Dispersion managed mode-locking dynamics in a Ti:Sapphire laser

We present what is to our knowledge the most complete 1-D numerical analysis of the evolution and the propagation dynamics of an ultrashort laser pulse in a Ti:Sapphire laser oscillator. This study confirms the dispersion managed model of mode-locking, and emphasizes the role of the Kerr nonlinearity in generating mode-locked spectra with a smooth and well-behaved spectral phase. A very good agreement with preliminary experimental measurements is found.Comment: 11 pages, 4 figures, submitted to Optics Letter

Formation and seasonal occurrence of xylem embolism in Alnus cordata.

We investigated the vulnerability of xylem to embolism and the seasonal occurrence of xylem embolism in Italian alder (Alnus cordata Loisel.) by acoustic and hydraulic methods. Wood anatomy was also studied. More than eighty percent of the vessels were less than 50 mm long and no vessels were longer than 120 mm. Mean vessel diameter was 48 μm. Ultrasound acoustic emissions from root and branch segments dehydrating in air followed a similar pattern: in both tissues, emission peaks were recorded when the relative water content of the xylem was around 0.2. In branches dehydrating in air, xylem embolism increased linearly as water potential decreased. In trees in the field, more than 80 percent of hydraulic conductivity was lost in the tree crowns during winter. Recovery from winter embolism occurred mostly before bud burst. In summer, xylem embolism was low (< 30%) and acoustic emissions from roots, stem and branches of trees in the field were also low

Forest stand structure and coarse woody debris determine the biodiversity of beetle communities in Mediterranean mountain beech forests

Abstract The relationships between structural complexity, deadwood abundance, microhabitat type and species-diversity indicators are excellent tools to monitor biodiversity in forest ecosystems. In spite of their importance, correlations between structural traits and Coleoptera communities in Mediterranean mountain forests have only rarely been investigated. Consequently, the magnitude and direction of the relationships between forest traits and biodiversity indicators remain poorly understood. In this study, we analyzed whether biodiversity indices of saproxylic and non-saproxylic beetle communities could be influenced by stand structure, microhabitat type, and deadwood abundance in two protected beech forests located in the central and southern Apennines (namely Gran Sasso e Monti della Laga National Park, GSML, and Cilento, Vallo di Diano e Alburni National Park, CVDA). Standard measurements of forest structural traits and quantitative assessment of tree microhabitats and deadwood were carried out. Adult beetles were collected using window flight traps and emergence traps on decaying deadwood. The two beech forests were different in terms of both beetle communities and structural traits. A two-block partial least squares analysis 2B-PLS highlighted differences in biodiversity indices and structural traits between the two forest ecosystems. In GSML, we observed that biodiversity indices were positively correlated with the volume of coarse woody debris and the presence fungal infections, clefts into the sapwood, and woodpecker cavities, while more dominant beetle communities were found under denser canopy cover. In CVDA, Coleoptera abundance was positively correlated with the basal area and crown broken microhabitats. Our results point toward the relevance of ecological attributes in tracking changes in beetle biodiversity in specific forest contexts. In these protected Mediterranean mountain beech stands, in which the main forest management strategies have the primary objective of biodiversity conservation, we suggest to progressively increase the structural diversity and canopy dynamics, as well as the volume of coarse woody debris

Influenza dei cambiamenti d'uso del suolo e delle strategie di gestione del bosco sull'allocazione del carbonio nel suolo negli ecosistemi forestali

L'allocazione del C verso le strutture ipogee delle piante e uno dei principali flussi di C negli ecosistemi terrestri, sebbene ancora non ben quantificato. RAICH e NADELHOFFER (1989), dopo il riesame della letteratura su numerosi ecosistemi forestali, hanno suggerito che l'allocazione ipogea totale di C puo essere stimata dalla differenza fra tassi annuali di respirazione del suolo e caduta di lettiera epigea. DAVIDSON et al. (2002) hanno esteso le analisi dei dati pubblicati confermando le conclusioni di RAICH e NADELHOFFER per foreste mature, sebbene, come osservato da GOWER et al. (1996), l'uso di modelli per la stima del C totale allocato alle radici e per la costruzione di bilanci del C di un soprassuolo non era considerato un metodo valido per la misura dei flussi di C del suolo. Nel presente lavoro di revisione della letteratura abbiamo analizzato nuove misure di respirazione del suolo e di caduta di lettiera, includendo nell'analisi a scala globale sia foreste mature sia formazioni giovani. I risultati ottenuti concordano, in genere, con i lavori precedenti, affermando che la produzione epigea ed ipogea e controllata dagli stessi fattori. Attraverso un gradiente di C da lettiera oscillante fra 52 a 530 g m-2 anno-1, l'allocazione totale ipogea di C aumenta da circa 90 a 1800 g m-2 anno-1. Il rapporto fra allocazione totale ipogea di C e caduta di lettiera diminuisce approssimativamente da 12 a 2.5, con incrementi di C da lettiera da 50 a 200 g m-2 anno-1, ma varia poco quando il C da lettiera aumenta 200 a 500 g m-2 anno-1. Un'analisi di regressione applicata ai dati derivanti da foreste di tutto il mondo ha prodotto la seguente relazione: respirazione annuale del suolo = 140 + 3.09 × caduta annuale di lettiera. La pendenza della regressione indica che, in media, la respirazione del suolo e grossolanamente il triplo del C di lettiera epigea, implicando che l'allocazione ipogea totale di C rappresenta circa il doppio del C di lettiera epigea caduta annualmente. La regressione per i dati provenienti dalle formazioni giovani e piu ripida, rispetto a quanto osservato per le foreste mature, indicando un'eventuale proporzionalmente maggiore allocazione ipogea totale di C, ma l'assunzione dello stato stazionario e piu problematica per le foreste giovani. In effetti, queste deduzioni sono basate su ipotesi incerte sulla stabilita della scorta di C nel suolo. Tuttavia, le variazioni del C del suolo dovrebbero essere molto ampie per modificare la conclusione the l'allocazione ipogea totale di C e generalmente molto maggiore della caduta di lettiera. Queste relazioni permettono la realizzazione di semplici bilanci del C che possono essere usati per porre dei limiti sulla stima della produzione di radici fini in ecosistemi forestali. La determinazione dei tassi di respirazione radicale (radici vive) in ecosistemi forestali puo ulteriormente restringere il raggio di possibili tassi di produzione delle radici, e controllare le ipotesi che l'allocazione totale di C alle radici aumenta con la produzione primaria netta del soprassuolo e che il rapporto fra allocazione totale di C alle radici e produzione primaria netta del soprassuolo diminuisce lungo gradienti globali di disponibilita di risorse. La relazione statistica universale, derivata usando bilanci forestali del C, dovrebbe essere valutata a scala minore, per identificare come variano i modelli d'allocazione del C nelle foreste in funzione dell'eta del bosco, della composizione specifica, e delle pratiche di gestione

Sub two-cycle soliton-effect pulse compression at 800 nm in Photonic Crystal Fibers

The possibility of soliton self-compression of ultrashort laser pulses down to the few-cycle regime in photonic crystal fibers is numerically investigated. We show that efficient sub-two-cycle temporal compression of nanojoule-level 800 nm pulses can be achieved by employing short (typically 5-mm-long) commercially available photonic crystal fibers and pulse durations of around 100 fs, regardless of initial linear chirp, and without the need of additional dispersion compensation techniques. We envisage applications in a new generation of compact and efficient sub-two cycle laser pulse sources.Comment: 16 pages, 6 figure

Moving Auto-Correlation Window Approach for Heart Rate Estimation in Ballistocardiography Extracted by Mattress-Integrated Accelerometers

Continuous heart monitoring is essential for early detection and diagnosis of cardiovascular diseases, which are key factors for the evaluation of health status in the general population. Therefore, in the future, it will be increasingly important to develop unobtrusive and transparent cardiac monitoring technologies for the population. The possible approaches are the development of wearable technologies or the integration of sensors in daily-life objects. We developed a smart bed for monitoring cardiorespiratory functions during the night or in the case of continuous monitoring of bedridden patients. The mattress includes three accelerometers for the estimation of the ballistocardiogram (BCG). BCG signal is generated due to the vibrational activity of the body in response to the cardiac ejection of blood. BCG is a promising technique but is usually replaced by electrocardiogram due to the difficulty involved in detecting and processing the BCG signals. In this work, we describe a new algorithm for heart parameter extraction from the BCG signal, based on a moving auto-correlation sliding-window. We tested our method on a group of volunteers with the simultaneous co-registration of electrocardiogram (ECG) using a single-lead configuration. Comparisons with ECG reference signals indicated that the algorithm performed satisfactorily. The results presented demonstrate that valuable cardiac information can be obtained from the BCG signal extracted by low cost sensors integrated in the mattress. Thus, a continuous unobtrusive heart-monitoring through a smart bed is now feasible

ePhysio: A Wearables-Enabled Platform for the Remote Management of Musculoskeletal Diseases

Technology advancements in wireless communication and embedded computing are fostering their evolution from standalone elements to smart objects seamlessly integrated in the broader context of the Internet of Things. In this context, wearable sensors represent the building block for new cyber-physical social systems, which aim at improving the well-being of people by monitoring and measuring their activities and provide an immediate feedback to the users. In this paper, we introduce ePhysio, a large-scale and flexible platform for sensor-assisted physiotherapy and remote management of musculoskeletal diseases. The system leverages networking and computing tools to provide real-time and ubiquitous monitoring of patients. We propose three use cases which differ in scale and context and are characterized by different human interactions: single-user therapy, indoor group therapy, and on-field therapy. For each use case, we identify the social interactions, e.g., between the patient and the physician and between different users and the performance requirements in terms of monitoring frequency, communication, and computation. We then propose three related deployments, highlighting the technologies that can be applied in a real system. Finally, we describe a proof-of-concept implementation, which demonstrates the feasibility of the proposed solution

Disabilità e società

The book focuses on a well-established stream of research on disability which, both internationally and nationally, has proved fruitful in theoretical and analytical aspect, and was certainly fundamental in the process that led to the recognition of the rights of people with disabilities and the implementation of inclusive policies. The rigorous analysis present in all the chapters of the book also highlight the wide distance between the principles that guide the reflection on this issue, the policies for disability and the living conditions that people with disabilities experience daily. From the book emerges that the challenge is not merely the recognition of the rights of persons with disabilities but also making these rights enforceable. For this to be possible, both efficient and effective policies and a cultural change which recognizes disabled people "as part of human diversity and humanity" is necessary. This means placing at the center of discussion the aspirations and the empowerment of people with disabilities. The book is designed for scholars of disability, but also for social operators who work with disabled people