Digital Parentship Practices of Instructional Technology Faculty Members: A Case Study

The purpose of the current study was to understand the digital parentship practices of faculty members with an Instructional Technology (IT) major within a qualitative approach. The participants of the study comprised of 13 faculty members from the IT field of any university in Turkey and who has one or more children aged 0-6 years old. The IT academician, in their role as mother or father, participated in the interview process. As digital literates, the participants of the study possess knowledge and expertise in the potential opportunities that technology offer, and also the possible risks that they pose to children. The findings showed that the majority of the participants do not hesitate to allow their children to use screen technology from an early age (from as young as 6 months old) in order to free up time for themselves or to attend to their work. This implies that the participants utilize technology in order to facilitate the role of parenting, even though they may appreciate it is seen as inappropriate. However, the academician parents who took part in this study applied more restrictive mediation so as to limit their children’s exposure to technology due to their very young age and owing to the children’s inability at that age to understand the potential risks. The findings of the study provided information so as to help understand the digital parentship practices of parents from the technology field, and to make suggestions about parenting strategies for younger children

1 Gbps free-space deep-ultraviolet communications based on III-nitride micro-LEDs emitting at 262 nm

The low modulation bandwidth of deep-ultraviolet (UV) light sources is considered as the main reason limiting the data transmission rate of deep-UV communications. Here, we present high-bandwidth III-nitride microlight- emitting diodes (µLEDs) emitting in the UV-C region and their applications in deep-UV communication systems. The fabricated UV-C µLEDs with 566 µm2 emission area produce an optical power of 196 µW at the 3400 A/cm 2 current density. The measured 3 dB modulation bandwidth of these µLEDs initially increases linearly with the driving current density and then saturates as 438 MHz at a current density of 71 A/cm 2, which is limited by the cutoff frequency of the commercial avalanche photodiode used for the measurement. A deep-UV communication system is further demonstrated. By using the UV-C µLED, up to 800 Mbps and 1.1 Gbps data transmission rates at bit error ratio of 3.8 × 10-3 are achieved assuming on-off keying and orthogonal frequency-division multiplexing modulation schemes, respectively

Incidental Meningioma: Modelling Growth Characteristics and Predicting Failure of Monitoring

Meningiomas are the commonest primary intracranial tumours. With the increased access to neuro-radiological investigations, there has been a tremendous increase in the number of incidental findings. Incidental meningioma accounts for 10% of these findings and for 30% of newly-diagnosed meningiomas. International guidelines advise that these tumours are best managed using active clinical-radiological monitoring, however, duration of surveillance and intervals in between scans, remain unspecified. This uncertainty has economic implications and causes patient anxiety. Previous literature has focused primarily on radiological prognostication with little attention to the effect of clinical factors such as comorbidity and performance status on prognosis of incidental meningiomas. Moreover, the temporal relationship between these factors and progression remains poorly defined. The aims of this thesis therefore were to investigate the prognostic relationship between radiological factors and the timing of progression and to examine how this is augmented by clinical factors including patient age, comorbidity and performance status. Moreover, a predictive model of progression was built based on these factors and used to inform duration of follow-up and appropriate time-points for scans. Radiological factors included in the model were: increasing tumour volume, peritumoural signal change, MR FLAIR/T2 hyperintense meningiomas and proximity to critical neurovascular structures. Patients were stratified into low, medium and high-risk groups and rates of disease progression at 5-years were 3%, 28% and 75% respectively. Low-risk patients had non-oedematous, small iso/hypointense meningiomas, distant from neurovascular structures. Older patients with co-morbidities were 15-times more likely to die than to receive intervention at 5-years following diagnosis, regardless of risk-group. After 5-years of follow-up the probability of disease progression plateaued in all risk groups. Active monitoring strategies based on these results were formulated. These have the potential to reduce the cost burden of incidental meningiomas. Prospective studies are needed to validate the model

Spectrum and energy efficient digital modulation techniques for practical visible light communication systems

The growth in mobile data traffic is rapidly increasing in an unsustainable direction given the radio frequency (RF) spectrum limits. Visible light communication (VLC) offers a lucrative solution based on an alternative license-free frequency band that is safe to use and inexpensive to utilize. Improving the spectral and energy efficiency of intensity modulation and direct detection (IM/DD) systems is still an on-going challenge in VLC. The energy efficiency of inherently unipolar modulation techniques such as pulse-amplitude modulation discrete multitone modulation (PAM-DMT) and asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) degrades at high spectral efficiency. Two novel superposition modulation techniques are proposed in this thesis based on PAM-DMT and ACO-OFDM. In addition, a practical solution based on the computationally efficient augmented spectral efficiency discrete multi-tone (ASE-DMT) is proposed. The system performance of the proposed superposition modulation techniques offers significant electrical and optical power savings with up to 8 dB in the electrical signal-to-noise ratio (SNR) when compared with DC-biased optical orthogonal frequency division multiplexing (DCO-OFDM). The theoretical bit error ratio (BER) performance bounds for all of the proposed modulation techniques are in agreement with the Monte-Carlo simulation results. The proposed superposition modulation techniques are promising candidates for spectrum and energy efficient IM/DD systems. Two experimental studies are presented for a VLC system based on DCO-OFDM with adaptive bit and energy loading. Micrometer-sized Gallium Nitride light emitting diode (m-LED) and light amplification by stimulated emission of radiation diode (LD) are used in these studies due to their high modulation bandwidth. Record data rates are achieved with a BER below the forward error correction (FEC) threshold at 7.91 Gb/s using the violet m-LED and at 15 Gb/s using the blue LD. These results highlight the potential of VLC systems in practical high speed communication solutions. An additional experimental study is demonstrated for the proposed superposition modulation techniques based on ASE-DMT. The experimentally achieved results confirm the theoretical and simulation based performance predictions of ASE-DMT. A significant gain of up to 17.33 dB in SNR is demonstrated at a low direct current (DC) bias. Finally, the perception that VLC systems cannot work under the presence of sunlight is addressed in this thesis. A complete framework is presented to evaluate the performance of VLC systems in the presence of solar irradiance at any given location and time. The effect of sunlight is investigated in terms of the degradations in SNR, data rate and BER. A reliable high speed communication system is achieved under the sunlight effect. An optical bandpass blue filter is shown to compensate for half of the reduced data rate in the presence of sunlight. This thesis demonstrates data rates above 1 Gb/s for a practical VLC link under strong solar illuminance measured at 50350 lux in clear weather conditions

Gb/s visible light communications with colloidal quantum dot color converters

This paper reports the utilization of colloidal semiconductor quantum dots as color converters for Gb/s visible light communications. We briefly review the design and properties of colloidal quantum dots and discuss them in the context of fast color conversion of InGaN light sources, in particular in view of the effects of self-absorption. This is followed by a description of a CQD/polymer composite format of color converters. We show samples of such color-converting composite emitting at green, yellow/orange and red wavelengths, and combine these with a blueemitting microsize LED to form hybrid sources for wireless visible light communication links. In this way data rates up to 1 Gb/s over distances of a few tens of centimeters have been demonstrated. Finally, we broaden the discussion by considering the possibility for wavelength division multiplexing as well as the use of alternative colloidal semiconductor nanocrystals