An Evaluation of Non-Contact Photoplethysmography-Based Methods for Remote Respiratory Rate Estimation.

The respiration rate (RR) is one of the physiological signals deserving monitoring for assessing human health and emotional states. However, traditional devices, such as the respiration belt to be worn around the chest, are not always a feasible solution (e.g., telemedicine, device discomfort). Recently, novel approaches have been proposed aiming at estimating RR in a less invasive yet reliable way, requiring the acquisition and processing of contact or remote Photoplethysmography (contact reference and remote-PPG, respectively). The aim of this paper is to address the lack of systematic evaluation of proposed methods on publicly available datasets, which currently impedes a fair comparison among them. In particular, we evaluate two prominent families of PPG processing methods estimating Respiratory Induced Variations (RIVs): the first encompasses methods based on the direct extraction of morphological features concerning the RR; and the second group includes methods modeling respiratory artifacts adopting, in the most promising cases, single-channel blind source separation. Extensive experiments have been carried out on the public BP4D+ dataset, showing that the morphological estimation of RIVs is more reliable than those produced by a single-channel blind source separation method (both in contact and remote testing phases), as well as in comparison with a representative state-of-the-art Deep Learning-based approach for remote respiratory information estimation.

Inferring Causal Factors of Core Affect Dynamics on Social Participation through the Lens of the Observer.

A core endeavour in current affective computing and social signal processing research is the construction of datasets embedding suitable ground truths to foster machine learning methods. This practice brings up hitherto overlooked intricacies. In this paper, we consider causal factors potentially arising when human raters evaluate the affect fluctuations of subjects involved in dyadic interactions and subsequently categorise them in terms of social participation traits. To gauge such factors, we propose an emulator as a statistical approximation of the human rater, and we first discuss the motivations and the rationale behind the approach.The emulator is laid down in the next section as a phenomenological model where the core affect stochastic dynamics as perceived by the rater are captured through an Ornstein-Uhlenbeck process; its parameters are then exploited to infer potential causal effects in the attribution of social traits. Following that, by resorting to a publicly available dataset, the adequacy of the model is evaluated in terms of both human raters' emulation and machine learning predictive capabilities. We then present the results, which are followed by a general discussion concerning findings and their implications, together with advantages and potential applications of the approach.

Using Gaze for Behavioural Biometrics.

A principled approach to the analysis of eye movements for behavioural biometrics is laid down. The approach grounds in foraging theory, which provides a sound basis to capture the uniqueness of individual eye movement behaviour. We propose a composite Ornstein-Uhlenbeck process for quantifying the exploration/exploitation signature characterising the foraging eye behaviour. The relevant parameters of the composite model, inferred from eye-tracking data via Bayesian analysis, are shown to yield a suitable feature set for biometric identification; the latter is eventually accomplished via a classical classification technique. A proof of concept of the method is provided by measuring its identification performance on a publicly available dataset. Data and code for reproducing the analyses are made available. Overall, we argue that the approach offers a fresh view on either the analyses of eye-tracking data and prospective applications in this field.

pyVHR: a Python framework for remote photoplethysmography.

Remote photoplethysmography (rPPG) aspires to automatically estimate heart rate (HR) variability from videos in realistic environments. A number of effective methods relying on data-driven, model-based and statistical approaches have emerged in the past two decades. They exhibit increasing ability to estimate the blood volume pulse (BVP) signal upon which BPMs (Beats per Minute) can be estimated. Furthermore, learning-based rPPG methods have been recently proposed. The present pyVHR framework represents a multi-stage pipeline covering the whole process for extracting and analyzing HR fluctuations. It is designed for both theoretical studies and practical applications in contexts where wearable sensors are inconvenient to use. Namely, pyVHR supports either the development, assessment and statistical analysis of novel rPPG methods, either traditional or learning-based, or simply the sound comparison of well-established methods on multiple datasets. It is built up on accelerated Python libraries for video and signal processing as well as equipped with parallel/accelerated ad-hoc procedures paving the way to online processing on a GPU. The whole accelerated process can be safely run in real-time for 30 fps HD videos with an average speedup of around 5. This paper is shaped in the form of a gentle tutorial presentation of the framework.

Gazing at Social Interactions Between Foraging and Decision Theory.

Finding the underlying principles of social attention in humans seems to be essential for the design of the interaction between natural and artificial agents. Here, we focus on the computational modeling of gaze dynamics as exhibited by humans when perceiving socially relevant multimodal information. The audio-visual landscape of social interactions is distilled into a number of multimodal patches that convey different social value, and we work under the general frame of foraging as a tradeoff between local patch exploitation and landscape exploration. We show that the spatio-temporal dynamics of gaze shifts can be parsimoniously described by Langevin-type stochastic differential equations triggering a decision equation over time. In particular, value-based patch choice and handling is reduced to a simple multi-alternative perceptual decision making that relies on a race-to-threshold between independent continuous-time perceptual evidence integrators, each integrator being associated with a patch.

[Native kidney ultrasound in obstructive uropathy].

The term "obstructive uropathy" refers to the complex structural and functional changes following the interruption of normal urinary runoff, which can occur at every level of the urinary tract. Depending on its origin, duration and severity, urinary tract obstructions can be acute or chronic, mono or bilateral, partial or complete. The obstruction can be localized or extended to the entire pielo-caliceal system and/or homolateral urethra. The term "hydronephrosis" indicates the dilation of the pelvis detected through imaging techniques. Among these, ultrasound is considered the gold standard in the diagnosis of obstructive uropathy: it allows to distinguish three degrees of urinary tract dilation, depending on the extent of the dilation itself and the thickness of the parenchyma. Nephrologists are confronted daily with patients who experience kidney failure and must be able to quickly distinguish between chronic and acute and, in the latter case, to discern between issues of nephrological or urological competence. This short review aims at helping them deal with this very common scenario, through the use of ultrasound.

Robust Single-Sample Face Recognition by Sparsity-Driven Sub-Dictionary Learning Using Deep Features.

Face recognition using a single reference image per subject is challenging, above all when referring to a large gallery of subjects. Furthermore, the problem hardness seriously increases when the images are acquired in unconstrained conditions. In this paper we address the challenging Single Sample Per Person (SSPP) problem considering large datasets of images acquired in the wild, thus possibly featuring illumination, pose, face expression, partial occlusions, and low-resolution hurdles. The proposed technique alternates a sparse dictionary learning technique based on the method of optimal direction and the iterative ℓ 0 -norm minimization algorithm called k-LiMapS. It works on robust deep-learned features, provided that the image variability is extended by standard augmentation techniques. Experiments show the effectiveness of our method against the hardness introduced above: first, we report extensive experiments on the unconstrained LFW dataset when referring to large galleries up to 1680 subjects; second, we present experiments on very low-resolution test images up to 8 × 8 pixels; third, tests on the AR dataset are analyzed against specific disguises such as partial occlusions, facial expressions, and illumination problems. In all the three scenarios our method outperforms the state-of-the-art approaches adopting similar configurations.

[An unusual presentation of Amyloidosis AL].

We describe the case of a 74-year-old man admitted to our Nephrology Unit with nephrotic syndrome and mild kidney disease. A complete panel of laboratoristic and instrumental tests did not provide useful information for diagnosis. No specific signs or symptoms suggested the presence of AL amyloidosis. As a matter of fact, diagnosis was reached thanks to the hystopathologic examination of renal tissue and bone marrow, since the associated B-cell lymphoproliferative disorder had not revealed itself through serum and urine electrophoresis and immunofixation. This recent case provides the opportunity to review about the disease and to revaluate the renal biopsy as a first line exam in a clinical context where laboratoristic and instrumental tests offer us poor information.

[Census of the renal and dialysis units by Italian Society of Nephrology: nephrologist's workload for renal patient assistance in Italy (2014-2015)]. / Censimento a cura della Società Italiana di Nefrologia delle strutture nefrologiche e della loro attività in Italia nel 2014-2015: il lavoro del nefrologo.

BACKGROUND: Given the public health challenge and burden of chronic kidney disease, the Italian Society of Nephrology (SIN) promoted acensusof the renal and dialysis units to analyse structural and human resources, organizational aspects, activities and workload referring to theyear 2014. METHODS: An online questionnaire, including 64 items exploring structural and human resources, organization aspects, activities and epidemiological data referred to 2014, was sent to chiefs of any renal or dialysis unit. RESULTS: Renal and dialysis activity was performed by over 2718 physicians (45 pmp). The management of the acute renal failure was one of the most frequent activities in the public renal units (12,206 patients in ICU and 140.00 dialysis sessions). There were performed about 9000 AV fistulas and 1700 central vascular catheters insertions. In the census, there are a lot of data regarding organization, workforce and workload of the renal unit in Italy. The benchmark data derived from this census show interesting comparisons between centres, regions and groups of regions. These data realised the clinical management of renal disease in Italy.

[Census of the renal and dialysis units by Italian Society of Nephrology: structure and organization for renal patient assistance in Italy (2014-2015)]. / Censimento a cura della Società Italiana di Nefrologia delle strutture nefrologiche e delle loro attività in Italia nel 2014-2015: l'organizzazione.

BACKGROUND: Given the public health challenge and burden of chronic kidney disease, the Italian Society of Nephrology (SIN) promoted a census of the renal and dialysis units to analyse structural and human resources, organizational aspects, activities and workload referring to the year 2014. METHODS: An online questionnaire, including 64 items exploring structural and human resources, organization aspects, activities and epidemiological data referred to 2014, was sent to chiefs of any renal or dialysis unit. RESULTS: 615 renal units were identified. From these 615 units, 332 were public renal centres (of which 318 centres answered to the census) and 283 were private dialysis centres (of which 113 centres answered to the census). The results show 6 public renal units pmp. Renal biopsies were 4624 (81 pmp). The nephrology beds are about 41 pmp. There are 7.304 nurses working in HD wards, 1.692 in the nephrology wards and only 613 for outpatients clinics. The benchmark data derived from this census show interesting comparisons between centres, regions and groups of regions. These data realised the clinical management of renal disease in Italy.

Usefulness of US imaging in overhydrated nephropathic patients.

Achievement of a normal hydration status is one of the major targets of hemodialysis. It is based on the estimation of "dry weight", the term used to define normal body fluid content. The concept of dry weight in hemodialysis patients is clinically undisputed, but it is not always easy to achieve in this population. Assessment of hydration status by clinical evaluation is imprecise and often unreliable. Measurement of the inferior vena cava (IVC) diameter has been shown to reflect individual fluid status. The relationship between variation in IVC diameter before and after hemodialysis session and weight loss has been investigated. Ultrasound (US) measurement of the IVC diameter is considered a valid measure of the hydration status and is routinely used in hemodialysis patients. Moreover, a relationship between IVC diameter, respiratory activity and hydration status, evaluated by considering both plasma volume and central venous pressure, has been demonstrated. In conclusion, assessment of hydration status based on blood pressure and central venous pressure can be considered reliable only in patients without signs of heart failure.

[Radiofrequency in the treatment of the renal neoplasias]. / La radiofrequenza nel trattamento delle neoplasie renali.

The tumors of the kidney are around the 3% of the neoplasia in adult patients and, at the postmortem examination, the renal neoplasias has a frequency of 1/300 for tumors diameter of 1 to 2 cms. In the treatment of the small neoplasias, techniques of nephron sparing and enucleation are used. These techniques have shown the same therapeutic effectiveness of the radical nephrectomy in patients with tumors smaller than 4 centimeters, with reduction of morbidity. However, there are few clinical situation in which the surgery has a high risk: patients with solitary kidney, chronic renal failure, multiple localizations involving also contralateral kidney, in patients with other malignancies and in von Hippel-Lindau Syndrome. Recently, percutaneous mininvasive techniques have been applied (ex. thermoablation): these techniques allow to reduce the duration of general anesthesia, they offer the possibility to use spinal anaesthesia (besides deep sedation and general anaesthesia) with reduction in mortality during surgery. The most commonly used among interstitial therapies is the radiofrequency (RF), which changes electromagnetic waves into heat. RF used both tomography and ultrasound-guided. The latter is the most recommended because it allows to follow the procedure in real-time. The treatment of renal tumors with RF, in which surgery is inadvisable, is safe and effective especially in peripheral and/or exophytic lesions lower than 4 cm. However the larger tumors can also be treated successfully with combined therapy or multiple sessions.

Color Doppler ultrasound and arteriovenous fistulas for hemodialysis.

Native arteriovenous fistula (AVF) is the vascular access of choice for hemodialysis patients. Compared with grafts and central venous catheters, AVFs last longer and are associated with fewer complications. The widespread use of the Doppler ultrasound (DUS) has increased the number of patients who are eligible for AVF by facilitating the identification of vessels that are suitable for fistula construction (preoperative vascular mapping). DUS can also extend native AVF survival by improving the early detection of complications (post-operative surveillance). It is the only imaging modality that furnishes both morphological and functional data on the native vascular access, and it is also the only imaging tool that can be used directly by the surgeon, an indisputable advantage. This review examines the numerous roles played by DUS in the construction and postoperative follow-up of AVFs, including preoperative vascular mapping, AVF maturation, and surveillance.

[Chest ultrasound in nephrology]. / L'ecografia polmonare in Nefrologia.

The pulmonary study represents a constant appointment for Nephroplogist who frequently asks for a chest-xray in the nephrologic patient, especially in dialysis therapy. The chest x-ray and the Computed Tomography are normally used in pulmonary study, but they are not always rapidly executable and not practicable in the ambulatory and in dialysis room. The ultrasonography has recently been proposed for the study of the lung because it can be carried out rapidly in every nephro-dialytic room, also in frequent follow-up and it doesn't need particular equipment and probes. In this paper we present the fundamental notions of the management of a correct pulmonary ultrasonographic examination and some of the most common pathological pictures (pleural effusion, interstitial and alveolar syndrome, pneumothorax, etc).

Enterovesical fistula and acute pyelonephritis in renal transplantation. Role of ultrasound.

The enterovesical fistula is a communication between the urinary tract and the colon and is a rare complication of various inflammatory and cancer diseases. The most frequent cause is represented by diverticulitis of the sigmoid colon and less frequently from Crohn's disease, tumors of the colon and bladder, trauma, radiation therapy and appendicitis. In this report we describe the occurrence of an enterovesical fistula in a patient with renal allograft from a cadaveric donor, which onsetted with signs of acute pyelonephritis and pneumaturia due to diverticulitis of the sigmoid colon, clinically silent. The ultrasound in the diagnosis of enterovesical fistula, yet with a minor role compared to computed tomography (CT), is fundamental being always the first level examination.

[Assessment of correct positioning and complications after insertion of central venous catheters using chest radiography]. / La radiografia del torace nella valutazione del corretto posizionamento e delle complicanze del catetere venoso centrale.

The central venous catheter (CVC) is a very common procedure in the daily medical practice. In fact the CVCs are used to administer liquids and chemotherapeutics, the parenteral nutrition management, the measurement of the central venous pressure, the administration of hemodialysis. The international guidelines recommends always verifying the correct positioning of the tip of the CVC and to identify possible complications before his use. In the clinical practice the radiography of the chest represents the technique used more diffusedly for the control of the positioning and the possible precocious complications of the temporary and permanent CVCs positioned in the central veins. The integrated use of conventional radiology, above all digital of last generation, spiral computed tomography and ultrasounds allows to nearly have in every situation the answers for a correct diagnosis. The nephrologist, necessarily brought to deal with CVC, cannot refuse from a knowledge of such tools.

[Color-Doppler imaging and arteriovenous fistula: preoperative evaluation and surveillance]. / Eco-color-Doppler e fistola artero-venosa: utilizzo pre e post-chirurgico.

The native arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis because of the lower incidence of complications and longer survival in comparison to grafts and central venous catheters. The use of color-Doppler sonography in the surgery of vascular accesses has increased the number of patients that are eligible for AVF as it allows to optimize the search for vessels suitable for surgical intervention (preoperative vascular mapping). Furthermore, color-Doppler imaging (CDI) has improved the survival of native AVF by increasing the early diagnosis of complications (postoperative surveillance). CDI is the only imaging technique able to provide both morphological and functional information about native vascular access and it is the only tool directly available to the nephrologist. This aspect is undoubtedly an additional value. Here we present a survey of the applications of CDI in the surgery and followup of AVF, with particular reference to preoperative mapping, AVF maturation and surveillance.

[Ultrasound assessment in renal infections]. / L'ecografia nelle infezioni del rene.

Urinary tract infections (UTIs) are a common clinical problem, especially among women. Ultrasound assessment is indicated in case of complicated UTIs, in particular in children, pregnant women and patients with chronic kidney disease. Even though B-mode imaging alone is rarely diagnostic in case of particular kidney infections such as focal and multifocal acute pyelonephritis, Doppler and power-Doppler (PD) techniques are able to increase its sensitivity. Contrast-enhanced ultrasound (CEUS) further improves the signal-to-noise ratio, thus increasing the diagnostic accuracy of ultrasound in case of renal infectious disease. Recent studies performed on kidney transplant recipients have indeed demonstrated the high sensitivity and specificity of CEUS in diagnosing acute pyelonephritis. Moreover, ultrasonography is a useful diagnostic tool in case of kidney abscesses, emphysematous pyelonephritis, early phases of pyonephrosis, and in the evaluation and monitoring of echinococcal cysts. Ultrasound imaging is less specific in diagnosing xanthogranulomatous pyelonephritis, malacoplakia and renal tuberculosis. Finally, several authors recommend routine ultrasound assessment in HIV patients, given the high incidence of renal complications in this population of patients.

[Ultrasonography in the hyperhydrated patient]. / La semeiotica ecografica nel paziente iperidratato.

The achievement of a normal hydration state is one of the major targets of hemodialysis. It is based on the estimation of ''dry weight'', which corresponds to the normal body fluid content. Even though the concept of dry weight in hemodialysis patients is clinically undisputed, it is not always easy to achieve in this population. Assessment of the hydration state by clinical examination is imprecise and often unreliable. Measurement of the inferior vena cava (IVC) diameter has been shown to reflect individual fluid status. The relationship between the variation of the IVC diameter before and after the hemodialysis session and weight loss has been investigated. Measurement of the IVC diameter by ultrasound is considered a valid measure of the hydration state and can be routinely used in hemodialysis patients. Moreover, a relationship between IVC diameter, respiratory activity and the hydration state, evaluated by considering both plasma volume and central venous pressure, has been demonstrated. In conclusion, assessment of the hydration state based on blood pressure and central venous pressure can be considered reliable only in patients without signs of heart failure.