Regularization, early-stopping and dreaming: A Hopfield-like setup to address generalization and overfitting.

In this work we approach attractor neural networks from a machine learning perspective: we look for optimal network parameters by applying a gradient descent over a regularized loss function. Within this framework, the optimal neuron-interaction matrices turn out to be a class of matrices which correspond to Hebbian kernels revised by a reiterated unlearning protocol. Remarkably, the extent of such unlearning is proved to be related to the regularization hyperparameter of the loss function and to the training time. Thus, we can design strategies to avoid overfitting that are formulated in terms of regularization and early-stopping tuning. The generalization capabilities of these attractor networks are also investigated: analytical results are obtained for random synthetic datasets, next, the emerging picture is corroborated by numerical experiments that highlight the existence of several regimes (i.e., overfitting, failure and success) as the dataset parameters are varied.

Measurement of the Cosmic Ray Helium Energy Spectrum from 70 GeV to 80 TeV with the DAMPE Space Mission.

The measurement of the energy spectrum of cosmic ray helium nuclei from 70 GeV to 80 TeV using 4.5 years of data recorded by the Dark Matter Particle Explorer (DAMPE) is reported in this work. A hardening of the spectrum is observed at an energy of about 1.3 TeV, similar to previous observations. In addition, a spectral softening at about 34 TeV is revealed for the first time with large statistics and well controlled systematic uncertainties, with an overall significance of 4.3σ. The DAMPE spectral measurements of both cosmic protons and helium nuclei suggest a particle charge dependent softening energy, although with current uncertainties a dependence on the number of nucleons cannot be ruled out.

Peritonectomy and hyperthermic intraperitoneal chemotherapy: cost analysis and sustainability.

BACKGROUND: Malignancies of the peritoneum remain a challenge in any hospital that accepts to manage them, due not only to difficulties associated with the complexity of the procedures involved but also the costs, which - in Italy and other countries that use a diagnosis-related group (DRG) system - are not adequately reimbursed. MATERIAL AND METHODS: We analyzed data relative to 24 patients operated on between September 2010 and May 2013 with special regard to operating room expenditure, ICU stay, duration of hospitalization, and DRG reimbursement. The total costs per patient included clinical, operating room, procedure, pathology, imaging, ward care, allied healthcare, pharmaceutical, and ICU costs. RESULTS: Postoperative hospital stay, drugs and materials, and operating room occupancy were the main factors affecting the expenditure for cytoreductive surgery and hyperthermic intraperitoneal chemotherapy. We had a median hospitalization of 14 days, median ICU stay of 2.4 days, and median operating room occupancy of 585 min. The median expenditure for each case was € 21,744; the median reimbursement by the national health system € 8,375. CONCLUSIONS: In a DRG reimbursement system, the economic effort in the management of patients undergoing peritonectomy procedures may not be counterbalanced by adequate reimbursement. Joint efforts between medical and administration parties are mandatory to develop appropriate treatment protocols and keep down the costs.

Buprenorphine versus tramadol as perineural adjuvants for postoperative analgesia in patients undergoing arthroscopic rotator cuff repair under middle interscalene block: a retrospective study.

BACKGROUND: The aim of this retrospective study was to compare buprenorphine and tramadol, in order to assess their different efficacy in prolonging postoperative analgesia and their associated side effects when used as perineural adjuvants with a local anesthetic. METHODS: The clinical records of 161 consecutive ASA 1-2 adult patients scheduled for arthroscopic rotator cuff repair and fulfilling the inclusion/exclusion criteria were reviewed retrospectively. The anaesthesia was performed using the middle interscalene block (MIB). The 161 patients were divided into three groups (A, B, T) according to their utilization of buprenorphine (B), tramadol (T) or neither of the latter (A) as perineural adjuvants: group A (54 patients) - levobupivacaine 0.75%, 0.4 mL/kg; group B (56 patients) - levobupivacaine 0.75%, 0.4 mL/kg + 0.15 mg buprenorphine; group T (51 patients) - levobupivacaine 0.75%, 0.4 mL/kg + 100 mg tramadol. RESULTS: The results showed that the group treated with buprenorphine benefited from a longer post-operative analgesia than that treated with local anesthetic alone (P<0.0001). Otherwise, a less evident not statistically significant (P=0.4825) difference turned out between the group treated with the anesthetic alone and the group treated with tramadol as adjuvant. No difference turned out to be between the local anesthetic alone treatment and the tramadol-local anesthetic one (P=0.4825; HR=0.863, 95% CI 0.574-1.299); on the contrary, a significant difference was demonstrated between the buprenophine-local anesthetic group and the local anesthetic alone one (P<0.0001; HR=0.330, 95% CI 0.216-0.530) CONCLUSION: Both buprenorphine and tramadol are effective as perineural adjuvants used in order to prolong the postoperative analgesia, buprenorphine proving more efficacious for this purpose than tramadol.

Action-related semantic content and negation polarity modulate motor areas during sentence reading: an event-related desynchronization study.

Our study evaluated motor cortex involvement during silent reading of sentences referring to hand actions. We aimed at defining whether sentential polarity (affirmative vs. negative) would modulate motor cortex activation using the event-related desynchronization (ERD) analysis of the mu rhythm. Eleven healthy volunteers performed a reading task involving 160 sentences (80 affirmative: 40 hand-related, 40 abstract; 80 negative: 40 hand-related, 40 abstract). After reading each sentence, subjects had to decide whether the verb was high or low frequency in Italian. Electroencephalographic (EEG) activity was recorded with 32 surface electrodes and mu ERD analyses were performed for each subject. Hand-action related sentences induced a greater mu ERD over the left premotor and motor hand areas compared to abstract sentences. Mu ERD was greater and temporally delayed when the hand-related verbs were presented in the negative versus affirmative form. As predicted by the "embodied semantic" theory of language understanding, motor areas were activated during sentences referring to hand actions. In addition, motor cortex activation was larger for negative than affirmative motor sentences, a finding compatible with the hypothesis that comprehension is more demanding in the specific case of motor content negation.

Tramadol and 0.5% levobupivacaine for single-shot interscalene block: effects on postoperative analgesia in patients undergoing shoulder arthroplasty.

BACKGROUND: The aim of this study was to evaluate the efficacy of tramadol as an adjuvant to the local anaesthetic solution in patients undergoing shoulder arthroscopy for rotator cuff tear after middle interscalene block (MIB). METHODS: We enrolled 120 patients (ASA I-II), scheduled for arthroscopic surgery for rotator cuff tear. The patients were sedated with midazolam 0.02 mg/kg and haloperidol 2 mg i.v. before performing MIB. All subjects underwent a MIB with 0.4 mL/kg of 0.5% levobupivacaine. After computerized randomization, all patients were allocated in 1 of 3 groups, each including 40 subjects. Group Placebo (Group P) received 0.4 mL/kg of 0.5% levobupivacaine plus isotonic sodium chloride for MIB and isotonic sodium chloride i.m. Group "Perineural Tramadol" (Group TPN) received 0.4 ml/Kg of 0.5% levobupivacaine plus 1.5 mg/kg of tramadol perineurally and isotonic sodium chloride i.m. Group "Intramuscular Tramadol" (Group TIM) received 0.4 ml/Kg of 0.5% levobupivacaine plus isotonic sodium chloride perineurally and 1.5 mg/kg of tramadol i.m. RESULTS: The MIB onset times were not statistically different in the three groups. The duration of analgesia was significantly longer in Groups TPN and TIM, where tramadol was administered, either i.m. or perineurally, compared with the placebo group. A significant statistical difference was found in the duration of analgesia between the group TPN and TIM. CONCLUSION: The addition of tramadol to the local anaesthetic solution administered for MIB provided a longer duration of analgesia compared with placebo and i.m tramadol administration in patients undergoing arthroscopic surgery for rotator cuff tear.

Alemanno's brachial plexus block ten years later: topographic study of the anesthetized areas.

AIM: The study analyzes the extension of anesthesia induced by Alemanno's brachial plexus block technique on the various areas of competence of the different nerves. METHODS: The study was conducted on 58 patients in ASA classes 1 and 2 scheduled to receive shoulder arthroscopy. At the end of the operation, about 2 hours after induction of anesthesia, extension of anesthesia was evaluated by the pin-prick test. RESULTS: Anesthesia was achieved in 100% of cases for the circumflexus, musculocutaneous and radial nerves; the median nerve escaped in 7% of cases, the medial cutaneous nerve of forearm in 20%, the ulnar nerve in 27.5%, the medial cutaneous nerve of arm and intercostobrachial nerves in 46%; no major complications were associated with the technique. CONCLUSION: Alemanno's technique is recommended for operations on the shoulder and humerus, whereas more peripheral techniques may be preferable for interventions on the forearm and hand.

[Sopraclavicular techniques for brachial plexus block]. / Tecnichi sopraclaveari di blocco del plesso brachiale.

BACKGROUND: Aim of the present study is to review the four different methods of brachial plexus block, with supraclavicular approach, which have reached the higher approval or given less side effects. METHODS: The Author reviewed the following techniques: Kulenkampff's (1911), Winnie's (1970), Brown's (1988) and Alemanno's (1992). CONCLUSIONS: The four methods that were presented in the last century differ not for the results, which are more or less the same, but for the possible side effects, which result to be less with the latest techniques.

[A new approach to the brachial plexus: clinical results]. / Un nuovo approccio al plesso brachiale: risultati clinici.

The paper reports the results of a new brachial plexus blockade technique using a supraclavicular route which was carried out in 74 patients. From the analysis of results it can be seen that the technique is comparable to that of Moore and Winnie in terms of the success of the blockade. However, this technique appears to be safer in relation to complications such as pneumothorax and subarachnoid injection.

[A new approach to the brachial plexus]. / Un nuovo approccio al plesso brachiale.

In order to avoid complications such as pneumothorax or subarachnoid injection, the paper proposes a new approach to brachial plexus using a supraclavear route based on the pulse of the subclavian artery and 7th cervical vertebra. Complications are unlikely using this route.

[Cerebral edema: osmotic therapy in clinical practice]. / Edema cerebrale: la terapia osmotica nella pratica clinica.

Having described the therapeutic protocol to be followed in cases of cerebral edema, starting with aspecific measures (hyperventilation in a position of 30 degrees, etc.) for slight cases and progressing to specific therapy (osmotherapy, barbiturates) for more severe cases, the paper focuses on osmotherapy and illustrates the theoretical principles on which it is based and its use in clinical practice.