Laminar-turbulent transition in Raman fiber lasers:a first passage statistics based analysis

Loss of coherence with increasing excitation amplitudes and spatial size modulation is a fundamental problem in designing Raman fiber lasers. While it is known that ramping up laser pump power increases the amplitude of stochastic excitations, such higher energy inputs can also lead to a transition from a linearly stable coherent laminar regime to a non-desirable disordered turbulent state. This report presents a new statistical methodology, based on first passage statistics, that classifies lasing regimes in Raman fiber lasers, thereby leading to a fast and highly accurate identification of a strong instability leading to a laminar-turbulent phase transition through a self-consistently defined order parameter. The results have been consistent across a wide range of pump power values, heralding a breakthrough in the non-invasive analysis of fiber laser dynamics.

Parenting a child with chronic illness as they transition into adulthood:a systematic review and thematic synthesis of parents’ experiences

Objective - To understand how parents view and experience their role as their child with a long-term physical health condition transitions to adulthood and adult healthcare services. Methods - Five databases were systematically searched for qualitative articles examining parents’ views and experiences of their child’s healthcare transition. Papers were quality assessed and thematically synthesised. Results - Thirty-two papers from six countries, spanning a 17-year period were included. Long-term conditions were diverse. Findings indicated that parents view their child’s progression toward self-care as an incremental process which they seek to facilitate through up-skilling them in self-management practices. Parental perceptions of their child’s readiness, wellness, competence and long-term condition impacted on the child’ progression to healthcare autonomy. A lack of transitional healthcare and differences between paediatric and adult services served as barriers to effective transition. Parents were required to adjust their role, responsibilities and behaviour to support their child’s growing independence. Conclusion - Parents can be key facilitators of their child’s healthcare transition, supporting them to become experts in their own condition and care. To do so, they require clarification on their role and support from service providers. Practice Implications - Interventions are needed which address the transitional care needs of parents as well as young people.

Investigating optical complexity of the phase transition in the intensity of a fibre laser radiation

Fibre lasers have been shown to manifest a laminar-to-turbulent transition when increasing its pump power. In order to study the dynamical complexity of this transition we use advanced statistical tools of time-series analysis. We apply ordinal analysis and the horizontal visibility graph to the experimentally measured laser output intensity. This reveal the presence of temporal correlations during the transition from the laminar to the turbulent lasing regimes. Both methods allow us to unveil coherent structures with well defined time-scales and strong correlations both, in the timing of the laser pulses and in their peak intensities.

Acoustic and Magnetic Techniques for the Isolation and Analysis of Cells in Microfluidic Platforms

Cancer comprises a collection of diseases, all of which begin with abnormal tissue growth from various stimuli, including (but not limited to): heredity, genetic mutation, exposure to harmful substances, radiation as well as poor dieting and lack of exercise. The early detection of cancer is vital to providing life-saving, therapeutic intervention. However, current methods for detection (e.g., tissue biopsy, endoscopy and medical imaging) often suffer from low patient compliance and an elevated risk of complications in elderly patients. As such, many are looking to “liquid biopsies” for clues into presence and status of cancer due to its minimal invasiveness and ability to provide rich information about the native tumor. In such liquid biopsies, peripheral blood is drawn from patients and is screened for key biomarkers, chiefly circulating tumor cells (CTCs). Capturing, enumerating and analyzing the genetic and metabolomic characteristics of these CTCs may hold the key for guiding doctors to better understand the source of cancer at an earlier stage for more efficacious disease management.

The isolation of CTCs from whole blood, however, remains a significant challenge due to their (i) low abundance, (ii) lack of a universal surface marker and (iii) epithelial-mesenchymal transition that down-regulates common surface markers (e.g., EpCAM), reducing their likelihood of detection via positive selection assays. These factors potentiate the need for an improved cell isolation strategy that can collect CTCs via both positive and negative selection modalities as to avoid the reliance on a single marker, or set of markers, for more accurate enumeration and diagnosis.

The technologies proposed herein offer a unique set of strategies to focus, sort and template cells in three independent microfluidic modules. The first module exploits ultrasonic standing waves and a class of elastomeric particles for the rapid and discriminate sequestration of cells. This type of cell handling holds promise not only in sorting, but also in the isolation of soluble markers from biofluids. The second module contains components to focus (i.e., arrange) cells via forces from acoustic standing waves and separate cells in a high throughput fashion via free-flow magnetophoresis. The third module uses a printed array of micromagnets to capture magnetically labeled cells into well-defined compartments, enabling on-chip staining and single cell analysis. These technologies can operate in standalone formats, or can be adapted to operate with established analytical technologies, such as flow cytometry. A key advantage of these innovations is their ability to process erythrocyte-lysed blood in a rapid (and thus high throughput) fashion. They can process fluids at a variety of concentrations and flow rates, target cells with various immunophenotypes and sort cells via positive (and potentially negative) selection. These technologies are chip-based, fabricated using standard clean room equipment, towards a disposable clinical tool. With further optimization in design and performance, these technologies might aid in the early detection, and potentially treatment, of cancer and various other physical ailments.

Bioengineered Approaches to Prevent Hypertrophic Scar Contraction

Burn injuries in the United States account for over one million hospital admissions per year, with treatment estimated at four billion dollars. Of severe burn patients, 30-90% will develop hypertrophic scars (HSc). Current burn therapies rely upon the use of bioengineered skin equivalents (BSEs), which assist in wound healing but do not prevent HSc. HSc contraction occurs of 6-18 months and results in the formation of a fixed, inelastic skin deformity, with 60% of cases occurring across a joint. HSc contraction is characterized by abnormally high presence of contractile myofibroblasts which normally apoptose at the completion of the proliferative phase of wound healing. Additionally, clinical observation suggests that the likelihood of HSc is increased in injuries with a prolonged immune response. Given the pathogenesis of HSc, we hypothesize that BSEs should be designed with two key anti-scarring characterizes: (1) 3D architecture and surface chemistry to mitigate the inflammatory microenvironment and decrease myofibroblast transition; and (2) using materials which persist in the wound bed throughout the remodeling phase of repair. We employed electrospinning and 3D printing to generate scaffolds with well-controlled degradation rate, surface coatings, and 3D architecture to explore our hypothesis through four aims.

In the first aim, we evaluate the impact of elastomeric, randomly-oriented biostable polyurethane (PU) scaffold on HSc-related outcomes. In unwounded skin, native collagen is arranged randomly, elastin fibers are abundant, and myofibroblasts are absent. Conversely, in scar contractures, collagen is arranged in linear arrays and elastin fibers are few, while myofibroblast density is high. Randomly oriented collagen fibers native to the uninjured dermis encourage random cell alignment through contact guidance and do not transmit as much force as aligned collagen fibers. However, the linear ECM serves as a system for mechanotransduction between cells in a feed-forward mechanism, which perpetuates ECM remodeling and myofibroblast contraction. The electrospinning process allowed us to create scaffolds with randomly-oriented fibers that promote random collagen deposition and decrease myofibroblast formation. Compared to an in vitro HSc contraction model, fibroblast-seeded PU scaffolds significantly decreased matrix and myofibroblast formation. In a murine HSc model, collagen coated PU (ccPU) scaffolds significantly reduced HSc contraction as compared to untreated control wounds and wounds treated with the clinical standard of care. The data from this study suggest that electrospun ccPU scaffolds meet the requirements to mitigate HSc contraction including: reduction of in vitro HSc related outcomes, diminished scar stiffness, and reduced scar contraction. While clinical dogma suggests treating severe burn patients with rapidly biodegrading skin equivalents, these data suggest that a more long-term scaffold may possess merit in reducing HSc.

In the second aim, we further investigate the impact of scaffold longevity on HSc contraction by studying a degradable, elastomeric, randomly oriented, electrospun micro-fibrous scaffold fabricated from the copolymer poly(l-lactide-co-ε-caprolactone) (PLCL). PLCL scaffolds displayed appropriate elastomeric and tensile characteristics for implantation beneath a human skin graft. In vitro analysis using normal human dermal fibroblasts (NHDF) demonstrated that PLCL scaffolds decreased myofibroblast formation as compared to an in vitro HSc contraction model. Using our murine HSc contraction model, we found that HSc contraction was significantly greater in animals treated with standard of care, Integra, as compared to those treated with collagen coated-PLCL (ccPLCL) scaffolds at d 56 following implantation. Finally, wounds treated with ccPLCL were significantly less stiff than control wounds at d 56 in vivo. Together, these data further solidify our hypothesis that scaffolds which persist throughout the remodeling phase of repair represent a clinically translatable method to prevent HSc contraction.

In the third aim, we attempt to optimize cell-scaffold interactions by employing an anti-inflammatory coating on electrospun PLCL scaffolds. The anti-inflammatory sub-epidermal glycosaminoglycan, hyaluronic acid (HA) was used as a coating material for PLCL scaffolds to encourage a regenerative healing phenotype. To minimize local inflammation, an anti-TNFα monoclonal antibody (mAB) was conjugated to the HA backbone prior to PLCL coating. ELISA analysis confirmed mAB activity following conjugation to HA (HA+mAB), and following adsorption of HA+mAB to the PLCL backbone [(HA+mAB)PLCL]. Alican blue staining demonstrated thorough HA coating of PLCL scaffolds using pressure-driven adsorption. In vitro studies demonstrated that treatment with (HA+mAB)PLCL prevented downstream inflammatory events in mouse macrophages treated with soluble TNFα. In vivo studies using our murine HSc contraction model suggested positive impact of HA coating, which was partiall impeded by the inclusion of the TNFα mAB. Further characterization of the inflammatory microenvironment of our murine model is required prior to conclusions regarding the potential for anti-TNFα therapeutics for HSc. Together, our data demonstrate the development of a complex anti-inflammatory coating for PLCL scaffolds, and the potential impact of altering the ECM coating material on HSc contraction.

In the fourth aim, we investigate how scaffold design, specifically pore dimensions, can influence myofibroblast interactions and subsequent formation of OB-cadherin positive adherens junctions in vitro. We collaborated with Wake Forest University to produce 3D printed (3DP) scaffolds with well-controlled pore sizes we hypothesized that decreasing pore size would mitigate intra-cellular communication via OB-cadherin-positive adherens junctions. PU was 3D printed via pressure extrusion in basket-weave design with feature diameter of ~70 µm and pore sizes of 50, 100, or 150 µm. Tensile elastic moduli of 3DP scaffolds were similar to Integra; however, flexural moduli of 3DP were significantly greater than Integra. 3DP scaffolds demonstrated ~50% porosity. 24 h and 5 d western blot data demonstrated significant increases in OB-cadherin expression in 100 µm pores relative to 50 µm pores, suggesting that pore size may play a role in regulating cell-cell communication. To analyze the impact of pore size in these scaffolds on scarring in vivo, scaffolds were implanted beneath skin graft in a murine HSc model. While flexural stiffness resulted in graft necrosis by d 14, cellular and blood vessel integration into scaffolds was evident, suggesting potential for this design if employed in a less stiff material. In this study, we demonstrate for the first time that pore size alone impacts OB-cadherin protein expression in vitro, suggesting that pore size may play a role on adherens junction formation affiliated with the fibroblast-to-myofibroblast transition. Overall, this work introduces a new bioengineered scaffold design to both study the mechanism behind HSc and prevent the clinical burden of this contractile disease.

Together, these studies inform the field of critical design parameters in scaffold design for the prevention of HSc contraction. We propose that scaffold 3D architectural design, surface chemistry, and longevity can be employed as key design parameters during the development of next generation, low-cost scaffolds to mitigate post-burn hypertrophic scar contraction. The lessening of post-burn scarring and scar contraction would improve clinical practice by reducing medical expenditures, increasing patient survival, and dramatically improving quality of life for millions of patients worldwide.

Study of insulin-like growth factor signaling in mitochondrial function

Insulin-like Growth Factor-1 (IGF-1) signalling promotes cell growth and is associated with cancer progression, including metastasis, epithelial-mesenchymal transition (EMT), and resistance to therapy. Mitochondria play an essential role in cancer cell metabolism and accumulating evidence demonstrates that dysfunctional mitochondria associated with release of mitochondrial reactive oxygen species (ROS) can influence cancer cell phenotype and invasive potential. We previously isolated a mitochondrial UTP carrier (PNC1/SLC25A33) whose expression is regulated by IGF-1, and which is essential for mitochondrial maintenance. PNC1 suppression in cancer cells results in mitochondrial dysfunction and acquisition of a profound ROS-dependent invasive (EMT) phenotype. Moreover, over-expression of PNC1 in cancer cells that exhibit an EMT phenotype is sufficient to suppress mitochondrial ROS production and reverse the invasive phenotype. This led us to investigate the IGF-1-mitochondrial signalling axis in cancer cells. We found that IGF-1 signalling supports increased mitochondrial mass and Oxphos potential through a PI3K dependant pathway. Acute inhibition of IGF-1R activity with a tyrosine kinase inhibitor results in dysfunctional mitochondria and cell death. We also observed an adaptive response to IGF-1R inhibition upon prolonged exposure to the kinase inhibitor, where increased expression of the EGF receptor can compensate for loss of mitochondrial mass through activation of PI3K/mTOR signalling. However, these cells exhibit impaired mitochondrial biogenesis and mitophagy. We conclude that the IGF-1 is required for mitochondrial maintenance and biogenesis in cancer cells, and that pharmacological inhibition of this pathway may induce mitochondrial dysfunction and may render the cells more sensitive to glycolysis-targeted drugs.

La transition vers la vie adulte : les besoins des jeunes adultes présentant une déficience intellectuelle profonde et de leur famille, les facteurs qui l'influencent et les pistes de solutions pour la faciliter

Résumé : Introduction : Au Québec, jusqu’à l’âge de 21 ans, les enfants et adolescents ayant une déficience intellectuelle (DI) profonde ont des services de pédiatrie adaptés et l’opportunité de fréquenter des écoles spécialisées publiques. Toutefois, au-delà de cet âge, l’accès à ces services spécialisés est plus limité : le financement pour la fréquentation scolaire cesse et les jeunes adultes transfèrent des services de santé pédiatriques vers le secteur adulte. Malgré la mise en place de solutions visant à faciliter cette transition, des difficultés tendent à persister, une situation pouvant avoir des effets négatifs considérables au niveau de la personne ayant un handicap et de sa famille. Cependant, peu d’études se sont intéressées aux facteurs qui influencent le vécu de la transition vers la vie adulte des familles de jeunes personnes présentant une DI profonde, rendant difficile l’adaptation des programmes déjà existants de planification de la transition à la réalité de ces familles. Objectif : Ce projet vise à décrire les besoins des personnes présentant une DI profonde et de leur famille lors de la transition vers la vie adulte, en décrivant le vécu des parents lors de cette période et les facteurs qui l’influencent, ainsi qu’en explorant les pistes de solution à mettre en place. Méthodologie : Afin de réaliser cette étude qualitative, un devis descriptif interprétatif a été choisi. Deux entrevues semi-dirigées individuelles ont été réalisées auprès de quatorze parents, la deuxième entrevue permettant de valider et d’approfondir les résultats à l’aide d’un résumé de la première rencontre. Résultats : Plusieurs facteurs multisystémiques de l’ordre du soutien matériel, informatif, cognitif et affectif semblent influencer la transition vers la vie adulte. Ces différents facteurs contribuent au vécu particulièrement difficile des familles, qui vivent beaucoup d’anxiété et de frustration face au peu de soutien qui leur est offert. Plusieurs idées intéressantes ont été proposées par les parents pour répondre à ce manque de soutien, autant au plan du partage des connaissances, de l’amélioration de la collaboration inter-établissement que du soutien psychologique. Conclusion : Cette étude souligne l’importance d’impliquer l’ensemble des acteurs œuvrant auprès du jeune adulte et de sa famille dans la planification de la transition. La compréhension de la réalité des personnes avec une DI profonde et de leur famille devrait permettre de développer des interventions concrètes leur étant destinées dans de futurs projets.

El fenotipo "basal-her2" en el cáncer de mama: caracterización clínico-molecular e implicaciones terapéuticas

Clinically HER2+ (cHER2+) breast cancer (BC), as exclusively determined by immunohistochemistry of HER2 protein overexpression and/or fluorescence in situ hybridization of HER2 gene amplification, has been largely considered a single disease entity in terms of clinical outcome and in the susceptibility to the anti-HER2 monoclonal antibody trastuzumab (Herceptin). However, although the adjuvant/neoadjuvant use of the trastuzumab has been shown to significantly reduce recurrence risk when added to standard chemotherapy in women with early-stage cHER2+ BC, not all cases derive similar benefit from trastuzumab because a significant number of cHER2+ BC patients develop disease recurrence. Unfortunately, the identification of a robust clinical predictor of trastuzumab benefit, including HER2 itself, has proven challenging in the adjuvant/neoadjuvant setting. Thus, we suggest that a new generation of research needs to refine the prognostic taxonomy of cHER2+ BC and develop easy-to-use, clinicbased prediction algorithms to distinguish between good- and poor- responders to trastuzumab-based therapy ab initio. This study offered two hypotheses: 1.) HER2 overexpression can unexpectedly take place in a molecular background owned by basal-like BC (a commonly HER2-negative BC subtype which possesses many epithelial-mesenchymal transition (EMT) characteristics and exhibits robust cancer stem cell [CSC]-like features), thus generating a so-called basal/cHER2+ BC subtype; 2.) the basal/cHER2+ phenotype confers poor prognosis and delineates a subgroup of intrinsically aggressive cHER2+ BC with primary resistance to trastuzumab...

The impact of phosphoinositide metabolic enzymes in glioblastoma: a tale of phosphoinositide-specific phospholipase C PLCβ1 and 5-phosphatase SKIP

Background: Glioblastoma multiforme (GBM) is one of the deadliest and most aggressive form of primary brain tumor. Unfortunately, current GBM treatment therapies are not effective in treating GBM patients. They usually experience very poor prognosis with a median survival of approximately 12 months. Only 3-5% survive up to 3 years or more. A large-scale gene profile study revealed that several genes involved in essential cellular processes are altered in GBM, thus, explaining why existing therapies are not effective. The survival of GBM patients depends on understanding the molecular and key signaling events associated with these altered physiological processes in GBM. Phosphoinositides (PI) form just a tiny fraction of the total lipid content in humans, however they are implicated in almost all essential biological processes, such as acting as second messengers in spatio-temporal regulation of cell signaling, cytoskeletal reorganization, cell adhesion, migration, apoptosis, vesicular trafficking, differentiation, cell cycle and post-translational modifications. Interestingly, these essential processes are altered in GBM. More importantly, incoming reports have associated PI metabolism, which is mediated by several PI phosphatases such as SKIP, lipases such as PLCβ1, and other kinases, to regulate GBM associated cellular processes. Even as PLCβ1 and SKIP are involved in regulating aberrant cellular processes in several other cancers, very few studies, of which majority are in-silico-based, have focused on the impact of PLCβ1 and SKIP in GBM. Hence, it is important to employ clinical, in vitro, and in vivo GBM models to define the actual impact of PLCβ1 and SKIP in GBM. AIM: Since studies of PLCβ1 and SKIP in GBM are limited, this study aimed at determining the pathological impact of PI metabolic enzymes, PLCB1 and SKIP, in GBM patient samples, GBM cell line models, and xenograft models for SKIP. Results: For the first time, this study confirmed through qPCR that PLCβ1 gene expression is lower in human GBM patient samples. Moreover, PLCβ1 gene expression inversely correlates with pathological grades of glioma; it decreases as glioma grades increases or worsens. Silencing PLCβ1 in U87MG GBM cells produces a dual impact in GBM by participating in both pro-tumoral and anti-tumoral roles. PLCβ1 knockdown cells were observed to have more migratory abilities, increased cell to extracellular matrix (ECM) adhesion, transition from epithelial phenotype to mesenchymal phenotype through the upregulation of EMT transcription factors Twist1 and Slug, and mesenchymal marker, vimentin. On the other hand, p-Akt and p-mTOR protein expression were downregulated in PLCβ1 knockdown cells. Thus, the oncogenic pathway PI3K/Akt/mTOR pathway is inhibited during PLCβ1 knockdown. Consistently, cell viability in PLCβ1 knockdown cells were significantly decreased compared to controls. As for SKIP, this study demonstrated that about 48% of SKIP colocalizes with nuclear PtdIns(4,5)P2 to nuclear speckles and that SKIP knockdown alters nuclear PtdIns(4,5)P2 in a cell-type dependent manner. In addition, SKIP silencing increased tumor volume and weight in xenografts than controls by reducing apoptosis and increasing viability. All in all, these data confirm that PLCβ1 and SKIP are involved in GBM pathology and a complete understanding of their roles in GBM may be beneficial.

Role of non-coding RNA alterations in melanoma

Cutaneous melanoma (CM) is a potentially lethal form of skin cancer and its most important histopathologic factor for staging is Breslow thickness (BT). Its correct determination is fundamental for pathologists. A deeper understanding of the molecular processes guiding CM pathogenesis could improve diagnosis, treatment and prognosis. MicroRNAs (miRNAs) play a key role in CM biology. The firs aim was to investigate miRNA expression in reference to BT assessment. We found that the combined miRNA expression of miR-21-5p and miR-146a-5p above or below 1.5 was significantly associated with overall survival and successfully identified all superficially spreading melanoma (SSM) patients with relapsing suggesting that the combined assessment of these miRNAs expression could aid in SSM staging. Secondly, we focus on multiple primary melanoma (MPM) patients, which develop multiple primary melanomas in their lifetime, and represent a model of high-risk CM occurrence. We explored the miRNome of single CM and MPM: CM and MPM present several dysregulated miRNAs, including key miRNAs involved in epithelial-mesenchymal transition. A different miRNA profile was observed between 1st and 2nd melanoma from the same patient. MiRNA target analysis revealed a more differentiated and less invasive status of MPMs compared to CMs. This characterization of the miRNA regulatory network of MPMs highlights molecular features differentiating this subtype from CM. Recently, NGS experiments revealed the existence of miRNA variants (isomiRs) with different length and sequence. We identified a shorter 3’isoform as tenfold over-represented compared to the canonical form of miR-125a-5p. Target analysis revealed that miRNA shortening could change the pattern of target gene regulation. Finally, we study miRNA and isomiR dysregulation in benign nevi (BN) and CM and in CM and melanoma metastasis. The reported non-random dysregulation of specific isomiRs contributes to the understanding of the complex melanoma pathogenesis and serves as the basis for further functional studies.

Transition Matters. Il ruolo del designer nella transizione sostenibile e circolare dei materiali polimerici

La ricerca indaga il ruolo del designer nella transizione sostenibile e circolare all’uso di materiali polimerici. Nel contesto contemporaneo la plastica è utilizzata in quasi ogni settore merceologico ma la sua futura applicazione è messa in forte discussione a causa dei visibili impatti ambientali del suo uso irresponsabile. Un passaggio netto dalla totale dipendenza alla liberazione dei polimeri è difficile; è necessario un periodo di transizione che permetta di coesistere responsabilmente con i polimeri in attesa di trovare dei validi sostituti. L’obiettivo della ricerca è lavorare su questo periodo ponendo il designer e le sue competenze come soggetti chiave del movimento. La tesi di ricerca propone un approccio per calare le pratiche del Transition Design nella progettazione di sistemi-prodotto, nutrendosi degli attributi anticipatori dell’Advanced Design e puntando agli obiettivi del Circular Design, lavorando a partire dalle merci più critiche nel contesto contemporaneo: quelle in polimero fossile non riciclabile. Contributo della tesi è la figura del Transition Matter Designer, un progettista di transizioni dei materiali che prevede metamorfosi di sistemi-prodotto nel tempo grazie alle sue competenze a diverse scale del progetto: forma l’utente agli atteggiamenti circolari e sostenibili, caratterizza i materiali per individuarne nuovi usi, seleziona i processi produttivi adatti a prevenire scarti e ne anticipa i cicli di vita nei prodotti. I Knitted Fasteners sono il risultato della simulazione del lavoro del Transition Matter Designer nel tessile: un sistema di elementi di fissaggio, personalizzabili dallo stilista e integrati negli abiti a maglia, che permettono di eliminare l’uso di fashion fasteners in plastica e metallo, elementi che rendono difficile il riciclo dei capi. Dalla sperimentazione è emerso il modello concettuale della Transindustrial Production: un lavoro di collaborazione fra Transition Matter Designer e creativo per dare identità ai materiali polimerici circolari attraverso l’ibridazione fra artigianato e industria, tipico del Made in Italy.

Apoplastic And Intracellular Plant Sugars Regulate Developmental Transitions In Witches' Broom Disease Of Cacao.

Witches' broom disease (WBD) of cacao differs from other typical hemibiotrophic plant diseases by its unusually long biotrophic phase. Plant carbon sources have been proposed to regulate WBD developmental transitions; however, nothing is known about their availability at the plant-fungus interface, the apoplastic fluid of cacao. Data are provided supporting a role for the dynamics of soluble carbon in the apoplastic fluid in prompting the end of the biotrophic phase of infection. Carbon depletion and the consequent fungal sensing of starvation were identified as key signalling factors at the apoplast. MpNEP2, a fungal effector of host necrosis, was found to be up-regulated in an autophagic-like response to carbon starvation in vitro. In addition, the in vivo artificial manipulation of carbon availability in the apoplastic fluid considerably modulated both its expression and plant necrosis rate. Strikingly, infected cacao tissues accumulated intracellular hexoses, and showed stunted photosynthesis and the up-regulation of senescence markers immediately prior to the transition to the necrotrophic phase. These opposite findings of carbon depletion and accumulation in different host cell compartments are discussed within the frame of WBD development. A model is suggested to explain phase transition as a synergic outcome of fungal-related factors released upon sensing of extracellular carbon starvation, and an early senescence of infected tissues probably triggered by intracellular sugar accumulation.

On the determination of the rotational oblateness of Achernar

The recent interferometric study of Achernar, leading to the conclusion that its geometrical oblateness cannot be explained by the Roche approximation, has stirred substantial interest in the community, in view of its potential impact on many fields of stellar astrophysics. It is the purpose of this Letter to reinterpret the interferometric observations with a fast-rotating, gravity-darkened central star surrounded by a small equatorial disk, whose presence is consistent with contemporaneous spectroscopic data. We find that we can fit the available data only assuming a critically rotating central star. We identified two different disk models that simultaneously fit the spectroscopic, polarimetric, and interferometric observational constraints: a tenuous disk in hydrostatic equilibrium (i.e., with small scale height) and a smaller, scale height enhanced disk. We believe that these relatively small disks correspond to the transition region between the photosphere and the circumstellar environment and that they are probably perturbed by some photospheric mechanism. The study of this interface between photosphere and circumstellar disk for near-critical rotators is crucial to our understanding of the Be phenomenon and the mass and angular momentum loss of stars in general. This work shows that it is nowadays possible to directly study this transition region from simultaneous multitechnique observations.

Energy of the first excited state of (43)Ar

Results of proton-proton-gamma coincidence measurements using the (36)S+(9)Be reaction revealed a gamma ray of 201.27 +/- 0.16 keV that most probably corresponds to the transition between the predicted 7/2(-) first excited state to the 5/2(-) ground state of (43)Ar.

Diffusion anomaly and dynamic transitions in the Bell-Lavis water model

In this paper we investigate the dynamic properties of the minimal Bell-Lavis (BL) water model and their relation to the thermodynamic anomalies. The BL model is defined on a triangular lattice in which water molecules are represented by particles with three symmetric bonding arms interacting through van der Waals and hydrogen bonds. We have studied the model diffusivity in different regions of the phase diagram through Monte Carlo simulations. Our results show that the model displays a region of anomalous diffusion which lies inside the region of anomalous density, englobed by the line of temperatures of maximum density. Further, we have found that the diffusivity undergoes a dynamic transition which may be classified as fragile-to-strong transition at the critical line only at low pressures. At higher densities, no dynamic transition is seen on crossing the critical line. Thus evidence from this study is that relation of dynamic transitions to criticality may be discarded. (C) 2010 American Institute of Physics. [doi:10.1063/1.3479001]