Effectiveness of Hindman's theorem for bounded sums

We consider the strength and effective content of restricted versions of Hindman's Theorem in which the number of colors is specified and the length of the sums has a specified finite bound. Let $\mathsf{HT}^{\leq n}_k$ denote the assertion that for each $k$-coloring $c$ of $\mathbb{N}$ there is an infinite set $X \subseteq \mathbb{N}$ such that all sums $\sum_{x \in F} x$ for $F \subseteq X$ and $0 < |F| \leq n$ have the same color. We prove that there is a computable $2$-coloring $c$ of $\mathbb{N}$ such that there is no infinite computable set $X$ such that all nonempty sums of at most $2$ elements of $X$ have the same color. It follows that $\mathsf{HT}^{\leq 2}_2$ is not provable in $\mathsf{RCA}_0$ and in fact we show that it implies $\mathsf{SRT}^2_2$ in $\mathsf{RCA}_0$. We also show that there is a computable instance of $\mathsf{HT}^{\leq 3}_3$ with all solutions computing $0'$. The proof of this result shows that $\mathsf{HT}^{\leq 3}_3$ implies $\mathsf{ACA}_0$ in $\mathsf{RCA}_0$

Differential Contributions of Three Parenting Dimensions to Preschool Literacy and Social Skills in a Middle-Income Sample

This study investigated parenting practices among families of preschoolers in a middle-income community, as well as the contributions of these practices to children\u27s literacy and learning-related social skills. A total of 229 families of preschoolers were recruited. Parents completed a survey describing their parenting practices, while children\u27s literacy skills were directly assessed by using standardized measures. Parents also reported on children\u27s social development. Factor analyses supported a three-dimensional structure of parenting including the home learning environment, autonomy support/expectations, and management/discipline. Path models showed that the home learning environment predicted literacy skills; specifically, parents\u27 teaching about letters and sounds was associated with alphabet knowledge, while shared book reading was marginally linked to vocabulary. Management/discipline was uniquely related to self-regulation, while cooperative/compliant skills were associated with the home learning environment, support/expectations, and management/discipline. Findings suggested that parenting could be conceptualized as three relatively independent dimensions, each of which demonstrated domain-specific contributions to early literacy and social skills

Hypernatural Numbers as Ultrafilters

In this paper we present a use of nonstandard methods in the theory of ultrafilters and in related applications to combinatorics of numbers

Rotation reduces convective mixing in Jupiter and other gas giants

Recent measurements of Jupiter's gravitational moments by the Juno spacecraft and seismology of Saturn's rings suggest that the primordial composition gradients in the deep interior of these planets have persisted since their formation. One possible explanation is the presence of a double-diffusive staircase below the planet's outer convection zone, which inhibits mixing across the deeper layers. However, hydrodynamic simulations have shown that these staircases are not long-lasting and can be disrupted by overshooting convection. In this paper we suggests that planetary rotation could be another factor for the longevity of primordial composition gradients. Using rotational mixing-length theory and 3D hydrodynamic simulations, we demonstrate that rotation significantly reduces both the convective velocity and the mixing of primordial composition gradients. In particular, for Jovian conditions at $t\sim10^{8}~\mathrm{yrs}$ after formation, rotation reduces the convective velocity by a factor of 6, and in turn, the kinetic energy flux available for mixing gets reduced by a factor of $6^3\sim 200$. This leads to an entrainment timescale that is more than two orders of magnitude longer than without rotation. We encourage future hydrodynamic models of Jupiter and other gas giants to include rapid rotation, because the decrease in the mixing efficiency could explain why Jupiter and Saturn are not fully mixed.Comment: Accepted for publication in the Astrophysical Journal Letter

The Morphologies of the Small Magellanic Cloud

We compare the distribution of stars of different spectral types, and hence mean age, within the central SMC and find that the asymmetric structures are almost exclusively composed of young main sequence stars. Because of the relative lack of older stars in these features, and the extremely regular distribution of red giant and clump stars in the SMC central body, we conclude that tides alone are not responsible for the irregular appearance of the central SMC. The dominant physical mechanism in determining the current-day appearance of the SMC must be star formation triggered by a hydrodynamic interaction between gaseous components. These results extend the results of population studies (cf. Gardiner and Hatzidimitriou) inward in radius and also confirm the suggestion of the spheroidal nature of the central SMC based on kinematic arguments (Dopita et al; Hardy, Suntzeff & Azzopardi). Finally, we find no evidence in the underlying older stellar population for a ``bar'' or ``outer arm'', again supporting our classification of the central SMC as a spheroidal body with highly irregular recent star formation.Comment: 8 pages, accepted for publication in ApJ Letters (higher quality figures available at http://ngala.as.arizona.edu/dennis/mcsurvey.html

Perioperative Hypothermia (33°C) Does Not Increase theOccurrence of Cardiovascular Events in PatientsUndergoing Cerebral Aneurysm SurgeryFindings from the Intraoperative Hypothermia for AneurysmSurgery Trial

The IHAST Trial randomized patients undergoing cerebral aneurysm surgery to intraoperative hypothermia or normothermia. Cardiovascular events were prospectively followed until 3-month follow-up and were compared in hypothermic and normothermic patients. Conclusion: In patients undergoing cerebral aneurysm surgery, perioperative hypothermia was not associated with an increased occurrence of cardiovascular events

The effect of activity-related meridional flow modulation on the strength of the solar polar magnetic field

We studied the effect of the perturbation of the meridional flow in the activity belts detected by local helioseismology on the development and strength of the surface magnetic field at the polar caps. We carried out simulations of synthetic solar cycles with a flux transport model, which follows the cyclic evolution of the surface field determined by flux emergence and advective transport by near-surface flows. In each hemisphere, an axisymmetric band of latitudinal flows converging towards the central latitude of the activity belt was superposed onto the background poleward meridional flow. The overall effect of the flow perturbation is to reduce the latitude separation of the magnetic polarities of a bipolar magnetic region and thus diminish its contribution to the polar field. As a result, the polar field maximum reached around cycle activity minimum is weakened by the presence of the meridional flow perturbation. For a flow perturbation consistent with helioseismic observations, the polar field is reduced by about 18% compared to the case without inflows. If the amplitude of the flow perturbation depends on the cycle strength, its effect on the polar field provides a nonlinearity that could contribute to limiting the amplitude of a Babcock-Leighton type dynamo.Comment: 16 pages, 5 figures, accepted by Ap

Longitudinal Relations Between Parental Writing Support and Preschoolers' Language and Literacy Skills

Parental writing support was examined over time and in relation to children's language and literacy skills. Seventy‐seven parents and their preschoolers were videotaped writing an invitation together twice during one year. Parental writing support was coded at the level of the letter to document parents' graphophonemic support (letter–sound correspondence), print support (letter formation), and demand for precision (expectation for correcting writing errors). Parents primarily relied on only a couple print (i.e., parent writing the letter alone) and graphophonemic (i.e., saying the word as a whole, dictating letters as children write) strategies. Graphophonemic and print support in preschool predicted children's decoding skills, and graphophonemic support also predicted children's future phonological awareness. Neither type of support predicted children's vocabulary scores. Demand for precision occurred infrequently and was unrelated to children's outcomes. Findings demonstrate the importance of parental writing support for augmenting children's literacy skills. 本研究以一段长时间考查家长书写支援与儿童的语言和读写技能之关系。七十七名家长与其学前儿童在一年期间两次共同书写一份邀请书;所有书写过程均被录像。家长书写支援的编码,分三个层面进行:在字母层面上家长给予的字形音素支援(字母与发音的相关性),在书写层面上的支援 (字母的构成)和在精确层面上的要求(纠正书写错误的期待)。家长主要依靠几个支援策略:字母书写策略(家长只写出字母)和字形音素策略(即读出整个单字,然后口授字母,让儿童书写其单字)。家长给予学前儿童的字形音素和书写支援能预测儿童的解码技能;字形音素支援也能预测儿童未来的语音意识。这两种支援却不能预测儿童的词汇成绩。精确度的要求很少出现,与儿童的学习成果并无关联。研究结果说明家长书写支援对增强儿童读写能力的重要性。 Se examinó el apoyo de los padres a la escritura a través del tiempo y en relación a las habilidades de lenguaje y alfabetización de los niños. Setenta y siete padres y sus hijos preescolares fueron captados en video escribiendo una invitación juntos en dos ocasiones durante el año. El apoyo de los padres fue codificado al nivel de la letra para documentar el apoyo grafofonémico de los padres (la correspondencia entre la letra y su sonido), el apoyo letral (la formación de la letra), y la exigencia por la precisión (las expectativas en cuanto a la corrección de errores de escritura). Los padres dependían principalmente en sólo un par de estrategias de letra (por ejemplo: el padre escribiendo la letra solamente) y grafofonémicas (por ejemplo, diciendo la palabra completa, dictando letras mientras los niños escribían). El apoyo grafofonémico y letral en los preescolares predecía la habilidad de los niños de descifrar, y el apoyo grafofonémico también predecía la futura conciencia fonológica de los niños. Ninguna de las dos clases de apoyo pudo predecir la nota de los niños en cuanto a vocabulario. La exigencia por la precisión fue infrecuente y no mostró relación con el resultado de los niños. Los resultados demuestran la importancia del apoyo de los padres en la escritura para incrementar las habilidades alfabetizadoras de los niños. لقد تم فحص دعم الكتابة من قبل الوالدين عبر فترة من الزمن وعلاقته بلغة الأولاد ومهاراتهم في معرفة القراءة والكتابة. وقد تم تصوير فيديوهات لسبع وسبعين والداً ووالدةً وأولادهم ما قبل المدرسة وهم يكتبون دعوة معاً مرتين في سنة. وتم ترميز دعم كتابة الوالدين على مستوى الرسالة لتدوين دعم الخط الصوتي (علاقة الحرف بالصوت)، ودعم الخط (تركيب الحروف)، والطلب على الإتقان (توقع تصحيح أخطاء الكتابة). واعتمد الوالدان على إستراتيجيات معدودة للكتابة (أي يكتب الوالد بنفسه) وللخط الصوتي (أي ينطق الكلمة كوحدة واحدة ويملى الحروف والأولاد يكتبونها). وتنبأ دعم الخط الصوتي والكتابة مهارات الأطفال ما قبل المدرسة في تفكيك الخط وكذلك تنبأ دعم الخط الصوتي الوعي الصوتي المستقبلي لدى الأطفال. ومع ذلك، فلم يتنبؤ لا دعم الكتابة ولا الخط الصوتي علامات امتحانات مفردات الأطفال. ونادراً ما حدث الطلب على الإتقان ولم تتم علاقة بينه وبين نتائج الأولاد. وتبين النتائج أهمية دعم الوالدين للكتابة لتعزيز مهارات الأطفال في معرفة القراءة والكتابة. Пoмoщь poдитeлeй пpи cтaнoвлeнии нaчaльныx нaвыкoв пиcьмa y дeтeй в дaльнeйшeм, кaк выяcняeтcя, влияeт нa языкoвыe нaвыки и гpaмoтнocть дeтeй – этим cвязям и пocвящeнo дaннoe иccлeдoвaниe. Ceмьдecят ceмь poдитeлeй и иx дeти дoшкoльнoгo вoзpacтa, вмecтe пиcaвшиe oткpыткy‐пpиглaшeниe, двaжды в тeчeниe гoдa были cняты нa видeo. Пoмoщь poдитeлeй былa зaдoкyмeнтиpoвaнa пo cлeдyющим пapaмeтpaм: гpaфoфoнeмикa (cooтнoшeниe звyк‐бyквa), гpaфo‐мoтopикa (нaпиcaниe бyкв) и тpeбoвaниe тoчнocти (oжидaниe иcпpaвлeния oшибoк). Poдитeли, в ocнoвнoм, пpимeняли двe cтpaтeгии: гpaфичecкyю (пиcaли бyквy caмocтoятeльнo) и гpaфo‐фoнeмaтичecкyю (пpoизнocили cлoвo цeликoм, зaтeм диктoвaли eгo пo бyквaм, a дeти пиcaли). Гpaфoфoнeмикa и пoмoщь в нaпиcaнии бyкв пpeдoпpeдeляют нaвыки дeтeй дoшкoльнoгo вoзpacтa в дeкoдиpoвaнии peчи, a гpaфoфoнeмикa являeтcя eщe и пpeдиктopoм пocлeдyющeгo фoнoлoгичecкoгo paзвития peбeнкa. Hи oдин из пpaктикyeмыx типoв пoмoщи нe вызвaл pacшиpeния cлoвapнoгo зaпaca дeтeй. Tpeбoвaниe иcпpaвить oшибки вcтpeчaлocь нeчacтo и нe пoвлиялo впocлeдcтвии нa yлyчшeниe кaчecтвa дeтcкoгo пиcьмa. Peзyльтaты дeмoнcтpиpyют вaжнocть poдитeльcкoй пoддepжки пpи cтaнoвлeнии нaвыкoв пиcьмa для coвepшeнcтвoвaния нaвыкoв oпepиpoвaния cлoвoм в цeлoм. Nous avons examiné dans la durée et en relation avec les compétences des enfants en matière de langage et de littératie l'aide qu'apportent les parents à l'écriture des enfants. Nous avons enregistré en vidéo à deux reprises au cours d'une année soixante‐dix sept parents et leurs enfants d'âge préscolaire en train d'écrire ensemble une invitation. L'aide apportée par les parents a été codée au niveau de la lettre afin de distinguer l'aide grapho‐phonétique (correspondances lettres‐son), l'aide au graphisme (formation des lettres), et le degré de précision de leurs exigences (attentes relatives à la correction des erreurs d'écriture). Les parents s'intéressent d'abord seulement au graphisme (par exemple, des parents écrivent eux‐mêmes les lettres) et aux stratégies grapho‐phonétiques (par exemple, ils disent le mot entier ou dictent des lettres pendant que l'enfant écrit). L'aide grapho‐phonétique et au graphisme apportée au niveau préscolaire permet de prédire les compétences en décodage des enfants, et l'aide grapho‐phonétique permet aussi de prédire la conscience phonologique ultérieure. Aucun de ces types d'aide n'est prédictif des résultats en vocabulaire. Les exigences en matière de précision ne sont pas fréquentes et ne sont pas liées aux résultats des enfants. Ces résultats mettent en évidence l'importance qu'a l'aide des parents pour l'amélioration des compétences des enfants en littératie.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102675/1/rrq55.pd

Excitated state properties of 20-chloro-chlorophyll a

The excited-state and lasing properties of 20-chloro-chlorophyll a in ether solution were compared to those of chlorophyll a. Desactivation parameters and cross-sections were obtained from non-linear absorption spectroscopy in combination with a physico-mathematical methods package. The Cl substituent at C-20 (1) increases both intersystem crossing and internal conversion, (2) produces a blue-shift of the S1 absorption spectrum, and (3) leads to pronounced photochemistry

A nilpotent IP polynomial multiple recurrence theorem

We generalize the IP-polynomial Szemer\'edi theorem due to Bergelson and McCutcheon and the nilpotent Szemer\'edi theorem due to Leibman. Important tools in our proof include a generalization of Leibman's result that polynomial mappings into a nilpotent group form a group and a multiparameter version of the nilpotent Hales-Jewett theorem due to Bergelson and Leibman.Comment: v4: switch to TeXlive 2016 and biblate