A Low-Diversity Microbiota Inhabits Extreme Terrestrial Basaltic Terrains and Their Fumaroles : Implications for the Exploration of Mars

A major objective in the exploration of Mars is to test the hypothesis that the planet hosted life. Even in the absence of life, the mapping of habitable and uninhabitable environments is an essential task in developing a complete understanding of the geological and aqueous history of Mars and, as a consequence, understanding what factors caused Earth to take a different trajectory of biological potential. We carried out the aseptic collection of samples and comparison of the bacterial and archaeal communities associated with basaltic fumaroles and rocks of varying weathering states in Hawai'i to test four hypotheses concerning the diversity of life in these environments. Using high-throughput sequencing, we found that all these materials are inhabited by a low-diversity biota. Multivariate analyses of bacterial community data showed a clear separation between sites that have active fumaroles and other sites that comprised relict fumaroles, unaltered, and syn-emplacement basalts. Contrary to our hypothesis that high water flow environments, such as fumaroles with active mineral leaching, would be sites of high biological diversity, alpha diversity was lower in active fumaroles compared to relict or nonfumarolic sites, potentially due to high-temperature constraints on microbial diversity in fumarolic sites. A comparison of these data with communities inhabiting unaltered and weathered basaltic rocks in Idaho suggests that bacterial taxon composition of basaltic materials varies between sites, although the archaeal communities were similar in Hawai'i and Idaho. The taxa present in both sites suggest that most of them obtain organic carbon compounds from the atmosphere and from phototrophs and that some of them, including archaeal taxa, cycle fixed nitrogen. The low diversity shows that, on Earth, extreme basaltic terrains are environments on the edge of sustaining life with implications for the biological potential of similar environments on Mars and their exploration by robots and humans.Peer reviewe

Health, education, and social care provision after diagnosis of childhood visual disability

Aim: To investigate the health, education, and social care provision for children newly diagnosed with visual disability.Method: This was a national prospective study, the British Childhood Visual Impairment and Blindness Study 2 (BCVIS2), ascertaining new diagnoses of visual impairment or severe visual impairment and blindness (SVIBL), or equivalent vi-sion. Data collection was performed by managing clinicians up to 1-year follow-up, and included health and developmental needs, and health, education, and social care provision.Results: BCVIS2 identified 784 children newly diagnosed with visual impairment/SVIBL (313 with visual impairment, 471 with SVIBL). Most children had associated systemic disorders (559 [71%], 167 [54%] with visual impairment, and 392 [84%] with SVIBL). Care from multidisciplinary teams was provided for 549 children (70%). Two-thirds (515) had not received an Education, Health, and Care Plan (EHCP). Fewer children with visual impairment had seen a specialist teacher (SVIBL 35%, visual impairment 28%, χ2p < 0.001), or had an EHCP (11% vs 7%, χ2p < 0 . 01).Interpretation: Families need additional support from managing clinicians to access recommended complex interventions such as the use of multidisciplinary teams and educational support. This need is pressing, as the population of children with visual impairment/SVIBL is expected to grow in size and complexity.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited

Fault-tolerant quantum stabilizer codes for improving the fidelity of transversal CNOT gates

In support of large-scale practical quantum algorithms Quantum-Error-Correction-Codes (QECC) are designed for mitigating the component errors inherent in quantum circuits. A QECC attaches carefully selected redundancy to quantum information in such a way that the individual qubit errors can be corrected without corrupting the logical qubit state, where the encoding and decoding circuits are built by individual quantum gates. If these components are error-prone, they increase the qubit error probability, hence leading to an even more grave corruption of the data qubits. Therefore constructing QECCs reliant on fault tolerant circuitry is crucial for creating quantum solutions. Fault tolerant QECCs are capable of providing error rate improvements in quantum processors as long as components operate below a certain gate error probability. We start by quantifying the depolarization probability bound, below which the family of transversal QECCs give a better error probability than an uncoded gate. Both a low-complexity repetition code and Steane’s 7-bit QECC are characterized. In this context it is observed that the Frame-Error-Rates attained are lower-bounded according to the gate error probability occurring in the non-fault tolerant encoding circuits. We address this problem by proposing the ‘encoderless’ quantum code, which replaces the encoder circuit by a fault-tolerant single-qubit gate arrangement. As a further benefit, in contrast to state preparation techniques, our encoderless scheme requires no prior knowledge of the input information, therefore realistic unknown states can be encoded fault-tolerantly. Our encoderless quantum code delivers a frame error rate that is three orders of magnitude lower than that of the corresponding scheme relying on a non-fault-tolerant encoder, when the gate error probability is as high as 10−3. Next, we consider two practical applications of fault-tolerant QECCs, in quantum communication protocols; Quantum teleportation allows an unknown quantum state to be transmitted between two separated locations. To achieve this the system requires both classical and quantum channel, for communicating a pair of classical bits and an entangled quantum bit from the transmitter to the receiver. It is commonly assumed in the literature that both channels are error free, even though under realistic conditions this is unlikely to be the case. Hence we propose and investigate a secure and reliable quantum teleportation scheme, when both the classical and quantum channels exhibit errors. It is found that both the security and reliability of the teleportation may be improved, when powerful turbo codes are employed. Finally, we quantify the fault-tolerance improvements attained by a [4, 2, 2] error detection code in IBM’s open-access devices. Up to 100 logical gates are activated in the Ibmq Bogota and Ibmq Santiago devices and we found that a [4, 2, 2] code’s logical gate set may be deemed fault-tolerant for gate sequences larger than 10 gates. However, certain circuits did not satisfy the fault tolerance criterion. In some cases the encoded-gate sequences show a high error rate that is lower bounded at ≈ 0.1, whereby the error inherent in these circuits cannot be mitigated by classical post-selection. A comparison of the experimental results to a simple error model reveal that the dominant gate errors cannot be readily represented by the popular Pauli error model. Finally, it is most accurate to assess the fault tolerance criterion when the circuits tested are restricted to those that give rise to an output state with a low dimension

Microbial responses to multiple extreme environments

Microorganisms are the most ancient, abundant and diverse form of life on Earth. Their ability to tolerate a variety of stresses has enabled microbial colonisation of extreme environments, including hot springs, soda lakes and deep-sea vents. For decades, habitability studies have focused on the environmental effects of singular extremes, such as temperature, pressure, pH and salinity. Environments posing more than one simultaneous physical or chemical stress, nonetheless, are abundant in the natural world. It is therefore notable that so few studies have investigated the relationship between different extremes. This thesis explores the response of select microbes to synchronously occurring stresses, with the use of a new quantitative method. Understanding the relationship between stresses within multiple extreme environments is key to understanding the habitability of these settings. The effect of nutrient limitation and NaCl on bacterial growth was explored, allowing the expansion of kinetic growth models to produce the Mult-Min method, used throughout this thesis. This method investigates whether a multiplicative effect (a situation when all the extremes contribute to an effect on growth) or minimising effect (scenario where one stress dominates the effect on growth) is observed between extreme stresses. The resulting consequences for habitability are that these interactions (or indeed lack of) are not a simple process and cannot be assumed to be either multiplicative or minimising for all combinations of stresses; hence a method (such as the Mult-Min) is required. In addition, the effects of salt, temperature and pH on growth are examined. Salt exhibits a dominant effect on growth, with small amounts of perchlorate shown to be beneficial to Mg2+ requiring microorganisms. It is shown to enhance microbial viability up until a concentration relevant to that on the Martian surface. Compatible solutes, organic molecules used for cellprotection under extreme conditions, were also studied. This work addresses gaps in knowledge by comparing three of the most prevalent natural extremes, finding that salt has the most dominant effect on growth. Overall, use of the Mult-Min method shows the complexity of the relationship between extremes, illustrating the inadequacy of focusing on isolated extremes. This work demonstrates the importance of understanding not only how stresses interact in extreme environments, but also the extent to which particular stresses may affect growth

Turbo-coded secure and reliable quantum teleportation

Quantum teleportation allows an unknown arbitrary quantum state to be transmitted between two separate locations. To achieve this, the system requires both classical and quantum channels, for communicating two classical bits and an entangled quantum bit from the transmitter to the receiver. It is commonly assumed that both channels are error-free, however, under realistic conditions, this is unlikely to be the case. This study proposed and investigated a secure and reliable quantum teleportation scheme when both classical and quantum channels exhibit errors. It was found that the security and reliability of the teleportation could be improved when powerful turbo codes are employed

Mult-Min quantitative method of analysing effects of NaCl and phosphate on bacterial growth

Application of the Mult-Min quantiative method to experimental data investigating the effects of combined NaCl and phosphate limitation on growth of the moderately halophilic organim, Halomonas hydrothermalis. This is a method of analysing the effect of multiple extremes on bacterial growth.Cane, Rosie. (2020). Mult-Min quantitative method of analysing effects of NaCl and phosphate on bacterial growth, [dataset]. University of Edinburgh. https://doi.org/10.7488/ds/2807

Mitigation of decoherence-induced quantum-bit errors and quantum-gate errors using Steane's code

Quantum processors require Quantum Error Correction Codes (QECC's) for improving the fidelity of quantum logic gates. Fault tolerant QECC's are capable of providing error rate improvements in quantum processors as long as the components are operating below a certain gate error probability. In this contribution, we quantify the depolarization probability bound, below which transversal QECC's would give a better error probability than an uncoded gate. Both a low-complexity repetition code and Steane's 7-bit QECC are characterized

Experimental characterization of fault-tolerant circuits in small-scale quantum processors

Experiments conducted on open-access cloud-based IBM Quantum devices are presented for characterizing their fault tolerance using $[4,2,2]$-encoded gate sequences. Up to 100 logical gates are activated in the "IBMQ Bogota" and "IBMQ Santiago" devices and we found that a [4,2,2] code's logical gate set may be deemed fault-tolerant for gate sequences larger than 10 gates. However, certain circuits did not satisfy the fault tolerance criterion. In some cases the encoded-gate sequences show a high error rate that is lower bounded at approximately 0.1, whereby the error inherent in these circuits cannot be mitigated by classical post-selection. A comparison of the experimental results to a simple error model reveal that the dominant gate errors cannot be readily represented by the popular Pauli error model. Finally, it is most accurate to assess the fault tolerance criterion when the circuits tested are restricted to those that give rise to an output state with a low dimension

Gate-error-resilient quantum Steane codes

An encoderless quantum code is capable of connecting quantum information by replacing the encoder circuit with a fault-tolerant single-qubit gate arrangement. As a further benefit, in contrast to state preparation techniques, our encoderless scheme requires no prior knowledge of the input information, therefore totally unknown states can be encoded fault-tolerantly. Our encoderless quantum code delivers a frame error rate that is three orders of magnitude lower than that of the corresponding scheme relying on a non-fault-tolerant encoder, when the gate error probability is as high as 10 -3