Single and multiple-group penalized factor analysis: a trust-region algorithm approach with integrated automatic multiple tuning parameter selection

Penalized factor analysis is an efficient technique that produces a factor loading matrix with many zero elements thanks to the introduction of sparsity-inducing penalties within the estimation process. However, sparse solutions and stable model selection procedures are only possible if the employed penalty is non-differentiable, which poses certain theoretical and computational challenges. This article proposes a general penalized likelihood-based estimation approach for single and multiple-group factor analysis models. The framework builds upon differentiable approximations of non-differentiable penalties, a theoretically founded definition of degrees of freedom, and an algorithm with integrated automatic multiple tuning parameter selection that exploits second-order analytical derivative information. The proposed approach is evaluated in two simulation studies and illustrated using a real data set. All the necessary routines are integrated into the R package penfa

Graphene-based dental adhesive with anti-biofilm activity

BACKGROUND: Secondary caries are considered the main cause of dental restoration failure. In this context, anti-biofilm and bactericidal properties are desired in dental materials against pathogens such as Streptococcus mutans. To this purpose, graphene based materials can be used as fillers of polymer dental adhesives. In this work, we investigated the possibility to use as filler of dental adhesives, graphene nanoplatelets (GNP), a non toxic hydrophobic nanomaterial with antimicrobial and anti-biofilm properties. RESULTS: Graphene nanoplatelets have been produced starting from graphite intercalated compounds through a process consisting of thermal expansion and liquid exfoliation. Then, a dental adhesive filled with GNPs at different volume fractions has been produced through a solvent evaporation method. The rheological properties of the new experimental adhesives have been assessed experimentally. The adhesive properties have been tested using microtensile bond strength measurements (µ-TBS). Biocidal activity has been studied using the colony forming units count (CFU) method. The anti-biofilm properties have been demonstrated through FE-SEM imaging of the biofilm development after 3 and 24 h of growth. CONCLUSIONS: A significantly lower vitality of S. mutans cells has been demonstrated when in contact with the GNP filled dental adhesives. Biofilm growth on adhesive-covered dentine tissues demonstrated anti-adhesion properties of the produced materials. µ-TBS results demonstrated no significant difference in µ-TBS between the experimental and the control adhesive. The rheology tests highlighted the necessity to avoid low shear rate regimes during adhesive processing and application in clinical protocol, and confirmed that the adhesive containing the 0.2%wt of GNPs possess mechanical properties comparable with the ones of the control adhesive

Battery- and Petrol-Powered Chainsaws: An Investigation of Productivity in Conifer Thinning

In recent years, battery technology has been greatly improved and some types of battery chainsaws are currently comparable with light-type petrol machines, suggesting their possible introduction into forest operations. In this context, the aim of this study was to test and compare the performance, in a Douglas-fir thinning, of two chainsaws similar in terms of weight and power, the Stihl MS 220 CB battery-powered saw and the Stihl MS 201 CM petrol-powered saw, measuring the working times and calculating the productivities. The results showed that, within a working day (about 6 h gross time), an average of 15 trees of 0.56 m3 was felled in each area. No statistically significant differences between the two chainsaws were found in terms of gross and net productivity; and the same result was obtained when focusing the analysis only on operations conducted using the chainsaws. Moreover, the average battery charge duration was 1.04 h, while the full tank duration for the petrol model was 1.12 h. In conclusion, our study demonstrates that, on the basis of their performance, battery chainsaws can be introduced into thinning operations, but a solution is needed to manage batteries in the forest, since the actual need is for 7–8 charges per workday

Comparing the Productivity of the Latest Models of Li-Ion Battery and Petrol Chainsaws in a Conifer Clear-Cut Site

The recent technological development of batteries has allowed the production of powerful tools that are also used in forestry operations. For this reason, this study aimed to compare the performance of two latest chainsaw models in a conifer clear-cut. The examined chainsaws, the battery-powered Stihl MSA 300 and the petrol-powered MS 261 C-M, have comparable power and weight. The overall working times were recorded and then gross, net and felling/processing productivities were quantified. Our findings reported that in a working day (7.4 h gross time), each chainsaw felled and processed an average of 20 trees of 0.64 m3 with an average diameter at breast height of 28 cm. Considering the net productivity, no statistically significant differences were recorded between the two chainsaws. Investigating the productivities on operations conducted using the chainsaws, the battery chainsaw showed a lower average tree-processing productivity than that recorded for the petrol chainsaw. On average, the battery duration was 0.88 h, while the petrol tank duration was 0.97 h. Our study shows that battery chainsaws have great potential in forestry operations; however, considering the actual need for 8 charges per standard workday, optimizing battery management is an important objective for future work

Impacts of wood extraction on soil: assessing rutting and soil compaction caused by skidding and forwarding by means of traditional and innovative methods

Intensive forestry operations may cause soil compaction, plastic soil disturbances and rutting, which are responsible for undesirable effects on soils, vegetation and water bodies. Despite the numerous studies aimed to identify the main factors affecting soil damages, it still remains unclear whether wood extraction methods and driving direction (uphill or downhill) may affect the impacts of forest machines. This research analyses soil compaction and soil penetration resistance as well as rutting from forwarding and skidding using the same farm tractor in up- and downhill wood extraction. Rutting was estimated by 3D soil reconstruction derived by portable laser scanning (PLS) and close-range photogrammetry using structure for motion (SfM). Our findings showed that the direction of extraction did not affect soil damage severity during forwarding on a 25% slope. On the contrary, in order to reduce soil compaction, downhill skidding is preferable to uphill skidding. The results showed that the pressure on the ground caused by vehicles can be distributed horizontally, thus affecting also the soil between the wheel tracks. The soil bulk density inside the tracks after 10 forwarding passes increased by 40% and with 23% between the wheel tracks. The soil displacement in skidding trails (7.36 m(3) per 100 m of trail) was significantly higher than in forwarding (1.68 m(3) per 100 m of trail). The rutting estimation showed no significant difference between the PLS and SfM methods, even comparing the two digital surface models (DSMs) obtained, even if photogrammetry was preferred for technical and practical reasons

Buone prassi per la riduzione degli impatti durante le operazioni di esbosco

La pubblicazione affronta varie tematiche inerenti l'impiego di macchine e attrezzature altamente meccanizzate per l'esbosco dei prodotti legnosi e analizza in dettaglio le buone prassi raccomandate per ridurre gli impatti al suolo di macchine che sono sempre più potenti e pesanti. Risultati conclusivi del progetto SKIDDFOR

Serum concentrations of perfluorinated alkyl substances in farmers living in areas affected by water contamination in the Veneto Region (Northern Italy)

Abstract Human exposure to per- and polyfluorinated alkyl substances (PFASs) is a major public health concern because in the last decades several cases of overexposure of people to PFASs, in particular through contaminated water, occurred worldwide. In 2013–2017 a PFAS drinking water contamination was discovered and investigated in northern Italy (Veneto region) and high PFAS serum levels were detected in exposed people. 629 subjects were enrolled: 257 residing in municipalities in the areas under impact, 250 residing in municipalities in areas at presumed background exposure and 122 farmers living in contaminated rural areas producing and consuming own livestock and vegetables and frequently using well water. The highest PFAS serum concentrations (median PFOA concentrations 40 ng/g) were found in the subgroup of farmers. The main factors influencing PFAS serum levels of farmers were residence area and the related extent of drinking water contamination, gender, years of residence in the municipalities, well water consumption and consumption of own produced food. PFOA serum concentrations in farmers residing in the areas of the Veneto region impacted by PFAS contamination are among the highest found worldwide

A Comparison between the Latest Models of Li-Ion Batteries and Petrol Chainsaws Assessing Noise and Vibration Exposure in Cross-Cutting

Chainsaw operators are exposed to many hazards that can lead to health problems. The two most frequently documented ergonomics threats in the use of chainsaws are noise and vibration exposure. Since the use of battery chainsaws is increasing due to the growing improvements in battery life and power, the study aims to compare the difference in terms of noise emission and vibration levels of the following two new models of chainsaws: the battery-powered Stihl MSA 300 and the petrol-powered Stihl MS 261 C-M. Black pine and European beech logs were cross-cut in order to evaluate both noise and vibration exposure. The results show that the use of battery-powered chainsaws, in comparison to the petrol one, can reduce the daily vibration exposure by more than 51% and the noise dose by 11%. The daily vibration exposure of 1.60 ms−2 and 1.67 ms−2 measured for the battery-powered chainsaw on Black pine and on European beech, respectively, is far from the daily exposure action value set by the EU directives for health and safety requirements (2.5 ms−2). On the contrary, the daily noise exposure for the battery chainsaw was 93 dB(A), exceeding the upper exposure action value of 85 dB(A)