Ultrasonic needles for bone biopsy

Bone biopsy is an invasive clinical procedure where a bone sample is recovered for analysis during the diagnosis of a medical condition. When the architecture of the bone tissue is required to be preserved, a core-needle biopsy is taken. Although this procedure is performed while the patient is under local anaesthesia, the patient can still experience significant discomfort. Additionally, large haematoma can be induced in the soft tissue surrounding the biopsy site due to the large axial and rotational forces which are applied through the needle to penetrate bone. It is well documented that power ultrasonic surgical devices offer advantages of low cutting force, high accuracy and preservation of soft tissues. This paper reports a study of the design, analysis and test of two novel power ultrasonic needles for bone biopsy that operate using different configurations to penetrate bone. The first utilises micrometric vibrations generated at the distil tip of a full-wavelength resonant ultrasonic device, while the second utilises an ultrasonic-sonic approach where vibrational energy generated by a resonant ultrasonic horn is transferred to a needle via the chaotic motion of a free-mass. It is shown that the dynamic behaviour of the devices identified through experimental techniques closely match the behaviour calculated through numerical and FEA methods, demonstrating that they are effective design tools for these devices. Both devices were able to recover trabecular bone from the metaphysis of an ovine femur, and the biopsy samples were found to be comparable to a sample extracted using a conventional biopsy needle. Furthermore, the resonant needle device was also able to extract a cortical bone sample from the central diaphysis, which is the strongest part of the bone, and the biopsy was found to be superior to the sample recovered by a conventional bone biopsy needle

Familiar strangers

I am interested in dialogues of connection – from our ongoing internal ramblings, to the moments where strangers do not feel like strangers, to the conversations that wander late into the night. Our connections are the foundations of the human experience; they give weight to the every-day and ground us in time and place. Today, our digital devices have become invaluable tools for bringing people together. No matter where we ind our physical selves, we have the ability to tap into our digital worlds and access our most intimate social circles. But our seemingly insatiable desire for constant communication often alters the content of our conversations, encouraging rapid exchanges centered around control, character count, and speed. Contemporary sociologists worry that the disjunctive communication style of texts, Tweets, and Snaps is damaging our ability to engage in focused thought and conversation - dialogues critical to the development of our relationships. If our relationships are central to the human experience, we owe it to ourselves to explore the ways in which our daily interactions can expand beyond the simple exchange of words. Even in a digital age, there is an indisputable link between our social interactions and the physical spaces in which these interactions occur. Whether in our homes, restaurants, or on the streets, my work explores how objects within these environments can invite us to engage in internal and external dialogues. After all, our digital devices are just tools. And if it is a surface for social interaction, a printed memory, or a collection of objects that contain our own histories, we should not forget that the world around us contains a richness of other tools that can aid us in the pursuit of connection

The International Right to Health: What Does It Mean in Legal Practice and How Can It Affect Priority Setting for Universal Health Coverage?

The international right to health is enshrined in national and international law. In a growing number of cases, individuals denied access to high-cost medicines and technologies under universal coverage systems have turned to the courts to challenge the denial of access as against their right to health. In some instances, patients seek access to medicines, services, or technologies that they would have access to under universal coverage if not for government, health system, or service delivery shortfalls. In others, patients seek access to medicines, services, or technologies that have not been included or that have been explicitly denied for coverage due to prioritization. In the former, judicialization of the right to health is critical to ensure patients access to the technologies or services to which they are entitled. In the latter, courts may grant patients access to medicines not covered as a result of explicit priority setting to allocate finite resources. By doing so, courts may give priority to those with the means and incentive to turn to the courts, at the expense of the maximization of equity- and population-based health. Evidence- based, informed decision-making processes could ensure that the most clinically and cost-effective products aligning with social value judgments are prioritized. Governments should be equipped to engage in and defend rational priority setting as a means to promote fair allocation of resources to maximize population health. Rational priority setting is an evidence-based form of explicit priority setting, where the priority setting process is deliberate and transparent, the decision makers are specified, relevant stakeholders are involved, and the best available evidence about clinical and cost-effectiveness and social values is considered. The most rational priority setting processes will also account for the benefit to patients, the cost, the ethicality and the fairness. The priority setting process and institutions involved should then be held accountable through an appeals process, allowing independent review by health systems, health care, and other relevant experts, and an opportunity for judicial review. While the implementation of a three-step (1) rational priority setting, (2) appeals, and (3) judicial review process will differ depending on a country’s resource constraints, political systems, and social values, the authors argue that the three stages together will promote the greatest accountability and fairness. As a result, the courts could place greater reliance on the government’s coverage choices, and the population’s health could be most equitably distributed

Monitoring kidney optical properties during cold storage preservation with spatial frequency domain imaging.

Transplantation of kidneys results in delayed graft function in as many as 40% of cases. During the organ transplantation process, donor kidneys undergo a period of cold ischemic time (CIT), where the organ is preserved with a cold storage solution to maintain tissue viability. Some complications observed after grafting may be due to damage sustained to the kidney during CIT. However, the effects due to this damage are not apparent until well after transplant surgery has concluded. To this end, we have used spatial frequency domain imaging (SFDI) to measure spatially resolved optical properties of porcine kidneys over the course of 80-h CIT. During this time, we observed an increase in both reduced scattering (μs&') and absorption (μa) coefficients. The measured scattering b parameter increased until 24 h of CIT, then returned toward baseline during the remaining duration of the imaging sequence. These results show that the optical properties of kidney tissue change with increasing CIT and suggest that continued investigation into the application of SFDI to kidneys under CIT may lead to the development of a noninvasive method for assessing graft viability

A new transgenic reporter line reveals Wnt-dependent Snai2 re-expression and cranial neural crest differentiation in Xenopus

During vertebrate embryogenesis, the cranial neural crest (CNC) forms at the neural plate border and subsequently migrates and differentiates into many types of cells. The transcription factor Snai2, which is induced by canonical Wnt signaling to be expressed in the early CNC, is pivotal for CNC induction and migration in Xenopus. However, snai2 expression is silenced during CNC migration, and its roles at later developmental stages remain unclear. We generated a transgenic X. tropicalis line that expresses enhanced green fluorescent protein (eGFP) driven by the snai2 promoter/enhancer, and observed eGFP expression not only in the pre-migratory and migrating CNC, but also the differentiating CNC. This transgenic line can be used directly to detect deficiencies in CNC development at various stages, including subtle perturbation of CNC differentiation. In situ hybridization and immunohistochemistry confirm that Snai2 is re-expressed in the differentiating CNC. Using a separate transgenic Wnt reporter line, we show that canonical Wnt signaling is also active in the differentiating CNC. Blocking Wnt signaling shortly after CNC migration causes reduced snai2 expression and impaired differentiation of CNC-derived head cartilage structures. These results suggest that Wnt signaling is required for snai2 re-expression and CNC differentiation

Abstractive Multi-Document Summarization via Phrase Selection and Merging

We propose an abstraction-based multi-document summarization framework that can construct new sentences by exploring more fine-grained syntactic units than sentences, namely, noun/verb phrases. Different from existing abstraction-based approaches, our method first constructs a pool of concepts and facts represented by phrases from the input documents. Then new sentences are generated by selecting and merging informative phrases to maximize the salience of phrases and meanwhile satisfy the sentence construction constraints. We employ integer linear optimization for conducting phrase selection and merging simultaneously in order to achieve the global optimal solution for a summary. Experimental results on the benchmark data set TAC 2011 show that our framework outperforms the state-of-the-art models under automated pyramid evaluation metric, and achieves reasonably well results on manual linguistic quality evaluation.Comment: 11 pages, 1 figure, accepted as a full paper at ACL 201

On the Onset of Hydrothermal Convection in Porous Media in the Presence of Creeping Faults: Numerical Stability Analysis and Geological Applications

This thesis presents the effects of shear heating generated by creeping faults on the onset and pattern of hydrothermal convection. The implementation of a numerical stability analysis using the pseudo-arclength continuation method shows that imperfect bifurcation cases can stem from geometrical asymmetry and inhomogeneous material properties. This workflow was applied to a case study of a geothermal reservoir in Soultz-sous-Forêts and emphasises the necessity for a fully-coupled thermal-hydraulic-mechanical-chemical (THMC) approach in geothermal settings

Estimating the Spins of Stellar-Mass Black Holes by Fitting Their Continuum Spectra

We have used the Novikov-Thorne thin disk model to fit the continuum X-ray spectra of three transient black hole X-ray binaries in the thermal state. From the fits we estimate the dimensionless spin parameters of the black holes to be: 4U 1543-47, a* = a/M = 0.7-0.85; GRO J1655-40, a* = 0.65-0.8; GRS 1915+105, a* = 0.98-1. We plan to expand the sample of spin estimates to about a dozen over the next several years. Some unresolved theoretical issues are briefly discussed.Comment: 8 pages, 4 figures, 1 table; to appear in "Astrophysics of Compact Objects" eds. Y. F. Yuan, X. D. Li, D. Lai, AI