How does consciousness vary across the animal kingdom? Are some animals ‘more conscious’ than others? This article presents a multidimensional framework for understanding interspecies variation in states of consciousness. The framework distinguishes five key dimensions of variation: perceptual richness, evaluative richness, integration at a time, integration across time, and self-consciousness. For each dimension, existing experiments that bear on it are reviewed and future experiments are suggested. By assessing a given species against each dimension, we can construct a consciousness profile for (...) that species. On this framework, there is no single scale along which species can be ranked as more or less conscious. Rather, each species has its own distinctive consciousness profile. (shrink)

Interventional research on deceased organ donors and donor organs prior to transplant holds the promise of reducing the number of patients who die waiting for an organ by expanding the pool of transplantable organs and improving transplant outcomes. However, one of the key challenges researchers face is an assumption that someone who receives an organ that was part of an interventional research protocol is always a human subject of that same study. The consequences of this assumption include the need for (...) oversight by an institutional review board and for research-level informed consent from transplant recipients, all within the complex practical realities of the organ donation and transplantation process in the United States. The current national focus on this issue provides an opportunity to think critically about the policy goals of the human subjects regulations and their application to the nascent field of deceased organ donor intervention research. We propose that for donor research where the transplant recipient does not fall under the definition of human subject, the clinical consent model—rather than the consent model used for human research subjects—best facilitates the policy objectives of balancing clinical innovation, transparency, and protection of patients in an ethically responsible and legally compliant manner. (shrink)

Octopuses, squid, and cuttlefish are remarkable creatures, famed for their intelligence. They are invertebrates—animals without a backbone—and are much more distant from us in evolutionary terms than our fellow mammals, far more distant even than birds, reptiles, and fishes. The last common ancestor of humans and octopuses lived over 560 million years ago. These animals have evolved intelligence by a different path, and their ways of perceiving and interacting with the world are very different from our own. This resource aims (...) to take you inside the minds of octopuses, squid, cuttlefish, and their lesser-known relatives, the nautiluses, using the latest scientific evidence to present an accurate, up-to-date picture of what we know about their capabilities. (shrink)

This study examines the conflation of terms such as “knowledge” and “understanding” in peer-reviewed literature, and tests the hypothesis that little current research clearly distinguishes between importantly distinct epistemic states. Two sets of data are presented from papers published in the journal Public Understanding of Science. In the first set, the digital text analysis tool, Voyant, is used to analyze all papers published in 2014 for the use of epistemic success terms. In the second set of data, all papers published (...) in Public Understanding of Science from 2010–2015 are systematically analyzed to identify instances in which epistemic states are empirically measured. The results indicate that epistemic success terms are inconsistently defined, and that measurement of understanding, in particular, is rarely achieved in public understanding of science studies. We suggest that more diligent attention to measuring understanding, as opposed to mere knowledge, will increase efficacy of scientific outreach and communication efforts. (shrink)

The description Ausonius has given us of his family and of the teachers and professors of Bordeaux in the mid-fourth century is exceptional among our sources because of its detail and completeness. There is no reason to suppose that the picture he gives is untypical of life in the provinces and it makes a welcome change from the histories of aristocratic politics at Rome or Constantinople. It provides an excellent opportunity for a pilot study in which we may see how (...) the conflicting elements of social status were in practice reconciled and applied. In the traditional, and still prevalent view, the society of the Later Roman Empire was ‘crushed … in the iron clamp of castes separated from one another by barriers which could not be passed’. The evidence of Ausonius suggests that this judgement should be qualified. The society of the fourth century may have been stable. It was not static. (shrink)

Primary headaches are highly prevalent and represent a major cause of disability in young adults. Neurofeedback is increasingly used in the treatment of chronic pain; however, there are few studies investigating its efficacy in patients with headaches. We report the results of a cross-over sham-controlled study on the efficacy of neurofeedback in the prophylactic treatment of tension-type headache. Participants received ten sessions of infra-low frequency electroencephalographic neurofeedback and ten sessions of sham-neurofeedback, with the order of treatments being randomized. The study (...) also included a basic psychotherapeutic intervention — a psychoeducational session performed before the main study phases and emotional support provided throughout the study period. The headache probability was modeled as a function of the neurofeedback and sham-neurofeedback sessions performed to date. As a result, we revealed a strong beneficial effect of neurofeedback and no influence of the sham sessions. The study supports the prophylactic use of infra-low frequency neurofeedback in patients with TTH. From a methodological point of view, we advocate for the explicit inclusion of psychotherapeutic components in neurofeedback study protocols. (shrink)

Objective:Prior research examining sexual and intimacy concerns among metastatic breast cancer patients and their intimate partners is limited. In this qualitative study, we explored MBC patients’ and partners’ experiences of sexual and intimacy-related changes and concerns, coping efforts, and information needs and intervention preferences, with a focus on identifying how the context of MBC shapes these experiences.Methods:We conducted 3 focus groups with partnered patients with MBC [N = 12; M age = 50.2; 92% White; 8% Black] and 6 interviews with (...) intimate partners [M age = 47.3; 83% White; 17% Black]. Participants were recruited through the Fox Chase Cancer Center Tumor Registry and the Cancer Support Community. Qualitative data were analyzed using the Framework Method and Dedoose software.Results:Qualitative analyses revealed several key themes reflecting ways in which MBC shapes experiences of sex/intimacy: the heavy disease/treatment burden leads to significant, long-term sexual concerns and consequent heightened emotional distress for both patients and partners ; viewing the relationship as having “an expiration date” influences patients’ and partners’ concerns related to sex/intimacy and complicates coping efforts; and information needs extend beyond managing sexual side effects to include emotional aspects of intimacy and the added strain of the life-limiting nature of the disease on the relationship. The heightened severity of sexual concerns faced by patients with MBC, compounded by the terminal nature of the disease, may place patients and partners at risk for significant adverse emotional and interpersonal consequences.Conclusion:Findings suggest unique ways in which sex and intimate relationships change after a diagnosis of metastatic breast cancer from both patients’ and partners’ perspectives. Consideration of the substantial physical and emotional burden of MBC and the broader context of the relationship and intimacy overall is important when developing a sexuality-focused intervention in this population. Addressing sexual concerns is a critical part of cancer care with important implications for patients’ health and quality of life. (shrink)

1 Evidence-based policy requires researchers to provide the answers to ecological questions that are of interest to policy makers. To find out what those questions are in the UK, representatives from 28 organizations involved in policy, together with scientists from 10 academic institutions, were asked to generate a list of questions from their organizations. 2 During a 2-day workshop the initial list of 1003 questions generated from consulting at least 654 policy makers and academics was used as a basis for (...) generating a short list of 100 questions of significant policy relevance. Short-listing was decided on the basis of the preferences of the representatives from the policy-led organizations. 3 The areas covered included most major issues of environmental concern in the UK, including agriculture, marine fisheries, climate change, ecosystem function and land management. 4 The most striking outcome was the preference for general questions rather than narrow ones. The reason is that policy is driven by broad issues rather than specific ones. In contrast, scientists are frequently best equipped to answer specific questions. This means that it may be necessary to extract the underpinning specific question before researchers can proceed. 5 Synthesis and applications. Greater communication between policy makers and scientists is required in order to ensure that applied ecologists are dealing with issues in a way that can feed into policy. It is particularly important that applied ecologists emphasize the generic value of their work wherever possible. (shrink)

Researchers from diverse disciplines, including organismal and cellular physiology, sports science, human nutrition, evolution and ecology, have sought to understand the causes and consequences of the surprising variation in metabolic rate found among and within individual animals of the same species. Research in this area has been hampered by differences in approach, terminology and methodology, and the context in which measurements are made. Recent advances provide important opportunities to identify and address the key questions in the field. By bringing together (...) researchers from different areas of biology and biomedicine, we describe and evaluate these developments and the insights they could yield, highlighting the need for more standardisation across disciplines. We conclude with a list of important questions that can now be addressed by developing a common conceptual and methodological toolkit for studies on metabolic variation in animals. (shrink)

Social networks play a significant role in learning and thus in farmers’ adoption of new agricultural technologies. This study examined the effects of social network factors on information acquisition and adoption of new seed varieties among groundnut farmers in Uganda and Kenya. The data were generated through face-to-face interviews from a random sample of 461 farmers, 232 in Uganda and 229 in Kenya. To assess these effects two alternative econometric models were used: a seemingly unrelated bivariate probit model and a (...) recursive bivariate probit model. The statistical evaluation of the SUBP shows that information acquisition and adoption decisions are interrelated while tests for the RBP do not support this latter model. Therefore, the analysis is based on the results obtained from the SUBP. These results reveal that social network factors, particularly weak ties with external support, partially influence information acquisition, but do not influence adoption. In Uganda, external support, gender, farm size, and geographic location have an impact on information acquisition. In Kenya, external support and geographic location also have an impact on information acquisition. With regard to adoption, gender, household size, and geographic location play the most important roles for Ugandan farmers, while in Kenya information from external sources, education, and farm size affect adoption choice. The study provides insight on the importance of external weak ties in groundnut farming, and a need to understand regional differences along gender lines while developing agricultural strategies. This study further illustrates the importance of farmer participation in applied technology research and the impact of social interactions among farmers and external agents. (shrink)

Objectives To characterize the prevalence and content of pediatric triage policies.Methods We surveyed and solicited policies from U.S. hospitals with pediatric intensive care units. Policies were analyzed using qualitative methods and coded by 2 investigators.Results Thirty-four of 120 institutions (28%) responded. Twenty-five (74%) were freestanding children’s hospitals and 9 (26%) were hospitals within a hospital. Nine (26%) had approved policies, 9 (26%) had draft policies, 5 (14%) were developing policies, and 7 (20%) did not have policies. Nineteen (68%) institutions shared (...) their approved or draft policy. Eight (42%) of those policies included neonates. The polices identified 0 to 5 (median 2) factors to prioritize patients. The most common factors were short- (17, 90%) and long- (14, 74%) term predicted mortality. Pediatric scoring systems included Pediatric Logistic Organ Dysfunction-2 (12, 63%) and Score for Neonatal Acute Physiology and Perinatal Extensions-II (4, 21%). Thirteen (68%) policies described a formal algorithm. The most common tiebreakers were random/lottery (10, 71%) and life cycles (9, 64%). The majority (15, 79%) of policies specified the roles of triage team members and 13 (68%) precluded those participating in patient care from making triage decisions.Conclusions While many institutions still do not have pediatric triage policies, there appears to be a trend among those with policies to utilize a formal algorithm that focuses on short- and long-term predicted mortality and that incorporates age-appropriate scoring systems. Additional work is needed to expand access to pediatric-specific policies, to validate scoring systems, and to address health disparities. (shrink)

BackgroundMoral distress (MD) is an emotional and psychological response to morally challenging dilemmas. Moral distress is experienced frequently by nurses in the intensive care unit (ICU) and can result in emotional anguish, work dissatisfaction, poor patient outcomes, and high levels of nurse turnover. Opportunities to discuss ethically challenging situations may lessen MD and its associated sequela.ObjectiveThe purpose of this project was to develop, implement, and evaluate the impact of nursing ethics huddles on participants’ MD, clinical ethics knowledge, work satisfaction, and (...) patient care among ICU nurses.Sample and SettingThe sample, 32 nurses from three ICU settings in an 800-bed tertiary academic medical center, participated in six nursing ethics huddles over a two-month period.MethodsAlvita K. Nathaniel’s Theory of Moral Reckoning guided development of the nursing ethics huddle process.1 The Moral Distress Thermometer was administered at three data points: baseline level of MD, and pre- and post-huddle to determine changes in the subjects’ level of MD.2 Focused content analysis was used to analyze qualitative responses from questionnaires about the subjects’ perception of the effect of the huddles on work satisfaction and patient care. Knowledge attainment was evaluated via open-ended short-answer questions.ResultsOverall, use of nurse-ethicist-led nursing ethics huddles was associated with improved quality of work life, patient care, and clinical ethics knowledge. The change in pre- and post-nursing ethics huddles MD scores was statistically significant (p < 0.0001). (shrink)

As social media becomes increasingly popular, human subjects researchers are able to use these platforms to locate, track, and communicate with study participants, thereby increasing participant retention and the generalizability and validity of research. The use of social media; however, raises novel ethical and regulatory issues that have received limited attention in the literature and federal regulations. We review research ethics and regulations and outline the implications for maintaining participant privacy, respecting participant autonomy, and promoting researcher transparency when using social (...) media to locate and track participants. We offer a rubric that can be used in future studies to determine ethical and regulation-consistent use of social media platforms and illustrate the rubric using our study team’s experience with Facebook. We also offer recommendations for both researchers and institutional review boards that emphasize the importance of well-described procedures for social media use as... (shrink)

Temporal discounting is the tendency to devalue temporally distant rewards. Past studies have examined the k-value, the indifference point, and the area under the curve as dependent measures on this task. The current study included these three measures and a fourth measure, called the interest rate total score. The interest rate total score was based on scoring only those items in which the delayed choice should be preferred given the expected return based on simple interest rates. In addition, associations with (...) several individual difference measures were examined including intelligence, executive functions (inhibition, working memory, and set-shifting), thinking dispositions (Need for Cognition and Consideration of Future Consequences) and engagement in substance use and gambling behavior. A staircase temporal discounting task was examined in a sample of 99 university students. Replicating previous studies, temporal discounting increased with longer delays to reward and decreased with higher reward magnitudes. A hyperbolic function accounted for variance in temporal discounting better than an exponential function. Reaction time at the indifference point was significantly longer than at the other choice points. The four dependent measures of temporal discounting were all significantly correlated and were also significantly associated with our individual difference measures. That is, the tendency to wait for a larger delayed reward on all of the temporal discounting measures was associated with higher intelligence, higher executive functions and more consideration of future consequences. Associations between our measures of temporal discounting and outcomes related to substance use and gambling behavior were modest in our university sample. (shrink)

Let K be a computable field. Let F be a collection of recursive functions over K, possibly including field operations. We investigate the following question. Given an r.e. degree a, is there an injective map j: K $\longrightarrow \mathbb{N}$ such that j(K) is of degree a and all the functions in F are translated by restrictions of total recursive functions.

Let K be a countable field. Then a weak presentation of K is an isomorphism of K onto a field whose elements are natural numbers, such that all the field operations are extendible to total recursive functions. Given a pair of two non-finitely generated countable fields contained in some overfield, we investigate under what circumstances the overfield has a weak presentation under which the given fields have images of arbitrary Turing degrees or, in other words, we investigate Turing separability of (...) various pairs of non-finitely generated fields. (shrink)

The number of children with chronic critical illness (CCI) is a growing population in the United States. A defining characteristic of this population is a prolonged hospital stay. Our study assessed the proportion of pediatric patients with chronic critical illness in U.S. hospitals at a specific point in time, and identified a subset of children whose hospital stay lasted for months to years. The potential harms of a prolonged hospitalization for children with CCI, which include over treatment, infection, disruption of (...) family life, and the intensive utilization of resources—combined with the moral distress experienced by the clinicians who care for the children, suggest the need for ethical analysis of this growing issue to identify actions that could be taken at the clinical and health systems levels to reduce the harms associated with prolonged hospital stay.In this article we present three real cases from our study that involved a very long hospital stay. We applied a framework developed by Mackenzie, Rogers, and Dodds to analyze inherent, situational, and pathogenic vulnerabilities to examine the ways that interventions intended to remedy one source of harm for the children in our cohort inadvertently created other harms. We examined the complex ways that children with protracted hospitalization are vulnerable to the choices made by their family and clinicians, as well as by healthcare systems and communities. Finally, we used this analysis to summarize actions and ethical responses to this growing patient population. Such an understanding is essential to making clinical and ethical decisions that arise for children who are at risk for a very long stay in the hospital. (shrink)

Let F be a finitely generated field and let j : F → N be a weak presentation of F, i.e. an isomorphism from F onto a field whose universe is a subset of N and such that all the field operations are extendible to total recursive functions. Then if R1 and R2 are recursive subrings of F, for all weak presentations j of F, j is Turing reducible to j if and only if there exists a finite collection of (...) non-constant rational functions {Gi} over F such that for every x ε R1 for some i, Gi ε R2. We investigate under what circumstances such a collection of rational functions exists and conclude that in the case when R1 R2 are both holomorphy rings and F is of characteristic 0 or is an algebraic function field over a perfect field of constants, the existence of the above-described collection of rational functions is equivalent to the requirement that the non-archimedean primes which do not appear as poles of elements of R2 do not have factors of relative degree 1 in some simple extension of K. (shrink)

We investigate the issues of Diophantine definability over the non-finitely generated version of non-degenerate modules contained in the infinite algebraic extensions of the rational numbers. In particular, we show the following. Let k be a number field and let K inf be a normal algebraic, possibly infinite, extension of k such that k has a normal extension L linearly disjoint from K inf over k. Assume L is totally real and K inf is totally complex. Let M inf be a (...) non-degenerate O k -module, possibly non-finitely generated and contained in O Kinf . Then M inf contains a submodule M¯ inf such that M inf /M¯ inf is torsion and O k has a Diophantine definition over M¯ inf. (shrink)

One of the main theorems of the paper states the following. Let R-K-M be finite extensions of a rational one variable function field R over a finite field of constants. Let S be a finite set of valuations of K. Then the ring of elements of K having no poles outside S has a Diophantine definition over its integral closure in M.

The paper provides a new argument against the classical invariance criterion for logical terms: if all terms with a permutation invariant extension qualify as logical, then for any arbitrary true contingent sentence K of the meta-language, there would be a logically true object-language sentence 'φ' such that K follows from the sentence 'φ is true'. Thus, many logically true sentences would be a posteriori. To prevent this fatal consequence, we propose to alter the invariance criterion: not only the term's extension, (...) but also its semantic clause must satisfy certain invariance conditions. The paper ends with the observation that the new criterion makes explicit the dependency of the classification of terms into logical and non-logical ones at the different levels of the Tarskian hierarchy of languages. (shrink)

© 2017. The American Astronomical Society. All rights reserved.We present new observations of the low-mass companion to HD 984 taken with the Gemini Planet Imager as a part of the GPI Exoplanet Survey campaign. Images of HD 984 B were obtained in the J and H bands. Combined with archival epochs from 2012 and 2014, we fit the first orbit to the companion to find an 18 au orbit with a 68% confidence interval between 14 and 28 au, an eccentricity (...) of 0.18 with a 68% confidence interval between 0.05 and 0.47, and an inclination of 119°with a 68% confidence interval between 114°and 125°. To address the considerable spectral covariance in both spectra, we present a method of splitting the spectra into low and high frequencies to analyze the spectral structure at different spatial frequencies with the proper spectral noise correlation. Using the split spectra, we compare them to known spectral types using field brown dwarf and low-mass star spectra and find a best-fit match of a field gravity M6.5 ±1.5 spectral type with a corresponding temperature of K. Photometry of the companion yields a luminosity of log=2.88 ± 0.07 dex with DUSTY models. Mass estimates, again from DUSTY models, find an age-dependent mass of 34 ±1 to 95 ±4 M Jup. These results are consistent with previous measurements of the object. (shrink)

BackgroundBiobanking biospecimens and consent are common practice in paediatric research. We need to explore children and young people’s (CYP) knowledge and perspectives around the use of and consent to biobanking. This will ensure meaningful informed consent can be obtained and improve current consent procedures.MethodsWe designed a survey, in co-production with CYP, collecting demographic data, views on biobanking, and consent using three scenarios: 1) prospective consent, 2) deferred consent, and 3) reconsent and assent at age of capacity. The survey was disseminated (...) via the Young Person’s Advisory Group North England (YPAGne) and participating CYP’s secondary schools. Data were analysed using a qualitative thematic approach by three independent reviewers (including CYP) to identify common themes. Data triangulation occurred independently by a fourth reviewer.ResultsOne hundred two CYP completed the survey. Most were between 16–18 years (63.7%, N = 65) and female (66.7%, N = 68). 72.3% had no prior knowledge of biobanking (N = 73).Acceptability of prospective consent for biobanking was high (91.2%, N = 93) with common themes: ‘altruism’, ‘potential benefits outweigh individual risk’, 'frugality', and ‘(in)convenience’.Deferred consent was also deemed acceptable in the large majority (84.3%, N = 86), with common themes: ‘altruism’, ‘body integrity’ and ‘sample frugality’. 76.5% preferred to reconsent when cognitively mature enough to give assent (N = 78), even if parental consent was previously in place. 79.2% wanted to be informed if their biobanked biospecimen is reused (N = 80).ConclusionProspective and deferred consent acceptability for biobanking is high among CYP in the UK. Altruism, frugality, body integrity, and privacy are the most important themes. Clear communication and justification are paramount to obtain consent. Any CYP with capacity should be part of the consenting procedure, if possible. (shrink)

BackgroundThe ARRIVE (Animal Research: Reporting of In Vivo Experiments) guidelines are widely endorsed but compliance is limited. We sought to determine whether journal-requested completion of an ARRIVE checklist improves full compliance with the guidelines.MethodsIn a randomised controlled trial, manuscripts reporting in vivo animal research submitted to PLOS ONE (March–June 2015) were randomly allocated to either requested completion of an ARRIVE checklist or current standard practice. Authors, academic editors, and peer reviewers were blinded to group allocation. Trained reviewers performed outcome adjudication (...) in duplicate by assessing manuscripts against an operationalised version of the ARRIVE guidelines that consists 108 items. Our primary outcome was the between-group differences in the proportion of manuscripts meeting all ARRIVE guideline checklist subitems.ResultsWe randomised 1689 manuscripts (control: n = 844, intervention: n = 845), of which 1269 were sent for peer review and 762 (control: n = 340; intervention: n = 332) accepted for publication. No manuscript in either group achieved full compliance with the ARRIVE checklist. Details of animal husbandry (ARRIVE subitem 9b) was the only subitem to show improvements in reporting, with the proportion of compliant manuscripts rising from 52.1 to 74.1% (X2 = 34.0, df = 1, p = 2.1 × 10−7) in the control and intervention groups, respectively.ConclusionsThese results suggest that altering the editorial process to include requests for a completed ARRIVE checklist is not enough to improve compliance with the ARRIVE guidelines. Other approaches, such as more stringent editorial policies or a targeted approach on key quality items, may promote improvements in reporting. (shrink)

Our ability to rapidly distinguish new from already stored information is important for behavior and decision making, but the underlying processes remain unclear. Here, we tested the hypothesis that contextual cues lead to a preselection of information and, therefore, faster recognition. Specifically, on the basis of previous modeling work, we hypothesized that recognition time depends on the amount of relevant content stored in long-term memory, i.e., set size, and we explored possible age-related changes of this relationship in older humans. In (...) our paradigm, subjects learned by heart four different word lists written in different colors. On the day of testing, a color cue indicated with a probability of 50% that a subsequent word might be from the corresponding list or from a list of new words. The old/new status of the word had to be distinguished via button press. As a main finding, we can show in a sample of n = 49 subjects, including 26 younger and 23 older humans, that response times increased linearly and logarithmically as a function of set size in both age groups. Conversely, corrected hit rates decreased as a function of set size with no statistically significant differences between both age groups. As such, our findings provide empirical evidence that contextual information can lead to a preselection of relevant information stored in long-term memory to promote efficient recognition, possibly by cyclical top-down and bottom-up processing. (shrink)

Volume 24, Issue 7, July 2024, Page 6-12.

It is shown that for any computable field K and any r.e. degree a there is an r.e. set A of degree a and a field F ≅ K with underlying set A such that the field operations of F (including subtraction and division) are extendible to (total) recursive functions. Further, it is shown that if a and b are r.e. degrees with b ≤ a, there is a 1-1 recursive function $f: \mathbb{Q} \rightarrow \omega$ such that f(Q) ∈ a, (...) f(Z) ∈ b, and the images of the field operations of Q under f can be extended to recursive functions. (shrink)

We prove an effective version of the Lopez-Escobar theorem for continuous domains. Let $Mod(\tau )$ be the set of countable structures with universe $\omega $ in vocabulary $\tau $ topologized by the Scott topology. We show that an invariant set $X\subseteq Mod(\tau )$ is $\Pi ^0_\alpha $ in the Borel hierarchy of this topology if and only if it is definable by a $\Pi ^p_\alpha $ -formula, a positive $\Pi ^0_\alpha $ formula in the infinitary logic $L_{\omega _1\omega }$. As (...) a corollary of this result we obtain a new pullback theorem for positive computable embeddings: Let $\mathcal {K}$ be positively computably embeddable in $\mathcal {K}'$ by $\Phi $, then for every $\Pi ^p_\alpha $ formula $\xi $ in the vocabulary of $\mathcal {K}'$ there is a $\Pi ^p_\alpha $ formula $\xi ^{*}$ in the vocabulary of $\mathcal {K}$ such that for all $\mathcal {A}\in \mathcal {K}$, $\mathcal {A}\models \xi ^{*}$ if and only if $\Phi (\mathcal {A})\models \xi $. We use this to obtain new results on the possibility of positive computable embeddings into the class of linear orderings. (shrink)