Classic Paper Research Articles

GRP – A direct Godunov extension

The classical paper [40] by S. K. Godunov had a revolutionary effect on the field of numerical simulations of compressible fluid flows. Yet, for some twenty years after its publication, it was mostly used by the mathematical community in the Soviet Union. The seminal paper of van Leer [85] has inaugurated the period of universal interest in high-resolution extensions of Godunov's scheme. The first step to take was to modify the (locally) self-similar solution to the Riemann Problem (at discontinuities) by allowing piecewise-polynomial (rather than piecewise-constant) initial data. The GRP (Generalized Riemann Problem) analysis [6] provided analytical solutions (for piecewise-linear data) that could be readily implemented in a high-resolution robust code. This review paper focuses on the evolution of some mathematical aspects of this method. It addresses the three concepts of consistency, stability and convergence in the context of compact finite difference (or finite volume) schemes for systems of nonlinear hyperbolic conservation laws. The treatment utilizes the framework of “balance laws”, a common viewpoint in relevant physical conservation laws. The first significant observation is that under very mild conditions a weak solution is indeed a solution to the balance law (obtained by a formal application of the Gauss-Green formula). Since high-resolution schemes require the computation of several quantities per mesh cell (e.g., slopes), the notion of “consistency” must be extended to this framework. A combination of consistency hypothesis with stability of the scheme leads to a suitable convergence theorem, generalizing the classical convergence theorem of Lax and Wendroff [52]. Finally, the limit functions are shown to be entropy solutions by using a notion of “Godunov compatibility”, which serves as a substitute to the entropy condition.

Проверка измерительной инвариантности для тестов когнитивных и языковых способностей

<p style="text-align: justify;">This paper discusses the measurement invariance of assessment instruments. The purpose of measurement invariance testing is to assess the extent to which a measured construct has comparable meaning across different groups or measurement points, to ensure that comparisons of these groups or measures to each other are appropriate. The paper provides an overview of recent and classic papers discussing conceptual and methodological aspects of invariance testing. Specific focus is placed on the available data on invariance testing for the assessments of cognitive and language abilities, and on the significance of invariance for the accurate assessment of individual and between-group differences. Finally, current approaches to invariance testing within structural equation modelling and item response theory are discussed. This paper may serve as an introduction to the concept of measurement invariance. It will be useful to readers interested in improving the quality of measurement instruments and making more reliable inferences about psychological phenomena.</p>

MSphere of Influence: The power of observational research.

Katrina Velle is a cell biologist who uses microscopy to study amoebae. In this mSphere of Influence article, she reflects on how a classic paper on Listeria by Tilney and Portnoy made an impact on her by highlighting how much we can learn from simply looking at cells.

A note on odd partition numbers

Ramanujan’s partition congruences modulo ℓ∈{5,7,11}\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\ell \\in \\{5, 7, 11\\}$$\\end{document} assert that p(ℓn+δℓ)≡0(modℓ),\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\begin{aligned} p(\\ell n+\\delta _{\\ell })\\equiv 0\\pmod {\\ell }, \\end{aligned}$$\\end{document}where 0<δℓ<ℓ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0<\\delta _{\\ell }<\\ell $$\\end{document} satisfies 24δℓ≡1(modℓ).\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$24\\delta _{\\ell }\\equiv 1\\pmod {\\ell }.$$\\end{document} By proving Subbarao’s conjecture, Radu showed that there are no such congruences when it comes to parity. There are infinitely many odd (resp. even) partition numbers in every arithmetic progression. For primes ℓ≥5,\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\ell \\ge 5,$$\\end{document} we give a new proof of the conclusion that there are infinitely many m for which p(ℓm+δℓ)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p(\\ell m+\\delta _{\\ell })$$\\end{document} is odd. This proof uses a generalization, due to the second author and Ramsey, of a result of Mazur in his classic paper on the Eisenstein ideal. We also refine a classical criterion of Sturm for modular form congruences, which allows us to show that the smallest such m satisfies m<(ℓ2-1)/24,\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$m<(\\ell ^2-1)/24,$$\\end{document} representing a significant improvement to the previous bound.

Online Exam Portal

An online test is one that is conducted via the internet or an intranet utilizing a computer system. It is a web-based exam system. It works well as a mass education evaluation solution. Our system for online exams is built on a Browser/Server architecture. The multiple choice questions that are fed into the system are examined and automatically graded by the system. Even while it is comfortable, the classic pen and paper exam format has drawbacks in the current digital learning environment. IT students find these limits even more noticeable because they are used to using internet resources and platforms. In response, this proposal suggests creating an efficient, user-friendly, and safe online assessment system especially for IT students. This project goes beyond practicality. It increases assessment quality with interesting formats, empowers students with freedom, and promotes efficiency with quicker administration and grading. Teachers receive insightful data-driven information for bettering their curricula. In the end, it welcomes the digital age and uses cutting-edge evaluation techniques to get IT students ready for success

Ciliary propulsion through non-uniform flows

The classical paper by Lighthill (Commun. Pure Appl. Maths, vol. 109, 1952, p. 118) on the propulsion of ciliated microorganisms has become the reference against which many modern studies on swimming in low Reynolds number are compared. However, Lighthill's study was limited to propulsion in a uniform flow, whereas several biologically relevant microorganisms experience non-uniform flows. Here we propose a benchmark for ciliary propulsion in paraboloidal flows. We first consider the axisymmetric problem, with the microorganisms on the centreline of the background flow, and derive exact analytical solutions for the flow field. Our results reveal flow features, swimming characteristics and performance metrics markedly different from those generated in a uniform flow. In particular, the background paraboloidal flow introduces a Stokes quadrupole singularity at the leading-order flow field, generating vortices. Moreover, we determine the necessary conditions on the strength of the background flow for optimal power dissipation and swimming efficiency. We then consider the more general case of a microorganism off the centreline of the background flow. In this case, the squirmer experiences a paraboloidal, linear shear and uniform flows due to its position relative to the flow's centreline. Our findings show that while the linear shear flow does not affect the translational and rotational velocities of the squirmer, it does influence the velocity field and, therefore, the power dissipation.

Reducing the Chvátal rank through binarization

In a classical paper, Chvátal introduced a rounding procedure for strengthening the polyhedral relaxation P of an integer program; applied recursively, the number of iterations needed to obtain the convex hull of the integer solutions in P is known as the Chvátal rank. Chvátal showed that this rank can be exponential in the input size L needed to describe P. We give a compact extended formulation of P, described by introducing binary variables, whose rank is polynomial in L.

Enhancing Physiology Education Through Physiological Simulation

Advances in Physiology Education began publishing papers in 2005, using classic papers in physiology teaching [1]. This approach has several valuable outcomes: Classic experiments, conclusion of which form the foundation of much of our undergraduate teaching textbooks, require less specialized knowledge to understand and interpret the data and conclusions. It demonstrates the scientific method, demonstrating both "what do we know" and "how do we know." It promotes inquiry-based learning. It fosters data literacy, teaching students to interpret graphs and provides historical context for physiology [1]. Traditional practical classes achieve many of these outcomes while also providing a tactile experience, and have added benefits to students’ data literacy — in as much as the students perform the protocols themselves. Students will gain insight to what “squiggly lines” on a screen are measuring and the individual variability in what raw physiological recordings look like. Students will gain a greater appreciation for analytical techniques, and the manipulations and analysis that needs to be performed to interpret data. Students also gain an appreciation of the difference between textbook vs real data. Nevertheless, in person practical classes have limitations due to resource intensity, including space, materials, and curriculum time. HumMod (hummod.org) is a freely available mathematical model of Human Physiology, a "time-dependent physiologic simulation engine" [2]. JustPhysiology (justphysiology.com) is an education-focused web interface for HumMod [3]. We have written four physiology-based workshops utilizing simulated data from JustPhysiology. The JustPhysiology workshops were setup as a structured inquiry activity where students are expected to apply their content knowledge to interpret data, and students submitted their reports after each workshop for evaluation and feedback. In preparing the workshop activities for deployment, we trialed the activities with students who had previously completed our second year Human Physiology subject (and were thus familiar with the content). We then engaged students in focus group interviews —ascertaining the students’ perceptions of the learning experience. The outcome of the focus group interview suggests that students engaging with the workshop tasks enter into a positive learning cycle: [Formula: see text] The spontaneous emergence of a learning cycle, promoting deeper understanding of the physiology suggests that these data driven workshops will have improve student learning in Human Physiology.

Discovering the Intriguing Properties of Extrasynaptic γ-Aminobutyric Acid Type A Receptors.

Tonic inhibition in mouse hippocampal CA1 pyramidal neurons is mediated by α5 subunit-containing γ-aminobutyric acid type A receptors. By Caraiscos VB, Elliott EM, You-Ten KE, Cheng VY, Belelli D, Newell JG, Jackson MF, Lambert JJ, Rosahl TW, Wafford KA, MacDonald JF, Orser BA. Proc Natl Acad Sci U S A 2004; 101:3662-7. Reprinted with permission. In this Classic Paper Revisited, the author recounts the scientific journey leading to a report published in the Proceedings of the National Academy of Sciences (PNAS) and shares several personal stories from her formative years and "research truths" that she has learned along the way. Briefly, the principal inhibitory neurotransmitter in the brain, γ-aminobutyric acid (GABA), was conventionally thought to regulate cognitive processes by activating synaptic GABA type A (GABAA) receptors and generating transient inhibitory synaptic currents. However, the author's laboratory team discovered a novel nonsynaptic form of tonic inhibition in hippocampal pyramidal neurons, mediated by extrasynaptic GABAA receptors that are pharmacologically distinct from synaptic GABAA receptors. This tonic current is highly sensitive to most general anesthetics, including sevoflurane and propofol, and likely contributes to the memory-blocking properties of these drugs. Before the publication in PNAS, the subunit composition of GABAA receptors that generate the tonic current was unknown. The team's research showed that GABAA receptors containing the α5 subunit (α5GABAARs) generated the tonic inhibitory current in hippocampal neurons. α5GABAARs are highly sensitive to GABA, desensitize slowly, and are thus well suited for detecting low, persistent, ambient concentrations of GABA in the extracellular space. Interest in α5GABAARs has surged since the PNAS report, driven by their pivotal roles in cognitive processes and their potential as therapeutic targets for treating various neurologic disorders.

The Top 100 Classical and Contemporary Papers on Elbow Surgery: A Trend Analysis of Elbow Surgery Literature.

Bibliometric analyses provide an aggregate of the most frequently cited literature in a given field. The purpose of this study was to analyze the top 100 most-cited classical and contemporary papers relating to elbow surgery to serve as a reference for surgeons and trainees for educational and research purposes. A search was conducted for all papers containing the term "elbow" in the categories Orthopedics, Surgery, and Sports Science in the Clarivate Web of Science. Classical papers were those published from 1980 to 2009, and contemporary papers were those published from 2010 to 2019. Articles were assessed by country of origin, authors and their credentials, parent journal, level of evidence, and topic. Citation frequency ranged from 86 to 867. Among the classical group, there were more level IV papers compared with level I papers; however, the opposite was true in the contemporary group. The most common topic in the classical group was elbow anatomy and function, and the most common topic in the contemporary group was lateral epicondylitis and medial epicondylitis and associated therapies. This bibliometric analysis serves to help guide surgeons and trainees on the highly cited articles and important topics in elbow surgery, demonstrating a shift to prospective randomized controlled trials in recent years. Level V (Systematic Review with Level V as Lowest LOE).

Eric Ungar and vibration damping

This presentation honors Eric Ungar’s contributions to vibration damping. The classic paper titled “Loss Factors of Viscoelastic Systems in Terms of Energy Concepts,” which he co-authored with Edward Kerwin in 1962, takes center stage. Two significant contributions of the paper deserve detailed discussion. The first is the time dependence of total energy for viscoelastic systems with added mass, which results in ambiguous loss factor definitions off resonance. The second and most important contribution is an equation for the loss factor of a network of ideal viscoelastic springs. This equation reveals that the system loss factor is a weighted average of the loss factors of the viscoelastic springs, where the weights are the total energies in the viscoelastic springs. Next, the value of this work is illustrated by some recent work inspired by the 1962 paper. This recent work, which was published 60 years after the 1962 paper, involves the calculation of loss factors from finite element models of complex structures with viscoelastic elements. The presentation concludes with recollections that celebrate Eric Ungar’s talent in educating and inspiring generations of engineers and researchers. [Work supported by ONR under Grant N00014-22-1-2785.]

Effects of brightness variations on a smartphone-based version of Radner reading charts.

The purpose of this study was to evaluate the equivalence of smartphone-based measurements of near visual acuity under different screen brightness conditions with a standard near visual acuity test. On a sample of 85 participants, we have evaluated near visual acuity with a smartphone-based version of the Radner reading chart at three distinct screen brightness levels. Results have been compared with those obtained with classical Radner paper charts. We have found that, when a sufficient screen brightness is employed, the smartphone-based version of the Radner reading chart produces results that are in line with the paper Radner charts while low brightness levels lead to a significant underestimation of reading acuities. This result was consistent across different refractive conditions. In conclusion, we have shown that handheld devices, such as smartphones, can be potentially exploited for remote measurements of near visual acuity provided a correct control of brightness screen is employed.

On Thermal and Electrodynamic Aspects of the Superconductive Transition Process.

In a classic paper of 1960, W. H. Cherry and J. I. Gittleman discussed various thermal and electrodynamic aspects of the superconductive transition process relevant to practical applications. In a section of the paper that has remained unnoticed, they proposed a physical model for the Meissner effect. Earlier in 1940-1943, in work that has also remained unnoticed, K. M. Koch had introduced related physical ideas to explain the Meissner effect. Still earlier in 1937, J. C. Slater proposed a model to explain the perfect diamagnetism of superconductors. None of these ideas are part of the conventional London-BCS understanding of superconductivity, yet I will argue that they are essential to understand the Meissner effect, the most fundamental property of superconductors. The unconventional theory of hole superconductivity unifies and extends these ideas. A key missing element in the conventional theory as well as in these early theories is electron-hole asymmetry. A proper understanding of the Meissner effect may help with practical applications of superconductors, as well as to find new superconducting materials with desirable properties.

On the Benefits of Listen before Talk Scheme for NB-Fi Networks.

NB-Fi (Narrow Band Fidelity) is a promising protocol for low-power wide-area networks. NB-Fi networks use license-exempt Industrial, Scientific, and Medical (ISM) bands and, thus, NB-Fi devices can work in two modes: with and without Listen Before Talk (LBT). This paper compares these modes with different implementations of LBT in terms of packet loss rate (PLR), delay, energy consumption, and throughput. Interestingly, in some scenarios, the results contradict expectations from the classic papers on channel access because of the peculiarities of the NB-Fi technology. These contradictions are explained in the paper. The results show that LBT can significantly improve all the considered performance indicators when the network load exceeds 40 packets per second. With extensive simulation, we show that in a small NB-Fi network, the optimal PLR, delay, and energy consumption are obtained with the implementation of LBT that corresponds to non-persistent CSMA. In a large NB-Fi network, where some devices can be hidden from others, the best strategy to improve PLR, delay, throughput, and energy consumption is to use the implementation of LBT that corresponds to p-persistent CSMA.

94 Digitized Archimedes Spiral Drawing in the NKI-Rockland Sample

Objective:Digital cognitive assessments (DCAs) provide insight into cognition and behavior that remains inaccessible through standard assessment approaches. However, the availability of DCAs and the requisite toolkits to extract and analyze meaningful features from these datasets are largely constrained to technical specialists or through fee-for-service commercial entities. The NKI- Rockland Sample provides a large- scale lifespan data sample featuring DCAs, and also openly shares its DCA tasks through the open-source MindLogger platform along with pipelines for feature extraction and analyses. Here we present normative performance from a digital version of Archimedes Spiral Drawing.Participants and Methods:NKI-RS2 participants were largely drawn from the existing NKI-RS participant pool (n= 1,500), aged 885. The NKI-RS2 is in year 1 of data collection; here, we report on a subset of participants (n= 9) who performed a digitized version of the Archimedes Spiral Drawing task. This graphomotor task with well-established research and clinical utility in movement disordered populations was adapted for use for off-the-shelf tablet devices. The NKI-RS2 implements these tasks on an Apple iPad Pro2, sampling participant drawing at 120Hz, and featuring pixel- and millisecond- level resolution for all tasks. On the Spiral Drawing and Recall Tests participants traced five Archimedes spirals from the center outward through four windings presented on the iPad. They were then asked to replicate the spiral freehand three times. From these spiral drawings, we extracted time to completion, distance covered, speed/ speed variability, rotational smoothness, number of crossings, mean absolute error, bias, and goodness of fit to the ideal Archimedes spiral.Results:Comparing the tracing and recall conditions, participants showed significantly faster drawing speed (t[8]=5.32, p&lt; .001), more variable drawing speed (t[8]=5.93, p&lt; .001), reduced goodness of fit to the template t[8]=4.99, p&lt; .002, and reduced rotational smoothness (t[8]=7.43, p&lt; .0003) in the recall conditions. Collapsing across conditions, age predicted more variable drawing speed: t[8]= 2.77 p&lt; .019, greater tracing error (t[8] = 2.69, p&lt; .0227), and reduced rotational smoothness (t[8] = 2.67, p&lt; .024). Between conditions, age predicts a greater increase in drawing speed variability (t[8] = 9.76, p&lt; .0006).Conclusions:Using the open source MindLogger platform and off-the-shelf digital tablets, we were able to replicate classic paper and pen neuropsychological tests. By adapting these tasks to DCA, we were able to extract meaningful features that are not otherwise accessible (drawing speed, variability, etc.), or that would require additional hardware solutions (e.g., dwell time). By making these tasks and their processing pipelines available, the NKI-RS2 can facilitate the democratization of DCA and DCA analysis to a broader range of researchers and clinicians.

PANCHAGAVYA IN HUMAN LIFE AND HEALTH: A REVIEW

Gomutra (cow ghee), gomaya (cow dung), ksheera (cow milk), dadhi (cow curd) and sarpi (cow ghee) cumulatively known as Panchagavya. In India, the cow is worshipped as mother and commonly known as ‘Gaumata’. The ratio of ksheera, dadhi, ghrita, gomutra and gomaya is 16:10:8:2:1 according to Shastra yoga, and in Rastargini, it is 1:1:1:1:1 in panchagavya. panchagavya holds traditional as well as ritual values in human life. Each component of panchagavya also has medicinal properties individually. To assess the role of panchagavya and its therapeutic benefits in our day-to-day life and health and to untapped hidden areas mentioned about panchagavya in Ayurveda. Different Ayurvedic classical textbooks, research papers and journals were referred to. After a review of many Ayurvedic literatures and other data sources, the importance of panchagavya was seen. In Ayurveda, panchagavya has a great role in GIT and skin disorders. Panchagavya is also used in havan karma, which also purifies the environment and devotees. Panchagavya products serve irreplaceable medicinal importance in Ayurveda. It is also used in traditional Hindu rituals. During a pandemic, the importance of panchagavya was noticeable. In Ayurveda, there are many Ayurvedic formulations where gomutra and sarpi are used. For example, gomutra is used as bhavana dravya in Sanjeevani vati.

Анализ возможностей компьютеризированного адаптивного подхода к задачам психологической диагностики и обучения

&lt;p&gt;The article discusses the advantages and prospects for the implementation of an adaptive approach in the tasks of computerized ability testing, standardization of diagnostic methods and development of simulators for teaching professional skills in the zone of proximal development (development of "soft skills" and "hard skills"). The results of the analysis of the reliability of tests using an adaptive approach and comparison of the obtained results with the classical paper and computer form of ability diagnostics are presented. An assessment of the effectiveness and advantages of this approach to determining the level of complexity of test items using the method of convolution of applied Markov models into quantum representations is presented. The effectiveness of the method on small samples has been proved.&lt;/p&gt;

Looking back to light the path forward: Ghosts in the Nursery revisited.

The infant health movement was launched nearly 50 years ago with the publication of the now classic paper, Ghosts in the Nursery: A psychoanalytic approach to the problems of impaired infant-mother relationships, written by Selma Fraiberg, Edna Adelson, and Vivian Shapiro (1975). This paper offers us lessons for infant mental health practice that have been proven true time and again over the last 50 years. These lessons both underscore the factors essential to clinical progress across a range of interventions, and remind us of the significant challenges we face in these times of massive, global trauma and oppression, extreme economic hardship, and systemic racism. This commentary reviews the key lessons of Fraiberg and her colleagues' classic paper, addresses some of the challenges inherent in retaining the breadth and substance of Fraiberg's model in contemporary practice, and proposes a model for conceptualizing infant and early childhood mental health practice that is geared toward building the relational foundations of reflection (Slade, 2023).

Top Ten Contributions of Pediatric Hematology/Oncology to the Diagnosis and Treatment of Acute Lymphoblastic Leukemia.

Monumental progress has occurred in the diagnosis and treatment of childhood acute lymphoblastic leukemia dating back to the classic paper of Farber and colleagues in 1948. This historical review from the perspective of an individual, familiar with many of the waystations on this superhighway, will offer an admittedly personal review of the top 10 major contributions to the field. Fortunately, there have been many more additional advances beyond these 10 as we have witnessed an impressive improvement in overall survival from a few months 75 years ago to a cure rate of 85% in the world's more advanced countries. Other workers in the field assuredly would create a different list and ranking of these advances but the takeaway summation of the make-up and order of these lists is that advances have yielded improved and prolonged responses, a rational understanding of factors, both clinical and biological, that predict response and prognosis, the application of those factors to tailor therapy's intensity and duration to those factors and to discover and design modalities and targets of therapy that target our much more complete understanding of this most common malignancy of infants and children. On a very personal note, I vividly recall an early, ill-advised decision to devote my academic career to hematology/oncology, with one glaring exception, acute lymphoblastic leukemia, and other malignancies. The stark realities of clinical practice and the harsh unmet needs and mostly unanswered challenges redirected my path that resulted in participation in many of these advances, making my own journey so gratifying and that of most of our patients so favorable.

Anxiety, Desire, and the Object a: Lacan on Lucia Tower's "Countertransference".

Lacan's seminars are a treasure trove of innovative psychoanalytic explorations. In Seminar X, Anxiety, he takes up this Freudian theme and explores a number of interrelated ideas: castration, the difference between the sexes, two different forms of acting out, and what he terms his only original theoretical contribution: the object a and its "various incidences." The object a is described here in detail, especially in relation to Lacan's argument that analysts who are women have a freer relationship to their desire and the countertransferences it spawns than do men. Lacan discussed Lucia Tower's classic paper, "Countertransference," in light of these notions. This essay is a close reading of Lacan's close reading of Tower, whose account, he says, must be approached in all its "innocence and freshness."