Effectiveness of Problem-Based Learning Prior to Lectures on Learning and Retention

In the mandatory tutorial sections of an introductory probability and statistics course of just over 70 students in the Arts and Science undergraduate program, students were randomly assigned to small groups to work on accessible problems from upcoming material without any prior instruction on how to solve them. Solutions were ungraded, and marks were assigned for participation only. A multiyear study was conducted to test students for their level of retention one year later, comparing them to a previous control group. The test question concerned Bayes’ Theorem. Results suggest that the strategy improves student reasoning and retention of concepts while, as expected, a formula is long forgotten. However, low participation rates in the survey post-test produced a p-value of 20%, precluding a claim of statistical significance. Nonetheless, qualitative student feedback on surveys during the course showed a very strong positive response to the approach. Students reported the approach helped their thinking and reasoning, and assisted in their learning. They appreciated the informal, low-pressure environment of the problem-based learning (PBL) sessions, and reported that the sessions were beneficial for developing their own understanding of the concepts before going to lecture. Notwithstanding their positive feedback on PBL activities, students still expressed a preference for traditional instructional approaches where the teaching assistant leads them through solution procedures

Planar immersion lens with metasurfaces

The solid immersion lens is a powerful optical tool that allows light entering material from air or vacuum to focus to a spot much smaller than the free-space wavelength. Conventionally, however, they rely on semispherical topographies and are non-planar and bulky, which limits their integration in many applications. Recently, there has been considerable interest in using planar structures, referred to as metasurfaces, to construct flat optical components for manipulating light in unusual ways. Here, we propose and demonstrate the concept of a planar immersion lens based on metasurfaces. The resulting planar device, when placed near an interface between air and dielectric material, can focus electromagnetic radiation incident from air to a spot in material smaller than the free-space wavelength. As an experimental demonstration, we fabricate an ultrathin and flexible microwave lens and further show that it achieves wireless energy transfer in material mimicking biological tissue

Probing thermal transport and layering in disk media using scanning thermal microscopy

With the advent of heat assisted magnetic recording (HAMR) [1] the thermal transport properties of magnetic recording media have become a key performance characteristic. In particular it is important that lateral heat transport is minimised in order to heat only the localised bit area and conversely that vertical heat transport is optimised for fast cooling of the medium essential for the thermal stability of written bits. Magnetic media are multilayered and highly structured on the nanoscale rendering classical treatment of thermal transport inapplicable and the likelihood that the transport is dominated by interfaces and dimensions rather than bulk material properties. A technique for measuring thermal transport on the nanoscale is therefore highly desirable in the design of new magnetic media. In this study we explore the potential of scanning thermal microscopy (SThM) to resolve thermal transport on the nanoscale and use a multilayered, grain segregated conventional disk

Probing thermal transport and layering in disk media using scanning thermal microscopy

With the advent of heat assisted magnetic recording (HAMR) [1] the thermal transport properties of magnetic recording media have become a key performance characteristic. In particular it is important that lateral heat transport is minimised in order to heat only the localised bit area and conversely that vertical heat transport is optimised for fast cooling of the medium essential for the thermal stability of written bits. Magnetic media are multilayered and highly structured on the nanoscale rendering classical treatment of thermal transport inapplicable and the likelihood that the transport is dominated by interfaces and dimensions rather than bulk material properties. A technique for measuring thermal transport on the nanoscale is therefore highly desirable in the design of new magnetic media. In this study we explore the potential of scanning thermal microscopy (SThM) to resolve thermal transport on the nanoscale and use a multilayered, grain segregated conventional disk

Delayed Bacterial Endotheliitis and Endophthalmitis 11 Years after Cataract Surgery

Infective endophthalmitis is an uncommon complication following intraocular surgery. Chronic endophthalmitis may present some time after intraocular surgery, making the diagnosis challenging. Cutibacterium acnes is a well-recognised causative agent of these chronic infections. Practitioners should be aware of the conditions required to culture this slow-growing organism. We report a case of delayed low-grade endophthalmitis presenting 11 years after cataract surgery. Cutibacterium acnes and Staphylococcus warneri were cultured from Descemet’s membrane biopsy following three failed previous attempts at microbiological studies. Clinical features of the infection included discrete white granules on the iris, endothelium, and within the capsular bag of the patient’s right eye. The patient presented with no signs of systemic infection and the left eye was normal on examination. Bullous keratopathy, secondary to endothelial dysfunction was a feature of this infection. This retrospective case report illustrates the prolonged periods for which Cutibacterium acnes can remain latent before causing clinical signs. While uncommon, endothelial involvement may occur and clinicians should consider low-grade infective endophthalmitis in cases with corneal oedema

Non-Pharmacological Therapy for Atrial Fibrillation: Managing the Left Atrial Appendage

The prevalence of atrial fibrillation (AF) is increasing in parallel with an ageing population leading to increased morbidity and mortality. The most feared complication of AF is stroke, with the arrhythmia being responsible for up to 20% of all ischemic strokes. An important contributor to this increased risk of stroke is the left atrial appendage (LAA). A combination of the LAA's unique geometry and atrial fibrillation leads to low blood flow velocity and stasis, which are precursors to thrombus formation. It has been hypothesized for over half a century that excision of the LAA would lead to a reduction in the incidence of stroke. It has only been in the last 20–25 years that the knowledge and technology has been available to safely carry out such a procedure. We now have a number of viable techniques, both surgical and percutaneous, which will be covered in this paper

Velocity oscillations in confined channel flows of concentrated colloidal suspensions

We study the pressure-driven flow of concentrated colloids confined in glass micro-channels at the single particle level using fast confocal microscopy. For channel to particle size ratios $a/\bar{D} \lesssim 30$, the flow rate of the suspended particles shows fluctuations. These turn into regular oscillations for higher confinements ($a/\bar{D} \simeq 20$). We present evidence to link these oscillations with the relative flow of solvent and particles (permeation) and the effect of confinement on shear thickening.Comment: 4 pages, 6 figure

Apolipoprotein E Pathology in Vascular Dementia

Vascular dementia (VaD) is the second most common form of dementia and is currently defined as a cerebral vessel vascular disease leading to ischemic episodes. Apolipoprotein E (apoE) gene polymorphism has been proposed as a risk factor for VaD, however, to date there are few documented post-mortem studies on apoE pathology in the VaD brain. To investigate a potential role for the apoE protein, we analyzed seven confirmed cases of VaD by immunohistochemistry utilizing an antibody that specifically detects the amino-terminal fragment of apoE. Application of this antibody, termed N-terminal, apoE cleavage fragment (nApoECF) revealed consistent labeling within neurofibrillary tangles (NFTs), blood vessels, and reactive astrocytes. Labeling occurred in VaD cases that had confirmed APOE genotypes of 3/3, 3/4, and 4/4, with respect to NFTs, staining of the nApoECF co-localized with PHF-1 and was predominantly localized to large, stellate neurons in layer II of the entorhinal cortex. Quantitative analysis indicated that approximately 38.4% of all identified NFTs contained the amino-terminal fragment of apoE. Collectively, these data support a role for the proteolytic cleavage of apoE in the VaD and support previous reports that APOE polymorphism is significantly associated with susceptibility in this disease

Spinodal-assisted crystallization in polymer melts

Recent experiments in some polymer melts quenched below the melting temperature have reported spinodal kinetics in small-angle x-ray scattering before the emergence of a crystalline structure. To explain these observations we propose that the coupling between density and chain conformation induces a liquid-liquid binodal within the equilibrium liquid-crystalline solid coexistence region. A simple phenomenological theory is developed to illustrate this idea, and several experimentally testable consequences are discussed. Shear is shown to enhance the kinetic role of the hidden binodal