A new flightless species of the genus trichiorhyssemus clouët, 1901, from México (coleopteraaphodiidae: psammodiinae)

The first known flightless species of Trichiorhyssemus Clouët, 1901 – T. hispidus sp. nov. – is hereby described and illustrated, from the State of Veracruz, Mexico. A key to Western Hemisphere species of the genus is also included.Se describe a Trichiorhyssemus hispidus sp.nov. del Estado de Veracruz, México, primera especie braquiptera conocida de este género. Se incluye también una clave para las especies de Trichiorhyssemus del hemisferio occidental

Prospects of nanoelectronic biosensing with high-frequency impedance spectroscopy

In recent years the possibility to combine nanoelectronics and biosensing has opened a very wide and promising field of research, which holds the potential to revolutionize analytical biology and to enable pervasive diagnostics and personalized medicine. Integrated nanoelectronic biosensor platforms based on established CMOS technology can provide compensation and calibration hardware, programmable firmware, improved sensitivity due to the very small dimensions, high parallelism, remarkable cost and size reduction and, ultimately, the vast markets needed by the semiconductor industry. As is the case for all integrated nanoelectronic sensors, reliable and affordable design is possible only if accurate models are available to elucidate and quantitatively predict the signal transduction process. However, with the exception of a few efforts, calibrated analytical and numerical models to accurately describe the response are often still lacking for most biosensor concepts. Animated by the will to bridge this gap, in this work we develop compact analytical models and complex numerical simulation tools for the study of the transduction chain in impedimetric nanoelectronic biosensors. In particular, the 3D simulator ENBIOS, entirely developed and validated during this thesis, is a general-purpose tool that can be easily expanded to include new physical effects or more sophisticated descriptions of electrolytes and analytes coupled to semiconductor devices. The models point out the existence of two relevant cut-off frequencies governing the biosensor impedimetric response, they reveal the dependencies of biosensor response to the analyte and environmental conditions and they disclose the existence of well-defined signatures in the impedance signal. The analytical and numerical tools are carefully verified and then used to examine several case studies. The first one we consider is an impedimetric nanoelectrode array biosensor. In collaboration with Twente University, we study its response to conductive and dielectric micro-particles under well controlled experimental conditions. We show that the simulation results are in very good agreement with the measurements and we provide insight on optimum detection conditions. By studying the biosensor response to small particles, like proteins, viruses or DNA, we then confirm by simulation the advantages of high frequency impedance spectroscopy, in particular the ability of AC signals at frequency above electrolyte's dielectric relaxation cut-off frequency to overcome the Debye screening and to probe the electrolyte volume with sensitivity almost independent of the particle position and charge and of salt concentration. As a second notable example we consider the case of a Silicon Nanowire (SiNW) biosensor. We perform measurements and simulations on SiNWs in AC regime in collaboration with the CEA/LETI and EPFL/CLSE laboratories. We demonstrate the operation of SiNWs in AC in particular for pH sensing applications. We finally confirm potential advantage of a SiNW biosensor working at high frequency, in order to increase the response with respect to the DC operation.Negli ultimi anni la possibilit\ue0 di combinare nanoelettronica e biosensoristica ha aperto un campo di ricerca molto vasto e promettente, che ha il potenziale di rivoluzionare la biologia analitica e di consentire diagnostica pervasiva e medicina personalizzata. Le piattaforme di biosensori nanoelettronici integrati sono potenzialmente in grado di fornire compensazioni e calibrazioni hardware, firmware programmabili, una maggiore sensibilit\ue0 a causa delle ridotte dimensioni, elevato parallelismo, riduzione notevole dei costi e delle dimensioni e i vasti mercati necessari per il settore dei semiconduttori. Come nel caso di tutti i sensori nanoelettronici integrati, un progetto affidabile e conveniente \ue8 possibile solo se sono disponibili modelli accurati per comprendere e prevedere quantitativamente il processo di trasduzione del segnale. Tuttavia, con l'eccezione di alcuni pionieristici sforzi, mancano ancora spesso modelli analitici e numerici calibrati per descrivere accuratamente la risposta della maggior parte dei concept di biosensori. Animati dalla volont\ue0 di colmare questa lacuna, in questo lavoro sviluppiamo modelli analitici compatti e complessi strumenti di simulazione numerica per lo studio della catena di trasduzione in biosensori nanoelettronici impedimetrici. In particolare, il simulatore 3D ENBIOS, interamente sviluppato e convalidato durante questa tesi, \ue8 uno strumento generale che pu\uf2 essere facilmente ampliato per includere nuovi effetti fisici o descrizioni pi\uf9 sofisticate di elettroliti e analiti accoppiati ai dispositivi a semiconduttore. I modelli rilevano l'esistenza di due frequenze di taglio rilevanti che regolano la risposta impedimetrica del biosensore, rivelano le dipendenze della risposta del biosensore all'analita e alle condizioni ambientali e l'esistenza di firme ben definite nel segnale di impedenza. Gli strumenti analitici e numerici sono attentamente verificati e poi utilizzati per esaminare diversi casi di studio. Il primo che consideriamo \ue8 un biosensore impedimetrico a matrice di nanoelettrodi. In collaborazione con l'Universit\ue0 di Twente, studiamo la sua risposta a micro-particelle conduttive e dielettriche in condizioni sperimentali ben controllate. I risultati della simulazione sono in ottimo accordo con le misure e ci forniscono informazioni sulle condizioni di rilevamento ottimali. Studiando la risposta del biosensore a piccole particelle, come proteine, virus o DNA, confermiamo quindi tramite simulazioni i vantaggi della spettroscopia di impedenza ad alta frequenza, in particolare la capacit\ue0 dei segnali in AC a frequenza superiore alla frequenza di taglio di rilassamento dielettrico dell'elettrolita di superare lo screening di Debye e di sondare il volume dell'elettrolita con una sensibilit\ue0 quasi indipendente da posizione e carica della particella e dalla concentrazione salina. Come secondo esempio notevole consideriamo il caso di un biosensore a Nanofilo di Silicio (SiNW). Eseguiamo misure e simulazioni su SiNWs in regime AC in collaborazione con i laboratori CEA / LETI ed EPFL / CLSE. Dimostriamo il funzionamento dei SiNWs in AC, in particolare per applicazioni di misura del pH. Infine, confermiamo i vantaggi potenziali di un biosensore a SiNW operante in alta frequenza, al fine di aumentare l'intensit\ue0 della risposta rispetto al caso di funzionamento in DC

X-RAY TOMOGRAPHIE OF STEEL FIBRE REINFORCED SHOTCRETE (SFRS)

X-ray tomography is a commonly used diagnostic method in medicine. Its use has also spread into the field of engineering. The most important application is the non-destructive testing. The composite material steel fibre reinforced shotcrete is applied widespreadly in the geotechnique. The knowledge about the orientation of the steel fibres in the concrete is of decisive importance for modeling the mechanical behaviour. The poster shows the way of sampling about the computer tomography (Voxel model) up to the statistical evaluation of the fibre orientation

A configurational analysis of the antecedents of entrepreneurial orientation

Entrepreneurial orientation is widely acknowledged as a strong predictor of firm performance. It is therefore critical to understand the factors and conditions that nurture it. In this paper, we investigate what configurations of motivations and personality traits trigger entrepreneurial orientation in three strategic leadership situations: successor of a family business, family-oriented founder, non-family founder. Strategic leaders in these situations are differently exposed to the opportunities and constraints to pursue entrepreneurial posture, because of the influence of family embeddedness and organizational resistance. We apply Fuzzy Set Qualitative Comparative Analysis to a sample of 257 Italian SME owner/managers. We identify 12 coherent configurations of internal and external motivations, and personality traits that are all conducive to entrepreneurial orientation. These configurations are consistent with features of the family and organization environments in which the entrepreneurial action takes place; furthermore, in each strategic leadership situation, different configurations of attributes lead to entrepreneurial orientation

Satisfaction of entrepreneurs: a comparison between founders and family business successors

Although a substantial body of literature compares the job satisfaction of employees to that of the self-employed, scholars rarely take into account the heterogeneity of the latter population. We compare the level and the drivers of job satisfaction of founders and successors in family businesses. Building on the notion of procedural utility, which entails the gratification that individuals experience in the process of performing a task, we find that job satisfaction and perceived discretion in decision making is lower for successors. We also find that perceived discretion fully mediates the relationship between mode of entry into entrepreneurship and job satisfaction

The dark side of leadership: A systematic review of creativity and innovation

It is believed that workplace creativity and innovation are fostered by positive leader behaviours and positive workplace relationships and hindered by the opposite. However, some challenge this view, arguing that creativity and innovation can actually be fostered when employees experience what is increasingly referred to as the dark side of leadership and workplace mistreatment. Research on this area is sparse, contradictory and overly confusing. We begin by defining the dark side of leadership and then provide a comprehensive systematic review of 145 empirical studies on the topic. We review research on a broad range of constructs related to leadership and workplace mistreatment, such as abusive supervision, authoritarian leadership, destructive leadership, narcissistic leadership and relationship conflict. Our review reports the main effects, summarizes the results of the mediating and moderating variables, and highlights methodological shortcomings of the past literature. On this basis, several recommendations are made to advance this field of research

The entrepreneurial financing of the immigrant entrepreneurs: a literature review

There is an increasing interest in the phenomenon of immigrant entrepreneurship. Despite the growing number of studies, the financing aspect of immigrant entrepreneurship is still an emergent subject. In this paper, we critically and systematically review the field of the entrepreneurial financing of immigrant entrepreneurs. For this purpose, we conduct a two-step analysis of 37 systematically selected articles. In the first step, we provide an overall description of the field, while in the second step we perform a SWOT analysis on different aspects of the field, including the units of analysis, the main questions, and the use of theories and methods in the field. The review identifies gaps and weaknesses in the field, suggests potential opportunities for future research, and highlights some threats that could impede the implementation of future opportunities. Finally, the review suggests further questions to be explored for future advancement of knowledge in the field

EXPERIENCES WITH POLYMER-MODIFIED SHOTCRETE

Adhesive mortar for tiles can be significantly improved by modification. Why should sprayed concrete not benefit similarly for various applications? This question has been investigated through large-scale tests in a tunnel cross passage, in an access gallery of a salt mine and in a mining gravity shaft. In-situ tests are necessary because the sprayed concrete mix and the process engineering have a significant influence on the quality of the sprayed concrete. The fresh concrete properties and the properties of the sprayed concrete like early strength development, the ability to creep, adhesion, density and resistance to abrasion are all investigated