Abstract
Autoregressive Moving Average (ARMA) time series model fitting is a procedure often based on aggregate data, where parameter estimation plays a key role. Therefore, we analyze the effect of temporal aggregation on the accuracy of parameter estimation of mixed ARMA and MA models. We derive the expressions required to compute the parameter values of the aggregate models as functions of the basic model parameters in order to compare their estimation accuracy. To this end, a simulation experiment shows that aggregation causes a severe accuracy loss that increases with the order of aggregation, leading to poor accuracy.

Abstract
Dysfunction of arteriovenous access for hemodialysis is a challenge for the vascular surgeon. Some patients have complex vascular access with problems that are difficult to solve. Careful analysis of the vascular network with ultrasound and dissection of the veins during surgery can help to identify the best option for each access. We introduce and discuss the case of creation of a radio-cephalic fistula with outflow into the brachial vein in 64-year-old hemodialysis male patient. This technique enables extending fistula patency, arterializing the brachial vein, and improves cost efficiency.

Abstract
Vascular access dysfunction is a serious problem in dialysis units. Some patients have complex dysfunctions that are difficult to resolve. In this article, we report the case a of two patients with radiocephalic arteriovenous fistulae (RC-AVF) who had stenosis/occlusion of the forearm median vein and where we used the basilic vein of the forearm as a solution. We reviewed the use of this surgical solution in RC-AVF. Two male patients on hemodialysis exhibited stenosis/occlusion of the forearm median vein. The forearm basilic vein was isolated and rotated toward the forearm median vein in order to solve RC-AVF problems. One patient had fistula thrombosis 5 months after the procedure, while for the other patient, the fistula continues to work without problems. Literature describes only a few cases using the forearm basilic vein or the brachial vein for fistula recovery. This procedure increased the patency of fistulas. This approach has been proven to be a good solution for solving outflow problems using the superficial or deep veins, increasing fistula patency and avoiding the need to place a central venous catheter and all the related complications.

Abstract
Teaching/educating patients with end stage renal disease (ESRD) and identifying their self-care behaviors for vascular network preservation are very important. However, the self-care behaviors regularly performed by patients are still unknown. We compared self-care behaviors for vascular network preservation performed by patients who are/are not followed-up by the nephrologist. The study design was a prospective, observational and comparative study. Inclusion criteria were as follows: ESRD patients (at stages 4 or 5); at least 18 years old; in pre-dialysis with at least a 6-month follow-up period by the nephrologist or who started dialysis in emergency and were not followed-up by the nephrologist; with no memory problems; and medically stable. Primary outcome was the frequency of self-care behaviors for vascular network preservation. Secondary outcome was the comparison between self-care behaviors by ESRD patients who were/were not followed-up by the nephrologist. The study involved 145 patients, 64.1% were female, the mean age was 69.5 years and the self-care behaviors mean score was 36.8% (with a SD of 39.8%). The number of patients followed-up and not followed-up by the nephrologist was 109 (group 1) and 36 (group 2), respectively. Social characteristics were similar in the two groups (P > 0.05). The mean self-care behaviors were 29.4% and 59.2% in groups 1 and 2, respectively (P = 0.000). Patients performed self-care behaviors for vascular network preservation with a relatively low frequency (the mean score was 36.8% only). Patients not followed by the nephrologist performed self-care behaviors more often than those who were followed (59.2% vs. 29.4% respectively, P = 0.000).

Abstract
The size of a farm is one of the factors that influence its productivity, in an ambiguous relationship that is often discussed in the industrial economy. In Portugal, the Demarcated Douro Region (DDR) is characterized by very small farms. Usually, this trend is considered a limitating factor in the profitability of the wine farms. In order to assess the correctness of this sentence, the variation of wine productivity per land size, from 2010 to 2016, was studied in the DDR, considering its three distinctive areas: Baixo Corgo, Cima Corgo and Douro Superior. The farms were categorized in nine different size ranges; as these variables outnumber the available seven observations, the Generalized Maximum Entropy (GME) estimator was used, since it suits the need to solve an ill-conditioned problem. GME was applied with the MATLAB (MATrix LABoratory) software along with the Bootstrap technique. According to the simulations, larger farms (with an area greater than 20 ha) on Douro Superior and Cima Corgo reveal higher marginal productivity given the current state of the region. On the other hand, Baixo Corgo's results suggest that medium-sized farms (with area ranges between 2 and 5 ha) display higher marginal increments to the region wine productivity. © 2018 UniCeSV, University of Florence

Abstract
Understanding the role of the climate on the wine production is one of the major concerns of this sector since the environment usually determines the output of this industry. There are only a few previous studies that attempted to compile these environmental effects as an index, usually considering the temperature and the precipitation as their core variables. The present study suggests a new climate index which is based on descriptive statistics. Our index tries to mimic the target region characteristics and avoid the past studies premise of imposing previously conceived restrictions such as a fixed optimal climate. We then used yearly production and daily temperature data (1950-2016) from the Portuguese Minho wine region to test our proposed index and compare it with Ribéreau-Gayon and Peynaud (RGP, Ribéreau-Gayon et al., 2003) and Growing Degree-Days (GDD, Winkler et al., 1974) indexes. Our results showed that the newly proposed index may outperform the explanatory power of the other indexes and, in addition, may output interesting and unknown characteristics such as the different ideal temperatures regarding the studied region. © The Authors, published by EDP Sciences, 2018.