Disinclusion of unerupted teeth by mean of self-ligating brackets: effect of blood contamination on shear bond strength

Objectives: The aim of this study was to assess the effect of blood contamination on the shear bond strength and failure site of three different orthodontic self-ligating brackets. Study Design: 240 bovine permanent mandibular incisors were randomly divided into 12 groups of 20 specimens each. Orthodontic self-ligating brackets were tested under four different enamel surface conditions: a) dry, b) blood contamination before priming, c) blood contamination after priming, d) blood contamination before and after priming. Brackets were bonded to the teeth and subsequently tested using a Instron universal testing machine. Shear bond strength values and adhesive failure rate were recorded. Statistical analysis was performed using ANOVA and Tukey tests (strength values), and Chi squared test (ARI Scores). Results: Non-contaminated enamel surfaces showed highest bond strengths for all self ligating brackets. Under blood-contamination shear bond strengths lowered for all brackets tested. Groups contaminated before and after primer application showed the lowest shear bond strength. Significant differences in debond locations were found among the groups under the various enamel surface conditions. Conclusions: Blood contamination of enamel during the bonding procedure lowers bond strength values of self ligating brackets, expecially when contamination occur in different times of the bonding procedure

Clinical evaluation of bond failures and survival between mandibular canine-to-canine retainers made of flexible spiral wire and fiber-reinforced composite

Objectives: The purpose of this longitudinal prospective randomized study was to evaluate the clinical reliability of two different types of postorthodontic treatment retainers: a silanised-treated glass fibers-reinforced resin composite (FRC) and a directly bonded multistranded stainless steel wire. The hypothesis of the study was to assess if significant differences are present between failure rates of the two retainers. Study Design: This prospective study was based on an assessment of 87 patients (35 men and 52 women),with an average age of 24 years who required a lower arch fixed retainer after orthodontic treatment. Patients were divided in two groups. Assignment was carried out with random tables. A follow-up examination was carried out once a month. The number, cause, and date of single bond adhesive failures were recorded for both retainers over 12 months. Teeth that were rebonded after failure were not included in the success analysis. Statistical analysis was performed by means of a Fisher's exact test, Kaplan-Meier survival estimates, and log rank test. Results: Bond failure rate was significantly higher (P=0.0392) for multistranded metallic wire than for FRC. Conclusions: Glass fiber-reinforced resin composite retainers and multistranded metallic wires showed no significant difference in single bond failure rates over a one-year follow up

Arrival of Paleo-Indians to the Southern Cone of South America: New Clues from Mitogenomes

With analyses of entire mitogenomes, studies of Native American mitochondrial DNA (mtDNA) variation have entered the final phase of phylogenetic refinement: the dissection of the founding haplogroups into clades that arose in America during and after human arrival and spread. Ages and geographic distributions of these clades could provide novel clues on the colonization processes of the different regions of the double continent. As for the Southern Cone of South America, this approach has recently allowed the identification of two local clades (D1g and D1j) whose age estimates agree with the dating of the earliest archaeological sites in South America, indicating that Paleo-Indians might have reached that region from Beringia in less than 2000 years. In this study, we sequenced 46 mitogenomes belonging to two additional clades, termed B2i2 (former B2l) and C1b13, which were recently identified on the basis of mtDNA control-region data and whose geographical distributions appear to be restricted to Chile and Argentina. We confirm that their mutational motifs most likely arose in the Southern Cone region. However, the age estimate for B2i2 and C1b13 (11–13,000 years) appears to be younger than those of other local clades. The difference could reflect the different evolutionary origins of the distinct South American-specific sub-haplogroups, with some being already present, at different times and locations, at the very front of the expansion wave in South America, and others originating later in situ, when the tribalization process had already begun. A delayed origin of a few thousand years in one of the locally derived populations, possibly in the central part of Chile, would have limited the geographical and ethnic diffusion of B2i2 and explain the present-day occurrence that appears to be mainly confined to the Tehuelche and Araucanian-speaking grou

Reaching agility integrating freelancers in a hybrid workforce ecosystem : a study on Italian small-medium enterprises

LAUREA MAGISTRALENel corso dell’ultimo decennio, il mondo del lavoro ha subito diversi cambiamenti: fra questi, soprattutto nei paesi più sviluppati, si sta assistendo a un notevole tasso di crescita nel numero di lavoratori indipendenti o freelancer. Organizzazioni ed aziende stanno cercando di sfruttare appieno il potenziale di queste risorse, impiegandole non solo per scopi tattici, come avvenuto finora, ma anche sotto una prospettiva più strategica. In particolare, piuttosto che affidarsi a freelancer e e-lancer per colmare le lacune di competenze e know-how come una risposta ad hoc ad esigenze sul breve termine , oggi alcune compagnie stanno sviluppando un approccio più inclusivo per incorporare freelancer ad alta professionalità nella loro business strategy. Data la recente crescita, tali temi sono stati poco approfonditi dalla letteratura accademica. Da qui, il proposito di questa ricerca esplorativa è quello di fornire alle organizzazioni una maggiore comprensione delle principali implicazioni di adottare un modello di hybrid workforce e alcune best practice da adottare nell’ottica di sfruttare al meglio il potenziale di ogni tipo di talento. Essendo l’Agilty fondamentale dal punto di vista strategico per sopravvivere e competere in un mercato dinamico ed in continuo mutamento, scopo di questa tesi di ricerca è di indagare nello specifico l’impatto dell’inclusione di freelancers nel proprio business sulla workforce agility. Lo studio è stato condotto tramite casi studio su PMI Italiane e ha previsto 25 interviste a lavoratori indipendenti e a rappresentanti di 8 compagnie. I risultati ottenuti mostrano come le compagnie appartenenti a questa categoria demografica possano essere classificate sulla base del loro approccio in tre macro-gruppi, denominati Tradizionalismo, Flexible Hybridization Model, Open-Continuum. I principali contributi allo stato dell’arte della letteratura includono anche la definizione di alcune best-practice implementative per catturare il valore aggiunto di una forza lavoro di natura ibrida.In the last decade, the nature of workforce has been subject to several changes, including a remarkable rate of growth in the number of independent workers or freelancers, particularly in developed countries. Companies are trying to get the full potential from these resources, involving them not only for tactical purposes but also under a more strategic perspective. In particular, rather than relying on freelancers and e-lancers to tap high-skills gaps as an ad hoc response to urgent needs, now some companies are developing a more cohesive approach to incorporate highly skilled freelancers in their business strategy. Notwithstanding its recent growth, this area is still underdeveloped in academic research. Hence, purpose of this exploratory research is to provide organizations with an understanding of the main implications of embracing a hybrid workforce model, and with some best practises to adopt in order to fully exploit every talent’s potential. Being strategic agility key to sustain and compete in the dynamic and ever-evolving market environment, aim of this research thesis is to investigate specifically the impact of the use of freelancers on workforce agility. The study was conducted by means of case studies on Italian SMEs and contemplated 25 interviews to freelancers and representative members of 8 companies. Results show how companies with such demographics can be ascribed to three macro-groups based on their approach: Traditionalism, Flexible Hybridization Model and Open-Continuum. Main contributions to the state-of-art literature also include the definition of some implementational best-practices to capture value out of a hybrid workforce

Quantifying the legacy of the Chinese Neolithic on the maternal genetic heritage of Taiwan and Island Southeast Asia

There has been a long-standing debate concerning the extent to which the spread of Neolithic ceramics and Malay-Polynesian languages in Island Southeast Asia (ISEA) were coupled to an agriculturally driven demic dispersal out of Taiwan 4000 years ago (4 ka). We previously addressed this question using founder analysis of mitochondrial DNA (mtDNA) control-region sequences to identify major lineage clusters most likely to have dispersed from Taiwan into ISEA, proposing that the dispersal had a relatively minor impact on the extant genetic structure of ISEA, and that the role of agriculture in the expansion of the Austronesian languages was therefore likely to have been correspondingly minor. Here we test these conclusions by sequencing whole mtDNAs from across Taiwan and ISEA, using their higher chronological precision to resolve the overall proportion that participated in the “out-of-Taiwan” mid-Holocene dispersal as opposed to earlier, postglacial expansions in the Early Holocene. We show that, in total, about 20 % of mtDNA lineages in the modern ISEA pool result from the “out-of-Taiwan” dispersal, with most of the remainder signifying earlier processes, mainly due to sea-level rises after the Last Glacial Maximum. Notably, we show that every one of these founder clusters previously entered Taiwan from China, 6–7 ka, where rice-farming originated, and remained distinct from the indigenous Taiwanese population until after the subsequent dispersal into ISEA

A Hilton-Milner theorem for exterior algebras

Recent work of Scott and Wilmer and of Woodroofe extends the Erd\H{o}s-Ko-Rado theorem from set systems to subspaces of k-forms in an exterior algebra. We prove an extension of the Hilton-Milner theorem to the exterior algebra setting, answering in a strong way a question asked by these authors.Comment: 15 page

New Insights into the Runt Domain of RUNX2 in Melanoma Cell Proliferation and Migration

The mortality rate for malignant melanoma (MM) is very high, since it is highly invasive and resistant to chemotherapeutic treatments. The modulation of some transcription factors affects cellular processes in MM. In particular, a higher expression of the osteogenic master gene RUNX2 has been reported in melanoma cells, compared to normal melanocytes. By analyzing public databases for recurrent RUNX2 genetic and epigenetic modifications in melanoma, we found that the most common RUNX2 genetic alteration that exists in transcription upregulation is, followed by genomic amplification, nucleotide substitution and multiple changes. Additionally, altered RUNX2 is involved in unchecked pathways promoting tumor progression, Epithelial Mesenchymal Transition (EMT), and metastasis. In order to investigate further the role of RUNX2 in melanoma development and to identify a therapeutic target, we applied the CRISPR/Cas9 technique to explore the role of the RUNT domain of RUNX2 in a melanoma cell line. RUNT-deleted cells showed reduced proliferation, increased apoptosis, and reduced EMT features, suggesting the involvement of the RUNT domain in different pathways. In addition, del-RUNT cells showed a downregulation of genes involved in migration ability. In an in vivo zebrafish model, we observed that wild-type melanoma cells migrated in 81% of transplanted fishes, while del-RUNT cells migrated in 58%. All these findings strongly suggest the involvement of the RUNT domain in melanoma metastasis and cell migration and indicate RUNX2 as a prospective target in MM therapy

A genetic chronology for the Indian Subcontinent points to heavily sex-biased dispersals

Background India is a patchwork of tribal and non-tribal populations that speak many different languages from various language families. Indo-European, spoken across northern and central India, and also in Pakistan and Bangladesh, has been frequently connected to the so-called “Indo-Aryan invasions” from Central Asia ~3.5 ka and the establishment of the caste system, but the extent of immigration at this time remains extremely controversial. South India, on the other hand, is dominated by Dravidian languages. India displays a high level of endogamy due to its strict social boundaries, and high genetic drift as a result of long-term isolation which, together with a very complex history, makes the genetic study of Indian populations challenging. Results We have combined a detailed, high-resolution mitogenome analysis with summaries of autosomal data and Y-chromosome lineages to establish a settlement chronology for the Indian Subcontinent. Maternal lineages document the earliest settlement ~55–65 ka (thousand years ago), and major population shifts in the later Pleistocene that explain previous dating discrepancies and neutrality violation. Whilst current genome-wide analyses conflate all dispersals from Southwest and Central Asia, we were able to tease out from the mitogenome data distinct dispersal episodes dating from between the Last Glacial Maximum to the Bronze Age. Moreover, we found an extremely marked sex bias by comparing the different genetic systems. Conclusions Maternal lineages primarily reflect earlier, pre-Holocene processes, and paternal lineages predominantly episodes within the last 10 ka. In particular, genetic influx from Central Asia in the Bronze Age was strongly male-driven, consistent with the patriarchal, patrilocal and patrilineal social structure attributed to the inferred pastoralist early Indo-European society. This was part of a much wider process of Indo-European expansion, with an ultimate source in the Pontic-Caspian region, which carried closely related Y-chromosome lineages, a smaller fraction of autosomal genome-wide variation and an even smaller fraction of mitogenomes across a vast swathe of Eurasia between 5 and 3.5 ka