882 research outputs found
Mean Curvature Flow of High Codimension in Complex Projective Space
We study the mean curvature flow of smooth -dimensional compact
submanifolds with quadratic pinching in the Riemannian manifold
. Our main focus is on the case of high codimension, .
We establish a codimension estimate that shows in regions of high curvature,
the submanifold becomes approximately codimension one in a quantifiable way.
This estimate enables us to prove at a singular time of the flow, there exists
a rescaling that converges to a smooth codimension-one limiting flow in
Euclidean space. Under a cylindrical type pinching, we show that this limiting
flow is weakly convex and moves by translation. These estimates allow us to
analyse the behaviour of the flow near singularities and establish the
existence of the limiting flow. Lastly, we prove a decay estimate that shows
that the rescaling converges smoothly to a totally geodesic limit in infinite
time. This behaviour is only possible if the dimension of the submanifold is
even. Our approach relies on the preservation of the quadratic pinching
condition along the flow and a gradient estimate that controls the mean
curvature in regions of high curvature. This result generalises the work of
Pipoli and Sinestrari on the mean curvature flow of submanifolds of the complex
projective space
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Cryopreservation of winter-dormant apple: III Bud water status and survival after cooling to -30°c and during recovery from cryopreservation
Abstract
In a continuing study to improve the efficiency of dormant bud cryopreservation for
tissues hardened in maritime climates, the water status of dormant buds was monitored
between -4°C and recovery from liquid nitrogen (LN). Measurement of water content, simple
thermal analysis and differential scanning calorimetry were employed. Buds did not lose
water during cooling to, or holding at -30°C indicating that cryodehydration and/or other
adaptive responses contributed during this essential step. A bud exotherm that was an artefact
of warming was detected due to necessary handling at -4°C before cooling to -30°C. There
were no significant differences between cultivars with respect to water status at -30°C or
immediately upon rewarming from LN despite significant differences in post-LN survival.
Buds rehydrated in 5 days, but up to 14 days may be needed for recovery for some cultivars.
In some instances buds could be grafted without rehydration, taking up water across the early
graft union
Malignant transformation in a defined genetic background: proteome changes displayed by 2D-PAGE
<p>Abstract</p> <p>Background</p> <p>Cancer arises from normal cells through the stepwise accumulation of genetic alterations. Cancer development can be studied by direct genetic manipulation within experimental models of tumorigenesis. Thereby, confusion by the genetic heterogeneity of patients can be circumvented. Moreover, identification of the critical changes that convert a pre-malignant cell into a metastatic, therapy resistant tumor cell, however, is one necessary step to develop effective and selective anti-cancer drugs. Thus, for the current study a cell culture model for malignant transformation was used: Primary human fibroblasts of the BJ strain were sequentially transduced with retroviral vectors encoding the genes for hTERT (cell line BJ-T), simian virus 40 early region (SV40 ER, cell line BJ-TE) and H-Ras V12 (cell line BJ-TER).</p> <p>Results</p> <p>The stepwise malignant transformation of human fibroblasts was analyzed on the protein level by differential proteome analysis. We observed 39 regulated protein spots and therein identified 67 different proteins. The strongest change of spot patterns was detected due to integration of SV40 ER. Among the proteins being significantly regulated during the malignant transformation process well known proliferating cell nuclear antigen (PCNA) as well as the chaperones mitochondrial heat shock protein 75 kDa (TRAP-1) and heat shock protein HSP90 were identified. Moreover, we find out, that TRAP-1 is already up-regulated by means of SV40 ER expression instead of H-Ras V12. Furthermore Peroxiredoxin-6 (PRDX6), Annexin A2 (p36), Plasminogen activator inhibitor 2 (PAI-2) and Keratin type II cytoskeletal 7 (CK-7) were identified to be regulated. For some protein candidates we confirmed our 2D-PAGE results by Western Blot.</p> <p>Conclusion</p> <p>These findings give further hints for intriguing interactions between the p16-RB pathway, the mitochondrial chaperone network and the cytoskeleton. In summary, using a cell culture model for malignant transformation analyzed with 2D-PAGE, proteome and cellular changes can be related to defined steps of tumorigenesis.</p
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Cryopreservation of winter-dormant apple buds: II - tissue water status after desiccation at -4°c and before further cooling
Abstract
The established protocol for the cryopreservation of winter-dormant Malus buds requires
that stem explants, containing a single, dormant bud are desiccated at -4°C, for up to 14 days,
to reduce their water content to 25-30% of fresh weight. Using three apple cultivars, with
known differences in response to cryopreservation, the pattern of evaporative water loss has
been characterised, including early freezing events in the bud and cortical tissues that allow
further desiccation by water migration to extracellular ice. There were no significant
differences between cultivars in this respect or in the proportions of tissue water lost during
the desiccation process. Differential Scanning Calorimetry (to -90°C) of intact buds indicated
that bud tissues of the cultivar with the poorest response to cryopreservation had the highest
residual water content at the end of the desiccation process and froze at the highest
temperature
Keywords: Malus, cryopreservation, dormant bud, dehydratio
The step project:societal and political engagement of young people in environmental issues
Decisions on environmental topics taken today are going to have long-term consequences that will affect future generations. Young people will have to live with the consequences of these decisions and undertake special responsibilities. Moreover, as tomorrow’s decision makers, they themselves should learn how to negotiate and debate issues before final decisions are made. Therefore, any participation they can have in environmental decision making processes will prove essential in developing a sustainable future for the community.However, recent data indicate that the young distance themselves from community affairs, mainly because the procedures involved are ‘wooden’, politicians’ discourse alienates the young and the whole experience is too formalized to them. Authorities are aware of this fact and try to establish communication channels to ensure transparency and use a language that speaks to new generations of citizens. This is where STEP project comes in.STEP (www.step4youth.eu) is a digital Platform (web/mobile) enabling youth Societal and Political e-Participation in decision-making procedures concerning environmental issues. STEP is enhanced with web/social media mining, gamification, machine translation, and visualisation features.Six pilots in real contexts are being organised for the deployment of the STEP solution in 4 European Countries: Italy, Spain, Greece, and Turkey. Pilots are implemented with the direct participation of one regional authority, four municipalities, and one association of municipalities, and include decision-making procedures on significant environmental questions.</p
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Malignant transformation in a defined genetic background: Proteome changes displayed by 2D-PAGE
Background: Cancer arises from normal cells through the stepwise accumulation of genetic alterations. Cancer
development can be studied by direct genetic manipulation within experimental models of tumorigenesis.
Thereby, confusion by the genetic heterogeneity of patients can be circumvented. Moreover, identification of the
critical changes that convert a pre-malignant cell into a metastatic, therapy resistant tumor cell, however, is one
necessary step to develop effective and selective anti-cancer drugs. Thus, for the current study a cell culture model
for malignant transformation was used: Primary human fibroblasts of the BJ strain were sequentially transduced
with retroviral vectors encoding the genes for hTERT (cell line BJ-T), simian virus 40 early region (SV40 ER, cell line
BJ-TE) and H-Ras V12 (cell line BJ-TER).
Results: The stepwise malignant transformation of human fibroblasts was analyzed on the protein level by
differential proteome analysis. We observed 39 regulated protein spots and therein identified 67 different proteins.
The strongest change of spot patterns was detected due to integration of SV40 ER. Among the proteins being
significantly regulated during the malignant transformation process well known proliferating cell nuclear antigen
(PCNA) as well as the chaperones mitochondrial heat shock protein 75 kDa (TRAP-1) and heat shock protein HSP90
were identified. Moreover, we find out, that TRAP-1 is already up-regulated by means of SV40 ER expression
instead of H-Ras V12. Furthermore Peroxiredoxin-6 (PRDX6), Annexin A2 (p36), Plasminogen activator inhibitor 2
(PAI-2) and Keratin type II cytoskeletal 7 (CK-7) were identified to be regulated. For some protein candidates we
confirmed our 2D-PAGE results by Western Blot.
Conclusion: These findings give further hints for intriguing interactions between the p16-RB pathway, the
mitochondrial chaperone network and the cytoskeleton. In summary, using a cell culture model for malignant
transformation analyzed with 2D-PAGE, proteome and cellular changes can be related to defined steps of
tumorigenesi
How does the human RUNX3 gene induce apoptosis in gastric cancer? Latest data, reflections and reactions.
RUNX3 is the oldest known gene in the RUNX family. Data have demonstrated its function to be thoroughly involved the neurogenesis of the dorsal root ganglia, T-cell differentiation and tumorigenesis of gastric epithelium. As a TGF-beta target, RUNX3 protein is believed to be involved in TGF-beta-mediated tumor suppressor pathway; however, little is known about its role in apoptosis. According to recent data reported by Yamamura et al., (J Biol Chem 2006; 281:5267-76), RUNX3 interacts with FoxO3a/FKHRL1 expressed in gastric cancer cells to activate Bim and induce apoptosis. The cooperation between RUNX3 and the PI3K/Akt signaling pathway component FoxO3a/FKHRL1 suggests the putative role of RUNX3 in the homoeostasis of gastric cells and in stomach cancer control. Here we discuss recent breakthroughs in our understanding of the mechanisms of RUNX3 in gastric malignancy and comment on possible future trends and perspectives
Understanding the cryosurvival of cold-hardened, winter apple buds - critical water content and the role of non-differentiated secondary primordia
Análisis contrastivo del presente progresivo en español y griego
Στόχος αυτής της εργασίας είναι να αναλύσει τη χρήση του ενεστώτα διαρκείας σε Έλληνες μαθητές της ισπανικής ως ξένης/δεύτερης γλώσσας και σε δίγλωσσους που έχουν ως μητρική τους γλώσσα την ελληνική και ισπανική γλώσσα, προκειμένου να ανακαλύψει σε ποια συγκείμενα παρουσιάζουν δυσκολία οι ελληνόφωνοι, καθώς και τον βαθμό κατάκτησης του ρηματικού ποιού ενεργείας και από τις δυο κατηγορίες ατόμων. Για να γίνει αυτό, αρχικά, πραγματοποιείται μια αντιπαραβολική ανάλυση στον ενεστώτα διαρκείας στα ελληνικά και στα ισπανικά, ο οποίος στα ελληνικά εκφράζεται μονολεκτικά (απλός ενεστώτα) και στα ισπανικά και περιφραστικά (ρηματική έκφραση του estar + γερούνδιο).
Για τη διερεύνηση της χρήσης αυτού του φαινομένου μορφοσυντακτικής παραλλαγής, δόθηκε ερωτηματολόγιο σε 6 Έλληνες μαθητές ισπανικής γλώσσας επιπέδου Α και Β σύμφωνα με το ΚΕΠΑ, καθώς και σε 4 δίγλωσσους Ελληνο-Ισπανούς. Οι απαντήσεις που ελήφθησαν αναλύθηκαν ποσοτικά και έδειξαν ότι αυτές οι δύο ομάδες συμμετεχόντων δεν χρησιμοποιούν τον ισπανικό περιφραστικό τύπο στον ίδιο βαθμό, εφόσον οι μονόγλωσσοι χρησιμοποιούν περισσότερο τον μονολεκτικό τύπο (57,8%) και οι δίγλωσσοι τον περιφραστικό (44,1%).
Επιπλέον, η μελέτη μας καταδεικνύει ότι οι πληροφοριοδότες, επηρεαζόμενοι από το γραμματικό ποιόν ενεργείας, τείνουν να επιλέγουν την περίφραση με καταστάσεις που δηλώνουν διάρκεια και τον απλό ενεστώτα με καταστάσεις που δηλώνουν συνήθεια και επανάληψη. Όσον αφορά το λεξικό ποιόν ενεργείας, όλοι επιλέγουν τον περιφραστικό τύπο με ρήματα δραστηριότητας και τον μονολεκτικό τύπο με ρήματα επίτευξης και κατάστασης, ενώ με τα ρήματα που δηλώνουν συμβάν παρατηρούνται αντίθετες προτιμήσεις. Επιπλέον, η μεγάλη επαφή με την ισπανική γλώσσα, που λειτουργεί ως εξωγλωσσικός παράγοντας, είναι πιο ορατή στις επιλογές των δίγλωσσων, αφού χρησιμοποιούν αυτούς τους τύπους με μεγαλύτερη αποφασιστικότητα.El objetivo de este trabajo es analizar el uso del presente progresivo en estudiantes de ELE griegos y en bilingües griego-español con el fin de descubrir en qué contextos muestran dificultad los grecoparlantes, así como el grado de adquisición del aspecto verbal en estos dos perfiles. Para ello, en primer lugar se realiza un análisis contrastivo sobre el tiempo presente progresivo en griego y en español, el cual en griego se expresa en forma sintética (presente simple) y en español cuenta además con una forma analítica (perífrasis de estar+gerundio).
Para investigar el uso de este fenómeno de variación morfosintáctica se pasó un cuestionario a 6 alumnos griegos de ELE de nivel A y B según el MCER y a 4 bilingües griego-español. Las respuestas obtenidas se han analizado cuantitativamente y han demostrado que estos dos grupos de participantes no usan la forma analítica del español en la misma medida, porque los monolingües utilizan más la forma sintética (57,8%) y los bilingües la forma analítica (44,1%).
Además, este estudio demuestra que nuestros informantes, influidos por el aspecto morfológico, tienden a elegir la perífrasis con acciones progresivas y el presente simple con acciones habituales e iterativas. En cuanto al aspecto léxico, todos optan por la forma analítica con verbos de actividad y por la forma sintética con verbos de logro y de estado, mientras que con los verbos de realización se observan preferencias opuestas. Además, la alta exposición a la lengua española, como factor extralingüístico, es más evidente en las selecciones de los bilingües, ya que utilizan estas estructuras con un alto grado de certeza
Οι απόψεις των νηπιαγωγών και δασκάλων για τη μετάβαση στην πρώτη δημοτικού. Πρακτικές και προγράμματα μετάβασης
Σκοπός της παρούσας εργασίας είναι να μελετήσει το φαινόμενο της μετάβασης από το νηπιαγωγείο στην πρώτη τάξη του δημοτικού έτσι όπως βιώνεται σύμφωνα με τη γνώμη των εκπαιδευτικών των δυο βαθμίδων, προσχολικής και πρωτοβάθμιας εκπαίδευσης. Συγκεκριμένα, θέλαμε να εξετάσουμε τις γνώσεις των εκπαιδευτικών και των δύο βαθμίδων σχετικά με την έννοια της μετάβασης, πόσο σημαντική τη θεωρούν για την εξέλιξη των παιδιών και από ποιους παράγοντες επηρεάζεται η ομαλή μετάβαση των παιδιών. Επιπλέον, θέλαμε να εξετάσουμε την ύπαρξη συνεργασίας μεταξύ των εκπαιδευτικών και των γονιών και την εφαρμογή πρακτικών μετάβασης. Τέλος, θέλαμε να διερευνήσουμε την εικόνα των παιδιών και τα συναισθήματα των γονιών και των παιδιών κατά τη διάρκεια της μετάβασης σύμφωνα με τη γνώμη των εκπαιδευτικών. Για τους σκοπούς της έρευνας χρησιμοποιήθηκε η μέθοδος των ημιδομημένων συνεντεύξεων σε ένα δείγμα δεκατεσσάρων ατόμων που αποτελούνταν από επτά νηπιαγωγούς και επτά δασκάλους. Τα αποτελέσματα της έρευνας έδειξαν πόσο σημαντική είναι η συνεργασία μεταξύ των εκπαιδευτικών και των γονιών καθώς και την κοινή γραμμή που οφείλουν να ακολουθούν όλοι οι άμεσα εμπλεκόμενοι προκειμένου να καρπωθούν τα οφέλη μιας ομαλής μετάβασης. Επιπλέον, φάνηκε μια διαφορά στις πρακτικές ομαλής μετάβασης που εφαρμόζουν οι εκπαιδευτικοί. Ωστόσο και οι δύο θεωρούν τις πρακτικές βοηθητικές και απαραίτητες.The purpose of this survey is to study the transition period from the Nursery School to the first class of Primary School, based on both Nursery and Primary School teachers’ experiences. Specifically, we would like to examine how well informed the teachers of both grades are as far as the notion/meaning of this transition is concerned, how important for students’ development is and which factors influence this smooth transition. Furthermore, we would like to examine if there is cooperation between guardians and teachers and the transition practices application. Finally, we would like to investigate not only the children’s image but also parents and children’s feelings during the transition period according to the educators’ opinion. For the purpose of this survey, we applied the method of semi-structured interviews to a statistic pool of 14 people (consisting of 7 Nursery School and 7 Primary School teachers). The results of this survey showed how important cooperation between teachers and parents is as well as the fact that all the people involved in the survey should follow the same guidelines so as to reap the benefits of a smooth transition. In addition, a difference concerning the smooth transition policy the teachers apply was noticed. However, both groups regard these policies as supplementary and necessary
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