Ammonites from the latest Aalenian-earliest Bathonian of La Baume (Castellane area, SE France): palaeontology and biostratigraphy

Middle Jurassic strata are naturally exposed around the village called La Baume, near Castellane (Alpes de Haute Provence, SE France). We have realized both a detailed log and a bed-by-bed sampling for ammonite biostratigraphy in a 68 metres thick succession of subpelagic marls and limestones ("Calcaires à Zoophycos”) that spans the Middle Jurassic from uppermost Aalenian to lowermost Bathonian. The subpelagic succession can be roughly subdivided into three members. Ammonites from the Upper Aalenian Concavum Zone, all Lower Bajocian Zones (Discites Zone, Laeviuscula Zone including Ovale Subzone, Humpriesianum Zone), one Upper Bajocian Zone (Parkinsoni Zone) and probably one lower Bathonian Zone (Zigzag Zone) were found. A major gap of both the Niortense Zone and the Garantiana Zone, which was not previously described, was detected at the boundary between members 2 and 3. The main palaeontological interest of the ammonite fauna from La Baume is the richness and diversity of the family Sonniniidae, which is the subject of a systematic study and figurated along with some biostratigraphically significant forms. Biostratigraphical results and open problems are discusse

A surge of late-occurring meiotic double-strand breaks rescues synapsis abnormalities in spermatocytes of mice with hypomorphic expression of SPO11

Meiosis is the biological process that, after a cycle of DNA replication, halves the cellular chromosome complement, leading to the formation of haploid gametes. Haploidization is achieved via two successive rounds of chromosome segregation, meiosis I and II. In mammals, during prophase of meiosis I, homologous chromosomes align and synapse through a recombination-mediated mechanism initiated by the introduction of DNA double-strand breaks (DSBs) by the SPO11 protein. In male mice, if SPO11 expression and DSB number are reduced below heterozygosity levels, chromosome synapsis is delayed, chromosome tangles form at pachynema, and defective cells are eliminated by apoptosis at epithelial stage IV at a spermatogenesis-specific endpoint. Whether DSB levels produced in Spo11 +/− spermatocytes represent, or approximate, the threshold level required to guarantee successful homologous chromosome pairing is unknown. Using a mouse model that expresses Spo11 from a bacterial artificial chromosome, within a Spo11 −/− background, we demonstrate that when SPO11 expression is reduced and DSBs at zygonema are decreased (approximately 40 % below wild-type level), meiotic chromosome pairing is normal. Conversely, DMC1 foci number is increased at pachynema, suggesting that under these experimental conditions, DSBs are likely made with delayed kinetics at zygonema. In addition, we provide evidences that when zygotene-like cells receive enough DSBs before chromosome tangles develop, chromosome synapsis can be completed in most cells, preventing their apoptotic elimination

The emerging role of the industrial IoT in the smart factories : overview of the major applications and development of a qualitative framework

LAUREA MAGISTRALESono sempre più i dispositivi intelligenti e connessi presenti nelle case della gente oggi, ma il paradigma dell’IoT ha recentemente focalizzato la sua attenzione su un’industria che, nel corso della sua storia, ha subito diverse importanti trasformazioni: il settore industriale. Dotando gli asset fisici di sensori connessi, le aziende industriali sono in grado di trarre vantaggio da numerosi benefici, che comprendono il miglioramento dell’efficienza operativa, la riduzione del numero di incidenti sul posto di lavoro, la miglior gestione dei processi che si occupano del controllo qualità, il puntuale monitoraggio del flusso produttivo, etc. Questo lavoro si pone l’obiettivo di investigare la specifica applicazione dell’Industrial IoT nelle Industry 4.0 Smart Factories, analizzando il suo attuale stato di adozione e i maggiori trend che ne conseguono destinati a rivoluzionare l’intero settore. Per approfondire il tema, è stato analizzato il questionario Smart Factory 2018-19 lanciato dall’Osservatorio IoT del Politecnico di Milano ed è stato proposto un modello qualitativo composto da due dimensioni che consistono in due aspetti chiave dell’Industrial IoT and del suo specifico utilizzo nelle Smart Factories.Smart and connected devices are increasingly present in people’s home today, but the IoT paradigm has recently predated an industry which, over the course of history, experienced several disruptive transformations: the industrial sector. By equipping physical assets with connected sensors, industrial enterprises can take advantages from plenty of benefits, including the improvement of the overall operating efficiency, the reduction of workplace accidents, the management of the quality control processes, the accurate monitoring of the production flow, etc. This work focuses on investigating the specific application of the Industrial IoT in the Industry 4.0 Smart Factories, studying the current state of adoption and the major related trends that are expected to impact the manufacturing sector. With the aim of analysing the discussed topic, it has been performed the analysis of the Smart Factory Survey 2018-19 launched by the IoT Observatory of the Polytechnic University of Milan and it has been developed a qualitative framework consisting of two dimensions representing two key aspects of the Industrial IoT and its specific use in the Smart Factories

A surge of late-occurring meiotic double-strand breaks rescues synapsis abnormalities in spermatocytes of mice with hypomorphic expression of SPO11

Meiosis is the biological process that, after a cycle of DNA replication, halves the cellular chromosome complement, leading to the formation of haploid gametes. Haploidization is achieved via two successive rounds of chromosome segregation, meiosis I and II. In mammals, during prophase of meiosis I, homologous chromosomes align and synapse through a recombination-mediated mechanism initiated by the introduction of DNA double-strand breaks (DSBs) by the SPO11 protein. In male mice, if SPO11 expression and DSB number are reduced below heterozygosity levels, chromosome synapsis is delayed, chromosome tangles form at pachynema, and defective cells are eliminated by apoptosis at epithelial stage IV at a spermatogenesis-specific endpoint. Whether DSB levels produced in Spo11 (+/-) spermatocytes represent, or approximate, the threshold level required to guarantee successful homologous chromosome pairing is unknown. Using a mouse model that expresses Spo11 from a bacterial artificial chromosome, within a Spo11 (-/-) background, we demonstrate that when SPO11 expression is reduced and DSBs at zygonema are decreased (approximately 40 % below wild-type level), meiotic chromosome pairing is normal. Conversely, DMC1 foci number is increased at pachynema, suggesting that under these experimental conditions, DSBs are likely made with delayed kinetics at zygonema. In addition, we provide evidences that when zygotene-like cells receive enough DSBs before chromosome tangles develop, chromosome synapsis can be completed in most cells, preventing their apoptotic elimination

THE LATE ALBIAN GENUS SEMENOVICERAS (HOPLITIDAE, AMMONITINA): PALAEONTOLOGIC STUDY OF A FAUNA OF THE SEMENOVICERAS LITSCHKOVI ZONE FROM MANGYSHLAK (WEST KHAZAKSTAN)

The ammonites collected during an expedition to Mangyshlak in September, 1995,, are described. Three ammonitiferous levels were sampled in an arenaceous formation characterised by ferruginous, phosphatic metric concretions. The six species recognised in the two older levels belong to the genus Semenoviceras Wright, 1996 (pro Semenovites Glazunova, non  Tarbinskii, 1932), which was widespread in Central Asia mainly during the Late Albian. The third level yielded only a specimen of the mid-Cenomanian genus Cunningtoniceras, which will not be described. The second Semenoviceras -bearing level contained an extremely rich fauna of the S. litschkovi zone, S. pseudocoelonodum subzone, defined in the former Soviet Union and correlated with the Diploceras cristatum zone of western Europe. The present study allowed the intraspecific variability of Semenoviceras pseudocoelonodum (Semenov) to be defined, since the holotype was originally established on the basis of a single fragment. Furthermore, the subdivision in the subgenera Semenoviceras s. str. and Planihoplites is maintained.   &nbsp

THE APPEARANCE OF THE GENUS DESHAYESITES (KAZANSKY, 1914, AMMONOIDEA) IN THE LOWERMOST APTIAN (LOWER CRETACEOUS) OF LA BÉDOULE (SE FRANCE)

New palaeontological and biostratigraphic investigations were carried out at La Bédoule (SE France), which is the stratotype-area of the Bedoulian (Lower Aptian). The levels that directly overlie the last Barremian Pseudocrioceras-bearing bed revealed the occurrence of a fauna characterized by previously undescribed macroconchs of the genus Deshayesites, that we included in Deshayesites bedouliensis n. sp. and in D. aff. consobrinus (d’Orbigny). These forms are associated with the species Deshayesites antiquus Bogdanova, D. oglanlensis Bogdanova, D. cf. weissiformis Bogdanova, D. aff. weissiformis Bogdanova in Delanoy, D. cf. planicostatus Bogdanova, and D. aff. normani Casey. These ammonites characterize the basal Aptian Deshayesites tuarkyricus Zone. This Zone was defined in Turkmenistan but its recognition in the Mediterranean Tethys is confirmed by the present study. Contrary to previous assertions, the genus Prodeshayesites (which pre-dates Deshayesites in northern Germany and southern England), whose FAD was taken to mark the base of the Aptian, is absent at La Bédoule. Prodeshayesites is absent also in Turkmenistan and in all other Mediterranean localities. The FAD of the genus Deshayesites is taken to mark the base of the Aptian in the Mediterranean area.&nbsp

How Do Startups Integrate Strategies to Achieve Ambidexterity? Evidence from the Chinese Education-Technology Industry

The paper examines how startup organizations integrate strategies to achieve ambidexterity through an inductive study of three ventures in the Chinese education-technology industry. The paper utilizes a multicultural perspective on the nature of ambidexterity and contributes a conceptual framework of how startups in China sustain long-term competitive advantage through strategy integration. The concept of ambidexterity focuses on balancing the tensions between two strategic approaches: exploration (of new opportunities) vs. exploitation (of one’s core business). While existing literature illustrates the importance and challenges attaining ambidexterity given resource-constraints, there is limited examination on how startups integrate strategies to balance this tension. I thus ask: How can startups in China effectively integrate strategies to balance the tension between explorative and exploitative approaches? What are the specific building blocks of strategies implemented by these startups? This study follows an inductive grounded theory approach to build theory on how startups integrate strategies to attain ambidexterity. With an inductive research process, the study is exploratory: I study three ventures in a nascent industry in China—education technology (“edtech”) —to uncover patterns and interrelationships between theoretical constructs that emerged from the qualitative data. The three startups share similar founding timelines, size, and business offerings. I conducted onsite observations and semi-structured interviews, which served as the main source of data. I complemented this hand collected data with archival data (e.g. news articles) about the companies and industry. I find that startups utilize structural approaches to effectively integrate strategies and I inductively uncover three common integration mechanisms. While previous studies suggest that strategic tensions are balanced at the firm level, I go within the firm and find that differing levels of management (executive and frontline level) utilize different structures for integration and have differing strategic focus. While the executive level focuses on exploration as well as on integration, the frontline level is structurally independent and is primarily exploitation-oriented. To integrate these two approaches together, I find that startups commonly employ three mechanisms: (1) at the cognitive level, startups form a collectivist organizational identity so that employees with different roles still feel that they are all working towards the same common endgoal; (2) at the organizational structure level, startups use some variation of a "Strategy & Planning" department to manage the functional processes of redirect firm strategy while maintaining core firm focus; and (3) at the organizational design level, startups construct reward systems to align incentives for strategic integration within the startup. This unique approach enables each of employees to maximize their resources and capabilities, thus pushing the firm to sustain its competitive advantage. Synthesizing all parts together, these findings shed light on how executive and frontline levels of startups interact throughout strategy integration. Overall, by engaging in intensive field work to go inside the “black box” of the firm, this paper provides a rich, process-oriented perspective on how startups integrate conflicting tensions (exploration vs exploitation) to achieve long-term success in nascent markets. I hope that with the growth of quantitative “big data”, the theoretical framework that I present can be tested in future research.https://deepblue.lib.umich.edu/bitstream/2027.42/149475/1/How Do Startups Integrate Strategies to Achieve Ambidexterity.pd

A review of Monte Carlo simulations of polymers with PERM

In this review, we describe applications of the pruned-enriched Rosenbluth method (PERM), a sequential Monte Carlo algorithm with resampling, to various problems in polymer physics. PERM produces samples according to any given prescribed weight distribution, by growing configurations step by step with controlled bias, and correcting "bad" configurations by "population control". The latter is implemented, in contrast to other population based algorithms like e.g. genetic algorithms, by depth-first recursion which avoids storing all members of the population at the same time in computer memory. The problems we discuss all concern single polymers (with one exception), but under various conditions: Homopolymers in good solvents and at the $\Theta$ point, semi-stiff polymers, polymers in confining geometries, stretched polymers undergoing a forced globule-linear transition, star polymers, bottle brushes, lattice animals as a model for randomly branched polymers, DNA melting, and finally -- as the only system at low temperatures, lattice heteropolymers as simple models for protein folding. PERM is for some of these problems the method of choice, but it can also fail. We discuss how to recognize when a result is reliable, and we discuss also some types of bias that can be crucial in guiding the growth into the right directions.Comment: 29 pages, 26 figures, to be published in J. Stat. Phys. (2011