-
Trends in Plant Science Feb 2017Plants are developmentally disposed to significant changes in oxygen availability, but our understanding of the importance of hypoxia is almost entirely limited to... (Review)
Review
Plants are developmentally disposed to significant changes in oxygen availability, but our understanding of the importance of hypoxia is almost entirely limited to stress biology. Differential patterns of the abundance of oxygen, nitric oxide (NO), and reactive oxygen species (ROS), as well as of redox potential, occur in organs and meristems, and examples are emerging in the literature of mechanistic relationships of these to development. We describe here the convergence of these cues in meristematic and reproductive tissues, and discuss the evidence for regulated hypoxic niches within which oxygen-, ROS-, NO-, and redox-dependent signalling curate developmental transitions in plants.
Topics: Cell Differentiation; Oxidation-Reduction; Oxygen; Plants; Reactive Oxygen Species; Signal Transduction
PubMed: 27986423
DOI: 10.1016/j.tplants.2016.11.013 -
Angewandte Chemie (International Ed. in... Nov 2019We report the synthesis and spectroscopic identification of the trisbenzene complexes of strontium and barium M(Bz) (M=Sr, Ba) in low-temperature Ne matrix. Both... (Review)
Review
We report the synthesis and spectroscopic identification of the trisbenzene complexes of strontium and barium M(Bz) (M=Sr, Ba) in low-temperature Ne matrix. Both complexes are characterized by a D symmetric structure involving three equivalent η -bound benzene ligands and a closed-shell singlet electronic ground state. The analysis of the electronic structure shows that the complexes exhibit metal-ligand bonds that are typical for transition metal compounds. The chemical bonds can be explained in terms of weak donation from the π MOs of benzene ligands into the vacant (n-1)d AOs of M and strong backdonation from the occupied (n-1)d AO of M into vacant π* MOs of benzene ligands. The metals in these 20-electron complexes have 18 effective valence electrons, and, thus, fulfill the 18-electron rule if only the metal-ligand bonding electrons are counted. The results suggest that the heavier alkaline earth atoms exhibit the full bonding scenario of transition metals.
PubMed: 31498532
DOI: 10.1002/anie.201908572 -
Proceedings of the National Academy of... Dec 2019The environment has a strong influence on a population's evolutionary dynamics. Driven by both intrinsic and external factors, the environment is subject to continual...
The environment has a strong influence on a population's evolutionary dynamics. Driven by both intrinsic and external factors, the environment is subject to continual change in nature. To capture an ever-changing environment, we consider a model of evolutionary dynamics with game transitions, where individuals' behaviors together with the games that they play in one time step influence the games to be played in the next time step. Within this model, we study the evolution of cooperation in structured populations and find a simple rule: Weak selection favors cooperation over defection if the ratio of the benefit provided by an altruistic behavior, b, to the corresponding cost, c, exceeds [Formula: see text], where k is the average number of neighbors of an individual and [Formula: see text] captures the effects of the game transitions. Even if cooperation cannot be favored in each individual game, allowing for a transition to a relatively valuable game after mutual cooperation and to a less valuable game after defection can result in a favorable outcome for cooperation. In particular, small variations in different games being played can promote cooperation markedly. Our results suggest that simple game transitions can serve as a mechanism for supporting prosocial behaviors in highly connected populations.
Topics: Biological Evolution; Cooperative Behavior; Environment; Game Theory; Models, Biological; Population Dynamics
PubMed: 31772008
DOI: 10.1073/pnas.1908936116 -
Neonatology 2023Abandoning infants was a heritage of the Roman Empire. Foundling hospitals were established in Italy earlier and in greater number than in other countries; their goal... (Review)
Review
Abandoning infants was a heritage of the Roman Empire. Foundling hospitals were established in Italy earlier and in greater number than in other countries; their goal was to prevent infanticides. The Foundling Hospital in Rome, established in the Santo Spirito Church in 1204, paved the way toward modern hospital care and child protection. The Order of the Holy Spirit was appointed by Pope Innocent III to care for foundlings, and set up a network of infant nurseries all over Europe. Poor unmarried pregnant women received obstetric services free of charge. Infants were admitted anonymously by the ruota, a baby hatch or turning wheel. The Order's rule regulated infants' admission, care, nutrition by wet nurses, and boarding out to foster families in the countryside. Chief physicians of the Santo Spirito Hospital were often Sapienza University professors and/or personal physicians to the Popes. Among them were Realdo Colombo, Andrea Caesalpino, Giovanni Lancisi, Giuseppe Flajani, Domenico Morichini, and Tommaso Prelà. They made major scientific progress in anatomy and surgery: descriptions of the pulmonary blood transit, embryonic formation, fetal circulation, malaria transmission from mosquitos, and surgery for congenital malformations such as hydrocephalus, anal atresia, and cleft lip. Per year, 800-1,000 exposed infants were admitted. Despite sufficient funding and meticulous regulation of care and nutrition, mortality in the hospital during the first month of life was around 70%; the causes were neglected surveillance, cleanliness, and artificial nutrition. The institution persisted for more than 700 years due to numerous connections with the Vatican.
Topics: Pregnancy; Infant; Child; Infant, Newborn; Female; Humans; Rome; Italy; Europe; Hospitals; Hospitalization
PubMed: 37748448
DOI: 10.1159/000533709 -
Translational Pediatrics Oct 2018Transitions of care between individual providers or teams of providers have a high potential for errors due to the incomplete transfer of critical information and the... (Review)
Review
Transitions of care between individual providers or teams of providers have a high potential for errors due to the incomplete transfer of critical information and the need for ongoing care. The transition from the operating room (OR) to the intensive care unit (ICU) is a particularly dangerous time for critically ill children. Hand-offs of care between the OR and ICU teams during this key transition period require detailed communication of complete and accurate patient information at a time when the patient is perhaps most vulnerable from a physiologic standpoint. Improving the safety of transitions from the OR to the ICU is an active area of investigation, though there are a few notable best practices that are commonly employed in a number of centers. These best practices include having the appropriate personnel at the bedside for the hand-off, the use of scripts and the "sterile cockpit rule", the use of checklists, double verification of post-operative orders, and maintaining an overall safety culture.
PubMed: 30460182
DOI: 10.21037/tp.2018.09.09 -
Proceedings of the National Academy of... May 2018Quantum indistinguishability plays a crucial role in many low-energy physical phenomena, from quantum fluids to molecular spectroscopy. It is, however, typically ignored...
Quantum indistinguishability plays a crucial role in many low-energy physical phenomena, from quantum fluids to molecular spectroscopy. It is, however, typically ignored in most high-temperature processes, particularly for ionic coordinates, implicitly assumed to be distinguishable, incoherent, and thus well approximated classically. We explore enzymatic chemical reactions involving small symmetric molecules and argue that in many situations a full quantum treatment of collective nuclear degrees of freedom is essential. Supported by several physical arguments, we conjecture a "quantum dynamical selection" (QDS) rule for small symmetric molecules that precludes chemical processes that involve direct transitions from orbitally nonsymmetric molecular states. As we propose and discuss, the implications of the QDS rule include () a differential chemical reactivity of para- and orthohydrogen, () a mechanism for inducing intermolecular quantum entanglement of nuclear spins, () a mass-independent isotope fractionation mechanism, () an explanation of the enhanced chemical activity of "reactive oxygen species", () illuminating the importance of ortho-water molecules in modulating the quantum dynamics of liquid water, and () providing the critical quantum-to-biochemical linkage in the nuclear spin model of the (putative) quantum brain, among others.
PubMed: 29712864
DOI: 10.1073/pnas.1718402115 -
Entropy (Basel, Switzerland) Oct 2022Core quantum postulates including the superposition principle and the unitarity of evolutions are natural and strikingly simple. I show that-when supplemented with a... (Review)
Review
Core quantum postulates including the superposition principle and the unitarity of evolutions are natural and strikingly simple. I show that-when supplemented with a limited version of predictability (captured in the textbook accounts by the repeatability postulate)-these core postulates can account for all the symptoms of classicality. In particular, both objective classical reality and elusive information about reality arise, via quantum Darwinism, from the quantum substrate. This approach shares with the Relative State Interpretation of Everett the view that collapse of the wavepacket reflects perception of the state of the rest of the Universe to the state of observer's records. However, our "let quantum be quantum" approach poses questions absent in Bohr's Copenhagen Interpretation that relied on the preexisting classical domain. Thus, one is now forced to seek preferred, predictable, hence effectively classical but ultimately quantum states that allow observers keep reliable records. Without such relative states are simply "too relative", and the ensuing makes it difficult to identify events (e.g., measurement outcomes). Moreover, universal validity of quantum theory raises the issue of , pk=|ψk|2, relating probabilities and amplitudes (that is simply postulated in textbooks). Last not least, even preferred pointer states (defined by -nvironment-duced super)-are still quantum. Therefore, unlike classical states that exist objectively, quantum states of an individual system cannot be found out by an initially ignorant observer through direct measurement without being disrupted. So, to complete the 'quantum theory of the classical' one must identify and explain how the information about objectively existing states can appear to be essentially inconsequential for them (as it does for states in Newtonian physics) and yet matter in other settings (e.g., thermodynamics). I show how the mathematical structure of quantum theory supplemented by the only uncontroversial measurement postulate (that demands immediate repeatability-hence, predictability) leads to preferred states. These correspond to measurement outcomes. Their stability is a prerequisite for objective existence of effectively classical states and for events such as quantum jumps. Events at hand, one can now enquire about their probability-the probability of a pointer state (or of a measurement record). I show that the symmetry of entangled states- or -implies Born's rule. Envariance also accounts for the loss of phase coherence between pointer states. Thus, decoherence can be traced to symmetries of entanglement and understood without its usual tool-reduced density matrices. A simple and manifestly noncircular derivation of pk=|ψk|2 follows. Monitoring of the system by its environment in course of decoherence typically leaves behind multiple copies of its pointer states in the environment. Only pointer states can survive decoherence and can spawn such plentiful information-theoretic progeny. This allows observers to use -to find out pointer states indirectly, leaving systems of interest untouched. Quantum Darwinism shows how epistemic and ontic (coexisting in quantum state) separate into robust objective existence of pointer states and detached information about them, giving rise to -composite objects with system of interest in the core and multiple records of its pointer states in the halo comprising of environment subsystems (e.g., photons) which disseminates that information throughout the Universe.
PubMed: 36359613
DOI: 10.3390/e24111520 -
The Journal of Neuroscience : the... Aug 2022Category-based thinking is a fundamental form of logical thinking. Here, we aimed to investigate its neural process at the local circuit level in the prefrontal cortex...
Category-based thinking is a fundamental form of logical thinking. Here, we aimed to investigate its neural process at the local circuit level in the prefrontal cortex (PFC). We recorded single-unit PFC activity while male monkeys () performed a task in which the category and rule were prerequisites of logical thinking and the outcome contingency was its consequence. Different groups of neurons coded a single type of information discretely or multiple types in a transitional form. Results of time-by-time analysis of neuronal activity suggest an information flow from category-coding and rule-coding neurons to transitional intermediate neurons, and then to contingency-coding neurons. Category-coding, rule-coding, and contingency-coding neurons showed stable coding of information, whereas intermediate neurons showed dynamic coding, as if it integrated category and rule to derive contingency. A similar process was confirmed by using a spiking neural network model that consisted of subnetworks coding category and rule on the input layer and those coding contingency on the output layer, with a subnetwork for integration in the intermediate layer. These results suggest that category-based logical thinking is realized in the PFC by separated neural populations organized for working in a feedforward manner. To elucidate the neural process for logical thinking, we combined an in-depth analysis of single-unit activity data with a biologically plausible computational model. Results of time-by-time analysis of prefrontal neuronal activity suggest an information flow from category-coding and rule-coding neurons to transitional intermediate neurons, and then to contingency-coding neurons. Category-coding, rule-coding, and contingency-coding neurons showed stable coding, whereas intermediate neurons showed dynamic coding, as if they integrated category and rule to derive contingency. A spiking neural network model reproduced similar temporal changes of information as the recorded neuronal data. Our results suggest that the prefrontal cortex (PFC) is critically involved in category-based thought process, and this process may be produced by separated neural populations organized for working in a feedforward manner.
Topics: Animals; Macaca mulatta; Male; Neural Networks, Computer; Neurons; Prefrontal Cortex; Thinking
PubMed: 35803736
DOI: 10.1523/JNEUROSCI.2286-21.2022 -
Philosophical Transactions of the Royal... Nov 2009All evidence currently available indicates that obligatory sterile eusocial castes only arose via the association of lifetime monogamous parents and offspring. This is... (Review)
Review
All evidence currently available indicates that obligatory sterile eusocial castes only arose via the association of lifetime monogamous parents and offspring. This is consistent with Hamilton's rule (br(s) > r(o)c), but implies that relatedness cancels out of the equation because average relatedness to siblings (r(s)) and offspring (r(o)) are both predictably 0.5. This equality implies that any infinitesimally small benefit of helping at the maternal nest (b), relative to the cost in personal reproduction (c) that persists throughout the lifespan of entire cohorts of helpers suffices to establish permanent eusociality, so that group benefits can increase gradually during, but mostly after the transition. The monogamy window can be conceptualized as a singularity comparable with the single zygote commitment of gametes in eukaryotes. The increase of colony size in ants, bees, wasps and termites is thus analogous to the evolution of multicellularity. Focusing on lifetime monogamy as a universal precondition for the evolution of obligate eusociality simplifies the theory and may help to resolve controversies about levels of selection and targets of adaptation. The monogamy window underlines that cooperative breeding and eusociality are different domains of social evolution, characterized by different sectors of parameter space for Hamilton's rule.
Topics: Animals; Biological Evolution; Hymenoptera; Selection, Genetic; Sexual Behavior, Animal; Social Behavior
PubMed: 19805427
DOI: 10.1098/rstb.2009.0101 -
American Family Physician Aug 2011Constipation is traditionally defined as three or fewer bowel movements per week. Risk factors for constipation include female sex, older age, inactivity, low caloric... (Review)
Review
Constipation is traditionally defined as three or fewer bowel movements per week. Risk factors for constipation include female sex, older age, inactivity, low caloric intake, low-fiber diet, low income, low educational level, and taking a large number of medications. Chronic constipation is classified as functional (primary) or secondary. Functional constipation can be divided into normal transit, slow transit, or outlet constipation. Possible causes of secondary chronic constipation include medication use, as well as medical conditions, such as hypothyroidism or irritable bowel syndrome. Frail older patients may present with nonspecific symptoms of constipation, such as delirium, anorexia, and functional decline. The evaluation of constipation includes a history and physical examination to rule out alarm signs and symptoms. These include evidence of bleeding, unintended weight loss, iron deficiency anemia, acute onset constipation in older patients, and rectal prolapse. Patients with one or more alarm signs or symptoms require prompt evaluation. Referral to a subspecialist for additional evaluation and diagnostic testing may be warranted.
Topics: Adult; Age Factors; Algorithms; Chronic Disease; Constipation; Humans; Medical History Taking; Physical Examination; Referral and Consultation; Risk Factors; Sex Factors
PubMed: 21842777
DOI: No ID Found