Time In Cycles Research Articles

The Length of Perimenopausal Menstrual Cycles Increases Later and to a Greater Degree than Previously Reported

Information gathered prospectively by Treloar et al from white, college-educated American women purportedly showed that the length of menstrual cycles dropped slightly between age 20 and early perimenopause and, in the last 4 years before menopause, rose to 57 days. It is possible that these findings were biased by incorrectly identified dates of menopause; classifying mean values by calendar year; and/or excluding cycles that straddled two calendar years. The present investigators conducted a secondary analysis of prospectively collected data in 120 women from the original Treloar study who were taking part in the Tremin Research Program on Women's Health, an ongoing study of health and menstrual cycles covering the reproductive lifespan. Menopause was defined as the first day of the final menstrual period (FMP), calculating full 1-year intervals working back from the FMP. Straddling and nonstraddling cycles were assigned to new 12-month intervals based on the date when each cycle ended. Mean cycle lengths then were recalculated for each of the 10 years preceding menopause. Mean estimates of cycle length for each of the 4 years preceding menopause were 30.5, 35.0, 45.15, and 80.2 days, respectively. The corresponding figures from the original analysis were 33.6, 43.9, 55.9, and 54.6 days. The original and revised data differ significantly only for the year just before menopause. In this year, a majority of women are spending 75% or more of their time in cycles lasting longer than 40 days. The corrected version of the data demonstrates a greater difference between the second-to-last year and the last year before menopause. The proportion of a year spent in menstrual cycles exceeding 40 days may help to determine the time until menopause begins. This often is a critical factor when choosing between hormone therapy and hysterectomy for women with perimenopausal menorrhagia. This figure may also help to predict such postmenopausal states as an increased risk of osteoporosis.

The growth of carbon nanotube stacks in the kinetics-controlled regime

A CNT stack formation technique is used for the pseudo in-situ monitoring of CNT growth in the kinetics-controlled regime. CNT stacks are fabricated by water-assisted selective etching and the cyclic introduction of ethylene into the chemical vapor deposition (CVD) reactor. By varying the growth temperature and the ethylene flow rate within growth cycles, the reaction was shown to be first order with an activation energy of 201.2 kJ/mol. This technique can be implemented to monitor the initial stage of CNT growth by deceasing the ethylene flow time in growth cycles. Within one minute, the CNT growth reaches steady state. The formation of CNT stacks could be tailored to investigate the effects of growth parameters, such as pressure, temperature, and carbon source flow rate, on the CNT growth.

The length of perimenopausal menstrual cycles increases later and to a greater degree than previously reported

To demonstrate that the perimenopausal increase in menstrual cycle length presented by Treloar et al. was biased by misidentified menopause dates, mean values classified by calendar year, and exclusion of menstrual cycles straddling two calendar years; and to use the revised data to investigate women's experiences of longer perimenopausal cycles. Secondary analysis of prospectively collected menstrual cycle data. Center for Population and Health, Georgetown University. One hundred twenty white, college-educated, US women in the Tremin Research Program on Women's Health. None. Mean cycle length and time spent in >40-day cycles, by year before menopause. Mean estimates for each of the 4 years before menopause were 30.48, 35.02, 45.15, and 80.22 days, respectively, compared with the original analysis: 33.60, 43.91, 55.87, and 54.58 days. In the year before menopause, the majority of women spent >or=75% of their time in cycles >40 days long. Treloar's estimates of mean cycle length were biased. Long cycles occurred throughout perimenopause, but the largest increase in mean cycle length did not occur until the final year before menopause. New estimates of the time spent in cycles >40 days may be useful clinically as well as epidemiologically for assessing menopausal onset and symptomatology.

The effect of exogenous estradiol benzoate and altrenogest on uterine and ovarian blood flow during the estrous cycle in mares

In recent years, a positive relationship between genital perfusion and fertility has been established; in species other than horses, uterine and ovarian perfusion was improved by exogenous estrogen but impaired by exogenous progestin. The goal of the present study was to investigate the effect of exogenous estrogen and progestin on uterine and ovarian blood flow in cycling mares. Five Trotter mares were examined daily during three estrous cycles. Mares were given no treatment, altrenogest (0.044 mg/kg BW) orally from Day 0 (ovulation) to Day 14 and estradiol benzoate (5 mg i.m.) on Days 0, 5, and 10, in three cycles, respectively. There was no difference ( P>0.05) in the length of untreated versus estrogen-treated cycles (22.8±1.3 days and 23.2±1.5 days, respectively), but cycle length was increased ( P<0.05) in progestin-treated cycles (26.0±1.2 days). To facilitate comparisons among cycles with different lengths, data from Days 0 to 15 (diestrus) and from Days −6 to −1 (estrus) were analyzed. Transrectal Doppler sonography was used to evaluate blood flow in both uterine arteries and in the ovarian artery ipsilateral to the preovulatory follicle during estrus and ipsilateral to the corpus luteum during diestrus. Blood flow was assessed semiquantitatively using the pulsatility index (PI); high PI values indicated high resistance and a low perfusion and vice versa. An immediate effect of treatments occurred only after the administration of estradiol benzoate on Day 0; uterine PI values decreased ( P<0.05) between Days 0 and 1 and estrogen-treated mares but increased ( P<0.05) at the corresponding time in untreated cycles. Mean PI values for the uterine and ovarian arteries during both diestrus and estrus were higher ( P<0.05) in estrogen-treated versus untreated mares. Furthermore, mean uterine PI values during diestrus and estrus were higher ( P<0.05) in altrenogest-treated versus untreated mares. Neither estrogen nor altrenogest treatments had a significant immediate effect on ovarian PI values. Compared to untreated cycles, mean ovarian PI values were elevated ( P<0.05) only in the estrus following altrenogest administration. In conclusion, exogenous estrogen and progestin both decreased genital perfusion in cycling mares.

Evaluation of Korean food waste composting with fed-batch operations II: using properties of exhaust gas condensate

Abstract An evaluation of Korean food waste composting, with a fed-batch operation, was conducted using the properties of the exhaust gas condensate. The traditional indices, as well as condensate properties, showed the same patterns of variation over each reaction time in the batch cycles during fed-batch composting. Trends for the variation in the pH of the condensate (pHcn) corresponded to those of the traditional indices, such as pH of the compost (pHcm) and CO2 evolution in the exhaust gas. In addition, the carbon chemical forms in the condensate would indirectly represent the gaseous metabolites, such as CO2, NH3, and VFA, which are generally emitted from aerobic composting processes. The patterns and quantities of NH3 gas evolution in the exhaust gas, especially, could be effectively estimated by their correlations with the NH4 and NH3 concentrations in the condensate or the pHcn in each cycle of fed-batch composting. Therefore, it was considered that the measurement of the condensate properties might serve as more useful and convenient operating indices than the analysis of solid and gas samples, during the composting process.

The effective number of a population that varies cyclically in size. II. Overlapping generations

We consider haploid and dioecious age-structured populations that vary over time in cycles of length k. Results are obtained for both autosomal and sex-linked loci if the population is dioecious. It is assumed that k is small in comparison with numbers of haploid individuals (or of numbers of males and females) in any generation of a cycle. The inbreeding effective population size N e is then approximately given by the expression [ T∑ k−1 j=0 1/[ N e( j) T( j)]] −1, where N e( j) and T( j) are, respectively, the effective population size and generation interval that would hold if the population was at all times generated in the same way as at time j. The constant T, which is the effective overall generation interval, is defined to be k times the harmonic mean of the quantities T( j). Our expressions for T and N e, in terms of N e( j) and T( j), are general, but the N e( j)s are derived under the assumption that offspring are produced according to Poisson distributions.

Comparison of the circadian eclosion rhythm between non-diapause and diapause pupae in the onion fly, Delia antiqua

The influence of pupal diapause on adult eclosion rhythm of Delia antiqua was investigated. When non-diapause and diapause pupae were exposed to various photoperiods at 15, 20 and 25 °C, both of them emerged as adults close to the light-on time, but the phase of eclosion varied with photoperiod and temperature. Moreover, there was a significant difference in the eclosion time between non-diapause and diapause pupae; the eclosion peak of diapause pupae was earlier than that of non-diapause pupae. When non-diapause and diapause pupae were transferred to constant darkness (DD) after having experienced LD 12:12 at 15, 20 and 25 °C, both showed circadian rhythmicity in eclosion. Although the free-running period ( τ) decreased slightly as temperature increased in both non-diapause and diapause pupae, the latter tended to show shorter τ than the former. This observation suggests that the observed difference in eclosion time in LD cycles between non-diapause and diapause pupae is due to differences in τ.

Thermal component model for electrothermal analysis of IGBT module systems

The insulated gate bipolar transistor (IGBT) modules are getting more accepted and increasingly used in power electronic systems as high power and high voltage switching components. However, IGBT technology with high speed and greater packaging density leads to higher power densities on the chips and increases higher operating temperatures. These operating temperatures in turn lead to an increase of the failure rate and a reduction of the reliability. In this paper, the static and dynamic thermal behavior of IGBT module system mounted on a water-cooled heat sink is analyzed. Although three-dimensional finite element method (3-D FEM) delivers very accurate results, its usage is limited by an imposed computation time in arbitrary load cycles. Therefore, an RC component model (RCCM) is investigated to extract thermal resistances and time constants for a thermal network. The uniqueness of the RCCM is an introduction of the time constants based on the Elmore delay, which represents the propagation delay of the heat flux through the physical geometry of each layer. The dynamic behavior predicted by the thermal network is equivalent to numerical solutions of the 3-D FEM. The RCCM quickly offers insight into the physical layers of the components and provides useful information in a few minutes for the arbitrary or periodic power waveforms. This approach enables a system designer to couple the thermal prediction with a circuit simulator to analyze the electrothermal behavior of IGBT module system, simultaneously.

The effective number of a population that varies cyclically in size. I. Discrete generations

We consider a dioecious population having numbers of males and females that vary over time in cycles of length k. It is shown that if k is small in comparison with the numbers of males and females in any generation of the cycle, the effective population number (or size), N e, is approximately equal to the harmonic mean of the effective population sizes during any given cycle. This result holds whether the locus under consideration is autosomal or sex-linked and whether inbreeding effective population numbers or variance effective population numbers are involved in the calculation of N e. If, however, only two successive generations in the cycle are considered and the population changes in size between these generations, the inbreeding effective population number, N eI, differs from the variance effective population number, N eV. The mutation effective population number turns out to be the same as the number derived using calculations involving probabilities of identity by descent. It is also shown that, at least in one special case, the eigenvalue effective population number is the same as N eV.

Successful artificial insemination for indoor breeding in the Japanese monkey (Macaca fuscata) and the cynomolgus monkey (Macaca fascicularis)

Methods of artificial insemination (AI) for indoor breeding in the Japanese monkey and the Cynomolgus monkey were investigated. For the Japanese monkey AI was carried out in six females during the winter mating season and in six females during the summer non-mating season. During the mating season, semen was inseminated near ovulation time in natural menstrual cycles. In the mating season study, three females inseminated at the uterine cavity became pregnant. Three inseminated at the cervical canal failed to become pregnant. For the non-mating season study, ovulation was induced artificially by PMSG and hCG and AI was carried out near the induced ovulation time. In the non-mating season, no animals became pregnant. Of four Cynomolgus monkeys used, pregnancy occurred in two animals inseminated near ovulation time in natural menstrual cycles. AI occurred at the uterine cavity in one and cervical canal in the other. In both species ovulation was verified by laparoscopy. Semen was collected by penile electro-stimulation then diluted to 2.5 to 5.0×107/ml with Whitten's medium. Diluted semen of 0.2l was inseminated at the uterine cavity or cervical canal. Our results indicate the usefulness of vaginal AI as a method of artificial indoor breeding.

Sex-Hormone-Related Events in Migrainous Females. A Clinical Comparative Study Between Migraine With Aura and Migraine Without Aura

In this study, the relationship between hormonal-related events and migraine with aura (MA) and without aura (MO) was investigated. Subjects included 268 women suffering from MA (88) and MO (180). Data were collected on the relationship between sex-hormone-related events and migraine. Migraine during menses was observed in a significantly higher percentage of MO than MA patients (p < 0.03). Menstrual migraine was significantly more common in MO than in MA patients (p < 0.01). Migraine began during pregnancy in a significantly higher percentage of MA than of MO patients (p < 0.01). No significant difference was observed between the two groups of patients regarding the onset of migraine at menarche, after menopause, in the postpartum period or during the early cycles of oral contraceptives. Also, both groups of patients showed a similar migraine course during pregnancy, oral contraceptive use and menopause. Eight patients with coexisting migraine with aura and migraine without aura attacks reported the appearance of the aura symptom for the first time in the early cycles of oral contraceptive intake. These findings suggest that gonadal hormone fluctuation may influence both types of migraine.

Architectural timing verification of CMOS RISC processors

We consider the problem of verification and testing of architectural timing models ("timers") coded to predict cycles-per-instruction (CPI) performance of advanced CMOS superscalar (RISC) processors. Such timers are used for pre-hardware performance analysis and prediction. As such, these software models play a vital role in processor performance tuning as well as application-based competitive analysis, years before actual product availability. One of the key problems facing a designer, modeler, or application analyst who uses such a tool is to understand how accurate the model is, in terms of the actual design. In contrast to functional simulators, there is no direct way of testing timers in the classical sense, since the “correct” execution time (in cycles) of a program on the machine model under test is not directly known or computable from equations, truth tables, or other formal specifications. Ultimate validation (or invalidation) of such models can be achieved under actual hardware availability, by direct comparisons against measured performance. However, deferring validation solely to that stage would do little to achieve the overall purpose of accurate pre-hardware analysis, tuning, and projection. We describe a multilevel validation method which has been used successfully to transform evolving timers into highly accurate pre-hardware models. In this paper, we focus primarily on the following aspects of the methodology: a) establishment of cause-effect relationships in terms of model defects and the associated fault signatures; b) derivation of application-based test loop kernels to verify steady-state (periodic) behavior of pipeline flow, against analytically predicted signatures; and c) derivation of synthetic test cases to verify the “core” parameters characterizing the pipeline-level machine organization as implemented in the timer model. The basic tenets of the theory and its application are described in the context of an example processor, comparable in complexity to an advanced member of the PowerPC™ 6XX processor family.

Inhibin Concentrations Throughout the Menstrual Cycles of Normal, Infertile, and Older Women Compared With Those During Spontaneous Conception Cycles

LENTON, ELIZABETH A.; DE KRETSER, DAVID M.; WOODWARD, AMANDA J.; ROBERTSON, DAVID M. Author Information

Inhibin Concentrations throughout the Menstrual Cycles of Normal, Infertile, and Older Women Compared with Those during Spontaneous Conception Cycles

Plasma immunoreactive inhibin levels have been measured in a series of normal conception cycles (group I; n = 7), and the data compared to inhibin concentrations in normal menstrual cycles (group II; n = 8), in women with luteal phase defects (group III; n = 7), and in women in the perimenopausal period (group IV; n = 6). Daily plasma levels of LH, FSH, progesterone, estradiol, and inhibin were determined in each subject, and daily mean profiles for each hormone in each subject group were calculated and expressed as geometric means with 68% confidence limits. During the follicular and early luteal phases, inhibin concentrations in the normal nonpregnant group (group II) were significantly higher than those in the conception cycles of group I, but after implantation in the conception cycles, inhibin concentrations increased to levels in excess of those seen at any time in nonconception cycles (716-1352 U/L; P less than 0.02). The postimplantation rise in inhibin did not initially appear to follow the same pattern as progesterone. While progesterone concentrations rose within 24 h of the first detectable increase in hCG, inhibin levels did not increase until 3 days later, although after this point concentrations increased serially and in parallel with progesterone. LH and FSH concentrations were markedly suppressed after implantation. Follicular and early luteal inhibin concentrations in cycles with luteal phase defects were also higher than those in conception cycles, although this difference was only significant in the midfollicular phase. Follicular phase inhibin concentrations in cycles from older women (group IV) were lower than those in groups II and III, but were not distinguishable from those in the conception cycles. Estradiol concentrations in the same subjects were significantly lower during the early follicular phase, while follicular and luteal FSH concentrations were significantly higher than those during conception cycles. Finally, examination of the relationship between inhibin, FSH, and estradiol around menstruation in the older women revealed a far closer temporal association between FSH and estradiol than between FSH and inhibin. In conclusion, inhibin concentrations rise and fall throughout the human menstrual cycle in a manner that is similar to but at specific times significantly different from that of either of the ovarian steroids estradiol and progesterone. It is considered to be a peptide of granulosa cell origin and may be an indicator of the size of the follicular pool during the early stage of the cycle. However, although there is some degree of inverse correlation between profiles of inhibin and profiles of FSH, this relationship is not particularly clear.(ABSTRACT TRUNCATED AT 400 WORDS)

Replication of non-repetitive DNA during early, middle and late S phase: The general class and the subset transcribed

Synchronized cultures of Chinese hamster ovary cells were pulse-labelled with 5-bromodeoxyuridine (BrdU) during early (0–2.0 h), middle (2.5–4.0 h) and late (4.5–6.0 h) S phase in two successive cell cycles. In each case, the DNA containing BrdU in both strands was duplicated at the same time in both cycles and was isolated for further characterization by centrifugation in CsCl gradients. These DNAs were then radiolabelled by nick-translation and used in either DNA-DNA or RNA-DNA hybridization experiments. In the DNA-DNA experiments, advantage was taken of the substantial rate increases attainable in high concentrations of dextran sulfate to obtain complete reassociation curves with relatively small amounts of material. Assuming that no unresolved low repetition frequency components exist, renaturation kinetics suggest that early replicating DNA contains a greater proportion of non-repetitive sequences than DNA synthesized at later times, the order being early>middle>late. However, in terms of complexity the non-repeated DNA duplicated early had only 74% of the diverse sequences present in logphase cells, whereas that replicated in middle and late S phase had 82 and 79.5%, respectively. It therefore appears that while DNA synthesized at different times in S phase may contain varying proportions of non-repetitive sequences, when their diversity is taken into account very few of these sequences (25% or less) exhibit temporal control of replication. Finally, measurements with total cell RNA indicated that the transcribed fraction of non-repeated DNA showed a slight preference for replication in early S phase.

Autonomic blockade and sick sinus syndrome. New concept in the interpretation of electrophysiological and Holter data.

Autonomic blockade is commonly employed as a test of sinus node dysfunction. We compared primary and secondary atrial postpacing pauses and postextrasystolic sino-atrial responses before and after autonomic blockade in 56 patients with the clinical diagnosis of sick sinus syndrome. Pharmacological autonomic blockade was achieved by atropine 0.04 mg kg-1 and propranolol 0.2 mg kg-1, i.v. In a group of patients with a normal intrinsic heart rate the number of positive electrophysiologic variables associated with sinus node dysfunction declined after autonomic blockade. In 91% of these patients, sinus node function was characterized by a normal intrinsic recovery time, gradual exponential return to the constant sinus cycle length, and biphasic postextrasystolic return responses. Three patients in this group had intrinsic SA-block revealed by atrial pacing and verified by Holter monitoring. Besides normal intrinsic pacemaker properties in 53% of patients, rhythm monitoring revealed severe sinus node dysfunction as manifested by bradycardia and the tachycardia-bradycardia syndrome. SA-block and sinus arrest up to 29120 ms. In the abnormal intrinsic heart rate group, disturbed intrinsic rhythmicity was characterized in all by a prolonged corrected intrinsic recovery time (2320 +/- 2740 ms [+/- SD]), arrhythmia and/or bradycardia in the secondary postpacing cycles, chaotic postextrasystolic patterns, or prolonged sinoatrial conduction times. Significantly slow minimal heart rates during sleep significantly prolonged average sinus cycle lengths and positive ECGs for sinoatrial disorders in the waking period were present on the 24-h rhythm recording. It is concluded that intrinsic heart rate obtained by autonomic blockade is the best and most simple method for the diagnosis of intrinsic sinus node dysfunction. Combined autonomic blockade and electrophysiological tests can be of great value in unmasking the severity and degree of intrinsic dysfunction and analyzing the abnormality of secondary pacemaker function. These investigations, however, are rather insensitive and therefore ineffective in detecting autonomic sinus node dysfunction. To assess the role and significance of the autonomous neurovegetative tone in the genesis of sinoatrial disorders, rhythm monitoring is required.

Control of ovulation time in clomiphene-induced cycles

SummaryControl of ovulation time was attempted in clomiphene-induced cycles. Sixteen patients with anovulation were treated with clomiphene, 50–150 mg a day, and given a small dose of oestrogen in an attempt to regulate the time of ovulation. The clomiphene was started on day 5 of progestagen-induced uterine bleeding and continued for 5 days. Conjugated equine oestrogen, 0.1 mg, was given daily from days 9 to 14. Ovulation on days 14 to 16 of progestagen-induced bleeding was achieved. Treatment with clomiphene and oestrogen resulted in pregnancy in 6 of the 16 patients, who had all failed to conceive when treated with clomiphene alone. The results suggest that combination with oestrogen treatment is an effective means of controlling clomiphene ovulation time.

Short-term memory processes in text comprehension

Because of the limited capacity of the short-term, working memory system texts must be processed one sentences or major clause at a time in cycles. This cyclical processing strategy eliminates the limited capacity problem but creates a new one; namely: How does a reader maintain the coherence of a text which must be processed in fragments? Kintsch and van Dijk (1978) have suggested that part of short-term memory is set aside as a buffer in which propositions from earlier processing cycles are held over the guide the integration of new propositions into the long-term representation of the text as a whole. Two experiments are presented which provide empirical support for this claim. Using the kintsch and van Dijk (Psychological Review, 1978 , 85, 363–394) model to predict which propositions would be selected for inclusion in the short-term buffer, it was demonstrated that selected propositions are more available to subjects than unselected propositions from the same part of the text, and that the latter are no more availabe than unselected propositions from earlier in the text.

タマネギの光周反応に及ぼす交互照明の影響

The experiments were carried out to clarify the effect of cyclic lighting on the bulb formation and the interrelationship between light stimulus and darkness associated with photoperiodism, using the cultivars ‘Kaizuka-wase’, ‘Sensyu-ki’ and ‘Sapporo-ki’.The plants were started from seed and grown under short-day in greenhouse for 2 or 3 months prior to experimental use.During treatment periods the plants received 8 or 12hr of sunlight followed by intermittent lighting (500lx) in light-dark cycle with incandescent lamp during long dark period. Intermittent light were applied for 50, 33.33 and 25% of time in light-dark cycles of various lengths.The shorter the cycles became, the more the bulb formation was induced. Moreover, it was found that relationship between the bulb formation and the logarithm of length of cycle was inversely proportional. The 15-15 light-dark cycle (min) was as effective as continuous light except for ‘Sapporo-ki’ when light applied for 50% of time in the cycles.When 1 sec lighting followed by various lengths of darkness, the dark duration less than 3 sec promoted the bulb formation as well as continuous light, whereas those of the dark duration more than 5 sec decreased with length of darkness.From above mentioned results, we made the assumption that the ratio of the duration of light stimulus in darkness to the duration of light applied was inversely proportional to the logarithm of duration of light. With this assumption, the expected values obtained by cyclic lighting were in satisfactory agreement with the observed values.

Studies on the bulb formation in onion plants

This experiment was carried out to ascertain the photo-environmental factors except light quality on bulb formation of onion plants using cultivar Kaizuka-wase. Plants were grown under short-day condition until the start of the treatment.1. Plants were shaded to reduce the daylight of natural day-length (astronomical day-length 14h 20 m-14h 30m). One group was grown in full sunlight, two others under one layer of white or black cheesecloth, and the 4th under two layers of black cheesecloth. Those admitted 100, 70-75, 30-40 or 10-20 per cent of the full light respectively.Not only their bulb formation was retarded by 10-20 per cent of full light, but also failed to bulb by 30-40 per cent of light. Moreover, by 10-20 per cent of light, the symptoms of long-day induction did not appear in the pore of innermost leaf (Table 1).2. Plants were exposed to the reduced sunlight for 8 hours, followed by suppelementary incandescent light of about 2000 lux for 16 hours. Plants grown in full sunlight had the highest bulbing-ratio, followed by plants grown under 70-75, 30-40 and 10-20 per cent of full sunlight, the plants that received the lowest intensity, also, developed their bulb (Table 1).3. Plants were exposed to full sunlight for 8 hours and followed by incandescent light of about 2000, 750 or 240 lux for 16 hours. The higher the supplementary lighting became, the higher the bulbing-ratio became, and even under the lowest intensity their bulb well developed (Table 1).4. Onion plants were exposed to 16-, 20- and 24-hours day-length (sunlight of 8 hours, followed by supplementary incandescent light) for 10, 12 or 15 days and then followed by 8 hours day-length. Measurements were made at 20, 22 and 25 days after the beginning of long-day exposure.When total duration of light given during long-day was ′240 hours′ as follows: 24 hrs-10 days, 20 hrs-12 days and 16 hrs-15 days, at same duration after the beginning of long-day, the longer the day-length became, the more the bulb developed, in spite of same duration of given light.But, at same duration after the beginning of short-day or at 10 days after the beginning of short-day exposure, such as 20, 22 and 25 days after the beginning of long-day exposure for 24, 20 and 16 hours day-length respectively, there was no difference between the reciprocity (day-length times duration of long-day) (Fig. 1).5. Plants were given 8 hours of sunlight and 16 hours of darkness, the dark periods being interrupted with incandescent light of 1000 lux at different times after the beginning of dark period for 8 hours. Plants interrupted at 2 hours after the beginning of dark period had the highest value of bulbing-ratio, on the contrary, plants interrupted at 4 hours (middle of night) had the lowest value (Fig. 2).6. Plants were given 8 hours of sunlight and 16 hours of darkness, the dark periods being interrupted with incandescent light of 1000 lux for 50 per cent of the time in light-dark cycles of various lengths. Plants received additional light of 16 hours served as 24 hours day-length control.The light-dark cycles are as follows: 30-32, 60-16, 120-8, 240-4, 480-2 and 960-1 (length of one light-dark cycle, in minutes-number of cycles) In secondary experiment, plants were given 12 hours each of light and darkness, the light-dark cycles are as follows: 30-24, 60-12, 90-8, 120-6, 180-4, 240-3, 360-2 and 720-1.The shorter the cycles became, or the more the number of cycle became, the more the bulb formation was induced, besides, it was found that relation between length of cycles or number of cycle and bulb formation was linear logarithmic (Fig. 3 and Fig. 4).