406 research outputs found
Digitale Vegetationskartierung des Nationalparks Asinara (Sardinien)
Mit Methoden der Fernerkundung und der digitalen Bildanalyse wird eine digitale Vegetationskartierung für die Mittelmeerinsel Asinara (Sardinien) durchgeführt. Auf Grundlage von Feldarbeiten und hochauflösenden, multispektralen Satellitenbilddaten (Pléiades, 2 x 2 m) wird eine pixelbasierte Überwachte Klassifizierung mittels Maximum-Likelihood-Methode vorgenommen und die Genauigkeit des Resultats anschließend visuell und statistisch ausgewertet. Die Ergebnisse zeigen eindeutige Grenzen der Klassifizierung hochauflösender Bilddaten durch Einzelpixelverfahren auf. Dies wird im Hinblick auf potentielle Lösungsvorschläge diskutiert. Basierend auf dem Zwischenergebnis wird unter Einbeziehung zusätzlicher Geodaten und visueller Interpretation eine Überarbeitung der Daten vorgenommen. Das Ergebnis stellt die bislang hochauflösendste flächenhafte Vegetationskartierung für den Nationalpark Asinara dar.Using remote sensing techniques and digital image analysis we conducted a digital mapping of vegetation types on the Mediterranean island of Asinara (Sardinia). Based on field data and high resolution satellite pictures (Pléiades, 2 x 2 m) a pixel-based Supervised Classification via Maximum-Likelihood-Algorithm was realised and statistically as well as visually evaluated. The results show clear limits of pixel-based classifications with high resolution data. Editing these interim results by integrating auxiliary geodata together with visual interpretation of orthophotos we accomplished the first extensive high resolution mapping of vegetation types on Asinara
Dynamics of Nanometer-Scale Foil Targets Irradiated with Relativistically Intense Laser Pulses
In this letter we report on an experimental study of high harmonic radiation
generated in nanometer-scale foil targets irradiated under normal incidence.
The experiments constitute the first unambiguous observation of odd-numbered
relativistic harmonics generated by the component of the
Lorentz force verifying a long predicted property of solid target harmonics.
Simultaneously the observed harmonic spectra allow in-situ extraction of the
target density in an experimental scenario which is of utmost interest for
applications such as ion acceleration by the radiation pressure of an
ultraintense laser.Comment: 5 pages, 4 figure
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Stable laser-ion acceleration in the light sail regime
We present experimental results on ion acceleration with circularly polarized, ultrahigh contrast laser pulses focused to peak intensities of 5×1019 W cm-2 onto polymer targets of a few 10 nanometer thickness. We observed spatially and energetically separated protons and carbon ions that accumulate to pronounced peaks around 2 MeV containing as much as 6.5% of the laser energy. Based on particle-in-cell simulation, we illustrate that an early separation of heavier carbon ions and lighter protons creates a stable interface that is maintained beyond the end of the radiation pressure dominated acceleration process
Efficient ion acceleration by collective laser-driven electron dynamics with ultra-thin foil targets
Experiments on ion acceleration by irradiation of ultra-thin diamond-like
carbon (DLC) foils, with thicknesses well below the skin depth, irradiated with
laser pulses of ultra-high contrast and linear polarization, are presented. A
maximum energy of 13MeV for protons and 71MeV for carbon ions is observed with
a conversion efficiency of > 10%. Two-dimensional particle-in-cell (PIC)
simulations reveal that the increase in ion energies can be attributed to a
dominantly collective rather than thermal motion of the foil electrons, when
the target becomes transparent for the incident laser pulse
Effects of Early Childhood Intervention on Fertility and Maternal Employment: Evidence from a Randomized Controlled Trial
Acquisition of pneumococci specific effector and regulatory Cd4+ T cells localising within human upper respiratory-tract mucosal lymphoid tissue
The upper respiratory tract mucosa is the location for commensal Streptococcus (S.) pneumoniae colonization and therefore represents a major site of contact between host and bacteria. The CD4(+) T cell response to pneumococcus is increasingly recognised as an important mediator of immunity that protects against invasive disease, with data suggesting a critical role for Th17 cells in mucosal clearance. By assessing CD4 T cell proliferative responses we demonstrate age-related sequestration of Th1 and Th17 CD4(+) T cells reactive to pneumococcal protein antigens within mucosal lymphoid tissue. CD25(hi) T cell depletion and utilisation of pneumococcal specific MHCII tetramers revealed the presence of antigen specific Tregs that utilised CTLA-4 and PDL-1 surface molecules to suppress these responses. The balance between mucosal effector and regulatory CD4(+) T cell immunity is likely to be critical to pneumococcal commensalism and the prevention of unwanted pathology associated with carriage. However, if dysregulated, such responses may render the host more susceptible to invasive pneumococcal infection and adversely affect the successful implementation of both polysaccharide-conjugate and novel protein-based pneumococcal vaccines
How Much Can We Trust Maternal Ratings of Early Child Development in Disadvantaged Samples?
First Observation of Self-Amplified Spontaneous Emission in a Free-Electron Laser at 109 nm Wavelength
We present the first observation of Self-Amplified Spontaneous Emission
(SASE) in a free-electron laser (FEL) in the Vacuum Ultraviolet regime at 109
nm wavelength (11 eV). The observed free-electron laser gain (approx. 3000) and
the radiation characteristics, such as dependency on bunch charge, angular
distribution, spectral width and intensity fluctuations all corroborate the
existing models for SASE FELs.Comment: 6 pages including 6 figures; e-mail: [email protected]
Prolonged Graft Survival in Older Recipient Mice Is Determined by Impaired Effector T-Cell but Intact Regulatory T-Cell Responses
Elderly organ transplant recipients represent a fast growing segment of patients on the waiting list. We examined age-dependent CD4+ T-cell functions in a wild-type (WT) and a transgenic mouse transplant model and analyzed the suppressive function of old regulatory T-cells. We found that splenocytes of naïve old B6 mice contained significantly higher frequencies of T-cells with an effector/memory phenotype (CD4+CD44highCD62Llow). However, in-vitro proliferation (MLR) and IFNγ-production (ELISPOT) were markedly reduced with increasing age. Likewise, skin graft rejection was significantly delayed in older recipients and fewer graft infiltrating CD4+T-cells were observed. Old CD4+ T-cells demonstrated a significant impaired responsiveness as indicated by diminished proliferation and activation. In contrast, old alloantigen-specific CD4+CD25+FoxP3+ T-cells demonstrated a dose-dependent well-preserved suppressor function. Next, we examined characteristics of 18-month old alloreactive T-cells in a transgenic adoptive transfer model. Adoptively transferred old T-cells proliferated significantly less in response to antigen. Skin graft rejection was significantly delayed in older recipients, and graft infiltrating cells were reduced. In summary, advanced recipient age was associated with delayed acute rejection and impaired CD4+ T-cell function and proliferation while CD4+CD25+FoxP3+ T-cells (Tregs) showed a well-preserved function
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