From spider webs to a fibre-optic chemical sensor

From the spider’s perspective, silk is not only a building material but also a safety net, a weapon and a sensory organ to detect the presence of prey on its web. For scientists, dragline silk - directly extracted from spiders - is a tough, biodegradable and biocompatible optical fibre. These protein optical threads are made up of millions of repetitive protein sequences and domains that, unlike its silica counterpart, can interact with a multitude of chemical species. In this communication, we will explore the potential of using spider silk as a new type of fibre-optic chemical sensor

Automated elaborate resection planning for bone tumor surgery

PURPOSE: Planning for bone tumor resection surgery is a technically demanding and time-consuming task, reliant on manual positioning of planar cuts in a virtual space. More elaborate cutting approaches may be possible through the use of surgical robots or patient-specific instruments; however, methods for preparing such a resection plan must be developed. METHODS: This work describes an automated approach for generating conformal bone tumor resection plans, where the resection geometry is defined by the convex hull of the tumor, and a focal point. The resection geometry is optimized using particle swarm, where the volume of healthy bone collaterally resected with the tumor is minimized. The approach was compared to manually prepared planar resection plans from an experienced surgeon for 20 tumor cases. RESULTS: It was found that algorithm-generated hull-type resections greatly reduced the volume of collaterally resected healthy bone. The hull-type resections resulted in statistically significant improvements compared to the manual approach (paired t test, p < 0.001). CONCLUSIONS: The described approach has potential to improve patient outcomes by reducing the volume of healthy bone collaterally resected with the tumor and preserving nearby critical anatomy

InAs/Ga(1-x)In(x)Sb superlattices for infrared detector applications

The successful growth of InAs/Ga(1-x)In(x)Sb superlattices and their optical and structural characterization is discussed. Samples were grown by molecular beam epitaxy at fairly low substrate temperatures (less than 400 C). Structural quality was assessed by reflection high energy electron difrraction, transmission electron microscopy, and x ray diffraction. Excellent structures were achieved for growth on thick, strain relaxed GaSb buffer layers on GaAs substrates, despite a residual threading dislocation density of 10(exp 9)cm(exp -2) originating at the GaSb/GaAs interface. Despite a lattice mismatch of 1.7 percent, InAs/Ga(0.75)In(0.25)Sb superlattices are observed to be free of misfit dislocations at the thicknesses examined here, owing to the close lattice match between the superlattice and GaSb, which evenly distributes compressive and tensile stresses between the InAs and Ga(0.75)In(0.25)Sb layers. Photoluminescence and photoconductivity measurements indicate that the energy gaps of the strain-layer superlattices are smaller than those of InAs/GaSb superlattices with the same layer thicknesses, and are in agreement with the theoretical predictions of Smith and Mailhiot. Energy gaps of 80 to 250 meV (15 to 5 microns) have been measured for InAs/Ga(0.75)In(0.25)Sb superlattices with 45 to 25 A/25 A layer thickness. Results demonstrate that far-infrared cutoff wavelengths are compatible with the thin superlattice layers required for strong optical absorption in type-II superlattices

The Zwicky Transient Facility: Surveys and Scheduler

We present a novel algorithm for scheduling the observations of time-domain imaging surveys. Our Integer Linear Programming approach optimizes an observing plan for an entire night by assigning targets to temporal blocks, enabling strict control of the number of exposures obtained per field and minimizing filter changes. A subsequent optimization step minimizes slew times between each observation. Our optimization metric self-consistently weights contributions from time-varying airmass, seeing, and sky brightness to maximize the transient discovery rate. We describe the implementation of this algorithm on the surveys of the Zwicky Transient Facility and present its on-sky performance.Comment: Published in PASP Focus Issue on the Zwicky Transient Facility (https://dx.doi.org/10.1088/1538-3873/ab0c2a). 13 Pages, 11 Figure

Universal evaluation of MLC models in treatment planning systems based on a common set of dynamic tests

Reference standards; Commission on professional and hospital activities; Radiotherapy, Intensity-ModulatedEstándares de referencia; Comisión sobre actividades profesionales y hospitalarias; Radioterapia de intensidad moduladaEstàndards de referència; Comissió sobre activitats professionals i hospitalàries; Radioteràpia d'intensitat moduladaPurpose: To demonstrate the feasibility of characterising MLCs and MLC models implemented in TPSs using a common set of dynamic beams. Materials and methods: A set of tests containing synchronous (SG) and asynchronous sweeping gaps (aSG) was distributed among twenty-five participating centres. Doses were measured with a Farmer-type ion chamber and computed in TPSs, which provided a dosimetric characterisation of the leaf tip, tongue-and-groove, and MLC transmission of each MLC, as well as an assessment of the MLC model in each TPS. Five MLC types and four TPSs were evaluated, covering the most frequent combinations used in radiotherapy departments. Results: Measured differences within each MLC type were minimal, while large differences were found between MLC models implemented in clinical TPSs. This resulted in some concerning discrepancies, especially for the HD120 and Agility MLCs, for which differences between measured and calculated doses for some MLC-TPS combinations exceeded 10%. These large differences were particularly evident for small gap sizes (5 and 10 mm), as well as for larger gaps in the presence of tongue-and-groove effects. A much better agreement was found for the Millennium120 and Halcyon MLCs, differences being within ± 5% and ± 2.5%, respectively. Conclusions: The feasibility of using a common set of tests to assess MLC models in TPSs was demonstrated. Measurements within MLC types were very similar, but TPS dose calculations showed large variations. Standardisation of the MLC configuration in TPSs is necessary. The proposed procedure can be readily applied in radiotherapy departments and can be a valuable tool in IMRT and credentialing audits

Lymph Node Metastasis in Differentiated Thyroid Cancers

Lymph node metastasis is common in differentiated thyroid cancers. Therapeutic neck dissection removes macroscopic nodal metastasis, reduces local recurrence, and facilitates cancer surveillance. On the other hand, microscopic nodal metastasis is also increasingly recognized as a potential cause of persistent disease or early recurrences. Prophylactic neck dissection, by removing microscopic nodal metastasis, has been proposed to reduce recurrence and prevent future reoperation. When cancer recurs, regional nodal recurrence is most common, and the management should be individualized. We hereby present a narrative review on the management of nodal metastasis in differentiated thyroid cancers

Weaving our way towards a new generation of fibre-optic chemical sensors based on spider silk

From the spider’s perspective, silk is not only a building material but also a safety net, a weapon and a sensory organ to detect the presence of preys on its web. Indeed, this primeval material has been shaped over hundreds of millions of years by spiders to create a myriad of silk fibre types with different level of toughness, elasticity, stickiness depending on its attributed function in the web. From a human perspective, scientists are currently working on harnessing all the extraordinary properties of this material for applications spiders would never thought of, from biocompatible tissue engineering (enhancement of skin regeneration and nerve guides) to biodegradable electronics and development of specialised textile and composites. However, the potential of using spider silk fibre for chemical sensing has been overlooked. In this communication, we will explore the potential of using spider silk as a new type of fibre optic chemical sensor in a fully bio-inspired approach

From Spider Webs to a Biomimetic Optical Fibre Sensor

Can we use spider silk threads as natural, biological optical fibre sensors? In this communication, we will see how we can harness the optical properties of spider dragline silk and use it for sensing

Towards a new generation of fibre-optic chemical sensors based on spider silk threads

A spider uses up to seven different types of silk, all having specific functions, to build its web. For scientists, native silk - directly extracted from spiders - is a tough, biodegradable and biocompatible thread used mainly for tissue engineering and textile applications. Blessed with outstanding optical properties, this protein strand can also be used as an optical fibre and is, moreover, intrinsically sensitive to chemical compounds. In this communication, a pioneering proof-of-concept experiment using spider silk, in its pristine condition, as a new type of fibre-optic relative humidity sensor will be demonstrated and its potential for future applications discussed