Transducer generated arrays of robotic nano-arms

We consider sets of two-dimensional arrays, called here transducer generated languages, obtained by iterative applications of transducers (finite state automata with output). Each transducer generates a set of blocks of symbols such that the bottom row of a block is an input string accepted by the transducer and, by iterative application of the transducer, each row of the block is an output of the transducer on the preceding row. We show how these arrays can be implemented through molecular assembly of triple crossover DNA molecules. Such assembly could serve as a scaffold for arranging molecular robotic arms capable of simultaneous movements. We observe that transducer generated languages define a class of languages which is a proper subclass of recognizable picture languages, but it contains the class of all factorial local two-dimensional languages. By taking the average growth rate of the number of blocks in the language as a measure of its complexity, we further observe that arrays with high complexity patterns can be generated in this way.     

Thermodynamic analysis of nylon nucleic acids

The stability and structure of nylon nucleic acid duplexes with complementary DNA and RNA strands was examined. Thermal denaturing studies of a series of oligonucleotides that contained nylon nucleic acids (1-5 amide linkages) revealed that the amide linkage significantly enhanced the binding affinity of nylon nucleic acids towards both complementary DNA (up to 26 degrees C increase in the thermal transition temperature (T(m)) for five linkages) and RNA (around 15 degrees C increase in T(m) for five linkages) compared with nonamide linked precursor strands. For both DNA and RNA complements, increasing derivatization decreased the melting temperatures of uncoupled molecules relative to unmodified strands; by contrast, increasing lengths of coupled copolymer raised T(m) from less to slightly greater than T(m) of unmodified strands. Thermodynamic data extracted from melting curves and CD spectra of nylon nucleic acid duplexes were consistent with loss of stability due to incorporation of pendent groups on the 2'-position of ribose and recovery of stability upon linkage of the side chains.     

Multiplying with DNA

A functional machine is not only an assembly of parts, but also an assembly of processes. The processing of each part must obey laws that respect to the property of this part. For example, building any kind of computer entails selecting appropriate components and assembling their properties to function in computation. Here, we describe computation using a DNA strand as the basic unit and we have used this unit to achieve the function of multiplication. We exploit the phenomenon of DNA hybridization, in which each strand can represent two individual units that can pair to form a single unit. We represent the numbers we multiply in binary, with different lengths representing each digit present in the number. In principle, all combinations of the numbers will be present in solution. Following hybridization, there is present a collection of duplex molecules that are tailed by single-stranded ends. These intermediates are converted to fully duplex molecules by filling in the ends with DNA polymerase. The lengths that are present represent the digits that are present, and they may be separated by denaturing PAGE. The results give a series of bands for each power of two. The number of bands in the size domain for a particular power of two is converted to binary and the sum of all present bands is then added together. Experimentally, the result of this process always yields the correct answer.     

Deficits in gray matter volume are present in schizophrenia but not bipolar disorder

Studies using magnetic resonance (MR) imaging have provided strong evidence that patients with schizophrenia as a group have structural brain abnormalities, including enlarged ventricles and sulci as well as smaller cortical gray matter volumes. This study was undertaken to investigate whether the brain abnormalities found in schizophrenia could be distinguished from those seen in bipolar disorder. The MR scans of 23 patients with schizophrenia were compared to those of 17 healthy community volunteers and 14 patients with bipolar disorder. Images were processed using computer-based image processing techniques to generate quantitative measures of cerebrospinal fluid (CSF), gray matter and white matter volumes. Compared to the community volunteers, the schizophrenia group had larger total CSF volumes while the bipolar group had larger ventricles. Smaller cortical gray matter volumes were found in the schizophrenia group, but not in the bipolar group. The schizophrenia group had regional deficits in gray matter volumes in comparison with both the community volunteers and the bipolar group. These findings suggest that the brain tissue abnormalities found in schizophrenia and bipolar disorder may be distinguishable using MR imaging.     

A serotonin-4 receptor-like pseudogene in humans

Serotonin (5-HT) receptor interaction in the control of female rat lordosis behavior was examined. Ovariectomized rats, with bilateral implants in the ventromedial nucleus of the hypothalamus (VMN), were hormonally primed with 25 micrograms estradiol benzoate and 500 micrograms progesterone. Rats were infused with the 5-HT3 receptor antagonist, 3-tropanyl-indole-3 carbonylate (tropisetron; 500 ng), or were coinfused with the 5-HT3 receptor antagonist and the 5-HT2A/2C receptor agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI; 500, 1500, or 2000 ng). Additional ovariectomized, hormone-primed rats received bilateral VMN infusions with the 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT; 200 ng), or were coinfused with the 5-HT1A receptor agonist and the 5-HT3 receptor agonist, m-chlorophenyl-biguanide (mCPBG; 250, 500, or 1000 ng). Lordosis behavior was observed prior to VMN infusion, during the infusion and for 30 consecutive minutes thereafter. Tropisetron reduced the lordosis to mount (L/M) ratio in every animal investigated but the decline was attenuated by coinfusion with DOI. Similarly, the L/M ratio declined following infusion with 8-OH-DPAT and the decline was dose-dependently reduced by coinfusion with mCPBG. Only the 5-HT3 receptor agonist altered the quality of the lordosis reflex. These studies provide evidence that the effects of 5-HT on female rat lordosis behavior involve the integrated activity of at least 3 different 5-HT receptor families.     

Narratives of twenty to thirty year outcomes in schizophrenia

The functional significance of task-induced negative and positive cortical shifts were tested with the probe-stimulus method. Both shifts were induced within the same experimental situation in three variants of a CNV paradigm, where a slow positive wave (a variant of P300) appeared following S2. In Experiment I and II, S2 called for making or withholding a motor response (go/no-go); in Experiment III, S2 informed the subject about the correctness of a previous guess. Irrelevant probe-stimuli were applied in conjunction with the task during the CNV, the post-S2 positivity and the intertrial interval (ITI). The probe-evoked vertex EPs were smaller during the post-S2 positivity as compared to the CNV and the ITI. This was true not only for the motor task but also for the guessing task, where the effect is unlikely to have been contaminated by motor potentials. This indicates that positive shifts have an inhibitory effect on the processing of irrelevant probe-stimuli and possibly on information-processing in general.     

Intercommunity variations in the association between social ties and mortality in the elderly. A comparative analysis of three communities

Identical measures of social ties obtained from three community-based cohorts aged 65 and over from East Boston, MA; New Haven, CT; and two rural counties in Iowa permit the first direct cross-community comparison of the hypothesis that social isolation increases 5-year mortality risks (1982 to 1987) for older men and women. In sex-specific proportional hazards analyses, social ties were significantly and inversely related to mortality independently of age in all three cohorts (e.g., relative hazard (RH) = 1.97 to 3.06 for men and women, comparing those with no ties to those with four types of ties). After controlling for age, pack-years of smoking, body mass, chronic conditions, angina, and physical and cognitive disability, social ties remain significant predictors of mortality risk for the men and women in New Haven (RH = 2.4 and 1.8) and for women in Iowa (RH = 1.9). For the men in Iowa (RH = 1.4) and the men and women in East Boston (RH = 1.0 and 1.3), the associations are weaker and nonsignificant.     

Sex differences in the use of demand and withdraw behavior in marriage: Examining the social structure hypothesis.

Studies consistently show sex differences in married couples' use of demand and withdraw behavior. The social structure hypothesis proposes that these differences are the result of power differentials between spouses. This study examined the link between 3 aspects of marital power and demanding and withdrawal behavior. Contrary to social structure predictions, results showed that wives did not possess less decision-making ability or access to resources and appeared to exhibit greater situational power (i.e., domineering and dominant behaviors) than did their husbands during problem-solving discussions. Furthermore, the spouse who exhibited the most demands also exhibited the most domineering and dominant behaviors, whereas the spouse who exhibited the most withdrawal exhibited the least domineering and dominant behaviors during problem-solving discussions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Do medical conditions affect cognition in older adults?

Women with breast cancer today have many more therapeutic options available to them for their surgical therapy. Almost all patients with breast cancer have some options for breast conservation. Active patient involvement in analyzing and understanding the pros and cons of each of these options seems extremely important to the long-term emotional and psychological outcome of their breast cancer therapy. Several reports this year have reintroduced the issue of adequate local control. The common philosophy a decade ago was that because systematic therapy (adjuvant chemotherapy) was improving, local therapy would become of lesser importance. Several studies this year have indicated the extreme importance of local control in maximizing survival advantage because of the relationship of increasing local failure and deteriorating survival from systemic disease. Despite significant improvements in treatment, our screening and diagnostic approaches have still failed to identify the majority of lesions prior to the patient's own palpation of the tumor. Using new diagnostic modalities that do not involve surgery, the biopsy of lower probability lesions with great accuracy is expected to improve the efficacy of the current screening measures. Despite all the improvements, the most important therapeutic step in the management of breast cancer remains earlier diagnosis and earlier extirpation of the initial invasive focus of malignancy.