Amplitude response of a unilaterally constrained nonlinear micromechanical resonator

Dynamical systems that involve impacts frequently arise in engineering. This Letter reports a study of such a system at microscale that consists of a nonlinear resonator operating with an unilateral impact. The microresonators were fabricated on silicon-on-insulator wafers by using a one-mask process and then characterised by using the capacitively driving and sensing method. Numerical results concerning the dynamics of this vibro-impact system were verified by the experiments. Bifurcation analysis was used to provide a qualitative scenario of the system steady-state solutions as a function of both the amplitude and the frequency of the external driving sinusoidal voltage. The results show that the amplitude of resonant peak is levelled off owing to the impact effect and that the bandwidth of impacting is dependent upon the nonlinearity and the operating conditions

Performances analysis of a semi-displacement hull by numerical simulations

The flow field generated by the towing of a semi-displacement hull, free to heave and pitch, is numerically investigated in the velocity range 18 34 Kn. The numerical code adopted is the in-house developed Xnavis, which is a general purpose unsteady RANS based solver; the solver is based on a Finite Volume approach together with a Chimera technique for overlapping grids and a Level Set approach to handle the air/water interface. The generated wave pattern shows many interesting features with an evident wave plunging near the hull bow, while the stern remains completely dry for velocities over 30 Kn. The numerical outcomes are discussed in terms of total resistance, sinkage and trim

Applying dissipative dynamical systems to pseudorandom number generation: Equidistribution property and statistical independence of bits at distances up to logarithm of mesh size

The behavior of a family of dissipative dynamical systems representing transformations of two-dimensional torus is studied on a discrete lattice and compared with that of conservative hyperbolic automorphisms of the torus. Applying dissipative dynamical systems to generation of pseudorandom numbers is shown to be advantageous and equidistribution of probabilities for the sequences of bits can be achieved. A new algorithm for generating uniform pseudorandom numbers is proposed. The theory of the generator, which includes proofs of periodic properties and of statistical independence of bits at distances up to logarithm of mesh size, is presented. Extensive statistical testing using available test packages demonstrates excellent results, while the speed of the generator is comparable to other modern generators.Comment: 6 pages, 3 figures, 3 table

Intriguing Heteroleptic ZnII^{II} bis(dipyrrinato) Emitters in the Far-Red Region With Large Pseudo-Stokes Shift for Bioimaging

Novel heteroleptic ZnII bis(dipyrrinato) complexes were prepared as intriguing emitters. With our tailor-made design, we achieved far-red emissive complexes with a photoluminescence quantum yield up to 45% in dimethylsulfoxide and 70% in toluene. This means that heteroleptic Zn$^{II}$ bis(dipyrrinato) complexes retain very intense emission also in polar solvents, in contrast to their homoleptic counterparts, which we prepared for comparing the photophysical properties. It is evident from the absorption and excitation spectra that heteroleptic complexes present the characteristic features of both ligands: the plain dipyrrin (L$_{p}$) and the π-extended dipyrrin (L$_{π}$). On the contrary, the emission comes exclusively from the π-extended dipyrrin L$_{π}$, suggesting an interligand nonradiative transition that causes a large pseudo-Stokes shift (up to 4,600 cm$_{-1}$). The large pseudo-Stokes shifts and the emissive spectral region of these novel heteroleptic Zn$^{II}$ bis(dipyrrinato) complexes are of great interest for bioimaging applications. Thus, their high biocompatibiliy with four different cell lines make them appealing as new fluorophores for cell imaging

Robust decadal hydroclimate predictions for northern Italy based on a twofold statistical approach

The Mediterranean area belongs to the regions most exposed to hydroclimatic changes, with a likely increase in frequency and duration of droughts in the last decades. However, many climate records like, e.g., North Italian precipitation and river discharge records, indicate that significant decadal variability is often superposed or even dominates long-term hydrological trends. The capability to accurately predict such decadal changes is, therefore, of utmost environmental and social importance. Here, we present a twofold decadal forecast of Po River (Northern Italy) discharge obtained with a statistical approach consisting of the separate application and cross-validation of autoregressive models and neural networks. Both methods are applied to each significant variability component extracted from the raw discharge time series using Singular Spectrum Analysis, and the final forecast is obtained by merging the predictions of the individual components. The obtained 25-year forecasts robustly indicate a prominent dry period in the late 2020s/early 2030s. Our prediction provides information of great value for hydrological management, and a target for current and future near-term numerical hydrological predictions

Robust decadal hydroclimate predictions for northern Italy based on a twofold statistical approach

The Mediterranean area belongs to the regions most exposed to hydroclimatic changes, with a likely increase in frequency and duration of droughts in the last decades. However, many climate records like, e.g., North Italian precipitation and river discharge records, indicate that significant decadal variability is often superposed or even dominates long-term hydrological trends. The capability to accurately predict such decadal changes is, therefore, of utmost environmental and social importance. Here, we present a twofold decadal forecast of Po River (Northern Italy) discharge obtained with a statistical approach consisting of the separate application and cross-validation of autoregressive models and neural networks. Both methods are applied to each significant variability component extracted from the raw discharge time series using Singular Spectrum Analysis, and the final forecast is obtained by merging the predictions of the individual components. The obtained 25-year forecasts robustly indicate a prominent dry period in the late 2020s/early 2030s. Our prediction provides information of great value for hydrological management, and a target for current and future near-term numerical hydrological predictions

NUOVI CRITERI DI DIVISIBILITÀ

missing abstrac

Cyan-Emitting Cu(I) Complexes and Their Luminescent Metallopolymers

Copper complexes have shown great versatility and a wide application range across the natural and life sciences, with a particular promise as organic light-emitting diodes. In this work, four novel heteroleptic Cu(I) complexes were designed in order to allow their integration in advanced materials such as metallopolymers. We herein present the synthesis and the electrochemical and photophysical characterisation of these Cu(I) complexes, in combination with ab initio calculations. The complexes present a bright cyan emission (λem ~ 505 nm) in their solid state, both as powder and as blends in a polymer matrix. The successful synthesis of metallopolymers embedding two of the novel complexes is shown. These copolymers were also found to be luminescent and their photophysical properties were compared to those of their polymer blends. The chemical nature of the polymer backbone contributes significantly to the photoluminescence quantum yield, paving a route for the strategic design of novel luminescent Cu(I)-based polymeric materials

Whole-Transcriptome Analysis Unveils the Synchronized Activities of Genes for Fructans in Developing Tubers of the Jerusalem Artichoke

Helianthus tuberosus L., known as the Jerusalem artichoke, is a hexaploid plant species, adapted to low-nutrient soils, that accumulates high levels of inulin in its tubers. Inulin is a fructose-based polysaccharide used either as dietary fiber or for the production of bioethanol. Key enzymes involved in inulin biosynthesis are well known. However, the gene networks underpinning tuber development and inulin accumulation in H. tuberous remain elusive. To fill this gap, we selected 6,365 expressed sequence tags (ESTs) from an H. tuberosus library to set up a microarray platform and record their expression across three tuber developmental stages, when rhizomes start enlarging (T-0), at maximum tuber elongation rate (T-3), and at tuber physiological maturity (T-m), in "VR" and "K8-HS142"clones. The former was selected as an early tuberizing and the latter as a late-tuberizing clone. We quantified inulin and starch levels, and qRT-PCR confirmed the expression of critical genes accounting for inulin biosynthesis. The microarray analysis revealed that the differences in morphological and physiological traits between tubers of the two clones are genetically determined since T-0 and that is relatively low the number of differentially expressed ESTs across the stages shared between the clones (93). The expression of ESTs for sucrose:sucrose 1-fructosyltransferase (1-SST) and fructan:fructan 1-fructosyltransferase (1-FFT), the two critical genes for fructans polymerization, resulted to be temporarily synchronized and mirror the progress of inulin accumulation and stretching. The expression of ESTs for starch biosynthesis was insignificant throughout the developmental stages of the clones in line with the negligible level of starch into their mature tubers, where inulin was the dominant polysaccharide. Overall, our study disclosed candidate genes underpinning the development and storage of carbohydrates in the tubers of two H. tuberosus clones. A model according to which the steady-state levels of 1-SST and 1-FFT transcripts are developmentally controlled and might represent a limiting factor for inulin accumulation has been provided. Our finding may have significant repercussions for breeding clones with improved levels of inulin for food and chemical industry

International Variations in Surgical Morbidity and Mortality Post Gynaecological Oncology Surgery: A Global Gynaecological Oncology Surgical Outcomes Collaborative Led Study (GO SOAR1)

Gynaecological malignancies affect women in low and middle income countries (LMICs) at disproportionately higher rates compared with high income countries (HICs) with little known about variations in access, quality, and outcomes in global cancer care. Our study aims to evaluate international variation in post-operative morbidity and mortality following gynaecological oncology surgery between HIC and LMIC settings. Study design consisted of a multicentre, international prospective cohort study of women undergoing surgery for gynaecological malignancies (NCT04579861). Multilevel logistic regression determined relationships within three-level nested-models of patients within hospitals/countries. We enrolled 1820 patients from 73 hospitals in 27 countries. Minor morbidity (Clavien-Dindo I-II) was 26.5% (178/672) and 26.5% (267/1009), whilst major morbidity (Clavien-Dindo III-V) was 8.2% (55/672) and 7% (71/1009) for LMICs/HICs, respectively. Higher minor morbidity was associated with pre-operative mechanical bowel preparation (OR = 1.474, 95%CI = 1.054-2.061, p = 0.023), longer surgeries (OR = 1.253, 95%CI = 1.066-1.472, p = 0.006), greater blood loss (OR = 1.274, 95%CI = 1.081-1.502, p = 0.004). Higher major morbidity was associated with longer surgeries (OR = 1.37, 95%CI = 1.128-1.664, p = 0.002), greater blood loss (OR = 1.398, 95%CI = 1.175-1.664, p ≤ 0.001), and seniority of lead surgeon, with junior surgeons three times more likely to have a major complication (OR = 2.982, 95%CI = 1.509-5.894, p = 0.002). Of all surgeries, 50% versus 25% were performed by junior surgeons in LMICs/HICs, respectively. We conclude that LMICs and HICs were associated with similar post-operative major morbidity. Capacity to rescue patients from surgical complications is a tangible opportunity for meaningful intervention