than the statistical uncertainty affecting the FLUKA results. The agreement with the other tools was within 3–4%, partially ascribable to the differences among the simulation algorithms. Including the CT-based density map, the average difference was always within 4% irrespective of the medium (water, air, bone), except for a maximum 6% value when comparing FLUKA and 3D-RD in air. The results confirmed that the routines were properly developed, opening the way for the use of FLUKA for patient-specific, image-based dosimetry in nuclear medicine.
The increasing availability of SPECT/CT devices with advanced technology offers the opportunity for the accurate assessment of the radiation dose to the biological target volume during radionuclide ...therapy. Voxel dosimetry can be performed employing direct Monte Carlo radiation transport simulations, based on both morphological and functional images of the patient. On the other hand, for voxel dosimetry calculations the voxel S value method can be considered an easier approach than patient-specific Monte Carlo simulations, ensuring a good dosimetric accuracy at least for anatomic regions which are characterized by uniform density tissue. However, this approach has been limited because of the lack of tabulated S values for different voxel dimensions and radionuclides. The aim of this work is to provide a free dataset of values which can be used for voxel dosimetry in targeted radionuclide studies. Seven different radionuclides (89Sr, 90Y, 131I, 153Sm, 177Lu, 186Re, 188Re), and 13 different voxel sizes (2.21, 2.33, 2.4, 3, 3.59, 3.9, 4, 4.42, 4.8, 5, 6, 6.8 and 9.28 mm) are considered. Voxel S values are calculated performing simulations of monochromatic photon and electron sources in two different homogeneous tissues (soft tissue and bone) with DOSXYZnrc code, and weighting the contributions on the basis of the radionuclide emission spectra. The outcomes are validated by comparison with Monte Carlo simulations obtained with other codes (PENELOPE and MCNP4c) performing direct simulation of the radionuclide emission spectra. The differences among the different Monte Carlo codes are of the order of a few per cent when considering the source voxel and the bremsstrahlung tail, whereas the highest differences are observed at a distance close to the maximum continuous slowing down approximation range of electrons. These discrepancies would negligibly affect dosimetric assessments. The dataset of voxel S values can be freely downloaded from the website www.medphys.it.
Ipsilateral breast cancer recurrence (IBTR) occurs in about 7% of patients with primary invasive breast tumor. Salvage mastectomy and breast reconstruction are often discussed and latissimus dorsi ...(LD) flap is frequently proposed.
We retrospectively investigated 111 consecutive locally relapsing patients who underwent salvage mastectomy and immediate LD reconstruction. All included patients with IBTR previously underwent conserving surgery for BC, and received a postoperative irradiation. Primary endpoints were disease free survival and overall survival. Secondary endpoints were surgical complications and re-interventions.
Invasive ductal cancer was the most frequent histotype (60.4%) of breast cancer reappearance. rpT1, rpT2 and rpT3 were observed respectively in 50.5%, 20,7% and 3,6% of the patients. rpTis occurred in 11,7% of cases. Positive axillary nodes were observed in 9,9% of patients at reappearance. Post-operative complication other than seroma occurred in 17,1% of patients, while seroma at the donor site was observed in 61.3% of cases. At 5-year after surgery overall survival was 92% (95% CI: 85%–96%) and disease free survival was 78% (95% CI: 69%–85%).
Immediate latissimus dorsi flap reconstruction in selected patients with isolated breast tumor recurrence, which occurred after breast irradiation, provides an effective treatment with a satisfactory outcome.
Background: Indices for predicting survival are essential for assessing prognosis and assigning priority for liver transplantation in patients with liver cirrhosis. The model for end stage liver ...disease (MELD) has been proposed as a tool to predict mortality risk in cirrhotic patients. However, this model has not been validated beyond its original setting. Aim: To evaluate the short and medium term survival prognosis of a European series of cirrhotic patients by means of MELD compared with the Child-Pugh score. We also assessed correlations between the MELD scoring system and the degree of impairment of liver function, as evaluated by the monoethylglycinexylidide (MEGX) test. Patients and methods: We retrospectively evaluated survival of a cohort of 129 cirrhotic patients with a follow up period of at least one year. The Child-Pugh score was calculated and the MELD score was computed according to the original formula for each patient. All patients had undergone a MEGX test. Multivariate analysis was performed on all variables to identify the parameters independently associated with one year and six month survival. MELD values were correlated with both Child-Pugh scores and MEGX test results. Results: Thirty one patients died within the first year of follow up. Child-Pugh and MELD scores, and MEGX serum levels were significantly different among patients who survived and those who died. Serum creatinine, international normalised ratio, and MEGX60 were independently associated with six month mortality while the same variables and the presence of ascites were associated with one year mortality. MELD scores showed significant correlations with both MEGX values and Child-Pugh scores. Conclusions: In a European series of cirrhotic patients the MELD score is an excellent predictor of both short and medium term survival, and performs at least as well as the Child-Pugh score. An increase in MELD score is associated with a decrease in residual liver function.
Background and aims: Cirrhotic patients frequently undergo screening endoscopy for the presence of oesophageal varices (OV). In the future, this social and medical burden will increase due to the ...greater number of patients with chronic liver disease and their improved survival. In this study, our aims were (1) to identify clinical, biochemical, and ultrasonographic parameters which might non-invasively predict the presence of OV in patients with liver cirrhosis; (2) to evaluate the reproducibility of the obtained results in a different, although related, further group of patients; and (3) to assess the predictiveness of the identified rules in patients with compensated cirrhosis. Methods: In the first part of the study we retrospectively evaluated the presence of OV in 145 cirrhotic patients, and in the second part we evaluated the reproducibility of the study results in a subsequent group of 121 patients. Finally, we evaluated these parameters in a subgroup of 145 patients with compensated disease. All 266 patients underwent a complete biochemical workup, upper digestive endoscopy, and ultrasonographic measurement of spleen bipolar diameter. Platelet count/spleen diameter ratio was calculated for all patients. Results: The prevalence rates of OV were 61% and 58% in the first and second groups of patients, respectively. In the first part of the study, we found that platelet count, spleen diameter, platelet count/spleen diameter ratio, and Child- Pugh class were significantly different among patients with or without OV, although the platelet count/spleen diameter ratio was the only parameter which was independently associated with the presence of OV in a multivariate analysis. A platelet count/spleen diameter ratio cut off value of 909 had 100% negative predictive value for a diagnosis of OV. This result was reproduced in the second group of patients as well as in patients with compensated disease. In a cost-benefit analysis, screening cirrhotic patients according to the “platelet count/spleen diameter ratio strategy” was far more cost effective compared with the “scope all strategy”. Conclusions: The platelet count/spleen diameter ratio is the only parameter which is independently associated with the presence of OV, and its negative predictive value is reproducible. Its use is of value even in the subgroup of patients with compensated disease, and it is also cost effective.
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