23 research outputs found
Multi-stage recovery robustness for optimization problems: a new concept for planning under disturbances
No full textIn practical optimization problems, disturbances to a given instance are unavoidable due to unpredictable events which can occur when the system is running. In order to face these situations, many approaches have been proposed during the last years in the area of robust optimization. The basic idea of robustness is to provide a solution which can be used even if the input instance is disturbed, at the cost of optimality. However, the notion of robustness in every day life is much broader than that pursued in the area of robust optimization so far. In practice it is reasonable to consider a solution as robust, if a recovery strategy is available that can be applied when disturbing events occur in order to adapt the solution to the new situation. This suggests to study robustness and recoverability in a unified framework. Recently, a first tentative of unifying the notions of robustness and recoverability into a new integrated notion of recoverable robustness has been done in the context of railway optimization, see [28].. . Although this model represents a significant improvement, it has the following drawback: typically there is not only one disruption, but many of them might appear one after another. In this case, the solutions provided within the recoverable robustness are not satisfying.. . In this paper we extend the concept of recoverable robustness to deal not only with one single recovery step, but with many recovery steps. To this aim, we introduce the new notion of multi-stage recoverable robustness. We apply the new model in the context of timetabling and delay management problems
an observational study with a depiction of postoperative quality of life
No full textEinleitung: Der Erhalt der Arteria rectalis superior (ARS) bei der
Sigmaresektion wird kontrovers diskutiert. Die praktische Relevanz dieser
Methode ist unzureichend untersucht. Die ARS wird bei der tubulären
Sigmaresektion erhalten. Sie kann bei der anterioren Rektumresektion ebenfalls
erhalten werden. Die Gewebeperfusion gilt als ein entscheidender Faktor für
die Heilung von Anastomosen. Die vorliegende Arbeit untersucht den Einfluss
von Gefäßerhalt oder –ligatur auf das chirurgische Ergebnis und auf die
postoperative Lebensqualität und prüft nach Risikofaktoren für eine
Anastomoseninsuffizienz. Methoden: Es erfolgte die prospektive Erfassung aller
in den Jahren 2006-2008 wegen Sigmadivertikulitis im Sana Klinikum Lichtenberg
operierten Patienten. Demografische Rahmendaten, Krankheitsschwere nach
Hinchey und Hansen und Stock, operative Strategie und intra- und
postoperativer Verlauf bei Erhalt (Gruppe A) oder Ligatur (Gruppe B) der ARS
wurden erfasst. Ausschlusskriterien waren die primäre Anlage eines
endständigen Kolostomas und das Vorliegen eines Kolonkarzinoms. Die Erfassung
der postoperativen Lebensqualität erfolgte mittels SF-12 und QLQ-CR29.
Ergebnisse: Es wurden 213 offene und laparoskopische Sigmaresektionen bei
Sigmadivertikulitis ausgewertet. In Gruppe A wurden 100 und in Gruppe B 113
Patienten eingeschlossen. 163 (76,5%) der Operationen wurden ausschließlich
laparoskopisch durchgeführt, jeweils 25 (11,7%) wurden primär offen oder in
Konversion operiert (p=0,518). Es fand sich kein signifikanter Unterschied im
Alter oder der präoperativen Morbidität zwischen den Gruppen.
Anastomoseninsuffizienzen traten in einem Fall (A) bzw. 8 Fällen (B) auf
(p=0,038). Intraoperative Blutungen, die eine Ligatur oder Clipversorgung
notwendig machten, traten in 5 (A) bzw. 16 (B) Fällen auf (p=0,025). Die
Schnitt-Naht-Zeit lag bei 129 (A) bzw. 134 (B) Minuten (p=0,347). Die mittlere
Verweildauer betrug 15,2 (A), bzw. 18,2 (B) Tage (p=0,047). Bei einem BMI>30
kg/m² traten häufiger Anastomoseninsuffizienzen auf (p=0,006). Eine höhere
ASA-Klassifizierung war mit einem höheren Risiko eines Auftretens einer
Anastomoseninsuffizienz assoziiert (p<0,001). Bei einem durchschnittlichen
Nachbeobachtungszeitraum von 4,5 ±0,83 Jahren ergaben sich keine Vorteile
hinsichtlich der postoperativen Lebensqualität bei Erhalt der ARS. Diskussion:
Es liegen keine ausreichenden klinischen Daten vor, die die Frage des Erhaltes
oder der Ligatur der ARS in der Divertikulitischirurgie abschließend klären.
Diese Untersuchung stellt die hinsichtlich der Fragestellung bisher größte
untersuchte Patientenkohorte in der internationalen Literatur dar. Im eigenen
Patientengut zeigt sich bei gleicher präoperativer Morbidität bei Ligatur der
ARS ein signifikant häufigeres Auftreten von Anastomoseninsuffizienzen. Es
traten bei Erhalt der ARS signifikant weniger interventionsbedürftige
intraoperative Blutungen auf. Die stationäre Verweildauer war in der Gruppe
mit Erhalt der Arterie signifikant kürzer. Bei Adipositas und mit zunehmender
ASA-Klasse ist das Risiko des Auftretens einer Anastomoseninsuffizienz
signifikant erhöht.Background: Preservation of the superior rectal artery (SRA) in sigmoid
resection continues to be a matter of debate. The practical relevance of
preserving the SRA has not been thoroughly investigated and randomized
controlled trials are largely missing. In tubular sigmoid resection the SRA is
preserved. The artery can be preserved in anterior resection, too. Vascular
supply to bowel anastomosis has been determined as an important factor for
postoperative healing. This thesis investigates the influence of preserving or
ligating the SRA on surgical results, patient reported outcome, and risk
factors of anastomotic breakdown. Methods: All patients operated on for
diverticular disease between 2006 and 2008 at Sana Hospitals Berlin-
Lichtenberg were prospectively studied. Assessment included demographic
patient data, severity of disease according to Hinchey or Hansen and Stock
classifications, surgical strategy, and intra- and postoperative results of
either preservation (group A) or ligation (group B) of the SRA. Exclusion
criteria included end stoma, or colonic cancer. Patient reported outcome was
assessed using the SF-12 and QLQ-CR29 questionnaires. Results: Primary data
analysis included 213 patients with open and laparoscopic sigmoid resection.
Group A included 100 and group B 113 patients. 76.5% of procedures were
laparoscopic procedures, 11.7% were primary open surgery and 11.7% conversion
to open surgery (p=0.518). There was no difference in age or preoperative
morbidity. Anastomotic breakdown was seen in one patient in group A and in
eight patients in group B (p=0.038). Intraoperative bleeding with the need for
additional intervention was seen in five cases in group A and in 16 cases in
group B (p=0.025). Surgical times were 129 and 134 minutes in groups A and B
respectively (p=0.347). Hospital stay was 15.2 days in group A, and 18.2 days
in group B (p=0.047). Patients with a BMI>30 kg/m were at risk of anastomotic
breakdown compared to those patients with a BMI<30 kg/m (p=0.006). Similarly
increased preoperative morbidity was associated with anastomotic breakdown
(p<0.001). Patients were followed-up for a mean of 4.5 ± 0.83 years. There was
no positive influence of preservation of SRA in patient reported quality of
life afterwards. Conclusion: To date there is insufficient data
internationally to decide the question of preservation or ligation of the SRA
in surgery for diverticular disease. This investigation reports the largest
patient cohort related to preservation of the vascular supply in diverticular
disease published so far. Surgical results in this study demonstrated
increased anastomotic breakdown with ligation of the SRA. Operation protocolls
suggest an increased incidence of noticeable intraoperative bleeding with
ligation of the SRA. There was a significantly reduced hospital stay in
patients with preservation of the SRA. Adipositas and preoperative morbidity
increased the risk of anastomotic breakdown significantly
Entrepreneurial intention : perspectives from women in a South African province
No full textAbstract: The objective of this study was to assess the entrepreneurial intention of women in a South African province. The study employed a quantitative, exploratory research design, utilising a self-administered survey of 200 women in South Africa’s North West province. A non-probability sampling approach was followed. Data were analysed using the Statistical Package for Social Sciences (SPSS) by means of an exploratory factor analysis, Pearson’s product-moment correlation and multiple regression analysis. Findings revealed that moderate entrepreneurial intentions exist among women in the North West province. Entrepreneurial self-efficacy was found to yield the greatest influence on entrepreneurial intention, followed by risk-taking attributes and cultural perspectives. It also emerged that attitudes towards entrepreneurship, cultural perspectives, risk-taking and self-efficacy had a significant and positive relationship with entrepreneurial intention. There was no statistical difference in entrepreneurial intention in terms of age, educational qualifications and employment status. The study provides guidelines for governmental and non-governmental role players in harnessing and promoting entrepreneurial intention among women. The study provides insights into the existence of entrepreneurial intention in a rural setting in South Africa, which has been neglected in literature. This study contributes to the existing body of knowledge on entrepreneurial intention in South Africa. The findings can be used to guide policy interventions as they highlight factors which should be integrated into programmes enhancing women’s entrepreneurial intention
Sechs Thesen zum Verhältnis von Künstlicher Intelligenz, Bildung und Gesellschaft aus interdisziplinärer Perspektive
No full textBerges M, Eickhoff-Schachtebeck A, Engbring D, et al. KI-Bildung!. MedienPädagogik: Zeitschrift für Theorie und Praxis der Medienbildung. 2000:1-17.Bildung muss angesichts der tiefgreifenden gesellschaftlichen Einschreibung von KI-Systemen verändert werden. Diese Veränderungen fassen wir unter dem Begriff KI-Bildung und beschreiben sie im Folgenden in sechs Thesen. In ihnen fordern wir eine Entmystifizierung der Debatten im Sinne einer digitalen Aufklärung, betonen die Bedeutung eines kritisch-reflexiven und multiperspektivischen Zugangs und lehnen technik-deterministische und solutionistische Ansätze zur Lösung bildungspolitischer und sozialer Probleme ab. Als normatives Leitbild für die Gestaltung von KI-Bildung schlagen wir eine Orientierung an den Zielen der Bildung für nachhaltige Entwicklung vor. Mit Blick auf die informatische Bildung verbinden wir kreativ-gestaltende mit analytisch-interpretierenden Verfahren und zeigen Architektur- und Relevanzperspektiven von KI-Systemen auf. Abschliessend heben wir die politische Bedeutung der Teilhabe und Mitgestaltung im Rahmen von KI-Bildung hervor. Mit unseren Thesen zu KI-Bildung wollen wir wechselwirkende technologische, individuelle und gesellschaftliche Dimensionen berücksichtigen, die interdisziplinäre Auseinandersetzung befördern und unterschiedliche Fachperspektiven stärker in einen Austausch bringen.Given the far-reaching social integration of AI systems, education must undergo fundamental change. We summarise these necessary transformations under the term AI Education, outlined below in six theses. We call for a demystification of AI debates in the spirit of digital enlightenment, emphasising a critical, reflective, and multi-perspective approach, while rejecting technology-deterministic and solutionist responses to educational and societal challenges. As a normative framework for shaping AI Education, we propose aligning it with the goals of education for sustainable development. In the context of computer science education, we advocate combining creative-design and analytical-interpretive methods and present architectural and relevance-based perspectives on AI systems. Finally, we underscore the political significance of participation and co-design in AI Education. With these theses, we aim to address the interconnected technological, individual, and societal dimensions, foster interdisciplinary dialogue, and bridge diverse disciplinary perspectives.</p
The level of corporate entrepreneurship within small and medium-sized enterprises in the seafreight transport industry
No full textM. Comm.Small and Medium-sized Enterprises (SMEs) are widely regarded as the innovation and growth engine of the economy. As such, a large volume of research has been conducted on the subject area of SMEs. Furthermore, the topic of corporate entrepreneurship has gained popularity in the past few years. Despite the variety of literature and studies conducted on the topic of corporate entrepreneurship, very few studies combine the topics of corporate entrepreneurship within SMEs. This study aims to investigate the level of corporate entrepreneurship within SMEs operating in the seafreight transport industry in South Africa. The study furthermore aims to produce tangible recommendations for improving the level of corporate entrepreneurship within SMEs. The study is largely quantitative in nature and was conducted by means of the corporate entrepreneurship climate instrument (CECI), which is a paper-based questionnaire testing the six main indicators of corporate entrepreneurship. These indicators provide an accurate reflection on the currently prevailing level of corporate entrepreneurship within an organisation. The sample consisted of three SMEs with 47 respondents, who are registered members of the South African Association of Freight Forwarders (SAAFF), operating within the sea-freight transport industry. The three sample businesses were selected based on differing attributes such as size and maturity. The results of the research instrument were complemented by means of a comprehensive literature review addressing the topic of corporate entrepreneurship and SMEs. The results of the CECI were thus evaluated against popular findings in current academic literature on the topic of corporate entrepreneurship. This was done in order to establish consistency of results in line with current academic literature on the subject of corporate entrepreneurship. This approach thus further adds credibility to the results of the study. The study found that the prevailing level of corporate entrepreneurship can be classed as moderate within SMEs operating in the sea-freight transport industry, with areas such as rewards and reinforcement and organisational boundaries showing positive results. Other areas such as management support, as well as climatespecific variables showed disappointing levels of corporate entrepreneurship, thus highlighting areas for improvement. Furthermore, the larger businesses showed much more promising results than their smaller counterparts did in terms of the 11 | P a g e prevailing level of corporate entrepreneurship. The study further showed that females and respondents below the age of thirty tended to perceive corporate entrepreneurship much more positively than other respondents did. This study thus increases the understanding of corporate entrepreneurship within SMEs, as well as highlights areas in which SMEs can improve. This study adds value to the subject of corporate entrepreneurship and has a uniquely South African focus, which is lacking in current literature
Aportes a una estrategia de manejo integrado de Dasiops inedulis steyskal en el cultivo de maracuyá
No full textThe passion fruit crop in Colombia is affected by the presence of Dasiops inedulis S., a pest that affects yield by feeding on flower buds, leading to the use of pesticides to control its population, generating toxic residuals in fruit and affecting the health of the producers. A comparison of the management of the black fly of the button, between the one made by 3 farmers of the town of La Plata - Huila (T2), with the integrated management proposed by Corpoica (T1); Analyzing the technical, economic and environmental variables of both treatments. The T1 consisted of biweekly sampling to measure the incidence, recollection of affected flower buds, and chemical management when exceeding the 30% action threshold by rotating the following products: Spinosad, Malathion or Thiacloprid with deltamethrin. For the technical variable, T1 maintained a lower Dasiops population, with 17.4% while T2 had 24.8%; For the economic part, the weekly costs, production and the profitability of the crop, were compared, showing that the costs of T1 are slightly higher and the best profitability was obtained in farm 2 with 789,276cop / ha, more in the T2 than in the T1; For the environmental part an analysis of residuality in fruits was performed, showing that both treatments exceed the MRL allowed by the European Union, and the smallest number of applications in the 3 farms was in the T1 treatment, and supported by the environmental impact quotient of pesticides (EIQ), that shows us the impact caused in the producers, consumers and environment, was lower in the proposed management. It is possible to say that the integrated management proposal of Corpoica, allows to maintain a smaller population of fly D. inedulis without leaving high residuality in fruits and diminishing the chemical applications, considerably reducing the environmental impact of the management of this pest, and increasing the profit of the crop.124 páginas : ilustraciones, gráficas, mapasEl cultivo de maracuyá en Colombia se ve afectado por la presencia de Dasiops inedulis S., plaga que se alimenta de los botones florales, llevando al uso de plaguicidas para su control y dejando residuos en los frutos que generan riesgos para la salud de productores, trabajadores y consumidores. Se comparó el manejo tradicional de la mosca del botón realizado por tres agricultores del municipio de La Plata, Huila, con una estrategia del manejo integrado propuesto por Corpoica. Se analizaron variables técnicas, económicas y ambientales de ambos tratamientos. El MIP consistió en el muestreo bisemanal, la recolección de botones afectados y manejo químico solo cuando se sobrepasó el umbral de acción de 30%, rotando spinosad, malathion o thiaclorpid con deltametrina. Para la variable técnica el MIP mantuvo una población de Dasiops, con 17,4% mientras que el tradicional mantuvo un 24,8%. Las variables económicas comparadas fueron los costos semanales, producción y el margen de ganancia del cultivo, donde los costos del MIP son mayores y el mayor margen de ganancia se obtuvo en la finca 2 con 789.276 cop/ha más que en el tradicional. Para el impacto ambiental se realizó un análisis de residuos en frutos, mostrando que ambos tratamientos sobrepasan el LMR permitido por la unión europea. El tratamiento MIP presentó el menor número de aplicaciones en las tres fincas. Se puede decir que la propuesta de manejo integrado de Corpoica, permite mantener una menor población de mosca D. inedulis disminuyendo las aplicaciones químicas y dejando menos residuos de insecticidas en frutos, reduciendo considerablemente el impacto ambiental del manejo de esta plaga y aumentando el margen de ganancia.PregradoIngeniero(a) Agrónom
