Gemelli decision tree Algorithm to Predict the need for home monitoring or hospitalization of confirmed and unconfirmed COVID-19 patients (GAP-Covid19): preliminary results from a retrospective cohort study.

OBJECTIVE: To develop a deep learning-based decision tree for the primary care setting, to stratify adult patients with confirmed and unconfirmed coronavirus disease 2019 (COVID-19), and to predict the need for hospitalization or home monitoring. PATIENTS AND METHODS: We performed a retrospective cohort study on data from patients admitted to a COVID hospital in Rome, Italy, between 5 March 2020 and 5 June 2020. A confirmed case was defined as a patient with a positive nasopharyngeal RT-PCR test result, while an unconfirmed case had negative results on repeated swabs. Patients' medical history and clinical, laboratory and radiological findings were collected, and the dataset was used to train a predictive model for COVID-19 severity. RESULTS: Data of 198 patients were included in the study. Twenty-eight (14.14%) had mild disease, 62 (31.31%) had moderate disease, 64 (32.32%) had severe disease, and 44 (22.22%) had critical disease. The G2 value assessed the contribution of each collected value to decision tree building. On this basis, SpO2 (%) with a cut point at 92 was chosen for the optimal first split. Therefore, the decision tree was built using values maximizing G2 and LogWorth. After the tree was built, the correspondence between inputs and outcomes was validated. CONCLUSIONS: We developed a machine learning-based tool that is easy to understand and apply. It provides good discrimination in stratifying confirmed and unconfirmed COVID-19 patients with different prognoses in every context. Our tool might allow general practitioners visiting patients at home to decide whether the patient needs to be hospitalized.

A modified Shockley equation taking into account the multi-element nature of light emitting diodes based on nanowire ensembles.

In this work we study how the multi-element nature of light emitting diodes (LEDs) based on nanowire (NW) ensembles influences their current voltage (I-V) characteristics. We systematically address critical issues of the fabrication process that can result in significant fluctuations of the electrical properties among the individual NWs in such LEDs, paying particular attention to the planarization step. Electroluminescence (EL) maps acquired for two nominally identical NW-LEDs reveal that small processing variations can result in a large difference in the number of individual nano-devices emitting EL. The lower number of EL spots in one of the LEDs is caused by its inhomogeneous electrical properties. The I-V characteristics of this LED cannot be described well by the classical Shockley model. We are able to take into account the multi-element nature of such LEDs and fit the I-V characteristics in the forward bias regime by employing an ad hoc adjusted version of the Shockley equation. More specifically, we introduce a bias dependence of the ideality factor. The basic considerations of our model should remain valid also for other types of devices based on ensembles of interconnected p-n junctions with inhomogeneous electrical properties, regardless of the employed material system.

Compatibility of the selective area growth of GaN nanowires on AlN-buffered Si substrates with the operation of light emitting diodes.

AlN layers with thicknesses between 2 and 14 nm were grown on Si(111) substrates by molecular beam epitaxy. The effect of the AlN layer thickness on the morphology and nucleation time of spontaneously formed GaN nanowires (NWs) was investigated by scanning electron microscopy and line-of-sight quadrupole mass spectrometry, respectively. We observed that the alignment of the NWs grown on these layers improves with increasing layer thickness while their nucleation time decreases. Our results show that 4 nm is the smallest thickness of the AlN layer that allows the growth of well-aligned NWs with short nucleation time. Such an AlN buffer layer was successfully employed, together with a patterned SiOx mask, for the selective-area growth (SAG) of vertical GaN NWs. In addition, we fabricated light-emitting diodes (LEDs) from NW ensembles that were grown by means of self-organization phenomena on bare and on AlN-buffered Si substrates. A careful characterization of the optoelectronic properties of the two devices showed that the performance of NW-LEDs on bare and AlN-buffered Si is similar. Electrical conduction across the AlN buffer is facilitated by a high number of grain boundaries that were revealed by transmission electron microscopy. These results demonstrate that grainy AlN buffer layers on Si are compatible both with the SAG of GaN NWs and LED operation. Therefore, this study is a first step towards the fabrication of LEDs on Si substrates based on homogeneous NW ensembles.

A comparison of accelerometry and center of pressure measures during computerized dynamic posturography: a measure of balance.

Accelerometry (ACC) shows promise as an easily implemented clinical measure of balance. The purpose of the study was to estimate test-retest reliability of ACC measures and determine the relationship between ACC measured at the pelvis and underfoot center of pressure (COP) measures during sensory organization test (SOT) conditions. Eighty-one subjects were recruited from the community with no known orthopedic or vestibular deficits (19-85 years). Subjects completed three consecutive, ninety second trials for each of the six SOT conditions, while wearing the accelerometer. ACC and COP time series were described by calculating the normalized path length, root mean square (RMS), and peak-to-peak values. The test-retest reliability of the three measures within each SOT condition was estimated over three trials using the intraclass correlation coefficient. ACC and COP test-retest reliability were similar, ranging from 0.63 to 0.80 using ACC and 0.42 to 0.81 using COP for the measure of normalized path length. Linear regression between ACC and COP measures showed significant correlation under almost every SOT condition using both single and average measures across trials. The degree of association between COP and ACC was equivalent when using the first trial or the 3-trial average, suggesting that one trial may be sufficient. The use of accelerometry may have value in estimating balance function and minimizing clinical evaluation time.

Electronystagmographic investigation in X-linked ocular albinism.

Albinism represents the most frequent cause of nystagmus induced by visual sensory disorders. We studied five patients aged between three and five years with ocular albinism with the aim of identifying the characteristics of nystagmic oscillations. The patients underwent complete ophthalmological examination and electronystagmography (ENG). ENG revealed either pendular or jerk waveforms (or both) with the same complex effects of fixation seen in those with idiopathic congenital nystagmus. Three children presented face turn due to reduced severity of nystagmus in lateroversion. Latent nystagmus was not observed.

In vivo absorption spectrum of disulphonated aluminium phthalocyanine in a murine tumour model.

The absorption spectrum of aluminum phthalocyanine with an average disulphonation of 2.1 (hereafter called disulphonated aluminum phthalocyanine, A1S2Pc) was measured in vivo in a murine tumour model by means of time-resolved reflectance. Mice bearing the L1210 leukaemia were administered 2.5 or 5 mg/kg body weight (b.w.) of A1S2Pc intraperitoneally. Reflectance measurements were performed in the 650-695 nm range before and 1, 4 and 7 h after the drug administration. Fitting of the data with the diffusion theory allowed us to assess the absorption coefficient in both conditions (i.e. before and after). As a difference between the latter and the former data, the in vivo absorption spectrum of A1S2Pc was evaluated. 1 h after the administration of 2.5 mg/kg b.w. A1S2Pc, the absorption peak was centred at 685 nm, red-shifted about 15 nm with respect to the spectrum in aqueous solution. For the lower dose, the absorption line shapes 4 and 7 h after the administration remained very similar. The red shift of the absorption spectrum is consistent with the therapeutic efficacy of the photodynamic therapy which was measured at 672, 685 and 695 nm, and proved to be maximum at 685 nm for both the L1210 leukaemia and the MS-2 fibrosarcoma. With the higher drug dose, the absorption spectra taken from different animals showed significant differences. In particular, in some mice the line shape was similar to that measured with 2.5 mg/kg b.w., while in other subjects it showed a broadening or a second peak at shorter wavelengths. Measurements on some animals were performed also 18 and 24 h after the injection of 5 mg/kg b.w., leading to no time evolution or to a progressive line shape narrowing.

Absorption spectrum of hematoporphyrin derivative in vivo in a murine tumor model.

Time-resolved reflectance was used to measure the absorption spectrum of hematoporphyrin derivative (HpD) in vivo in a murine tumor model. Reflectance measurements were performed in the 600-640 nm range on mice bearing the L1210 leukemia. Then the animals were administered 25 mg/kg body weight of HpD intraperitoneally. One hour later the reflectance measurements were repeated. Fitting of the data using the diffusion theory allowed assessment of the absorption coefficient before and after the administration. As a difference between the latter and the former data, the in vivo absorption spectrum of HpD was evaluated. Maximum absorption was measured at 620-625 nm. Similar spectral behavior was obtained for HpD in solution in the presence of low-density lipoproteins.

[Sinus arrhythmia: quantitative evaluation and possible use in the diagnosis of sick sinus syndrome (author's transl)]. / L'aritmia sinusale: Valutazione quantitativa e prospettive di impiego nella diagnostica della malattia del nodo del seno.

This research was done in order to quantify the sinus arrhythmia and to determine any possible quantitative difference between normal subjects and patients with Sick Sinus Syndrome (SSS). The ECG of 200 normal subjects and 30 patients with SSS diagnosed with electrophysiologic evaluation have been studied. 50 consecutive PP intervals have been measured in each ECG, and the average and standard deviation (SD) were calculated. The variableness of the sinus cycle was expressed by the Sinus Arrhythmia Index (SAI), obtained by the ratio between the SD and the average length of the cycle. It was observed that in normal subjects the SAI decreases with aging, and its value is not related to the heart rate. The SAI was significantly higher in the patients with SSS than in the normal ones. Since a sinus arrhythmia of high degree may be observed in the SSS, the quantitative evaluation of this arrhythmia, obtained by the index we proposed, may be useful to the detection of this syndrome.