A virtual reality interface for the immersive manipulation of live microscopic systems.

For more than three centuries we have been watching and studying microscopic phenomena behind a microscope. We discovered that cells live in a physical environment whose predominant factors are no longer those of our scale and for which we lack a direct experience and consequently a deep intuition. Here we demonstrate a new instrument which, by integrating holographic and virtual reality technologies, allows the user to be completely immersed in a dynamic virtual world which is a simultaneous replica of a real system under the microscope.

A transition to stable one-dimensional swimming enhances E. coli motility through narrow channels.

Living organisms often display adaptive strategies that allow them to move efficiently even in strong confinement. With one single degree of freedom, the angle of a rotating bundle of flagella, bacteria provide one of the simplest examples of locomotion in the living world. Here we show that a purely physical mechanism, depending on a hydrodynamic stability condition, is responsible for a confinement induced transition between two swimming states in E.

Brownian fluctuations and hydrodynamics of a microhelix near a solid wall.

We combine two-photon lithography and optical tweezers to investigate the Brownian fluctuations and propeller characteristics of a microfabricated helix. From the analysis of mean squared displacements and time correlation functions we recover the components of the full mobility tensor. We find that Brownian motion displays correlations between angular and translational fluctuations from which we can directly measure the hydrodynamic coupling coefficient that is responsible for thrust generation.

3D dynamics of bacteria wall entrapment at a water-air interface.

Swimming bacteria can be trapped for prolonged times at the surface of an impenetrable boundary. The subsequent surface confined motility is found to be very sensitive to the physico-chemical properties of the interfaces which determine the boundary conditions for the flow. The quantitative understanding of this complex dynamics requires detailed and systematic experimental data to validate theoretical models for both flagellar propulsion and interfacial dynamics.

An optical reaction micro-turbine.

To any energy flow there is an associated flow of momentum, so that recoil forces arise every time an object absorbs or deflects incoming energy. This same principle governs the operation of macroscopic turbines as well as that of microscopic turbines that use light as the working fluid. However, a controlled and precise redistribution of optical energy is not easy to achieve at the micron scale resulting in a low efficiency of power to torque conversion.

Dynamic density shaping of photokinetic .

Many motile microorganisms react to environmental light cues with a variety of motility responses guiding cells towards better conditions for survival and growth. The use of spatial light modulators could help to elucidate the mechanisms of photo-movements while, at the same time, providing an efficient strategy to achieve spatial and temporal control of cell concentration. Here we demonstrate that millions of bacteria, genetically modified to swim smoothly with a light controllable speed, can be arranged into complex and reconfigurable density patterns using a digital light projector.

Microrheology of DNA hydrogel gelling and melting on cooling.

We present systematic characterisation by means of dynamic light scattering and particle tracking techniques of the viscosity and of the linear viscoelastic moduli, G'(ω) and G''(ω), for two different DNA hydrogels. These thermoreversible systems are composed of tetravalent DNA-made nanostars whose sticky sequence is designed to provide controlled interparticle bonding. While the first system forms a gel on cooling, the second one has been programmed to behave as a re-entrant gel, turning again to a fluid solution at low temperature.

Light controlled 3D micromotors powered by bacteria.

Self-propelled bacteria can be integrated into synthetic micromachines and act as biological propellers. So far, proposed designs suffer from low reproducibility, large noise levels or lack of tunability. Here we demonstrate that fast, reliable and tunable bio-hybrid micromotors can be obtained by the self-assembly of synthetic structures with genetically engineered biological propellers.

Delayed Diagnosis of Osteonecrosis of the Jaw (ONJ) Associated with Bevacizumab Therapy in Colorectal Cancer Patients: Report of Two Cases.

Medication-induced Osteonecrosis of the Jaw (MRONJ) has been reported not only after use of antiresorptive agents (bisphosphonates and denosumab), but also in cancer patients receiving antiangiogenic agents, alone or combined with antiresorptive drugs. We report two cases of MRONJ observed in colorectal cancer patients after bevacizumab therapy only. MRONJ was diagnosed, respectively, two and seven months after a tooth extraction; both the patients had received two courses of bevacizumab infusions (for a total of 29 and 10 administrations, respectively).

Active dynamics of colloidal particles in time-varying laser speckle patterns.

Colloidal particles immersed in a dynamic speckle pattern experience an optical force that fluctuates both in space and time. The resulting dynamics presents many interesting analogies with a broad class of non-equilibrium systems like: active colloids, self propelled microorganisms, transport in dynamical intracellular environments. Here we show that the use of a spatial light modulator allows to generate light fields that fluctuate with controllable space and time correlations and a prescribed average intensity profile.

A GPU Simulation Tool for Training and Optimisation in 2D Digital X-Ray Imaging.

Conventional radiology is performed by means of digital detectors, with various types of technology and different performance in terms of efficiency and image quality. Following the arrival of a new digital detector in a radiology department, all the staff involved should adapt the procedure parameters to the properties of the detector, in order to achieve an optimal result in terms of correct diagnostic information and minimum radiation risks for the patient. The aim of this study was to develop and validate a software capable of simulating a digital X-ray imaging system, using graphics processing unit computing.

Vibration detection by observation of speckle patterns.

When laser light illuminates a rough surface it is scattered into a speckle pattern that is strongly dependent on the surface geometry. Here, we show that it is possible to sense surface vibrations by measuring signal variations from a single pixel detector that collects a small portion of the scattered light. By carefully tuning the probing laser beam size and the detector's aperture it was possible to record a good quality signal in the acoustic band.

A multi-mode fiber probe for holographic micromanipulation and microscopy.

Holographic tweezers have revolutionized the way we do experiments at the micron scale. The possibility of applying controlled force fields on simultaneously trapped micro-particles has allowed to directly probe interactions and mechanical properties of colloids, macromolecules and living cells. Holographic micromanipulation requires the careful shaping of a laser beam that is then focused by a microscope objective onto a micro-hologram in the sample volume.

Hologram transmission through multi-mode optical fibers.

We demonstrate that a structured light intensity pattern can be produced at the output of a multi-mode optical fiber by shaping the wavefront of the input beam with a spatial light modulator. We also find the useful property that, as in the case for free space propagation, output intensities can be easily superimposed by taking the argument of the complex superposition of corresponding phase-only holograms. An analytical expression is derived relating output intensities ratios to hologram weights in the superposition.

Computerized tomographic findings in bisphosphonate-associated osteonecrosis of the jaw in patients with cancer.

Objectives: To study bisphosphonate-associated osteonecrosis of the jaw with respect to radiographic, demographic, and clinical features.

Study Design: Thirty-two patients with painful exposed bone in the jaws subsequent to treatment with bisphosphonates for various neoplastic diseases were examined with both dental panoramic radiograph and multislice spiral computerized tomography (CT). Each case was assessed for the following radiologic signs: structural alteration of trabecular bone, cortical bone erosion, osteosclerosis, small sequestrum, extensive sequestrum, and presence of periosteal new bone.

Vertical alveolar ridge augmentation by means of a titanium mesh and autogenous bone grafts.

The aim of this study is to evaluate a surgical protocol for vertical ridge augmentation in the maxilla and mandible using autogenous onlay bone graft associated with a titanium mesh. A group of 18 partially edentulous patients, presenting the need for vertical bone augmentation of at least 4 mm, were treated before implant placement. During the first surgery, an autogenous bone graft was harvested from either the mandibular ramus or the mental symphysis and secured by means of titanium screws.

Vestibular surgical access to the palatine root of the superior first molar: "low-dose cone-beam" CT analysis of the pathway and its anatomic variations.

Apicoectomy of the superior first molar palatine root until recently involved relatively destructive and laborious surgery because of the palatal access route, which not only necessitates an extensive flap, but also the readying of procedures required to deal with a possible hemorrhage from the palatine artery. With the advent of operative microscopy, endodontic surgery has become more precise and less invasive and its technical potential has increased; a possible innovative surgical technique may entail vestibular root access. The possibility of using low-dose, low-cost computed tomography (CT) dedicated to the jaw to obtain anatomic information to plan apicoectomy via the vestibular approach was evaluated; 31 patients were referred to CT with the NewTom apparatus.

Precision of transfer of preoperative planning for oral implants based on cone-beam CT-scan images through a robotic drilling machine.

In this study, an image-guided system for oral implant placement was assessed. A specially designed mechanical tool has been elaborated to transfer the preoperative implant axis planned on 3-dimensional imagery into a surgical template by a numerically controlled drilling machine. The main drawback of image-guiding systems is the use of preoperative computed tomography, which is expensive and delivers high radiation doses.