bluuebunny/crossref_metadata_2025 huggingface dataset:
Cardiopulmonary Physical Therapist; A rescuer for the patients suffering from COVID-19
Authors: Awan Malik Muhammad Ali , Qureshi Sidra , Khushnood Kiran
Published: June 2020

doi: https://doi.org/10.12669/pjms.36.5.2880

How to cite this:Awan MMA, Qureshi S, Khushnood K. Cardiopulmonary Physical Therapist; A rescuer for the patients suffering from COVID-19. Pak J Med Sci. 2020;36(5):1143-1144. doi: https://doi.org/10.12669/pjms.36.5.2880

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Biodiversity
Authors: Gonçalves M.
Published: June 2020

Our school is surrounded by tall buildings and cement and has little green areas, but even so, we managed to find a place to build a small bio-vegetable garden, an orchard of native trees, and a vineyard. Students also increased the number of flowerbeds and built nests for insectivorous birds, a pond for frogs, spots with aromatic plants, as well as a hotel for pollinating insects. Students are also sowing wild plants to increase local biodiversity.
Hajuda
Authors: Azevedo M.
Published: June 2020

A recent study by the National Institute of Statistics (INE) reveals that almost half of the Portuguese population will be over 65 within the next 60 years. Also, about 40% of this population is alone for 8 hours or more per day. Almost one million elderly people are in solitude or isolation. How can we promote the return of the population over 65 to active life? How can we help caregivers to provide care for their loved ones with the knowledge we acquire in class? A society was born: Hajuda (Help in English). The main goal is to help those who need it most. Whether they are in bed or in solitude and social isolation. The results have been very promising.
Pathfinder: open source software for analyzing spatial navigation search strategies
Authors: Cooke Matthew B. , O'Leary Timothy P. , Harris Phelan , Ma Ricky , Brown Richard E. , Snyder Jason S.
Published: June 2020

Spatial navigation is a universal behavior that varies depending on goals, experience and available sensory stimuli. Spatial navigational tasks are routinely used to study learning, memory and goal-directed behavior, in both animals and humans. One popular paradigm for testing spatial memory is the Morris water maze, where subjects learn the location of a hidden platform that offers escape from a pool of water. Researchers typically express learning as a function of the latency to escape, though this reveals little about the underlying navigational strategies. Recently, a number of studies have begun to classify water maze search strategies in order to clarify the precise spatial and mnemonic functions of different brain regions, and to identify which aspects of spatial memory are disrupted in disease models. However, despite their usefulness, strategy analyses have not been widely adopted due to the lack of software to automate analyses. To address this need we developed Pathfinder, an open source application for analyzing spatial navigation behaviors. In a representative dataset, we show that Pathfinder effectively characterizes the development of highly-specific spatial search strategies as male and female mice learn a standard spatial water maze. Pathfinder can read data files from commercially- and freely-available software packages, is optimized for classifying search strategies in water maze paradigms, and can also be used to analyze 2D navigation by other species, and in other tasks, as long as timestamped xy coordinates are available. Pathfinder is simple to use, can automatically determine pool and platform geometry, generates heat maps, analyzes navigation with respect to multiple goal locations, and can be updated to accommodate future developments in spatial behavioral analyses. Given these features, Pathfinder may be a useful tool for studying how navigational strategies are regulated by the environment, depend on specific neural circuits, and are altered by pathology.
scRepertoire: An R-based toolkit for single-cell immune receptor analysis
Authors: Borcherding Nicholas , Bormann Nicholas L. , Kraus Gloria
Published: June 2020

Single-cell sequencing is an emerging technology in the field of immunology and oncology that allows researchers to couple RNA quantification and other modalities, like immune cell receptor profiling at the level of an individual cell. A number of workflows and software packages have been created to process and analyze single-cell transcriptomic data. These packages allow users to take the vast dimensionality of the data generated in single-cell-based experiments and distill the data into novel insights. Unlike the transcriptomic field, there is a lack of options for software that allow for single-cell immune receptor profiling. Enabling users to easily combine mRNA and immune profiling, scRepertoire was built to process data derived from 10x Genomics Chromium Immune Profiling for both T-cell receptor (TCR) and immunoglobulin (Ig) enrichment workflows and subsequently interacts with a number of popular R packages for single-cell expression, such as Seurat. The scRepertoire R package and processed data are open source and available on GitHub and provides in-depth tutorials on the capability of the package.
Recent advances in understanding the molecular basis of melanogenesis in melanocytes
Authors: Ohbayashi Norihiko , Fukuda Mitsunori
Published: June 2020

Melanin pigments are responsible for human skin and hair color, and they protect the body from harmful ultraviolet light. The black and brown melanin pigments are synthesized in specialized lysosome-related organelles called melanosomes in melanocytes. Mature melanosomes are transported within melanocytes and transferred to adjacent keratinocytes, which constitute the principal part of human skin. The melanosomes are then deposited inside the keratinocytes and darken the skin (a process called tanning). Owing to their dark color, melanosomes can be seen easily with an ordinary light microscope, and melanosome research dates back approximately 150 years; since then, biochemical studies aimed at isolating and purifying melanosomes have been conducted. Moreover, in the last two decades, hundreds of molecules involved in regulating melanosomal functions have been identified by analyses of the genes of coat-color mutant animals and patients with genetic diseases characterized by pigment abnormalities, such as hypopigmentation. In recent years, dynamic analyses by more precise microscopic observations have revealed specific functions of a variety of molecules involved in melanogenesis. This review article focuses on the latest findings with regard to the steps (or mechanisms) involved in melanosome formation and transport of mature melanosomes within epidermal melanocytes. Finally, we will touch on current topics in melanosome research, particularly on the "melanosome transfer" and "post-transfer" steps, and discuss future directions in pigment research.
Recent advances in urodynamics in women
Authors: Baines Georgina , Da Silva Ana Sofia , Araklitis George , Robinson Dudley , Cardozo Linda
Published: June 2020

Urodynamics is the study of the storage and evacuation of urine from the urinary tract. The aim is to reproduce the patient’s symptoms and provide a pathophysiological explanation for them by identifying all factors that contribute to the lower urinary tract dysfunction, including those that are asymptomatic. Urodynamics consists of various tests, each of which is designed to assess a different aspect of lower urinary tract function. There is a lack of evidence regarding when urodynamics should be used in the non-neurogenic bladder. Some small randomised controlled trials suggest that urodynamics does not alter the outcome of surgery for stress urinary incontinence when compared with office evaluation alone. However, this is widely felt to be inaccurate and many health-care professionals still advocate the use of urodynamics prior to any invasive treatment, especially surgery on the lower urinary tract. There have been few technological advances in urodynamics in recent years. Air-charged rather than fluid-filled catheters were thought to help reduce artefact, but the evidence is unclear, and there is doubt over their accuracy. Ambulatory urodynamics is carried out over a longer period of time, enabling physiological bladder filling, but it remains invasive and artificial. To attempt to replicate symptoms more accurately, there have been efforts to develop wireless devices to measure detrusor pressure directly. These may be promising but are far from suitable in humans at present. Urodynamics continues to provide useful information for assessing lower urinary tract function, but further large studies are required to assess its value and develop innovations to improve the accuracy of the tests and acceptability to patients.
Getting back to work: lessons from around the world
Authors: McNee Damien
Published: June 2020

Standard Operating Procedures (SOPs) and their implications will play a fundamental role in the phased re-introduction of clinical dentistry post COVID-19. These SOP documents will continually be updated as new scientific rationales emerge. Each individual SOP will have key themes dictating how dental appointments are managed, emanating from the initial work of Peng et al (2020). This article provides a snapshot into how some countries are adapting to the changes, and demonstrating the wide variances seen. The article is intended to draw parallels between how each country is responding differently to prevent undue transmission of the SARS-CoV-2 virus in the dental setting.

CPD/Clinical Relevance: Those involved with implementation of emerging SOPs into their clinical practice will be required to understand why these new protocols are necessary and how they will act to prevent viral transmission of SARS-CoV-2.
Suggestions for Non-Aerosol or Reduced-Aerosol Restorative Dentistry (for as Long as is Necessary)
Authors: Burke FJ Trevor , Mackenzie Louis , Sands Peter
Published: June 2020

The advent of coronavirus and the associated disease COVID-19 has led to the closure of dental practices in the UK and, indeed, in many parts of the world. In order to get dental practices operating again, it is suggested that it is necessary to adopt a new way of working. Principal among concerns has been the potential carriage of droplets (from an infected patient) into the aerosols resulting from the use of the turbine handpiece and from ultrasonic and sonic scalers, and other instruments used in restorative dentistry (current terminology being Aerosol Generating Procedures [AGPs]). It is therefore the aim of this paper to review restorative techniques and suggest those which are appropriate to aerosol-free, or reduced-aerosol restorative dentistry.

CPD/Clinical Relevance: With anxieties regarding aerosol generating procedures abounding, it may be helpful to review procedures which either reduce or avoid these AGPs.
Cracked tooth syndrome diagnosis part 1: integrating the old with the new
Authors: Bailey Oliver , Whitworth John
Published: June 2020

This article is the first of a two-part series on cracked tooth syndrome (CTS). It seeks to aid the clinician in understanding the pathogenesis and clinical features of the condition and review established and new diagnostic tests that will allow greater confidence and predictability in diagnosing teeth with CTS.

CPD/Clinical Relevance: This article gives the clinician greater confidence and predictability in diagnosing teeth with CTS.
The Impact of COVID-19 on dental education and training
Authors: Doughty Faye , Moshkun Catherine
Published: June 2020

COVID-19 has had a huge impact on dentistry. Dental care professionals work in close proximity with patients, they are therefore at high risk of contracting coronavirus. As of 25th March, all routine dentistry was postponed.

The pandemic has led to clinic closures, university closures and postponement of exams and interviews. This has resulted in a deficit in clinical exposure for undergraduates and trainees. Changes in examination format have been implemented to prevent delays in course completions. The GDC have reassured that measures are being put in place to reduce the effect of COVID-19 on training.

CPD/Clinical Relevance: This article aims to explore the impact of SARS-CoV-2 on dental education and dental training programmes in the UK.
How close is the axillary nerve to the inferior glenoid? A magnetic resonance study of normal and arthritic shoulders
Authors: Makki D , Selmi H , Syed S , Basu S , Walton M
Published: June 2020

Introduction

Axillary nerve injury is a major complication of shoulder surgery during glenoid exposure. The aim of this study was to measure the mean distance between the inferior glenoid and the axillary nerve in healthy shoulders and then to compare this distance between osteoarthritic and rotator cuff deficient glenohumeral joints.

Methods

The magnetic resonance images of 50 patients with normal glenohumeral joints were reviewed. The infra-glenoid tubercle was determined as a fixed point and the distance to the axillary nerve was measured. Two separate assessors measured on the same sagittal sections. With a study power of 80%, the sample needed in each comparison group was 28 patients. Measurements were then performed on scans in patients with osteoarthritis and cuff tear arthropathy. The mean distance was compared between groups.

Results

The mean distance between the infra-glenoid tubercle and axillary nerve was 12mm (standard deviation, SD, 5.6mm) in normal shoulders, 10.6mm (SD 5.4mm) in shoulders with osteoarthritis and 9.7mm (SD 3.7mm) in those with cuff tear arthropathy. For this sample size of 50 patients with a confidence interval of 95%, the mean range is 12mm (95% CI 10.4–13.6). A comparison between normal shoulder and osteoarthritis showed a p-value of 0.3, and between normal and cuff tear arthropathy a p-value of 0.06. This was not statistically significant.

Conclusions

The axillary nerve lies on average 12mm from the infra-glenoid tubercle. The presence of inferior osteophytes in glenohumeral osteoarthritis and the proximal migration of humeral head in cuff tear arthropathy does not seem to alter the course of the nerve significantly in relation to the inferior glenoid tubercle.
An open and closed case: timing of closure following laparostomy
Authors: Granger S , Fallon J , Hopkins J , Pullyblank A
Published: June 2020

Introduction

Laparostomy is important in the management of patients with intra-abdominal gastrointestinal catastrophe or trauma. It carries significant risk and is resource intensive, both in terms of nursing and surgically. The main goal is to achieve prompt myofascial closure (MFC) in order to minimise morbidity and mortality. Early MFC was initially defined as within 2–3 weeks but there is growing evidence that this should be measured in days.

Methods

Retrospective analysis was undertaken of laparostomy cases between 2016 and 2018 at an acute trust and trauma centre serving a population of 500,000. Indication, duration of open abdomen (OA), number of relook procedures and consultant presence were examined to see whether they affected MFC rates, morbidity and mortality.

Results

Overall, 76 laparostomies were performed during the 3-year study period. The most common indication was peritonitis (68.4%). As duration of OA and number of relook procedures increased, the chances of MFC fell significantly. After day 1, MFC rates fell by 20% with each subsequent 24 hours. Leaving the abdomen open primarily at index procedure compared with performing laparostomy following a postoperative complication was associated with significantly higher MFC rates (92.6% vs 68.2%, (p=0.006). The mortality rate was 15.8%.

Conclusions

If the OA is not closed within five days or by the third relook procedure, then achieving MFC is unlikely. Alternative methods should be employed to close the abdomen rather than continuing to take the patient back to theatre for relook laparotomies while increasing the risk of morbidity and mortality. A proactive strategy to forming primary laparostomy at the index procedure has high closure rates.
Paclitaxel coated-balloon (PCB) versus standard plain old balloon (POB) fistuloplasty for failing dialysis access
Authors: Karmota AG
Published: June 2020

Introduction

This study aimed to evaluate the safety and efficacy of paclitaxel-coated balloon compared with conventional plain balloon for the treatment of failing native dialysis access.

Materials and methods

This prospective study included 60 patients presenting to the Kasr Alainy Hospitals and Aseer Central Hospital in the period from September 2015 to December 2017 with failing native vascular access. Dilatation with a plain balloon was done in 30 patients (group I) and with a paclitaxel-coated balloon in 30 patients (group II) with either stenosis or occlusion. The majority were outflow lesions, with 20 (66.7 %) patients in group I and 21 (70%) patients in group II. Mean balloon diameter was 7.1mm (± 1.5mm) compared with 6.5mm (± 1.2mm) and length 66mm (± 19.1mm) compared with 54.6mm (± 15.7mm), respectively. Safety endpoint was reported as 30 day’s freedom from procedure-related major complications and mortality. Procedural technical success was defined as a residual diameter 30% or less for treated lesions. Target lesion primary patency, circuit primary patency and secondary patency were reported at 3, 6 and 12 months.

Results

There were no 30-day procedure-related major complications or mortality in either group. Procedural technical success of 100% was achieved in both groups. Target lesion primary patency, circuit primary patency and secondary patency in group II were better than in group I, especially at 12 months (90% vs 66.7%, 83.3% vs 60% and 96.7% vs 93.3%, respectively). There was a statistically significant difference in target lesion primary patency (p = 0.029) in patients who were treated with paclitaxel-coated balloon angioplasties.

Conclusion

The paclitaxel-coated balloon proved to be safe and effective, and improved the patency of failing vascular access. Results are comparable with previous studies.
Safety and efficacy of duodenal stent insertion for gastric outlet obstruction: characterisation of a regional district general hospital service
Authors: Bryce A , Wohlgemut JM , Coyle T , Hannay J
Published: June 2020

Introduction

Placement of a duodenal or pyloric stent is a recognised palliative procedure for symptomatic relief of malignant gastric outlet obstruction. This procedure can be associated with significant complications, reinterventions and poor long-term relief of obstructive symptoms. However, there may be a faster return to diet and shorter hospital stay in comparison to other palliative procedures (eg gastrojejunostomy). The aim of this study was to determine the safety and efficacy of duodenal stenting in our regional district general hospital in comparison to that of larger tertiary centres.

Materials and methods

All patients with gastric outlet obstruction who had duodenal stent placement attempted in our region between 1 August 2013 and 31 July 2018 were identified by retrospective analysis of prospectively maintained coding databases and medical notes. Patient demographics, safety outcomes and efficacy outcomes were then extracted. Results were interpreted with respect to data from best available published evidence from larger tertiary centres.

Results

Of 43 duodenal stent insertion attempts, 84% had a successful return to diet, 18% underwent reintervention, 18% suffered adverse events, mean length of stay post-intervention was 8.6 days and mean survival post-intervention was 132 days.

Conclusions

Patients with malignant gastric outlet obstruction in whom duodenal stent placement was attempted had similar outcomes to published data from larger tertiary centres. Duodenal stent placement remains an acceptable treatment option for these patients in our region.
Can Epstein–Barr virus play a role in upper urinary tract urothelial carcinomas?
Authors: Dere Y , Ekmekçi S , Akarken İ , Küçük Ü
Published: June 2020

Introduction

Upper urinary tract urothelial carcinomas are very rare tumours with different biological behaviours. The Epstein–Barr virus, which is the first known oncogenic virus, is being investigated for various malignant tumours. It is known that this virus is associated with nasopharyngeal carcinoma, as well as multiple haematological malignancies, head and neck and gastric cancers. We aimed to determine the presence of the Epstein–Barr virus in upper urinary tract urothelial carcinomas using chromogenic in situ hybridisation (CISH).

Materials and methods

A total of 44 upper urinary tract urothelial carcinomas from two different centres were included. Demographic data and survival rates were obtained from hospital records. One demonstrative paraffin block from each case was stained using Epstein–Barr encoded RNA (EBER) with an automated CISH procedure. The positivity of EBER was statistically analysed for prognostic factors.

Results

Among all patients, 38 were male and 6 were female. The mean age of the patients was 65.93 years. At the time of the study, 15 patients had died and 29 were alive. EBER-CISH positivity was found in 13 patients. Four showed strong EBER-CISH expression and nine showed weak expression. EBER-CISH positivity was not statistically related to any of the prognostic factors or to overall survival.

Discussion

Although EBER-CISH positivity showed no significant relation with prognostic factors, it was observed in one-third of all cases. Therefore, we think that the Epstein–Barr virus may have a role in the pathogenesis of upper urinary tract urothelial carcinomas. This finding needs to be supported by larger studies.
Primary colonic squamous cell carcinoma: a case report and review of the literature
Authors: Linardoutsos D , Frountzas M , Feakins RM , Patel NH , Simanskaite V , Patel H
Published: June 2020

Colonic squamous cell carcinoma is extremely rare, with no clear pathogenesis. It usually presents as an emergency. We present the surgical management of a descending colon squamous cell carcinoma, together with a review of the available cases of colonic squamous cell carcinoma in the literature.

A 69-year-old woman presented with a palpable mass and abdominal pain. She underwent ultrasound and colonoscopy, which revealed a large obstructing mass at the descending colon, the biopsies of which were not diagnostic. Unfortunately, she was readmitted with bowel obstruction and underwent extended right hemicolectomy with en-bloc excision of attached small bowel and omentum because of local mass expansion. Histopathological analysis demonstrated squamous cell carcinoma with lymph node metastases. Palliative chemotherapy followed, owing to liver and peritoneal deposits.

Sixty-six cases of colonic squamous cell carcinoma have been reported in the literature. The most common location is the right colon. Most cases present at a late stage. Several theories for the pathogenesis of colonic squamous cell carcinoma have been reported; the most popular is the squamous transformation of a pluripotent stem cell.
Nanoscale phase modulator and optical switch based on graphene-coated fiber
Authors: Xu Zhengtian , Yang Shu , Wang Jun
Published: June 2020

The new, to the best of our knowledge, phase modulator and optical switch based on graphene-coated fiber are proposed and studied. The fields of surface plasmon polaritons (SPP) modes are highly concentrated on the graphene so that very high effective indices (

>

400

) can be achieved. By virtue of this feature, the dimensions of these devices can be as small as several nanometers in length. The minimum transmission losses for the phase modulator and optical switch are 0.54 dB and 0.18 dB, respectively. The maximum voltage adjustment range needed is only 0.3 V. The optical switch possesses a complete switch-off state and is adaptable to variation in phase difference and light intensity. The performance of these devices can be effectively tuned by the parameters, such as the graphene-coated lengths and the applied voltages. These devices may have important applications in fiber-based systems and other nanoscale optic and optoelectronic systems.
Estimation of statistical properties of rough surface profiles from the Hurst exponent of speckle patterns
Authors: Camargo A. L. P. , Dias M. R. B. , Lemos M. R. , Mello M. M. , da Silva L. , dos Santos P. A. M. , Huguenin J. A. O.
Published: June 2020

We applied the Hurst exponent technique to an experimental study of rough metallic surface profiles and the speckle patterns generated by them. Characterization of important statistical properties of the surface profile and speckle patterns were performed. We observed a clear correlation between the Hurst exponent of a surface profile and the one calculated from the associated speckle patterns. Therefore, in principle, information of the Hurst exponent of the profile can be obtained from the Hurst exponent of speckle patterns. Range and sampling analyses were performed in the Hurst exponent calculations showing the robustness of the method. As an additional application, we performed a basic simulation to show that the Hurst exponent is sensitive to surface waviness.
Theoretical analysis of ultra-fast multi-wavelength switch containing Kerr nonlinear material and its application as simultaneous AND and NOR logic gates
Authors: Moshiri Seyyed Mohammad Mehdi , Khodadadi Maryam , Nozhat Najmeh
Published: June 2020

In this paper, an all-optical plasmonic multi-wavelength switch based on Kerr nonlinear material is proposed. It consists of circular waveguides wrapped around three side-coupled nano-ring resonators. Fundamentally, introducing the circular waveguide increases the coupling coefficient and switching modulation depth. The transmission response of the proposed multi-switching structure is studied theoretically based on coupled mode and transfer matrix theories. The validity of the derived transmission formula is confirmed by the numerical result obtained by the finite element method. Also, based on the self-phase modulation and cross-phase modulation (XPM) nonlinear effects, the resonance wavelengths are effortlessly tuned by changing the intensity of the incident lightwave without changing the dimensions of the structure. As a result, by utilizing the XPM effect, the required input signal intensity is significantly decreased to

6.5

M
W

/

c
m

2

. The obtained modulation depths are 18.08, 31.83, and 28.40 dB at wavelengths of 850, 1310, and 1550 nm, respectively. Finally, to show the application of the proposed switch, the simultaneous AND and NOR logic gates are designed with intensity contrast ratios of 78.81 and 85.49 dB, respectively. The proposed plasmonic switch has many advantages such as being multi-wavelength and having low required switching intensity, ultra-fast switching time of 23 fs, and optical bistability. These features are promising for future integrated plasmonic devices for applications such as communications, signal processing, and sensing.
James C. Wyant College of Optical Sciences: introduction to the focus issue
Authors: Sasián José
Published: June 2020

This focus issue presents a snapshot of some of the research at the Wyant College of Optical Sciences at the University of Arizona in Tucson, Arizona. While formally the research areas in the College are in the optical engineering, optical physics, photonics, and image science fields, the papers in this feature issue provide a glimpse into the research depth and breadth at the Wyant College.
Cosine beam: diffraction-free propagation and self-healing
Authors: Bencheikh Abdelhalim , Chabou Saoussene , Boumeddine Ouis Chouaib , Bekkis Hocine , Benstiti Abdeldjallil , Beddiaf Laarfa , Moussaoui Widad
Published: June 2020

In this paper we revisit the nondiffracting properties of the cosine beam (CB). Since the CB is of infinite extension and not physically realizable, we use two apodization pupils to manage its transverse extent: the first one is a Gaussian apodized pupil, giving rise to the cosine-Gauss (CG) beam, and the second one is a window (aperture) apodized pupil, giving rise to the cosine-windowed beam. Based on the second-order intensity moments, we demonstrate analytical expressions for the CG beam width and its nondiffracting range as a function of some key parameters. By considering the CG beam a standing wave resulting from the superposition of two oppositely oblique traveling Gaussian beams, we extend the study to higher-order CG beams. The latter is generated by the superposition of two oppositely oblique Hermite–Gauss (

HG

n

) beams of order

n

, giving birth to a standing nondiffracting Hermite–cosine–Gauss (

HCG

n

) beam of order

n

. We also demonstrate the expressions of the higher-order CG beam width and its nondiffracting range

z

max

. After demonstrating the nondiffracting nature of the HCG beam family, we test their ability to self-heal and recover against obstacles, and we show the limit distance from which

HCG

n

beams self-heal as a function of obstruction size and CG parameter. The results of this paper are of big interest in fields involving structured light such as particle manipulation, imaging, and light sheet microscopy.
Generalized temporal synthesis method for a birefringent laser pulse shaper
Authors: Halassi Abderezzaq , Driouche Youcef , Hamdi Rachid , Benkelfat Badr-Eddine
Published: June 2020

We propose a new method for the synthesis of arbitrary temporal output pulse profiles by using a birefringent laser pulse shaper. This shaper contains a series of

N

birefringent crystals placed between input and output polarizers. The synthesis method starts with the linear time-invariant system theory to determine the optimal amplitudes of the replica pulses at the output polarizer and the time delay between them, and then uses the temporal Jones matrix formalism to obtain the angle of each crystal. The design procedure is demonstrated for an eight-stage birefringent laser pulse shaper. Several examples of predefined output pulse profiles are given to show the potential of the proposed birefringent laser pulse shaper.
Hyperbolic metamaterial for the Tamm plasmon polariton application
Authors: Bikbaev Rashid G. , Vetrov Stepan Ya. , Timofeev Ivan V.
Published: June 2020

The possibility of using a hyperbolic metamaterial to form conventional and epsilon-near-zero Tamm plasmon polaritons in the near-infrared and visible spectral ranges is demonstrated. The spectral properties of the hyperbolic metamaterial are investigated in the framework of the effective medium theory and confirmed by the transfer matrix method. It is found that at the oblique incidence of light onto a structure, the I-type hyperbolic metamaterial can be implemented, while II-type cannot. The sensitivity of the epsilon-near-zero wavelength to the variation in the angle of light incidence for TE and TM waves is demonstrated. It is shown that both the high-quality and broadband Tamm plasmon polaritons are excited in the investigated structures.
Generation of a variety of Airy beams using a dynamic diffractive optical phase element
Authors: Benstiti Abdeldjalil , Ferria Kouider , Bencheikh Abdelhalim
Published: June 2020

We demonstrate theoretically the generation of a variety of dynamic 2D Airy beams. We generate single, 2D dual-, and quad-Airy-like beams using a dynamic optical phase, obtained by the propagation of two crossed standing ultrasonic waves (UWs) in a liquid medium (water). These UWs create sinusoidal variation of the liquid medium refractive index in two dimensions. Using the asymptotic behavior of the sine function near zero, the 2D sinusoidal phase created by the piezoelectric transducer is reduced to a 2D periodic cubic phase. As it is known, the latter converts an input plane wave (Gaussian beam) into an Airy (Airy-like) beam in the far field. By acting on the dynamic optical phase parameters, one can change the characteristics of the obtained Airy beam (trajectory and acceleration). Using combined Gaussian beams, we clearly demonstrate the existence of a variety of combined dynamic Airy beams, such as Airy, dual-Airy, symmetric-Airy, anti-symmetric-Airy, and quad-Airy beams. We believe that the present work is of significant interest in the fields of dynamic focusing, curved manipulation, and transportation of microparticles.
Left/right asymmetry of the dipole field due to reflection from a periodic multilayer of a topological insulator and a columnar thin film
Authors: Scaglione Antonio , Chiadini Francesco , Fiumara Vincenzo , Lakhtakia Akhlesh
Published: June 2020

The problem of a vertical electric dipole radiating above a periodic multilayer whose unit cell comprises a layer of a topological insulator (TI) and a columnar thin film (CTF) was solved in order to investigate the left/right asymmetry of the total electric field in the far zone in the half-space containing the dipole. Occurring in a wide range of the polar observation angle, the left/right asymmetry of E
ϕ
is due to both the CTFs and the TI layers. Occurring in a narrow range of the polar observation angle, the left/right asymmetry of E
θ
is entirely due to the TI layers. For presently available values of the magnitude of the surface admittance γTI of TIs, significant left/right asymmetry occurs if the number of unit cells in the periodic TI/CTF multilayer is high enough.
Terahertz metasurface ultra-thin collimator for power enhancement
Authors: Suzuki Takehito , Endo Kota , Kondoh Satoshi
Published: June 2020

Manipulation of electromagnetic waves from radio to visible wavelengths could lead to technology to investigate unexplored wavebands. However, flexible control of terahertz waves is difficult, because few naturally occurring, appropriate materials and sophisticated optical components exist. We propose a 2.28-µm (0.02λ) ultra-thin terahertz metasurface collimator with a high directivity of 4.6 times (6.6 dB) consisting of 339 pairs of meta-atoms compared with a single terahertz continuous-wave source. The metasurface exhibits an extremely high refractive index of 15.0 and a low reflectance of 15.5% at 3.0 THz, and with Fresnel reflections for naturally occurring dielectric materials with high refractive indices avoided. This metasurface collimator should facilitate ground-breaking applications such as arbitrary phase converters, solid immersion lenses, and cloaking.
Realization and simulation of high-power holmium doped fiber lasers for long-range transmission
Authors: Le Gouët Julien , Gustave François , Bourdon Pierre , Robin Thierry , Laurent Arnaud , Cadier Benoit
Published: June 2020

We report on our realization of a high-power holmium doped fiber laser, together with the validation of our numerical simulation of the laser. We first present the measurements of the physical parameters that are mandatory to model accurately the laser-holmium interactions in our silica fiber. We then describe the realization of the clad-pumped laser, based on a triple-clad large mode area holmium (Ho) doped silica fiber. The output signal power is 90 W at 2120 nm, with an efficiency of about 50% with respect to the coupled pump power. This efficiency corresponds to the state of the art for clad-pumped Ho-doped fiber lasers in the 100 W power class. By comparing the experimental results to our simulation, we demonstrate its validity and use it to show that the efficiency is limited, for our fiber, by the non-saturable absorption caused by pair-induced quenching between adjacent holmium ions.
Design and validation of a high-efficiency planar solar thermophotovoltaic system using a spectrally selective emitter
Authors: Bhatt Rajendra , Gupta Mool
Published: June 2020

This paper presents a detailed-balance analysis required for the achievement of a high-efficiency spectral selective STPV system utilizing thermodynamic and optical modeling approaches. Key parameters affecting the design and optimization of spectrally selective surfaces that are essential for high-efficiency STPV applications are investigated. A complete GaSb-based planar STPV system utilizing a micro-textured absorber and a nanostructure multilayer metal-dielectric coated selective emitter was fabricated and evaluated. The micro-textured absorber features more than 90% absorbance at visible and near-infrared wavelengths. The selective emitter, consisting of two nanolayer coatings of silicon nitride (Si3N4) and a layer of W in between, exhibits high spectral emissivity at wavelengths matching the spectral response of the GaSb cells. The performance of the STPV system was evaluated using a high-power laser diode as a simulated source of concentrated incident radiation. When operated at 1670 K, an output power density of 1.75 W/cm2 and a system efficiency of 8.6% were recorded. This system efficiency is higher than those of previously reported experimental STPV systems. Optical and thermal losses that occurred at multiple stages of the energy transport process were modeled and quantified. Essential guidelines to mitigate these losses and further enhance the system performance are also provided.
High-repetition rate, mid-infrared, picosecond pulse generation with µJ-energies based on OPG/OPA schemes in 2-µm-pumped ZnGeP2
Authors: Hinkelmann Moritz , Baudisch Matthias , Wandt Dieter , Morgner Uwe , Zawilski Kevin , Schunemann Peter , Neumann Jörg , Rimke Ingo , Kracht Dietmar
Published: June 2020

We report on two different concepts to generate µJ-level mid-infrared laser pulses with sub-10 ps pulse duration via nonlinear parametric generation at high pulse repetition rates. Both schemes rely on the recent development of compact and efficient CPA-free, Ho:YLF-based 2-µm laser sources pumping the highly nonlinear crystal ZnGeP2 used for parametric amplification. The first concept comprises a simplified OPG/OPA scheme efficiently producing signal and idler radiation at fixed wavelengths of 3.0 and 6.5 µm, respectively. In the second concept, we demonstrate a wide spectral tunability of the picosecond, µJ pulses over the entire tuning range between 2.5 and 12 µm maintaining a constant bandwidth of sub-20 cm−1 by integrating a two-color pumping scheme and a spectral shaper into the setup. The presented compact and efficient mid-IR picosecond radiation sources offer a way towards low-cost mid-IR material processing and spectroscopic applications.
Extracting information from single qubits among multiple observers with optimal weak measurements
Authors: Peng Xing-Xiang , Yin Peng , Zhang Wen-Hao , Li Gong-Chu , He De-Yong , Xu Xiao-Ye , Xu Jin-Shi , Chen Geng , Li Chuan-Feng , Guo Guang-Can
Published: June 2020

In the context of quantum information, major efforts have been made to maximize the mutual information by measuring single copies of signal states. In general, one execution of optimal projective measurement extracts all the accessible mutual information. However, in some scenarios, weak measurements are preferred because of kinds of specific requirements, e.g., to distribute secret keys to multi-observers. In this study, we propose a method to construct optimal weak measurements for multi-party quantum communications. Utilizing the method in [Physical Review Letters 120, 160501 (2018)] to classify the mutual information, the theoretical study shows that by successively performing this optimal weak measurement, all accessible information can be obtained by multiple observers. This conclusion is experimentally verified by a cascaded measurement apparatus that can perform six successive weak measurements on heralded single photons. The experimental results clearly indicate that almost all accessible mutual information is extracted by this sequence of optimal weak measurements; meanwhile, none of the information is destroyed or residual. Thus, this optimal weak measurement is an efficient and reliable tool for performing quantum communication tasks. The consistence between the experimental and theoretical results verifies that the classifying method in [Phys. Rev. Lett. 120, 160501 (2018)] can be applied to characterize realistic quantum measurements.
Shallow-etched thin-film lithium niobate waveguides for highly-efficient second-harmonic generation
Authors: Zhao Jie , Rüsing Michael , Javid Usman A. , Ling Jingwei , Li Mingxiao , Lin Qiang , Mookherjea Shayan
Published: June 2020

High-fidelity periodic poling over long lengths is required for robust, quasi-phase-matched second-harmonic generation using the fundamental, quasi-TE polarized waveguide modes in a thin-film lithium niobate (TFLN) waveguide. Here, a shallow-etched ridge waveguide is fabricated in x-cut magnesium oxide doped TFLN and is poled accurately over 5 mm. The high fidelity of the poling is demonstrated over long lengths using a non-destructive technique of confocal scanning second-harmonic microscopy. We report a second-harmonic conversion efficiency of up to 939 %.W−1 (length-normalized conversion efficiency 3757 %.W−1.cm−2), measured at telecommunications wavelengths. The device demonstrates a narrow spectral linewidth (1 nm) and can be tuned precisely with a tuning characteristic of 0.1 nm/°C, over at least 40 °C without measurable loss of efficiency.
Modeling the Lamb mode-coupling constant of quantum well semiconductor lasers
Authors: Vallet Arthur , Chusseau Laurent , Philippe Fabrice , Jean-Marie Alain , Brévalle Gaëlle , Alouini Mehdi , Paranthoën Cyril
Published: June 2020

We theoretically compute the coupling constant C between two emission modes of an extended cavity laser with a multiple quantum-well active layer. We use an optimized Monte Carlo model based on the Markov chain that describes the elementary events of carriers and photons over time. This model allows us to evaluate the influence on C of the transition from a class A laser to a class B laser and illustrates that the best stability of dual-mode lasers is obtained with the former. In addition, an extension of the model makes it possible to evaluate the influence of different mode profiles in the cavity as well as the spatial diffusion of the carriers and/or the inhomogeneity of the temperature. These results are in very good agreement with previous experimental results, showing the independence of C with respect to the beating frequency and its evolution versus the spatial mode splitting in the gain medium.
Airy transform of Laguerre-Gaussian beams
Authors: Zhou Guoquan , Wang Fei , Feng Shangshen
Published: June 2020

Airy transform of Laguerre-Gaussian (LG) beams is investigated. As typical examples, the analytic expressions for the Airy transform of LG01, LG02, LG11, and LG12 modes are derived, which are special optical beams including the Airy and Airyprime functions. Based on these analytical expressions, the Airy transform of LG01, LG02, LG11, and LG12 modes are numerically and experimentally investigated, respectively. The effects of the control parameters α and β on the normalized intensity distribution of a Laguerre-Gaussian beam passing through Airy transform optical systems are investigated, respectively. It is found that the signs of the control parameters only affect the location of the beam spot, while the sizes of the control parameters will affect the characteristics of the beam spot. When the absolute values of the control parameters α and β decrease, the number of the side lobes in the beam spot, the beam spot size, and the Airy feature decrease, while the Laguerre-Gaussian characteristic is strengthened. By altering the control parameters α and β, the performance of these special optical beams is diversified. The experimental results are consistent with the theoretical simulations. The Airy transform of other Laguerre-Gaussian beams can be investigated in the same way. The properties of the Airy transform of Laguerre-Gaussian beams are well demonstrated. This research provides another approach to obtain special optical beams and expands the application of Laguerre-Gaussian beams.
High-throughput imaging surface plasmon resonance biosensing based on ultrafast two-point spectral-dip tracking scheme
Authors: Zeng Youjun , Wang Xueliang , Zhou Jie , Miyan Ruibiao , Qu Junle , Ho Ho-Pui , Zhou Kaiming , Gao Bruce Zhi , Chen Jiajie , Shao Yonghong
Published: June 2020

Wavelength interrogation surface plasmon resonance imaging (λSPRi) has potential in detecting 2-dimensional (2D) sensor array sites, but the resonance wavelength imaging rate limits the application of detecting biomolecular binding process in real time. In this paper, we have successfully demonstrated an ultrafast λSPRi biosensor system. The key feature is a two-point tracking algorithm that drives the liquid crystal tunable filter (LCTF) to achieve fast-tracking of the resonance wavelength movement caused by the binding of target molecules with the probe molecules on the sensing surface. The resonance wavelength measurement time is within 0.25s. To date, this is the fastest speed ever reported in λSPRi. Experiment results show that the sensitivity and dynamic are 2.4 × 10−6 RIU and 4.6 × 10−2 RIU, respectively. In addition, we have also demonstrated that the system has the capability of performing fast high-throughput detection of biomolecular interactions, which confirms that this fast real-time detecting approach is most suitable for high-throughput and label-free biosensing applications.
Snapshot multispectral endomicroscopy
Authors: Meng Ziyi , Qiao Mu , Ma Jiawei , Yu Zhenming , Xu Kun , Yuan Xin
Published: June 2020

Multispectral endomicroscopy provides tissue functional information in addition to structural information for accurate disease diagnosis. In this Letter, we propose a snapshot multispectral endomicroscope that employs a fiber bundle to deliver an in-body tissue spatial–spectral datastream to an external compressive spectral imager. Equipped with an end-to-end deep-learning-based reconstruction algorithm, we are able to capture tissue multispectral data in video rates and reconstruct high-resolution multispectral images with up to 24 spectral channels in near-real time.
Impact of excitation energy on the excitonic luminescence of cesium lead bromide perovskite nanosheets
Authors: Lao Xiangzhou , Bao Yitian , Xu Shijie
Published: June 2020

An excitation-energy-dependent luminescence phenomenon is reported in cesium lead bromide (

C
s
P
b
B
r

3

) perovskite nanosheets. At 10 K, the relative integrated luminescence intensity between the trapped exciton (TX) emission and the free exciton (FX) emission shows an interesting tendency with increasing the optical excitation energy from 2.431 eV (510 nm) to 3.758 eV (330 nm). To interpret such phenomenon, we develop a quantitative model on the basis of the biological population growth theory. A good agreement between experiment and theory is obtained. It is thus revealed that the lower capture coefficient of the TX level to the excited excitons via multiphonon emission relative to the FX level shall be the major cause of the observed phenomenon. These findings may help to deepen the current understanding of the complex luminescence mechanisms of these emerging light-emitting materials.
Low-loss fs-laser-written surface waveguide lasers at >2  µm in monoclinic Tm3+:MgWO4
Authors: Kifle Esrom , Loiko Pavel , Vázquez de Aldana Javier Rodríguez , Romero Carolina , Llamas Víctor , Serres Josep Maria , Aguiló Magdalena , Díaz Francesc , Zhang Lizhen , Lin Zhoubin , Lin Haifeng , Zhang Ge , Zakharov Viktor , Veniaminov Andrey , Petrov Valentin , Griebner Uwe , Mateos Xavier , Wang Li , Chen Weidong
Published: June 2020

Surface channel waveguides (WGs) based on a half-ring (40–60-µm-diameter) depressed-index cladding (type III) geometry are fabricated in monoclinic

Tm

3
+

:

MgWO

4

by femtosecond (fs) laser writing at a repetition rate of 1 kHz. The WGs are characterized by confocal laser microscopy and

μ

-Raman spectroscopy. A

Tm

3
+

:

MgWO

4

WG laser generates 320 mW at

∼

2.02

µ

m

with a slope efficiency of 64.4%. The WG emits a transverse single-mode and linear polarization (

E

|

|

N
m

). A remarkable low loss of

<
0.1

dB

/

cm

is measured for the WG. Vibronic laser emission at

∼

2.08

µ

m

is also achieved.