Cons and pros: prison education through the eyes of the prison educated*

ABSTRACT

While much has been written within academic journals about prisoners, rarely is there anything written by prisoners. In this essay, we, a group of prisoners who are earning or have earned college degrees while incarcerated in Texas, address the purpose, merits, and pitfalls of prison education and reform. Written as a response to the essays appearing in this special issue, we discuss our experiences of being othered as inmates, the impact of societal bias against us, our perspectives on prison education, and our own ideas for reforming prisons and making them more humane.     

Radar cross section of trihedral corner reflectors using PO and MEC

Physical optics (po) and the method of equivalent currents (mec) are used for the formulation and calculation of the backscatter cross section of both the triangular and square trihedral corner reflectors. Scattering from a trihedral corner reflector is dominated by single, double, and triple reflections by the interior walls. A physical optics integration is performed on the entire surface of each plate for the evaluation of the singly reflected fields. Doubly and triply reflected fields are evaluated by first using geometrical optics (go) at initial reflections to calculate the incident plane wave on the plate where the last reflection occurs. Physical optics is then applied on the illuminated area of that plate. First-order diffractions, which are based on the fringe current expressions for the exterior edges of the trihedral, are also included in the analysis. Predictions compare very well with both experimental and fdtd data.     

Amplified spontaneous emission effects in semiconductor laseramplifiers

The analysis presented provides a quantitative method for predicting semiconductor laser amplifier performance in the presence of ASE (amplified spontaneous emission). It indicates that in order to increase the fraction of pump power that contributes to the amplification of the input laser field relative to that spent in overcoming internal losses, an amplifier should operate at as high an excitation level as possible. This may mean operating an amplifier above its free-running oscillation threshold. A limitation to the maximum pump power is the increase in ASE. With too high an excitation, ASE dominates over the amplified input laser field, resulting in a quenching of the amplifier gain, efficiency and coherence. ASE effects may be mitigated by increasing the input laser intensity, decreasing the amplifier facet reflectivities, or, in some cases, tuning the master oscillator so that it is resonant with the amplifier. The analysis indicates that minimizing the facet reflectivity is the most effective way to circumvent ASE limitations to power scaling semiconductor laser amplifiers     

A 0D Lead‐Free Hybrid Crystal with Ultralow Thermal Conductivity

Organic–inorganic hybrid materials are of significant interest owing to their diverse applications ranging from photovoltaics and electronics to catalysis. Control over the organic and inorganic components offers flexibility through tuning their chemical and physical properties. Herein, it is reported that a new organic–inorganic hybrid, [Mn(C₂H₆OS)₆]I₄, with linear tetraiodide anions exhibit an ultralow thermal conductivity of 0.15 ± 0.01 W m^?1 K^?1 at room temperature, which is among the lowest values reported for organic–inorganic hybrid materials. Interestingly, the hybrid compound has a unique 0D structure, which extends into 3D supramolecular frameworks through nonclassical hydrogen bonding. Phonon band structure calculations reveal that low group velocities and localization of vibrational energy underlie the observed ultralow thermal conductivity, which could serve as a general principle to design novel thermal management materials.     

Adhesion and Surface Interactions of a Self‐Healing Polymer with Multiple Hydrogen‐Bonding Groups

The surface properties and self‐adhesion mechanism of self‐healing poly(butyl acrylate) (PBA) copolymers containing comonomers with 2‐ureido‐4[1H]‐pyrimidinone quadruple hydrogen bonding groups (UPy) are investigated using a surface forces apparatus (SFA) coupled with a top‐view optical microscope. The surface energies of PBA–UPy4.0 and PBA–UPy7.2 (with mole percentages of UPy 4.0% and 7.2%, respectively) are estimated to be 45–56 mJ m^?2 under dry condition by contact angle measurements using a three probe liquid method and also by contact and adhesion mechanics tests, as compared to the reported literature value of 31–34 mJ m^?2 for PBA, an increase that is attributed to the strong UPy–UPy H‐bonding interactions. The adhesion strengths of PBA–UPy polymers depend on the UPy content, contact time, temperature and humidity level. Fractured PBA–UPy films can fully recover their self‐adhesion strength to 40, 81, and 100% in 10 s, 3 h, and 50 h, respectively, under almost zero external load. The fracture patterns (i.e., viscous fingers and highly “self‐organized” parallel stripe patterns) have implications for fabricating patterned surfaces in materials science and nanotechnology. These results provide new insights into the fundamental understanding of adhesive mechanisms of multiple hydrogen‐bonding polymers and development of novel self‐healing and stimuli‐responsive materials.     

Matrix Metalloproteinase Responsive,Proximity‐Activated Polymeric Nanoparticles for siRNA Delivery

Small interfering RNA (siRNA) has significant potential to evolve into a new class of pharmaceutical inhibitors, but technologies that enable robust, tissue‐specific intracellular delivery must be developed before effective clinical translation can be achieved. A pH‐responsive, smart polymeric nanoparticle (SPN) with matrix metalloproteinase (MMP)‐7‐dependent proximity‐activated targeting (PAT) is described here. The PAT‐SPN is designed to trigger cellular uptake and cytosolic delivery of siRNA once activated by MMP‐7, an enzyme whose overexpression is a hallmark of cancer initiation and progression. The PAT‐SPN is composed of a corona‐forming polyethylene glycol (PEG) block, an MMP‐7‐cleavable peptide, a cationic siRNA‐condensing block, and a pH‐responsive, endosomolytic terpolymer block that drives self‐assembly and forms the PAT‐SPN core. With this novel design, the PEG corona shields cellular interactions until it is cleaved in MMP‐7‐rich environments, shifting the SPN ζ‐potential from +5.8 to +14.4 mV and triggering a 2.5 fold increase in carrier internalization. The PAT‐SPN exhibits pH‐dependent membrane disruptive behavior that enables siRNA escape from endo‐lysosomal pathways. Intracellular siRNA delivery and knockdown of the model enzyme luciferase in R221A‐Luc mammary tumor cells is significantly increased by MMP‐7 pre‐activation (p < 0.05). These combined data indicate that the PAT‐SPN provides a promising new platform for tissue‐specific, proximity‐activated siRNA delivery to MMP‐rich pathological environments.     

从PC至移动应用,DisplayPort技术方兴未艾

未来几年内,HDMI与DisplayPort将作为两种消费者可用的数字视频接口同时主宰市场.HDMI将继续在消费视频产品中存在,而DisplayPort则将取代VGA和DVI,成为PC显示器接口.     

Fabrication and characterisation of D-fibres with a range of accurately controlled core/flat distances

The fabrication and evaluation of D-fibres, whose optical properties are compatible with standard single-mode fibre designs, is reported. The high tolerances achieved in the process of drawing a tapered preform are shown to be necessary for predicting the transverse coupling behaviour of the fibres.